INTERIM REPORT
WITH OPERATIONAL DATA
|JOI iCT
JOHNSON CITY, TENNESSEE
June 1967--September 1969
U.S. ENVIRONMENTAL PROTECTION AGENCY
1972
-------
INTERIM REPORT
WITH OPERATIONAL DATA
JOINT USPHS-TVA COMPOSTING PROJECT
JOHNSON CITY, TENNESSEE
June 1967September 1969
This open-file report (SW-31r.l.of)
was written by G. E. STONE and C. C. WILES
under the direction of C. A. CLEMONS
U.S. ENVIRONMENTAL PROTECTION AGENCY
1972
-------
PREFACE
The completion of this report was made possible by the cooperation
of many individuals, two Federal agencies, and a municipality.
The Tennessee Valley Authority (TVA) must be credited with the fore-
sight to develop a composting system in a part of the country where the
soil would benefit from the compost produced by a successful composting
facility. The design and operation of the facility has been the sole
responsibility of TVA. 0. M. Derryberry, F. E. Gartrell, 0. W. Kochtitzky,
W. K. Seaman, Jack Taylor, Carroll Duggan, and Virgil Rader are just a
few of the TVA people participating. David Burkhalter and James Hosier,
as city managers, have been responsible for implementing the needed coop-
eration from the Johnson City municipality.
John S. Wiley, well known for his pilot research on composting, served
as Research Director until his retirement on July 1, 1968. Gordon E. Stone
became Project Engineer in July 1967. Fred J. Stutzenbergeir, staff micro-
biologist; Donald J. Dunsmore, staff sanitary engineer; and Richard D.
Lossin, staff chemist, performed the majority of the tests and studies
reported. Some of the assay work was performed by personnel of the Research
Services Laboratory in Cincinnati, Ohio. W. L. Gaby and his staff at East
Tennessee State University worked closely with project personnel in deter-
mining that compost was safe, under study conditions, for agricultural
iii
-------
use. (Mrs.) Mirdza L. Peterson, research microbiologist, served as the
contract officer for a portion of these studies. (Mrs.) Marie T. Presnell,
serving as administrative assistant, has been a key person in assuring
the continued smooth operation of the project. The chief Cincinnati-
based managers have been Harry Stierli and Charles G. Gunnerson.
Andrew W. Breidenbach provided the general direction for the entire
project.
iv
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SUMMARY
The Joint USPHS-TVA Composting Project began operation in June 1967.
The purposes were to provide the then Bureau of Solid Waste Management*with
more comprehensive knowledge about windrow composting as a solid waste
management tool and permit better assessment of available information
about this subject. Results of investigations and operational experiences
obtained from the project during the period June 1967 to September 1969,
are discussed in this report.
During the period, the plant processed an average of 34 tons of raw
refuse per processing day received from a population of 31,200. Approxi-
mately 27 percent of the incoming refuse was rejected as noncompostable
and returned to the city's landfill for disposal. The yield of unscreened
compost was about 50 percent of the incoming refuse (wet weight basis) but
trouble with the equipment for grinding compost hindered the production
of an acceptable grade.
Investigations of the potential hazard to health from pathogenic
organisms in compost showed that windrow temperatures of 122 to 130 F
maintained for at least 7 days destroyed pathogens expected in refuse
and those known to be in sewage sludge. Time-temperature studies showed
that windrow temperatures at the 1-1/2-ft depth averaged above 140 F
for 2 to 3 weeks or more.
Sewage sludge, cow manure, paunch manure, aged poultry manure, animal
blood, and pepper canning wastes in varying amounts were all successfully
AThe Federal solid waste management effort is now part of various
components of the U.S. Environmental Protection Agency.
-------
composted with the refuse. In the amounts used they did not greatly
affect the composting process or the product. The addition of urea-
ammonium nitrate appeared to''inhibit microbial activity and resulted in
a loss of nitrogen in the product. Although limestone added to the refuse
appeared to aid the composting process, it also caused a loss of nitrogen
and resulted in a poorer product.
Total construction costs, including costs of modifications made during
the period, were $958,375. Actual cost for operating the plant during
1968, at a level less than capacity, was $18.45 per ton of refuse processed.
Projected to full capacity, the operating cost in 1969, was $13.40 per ton
of refuse processed.
Because production of an acceptable grade of compost was delayed,
agricultural testing of the compost is only in preliminary stages. There-
fore, insufficient data are available to assess the agricultural value of
the compost produced.
vi
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CONTENTS
INTRODUCTION 1
Johnson City, Tennessee 3
Location, Climate, Population, Etc 3
Composition of the Municipal Refuse 12
USPHS-TVA Composting Project 12
Description of the Project 12
Description of the Composting Plant 16
Construction Costs 37
Modifications Made Since Startup 37
Staffing 42
Operations and Processes 44
Operating Schedules 44
Production 45
Receiving 47
Grinding 51
Addition of Sewage Sludge 57
Handling and Storage 60
Windrow Maintenance 61
Curing and Drying 63
Screening and Grinding 64
Fly Control 65
Removal of Plastics and Glass 68
Project Studies and Investigations 69
Composting Process Studies 69
Temperature Studies 69
Effect of Windrow Turning Frequency 83
Effect of Composting Sewage Sludge With Refuse .... 84
Effect of Adding a Nitrogen Compound to Composting
Refuse 96
Effect of Adding a Buffering Agent to Composting
Refuse 101
Effect of Composting Other Wastes With Refuse 109
Effect of Covering a Windrow With Plastic Sheeting . . 118
Effect of Covering Windrows With Old Compost 121
pH Observations 123
VII
-------
Microbiological and Fly Population Studies 123
Bacteriological Statistical Experiments . . 123
Survival of Mycobacteriwn phlei 127
Pathogen Survival Studies Under Contract 128
Cellulolytic Activity in Composting 140
Fly Population Counts 142
Chemical and Physical Characteristics 145
Sampling Techniques 145
Moisture Content of Raw Refuse 147
Weight and Volume Losses in Composting 148
Elemental Composition of Compost 149
Analyses for Carbon/Nitrogen Ratios 149
Analyses for Chemical Oxygen Demand 154
Cellulose, Starch, and Sugar Content 157
Calorific Value of Refuse and Compost 157
Cost Studies 157
Capital Cost 160
Operating Cost 160
Labor Cost 165
Cost Data Projected to Other Plants 165
Plant Income 172
Demonstration and Utilization ; 172
REFERENCES 181
TABLES
1 Meteorological Data for Johnson City Area 6
2 Meteorological Data for Johnson City Area
Normals, Means, and Extremes 7
3 Municipal Refuse Production 13
4 Composition of Refuse 14
5 Description of Machinery and Equipment
USPHS-TVA Composting Project, Johnson City 20
6 Processing Data for January 1968 Through June 1969 46
7 Performance of Receiving Machinery 50
viii
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8 Average Performance of Rasper 52
9 Compost Fortified With Nitrogen 99
10 Compost Fortified With Nitrogen 102
11 Mycobacterium Survival in Compost 129
12 Adult Fly Counts With Scudder Grill - 1967 143
13 Fly Population Data 144
14 Elements in Finished Compost 150
15 Concentration of Certain Trace Elements in
Screened Compost 151
16 Nitrogen Content of Some Organic Materials and Soil .... 152
17 Carbon/Nitrogen Ratios of Compost Containing
Additives 156
18 Construction Costs for the USPHS-TVA Windrow
Composting Plant 161
19 Yearly Investment Costs for the USPHS-TVA
Windrow Composting Plant 162
20 Actual Cost of Operations for the USPHS-TVA
Composting Plant 163
21 Actual Annual Costs of Operating the USPHS-TVA
Plant Projected to Full Capacity 164
22 Summary of Actual Costs for the USPHS-TVA
Composting Plant, Johnson City, Tennessee 166
23 Salaries of TVA Personnel 167
24 Estimated Capital Costs for Windrow Composting
Plants 168
25 Estimated Investment Costs for Windrow Composting
Plants . 169
26 Estimated Yearly Operating Costs for Various
Capacity Windrow Composting Plants 170
27 Summary of Estimated Capital, Operating and Total
Costs for Various Size Windrow Composting Plants ..... 171
28 USPHS-TVA Plant Construction Costs Projected to
a 50-Ton Per Day Plant 173
29 USPHS-TVA Plant Construction Costs Projected to
a 100-Ton Per Day Plant . . 174
30 USPHS-TVA Plant Annual Operating Costs Projected
to a 50-Ton Per Day Plant 175
31 USPHS-TVA Plant Annual Operating Costs Projected
to a 100-Ton Per Day Plant 176
32 USPHS-TVA Plant Annual Operating Costs Projected
to a 100-Ton Per Day Plant 177
33 USPHS-TVA Plant Annual Operating Costs Projected
to a 200-Ton Per Day Plant 178
IX
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FIGURES
1 Map of the Johnson City-Kingsport-Bristol,
Tennessee Area 4
2 Average High and Low Temperatures Recorded at the
Plant for the Period August 1967-July 1969 8
3 Monthly Precipitation Recorded at the Plant for the
Period August 1967-July 1969 9
4 Map of Johnson City, Tennessee Showing the Location
of the Compost Plant 10
5 Joint USPHS-TVA Composting Project, Johnson City,
Tennessee 18
6 Process Flow Diagram 19
7 Receiving Building With a 65 Cubic Yards Compaction
Trailer Discharging Refuse 24
8 The Hopper in the Receiving Building 25
9 Receiving Building on the Left and Processing
Building on the Right 26
10 The Picking Station Inside the Processing Building 27
11 The Hammermill Used to Shred or Grind Refuse 29
12 The Dorr-Oliver Rasper 30
13 The Permutit Dual Cell Gravity Sludge Concentrator
Used to Dewater Sewage Sludge 32
14 The Cylindrical Mixer for Intimately Mixing Dewatered
Sewage Sludge With the Ground or Shredded Refuse 34
15 A Windrow of Ground or Shredded Refuse 35
16 The Windrow Turning Machine 36
17 The Storing and Curing Shed (left) and Processing
Building (right) 38
18 The Final Screening and Grinding Equipment 39
19 Quantity of Refuse Received at the USPHS-TVA
Composting Project by Seasons 48
20 Average Temperatures at the 1-1/2-ft Depth in
Windrows 1 Thru 44 70
21 Average Temperature at the 1-1/2-ft Depth in
Windrows 1A Thru 34A 71
22 Average Temperatures at the 1-1/2-ft Depth in
Windrows IB Thru 34B 72
23 Average Temperatures at the 1-1/2-ft Depth in
Windrows 1C Thru 34C 73
24 Average Temperatures at the 1-1/2-ft Depth of
Six Selected Windrows 74
25 Temperature Profiles of a Selected Windrow During
the First 11 Days of Composting 76
26 Continuous Temperature Record of Windrow 17E,
22nd to 28th Day (Station 1) 77
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27 Continuous Temperature Record of Windrow 17E,
22nd to 28th Day (Station 2) 78
28 Temperature Profile of Windrow 17E 79
29 Temperature Profile of Windrow 17H 80
30 Temperature Profiles at the 8" Depth of Windrow
17H (Nov. 4, 1968-Dec. 30, 1968) 82
31 Temperatures in Windrows With 2 Percent Sludge
Solids (1-1/2-ft Depth) 86
32 Temperatures in Windrows With 3-5 Percent Sludge
Solids (1-1/2-ft Depth) 87
33 Temperatures in Windrows With 9 Percent Sludge
Solids (1-1/2-ft Depth) 88
34 pH of Windrows With 2 Percent Sludge Solids
(1-1/2-ft Depth) 89
35 Average pH of Windrows With 3-5 Percent Raw
Sludge Solids (1-1/2-ft Depth) 90
36 pH of Windrows With 9 Percent Sludge Solids
(1-1/2-ft Depth) 91
37 Temperatures of a Windrow With 34 Percent Sludge
Solids (1-1/2-ft Depth) . . 94
38 pH of a Windrow With 34 Percent Sludge Solids
(1-1/2-ft Depth) 95
39 Temperature and pH of a Windrow Containing 50
Percent Sludge Solids (1-1/2-ft Depth) 97
40 Temperature of Windrows Containing Urea-Ammonium
Nitrate 100
41 Temperature of Windrows With Urea-Ammonium Nitrate 103
42 Temperatures of Windrows With Limestone and Sludge
Added . . ' 105
43 pH of Windrow With Limestone and Sludge Added 106
44 Temperature of Windrow With Limestone Dust Added ...... 107
45 pH of Windrow With Limestone Dust Added 108
46 Temperature and pH of Refuse Composted With
Cow Manure Ill
47 Temperature of Refuse Composted With Paunch Manure ...... 112
48 pH of Refuse Composted With Aged Chicken Manure 114
49 Temperature and pH of Refuse Composted With Fresh
Chicken Manure 116
50 Temperature of Refuse Composted With Slaughterhouse
Blood 117
51 Temperature of Sludge-Refuse Mixture Composted
With Pepper Canning Wastes 119
52 pH of Sludge-Refuse Mixture Composted With
Pepper Canning Wastes 120
53 Average pH of Windrows 1A Thru 34A (1-1/2-ft
Depth) . 124
54 Average Carbon to Nitrogen Ratio of 24 Windrows
Containing 3-5 Percent Sewage Sludge 153
XI
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55 Carbon to Nitrogen Ratio of a Windrow Without
Sewage Sludge 155
56 Chemical Oxygen Demand of Composting Refuse 158
57 Sugar, Starch, and Cellulose Content of Composting
Refuse 159
APPENDICES
Appendix I 183
Methods Used for Chemical Analyses . 183
Appendix II 196
Statement of Operations
Division of Reservoir Properties - . 196
Appendix III . . . . 203
Preliminary Results of Agricultural Research
on Compost 203
Table 1 '. 207
Table 2 209
Table 3 . . . . 212
xii
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INTERIM REPORT
JOINT USPHS-TVA COMPOSTING PROJECT, JOHNSON CITY, TENNESSEE
June 1967 - September 1969
INTRODUCTION
The natural phenomenon of the degradation of wastes by microbiological
activity has been utilized by agriculturists for centuries to produce humus.
In modern times the stress upon the environment caused by wastes and the
need to replenish the organic constituents removed from soils by intensive
farming have created an interest in large-scale composting.*
In Europe, large-scale composting has received attention because of
its possibilities for supplying organic material for the soil and a
considerable number of plants have been operated successfully over the last
twenty-five years. In America, where there has been a different attitude
toward the conservation of resources and where the need for the replenish-
ment of organics in the soil has been less acute, composting has only
recently received attention, and here the greatest emphasis has been on its
use as a method of waste disposal.1
In the United States, the University of California studied the com-
posting of municipal wastes from 1950 to 1952.2 One conclusion of this
study was that composting offered an alternative method of refuse disposal
that would help alleviate the growing difficulty of finding landfill sites
*Mention of commercial products or processes throughout this report
does not imply endorsement by the U.S. Government.
-------
and problems of air pollution that result from incineration. However,
Wiley and Kochtitsky concluded that the inability to dispose of large
quantities of compost at a favorable price was probably a major factor
in the closing of six of nine plants during the period 1962 to 1964.3
In addition to a lack of marketing knowledge, there was a dearth of reli-
able cost data. Certain environmental and public health aspects also re-
quired study in the United States.
In the early 1960's, F. E. Gartrell of the Tennessee Valley Authority
(TVA) proposed a full-scale composting project to be jointly sponsored by
TVA, the U.S. Public Health Service (USPHS), and a municipality in the
Tennessee Valley. Both USPHS and TVA were interested in a sanitary method
of waste disposal and TVA was also interested in the use of compost for
soil improvement. In March 1963, the Division of Agricultural Development,
TVA initiated a project called "The Use of Municipal and Industrial Organic
Waste in the Production of Soil Amendments and Fertilizers." The compost
plant was to investigate the process as a method for disposing of wastes
and at the same time reclaiming waste for the benefit of the land.
In August 1964, the USPHS and the TVA agreed upon a joint research
and demonstration project for composting solid wastes and sewage sludge.
In November 1964, USPHS detailed John S. Wiley to the Division of Health
and Safety, (now the Office of Health and Environmental Science) TVA, to
collaborate in the detailed planning of the project. Under the agreement,
TVA would have financed and constructed the composting plant. When the
Solid Waste Disposal Act was passed in October 1965, the Bureau of Budget
directed that the proposed plant be financed from funds available under
-------
the terms of the Act to the Department of Health, Education, and Welfare.
Johnson City had been selected as the site for the composting project on
the basis of two surveys of six Tennessee Valley area cities. One survey,
conducted by TVA engineers and representatives of state and local health
departments, covered disposal of refuse and sewage sludge. The other,
made by TVA agricultural specialist, investigated the use of chemical and
organic fertilizers in the vicinity of these cities. On February 15, 1966,
the two agencies and Johnson City, Tennessee, signed a cooperative agree-
ment for the construction and operation of the "Joint USPHS-TVA Composting
Project, Johnson City, Tennessee." Ground was broken for the plant on
May 18, 1966; construction was completed and the plant was put in operation
on June 20, 1967.
Johnson City, Tennessee
Location, Climate, Population, Etc. Johnson City, in Washington County,
is in the extreme northeastern corner of Tennessee at longitude 82° 21' W.,
latitude 36° 19' N. (Figure 1). It lies near the junction of the Watauga
River and the South Fork Holston River in the headwaters of the Tennessee
River system. The terrain immediately surrounding the city ranges from
gently rolling on the east and south to very hilly on the west and north.
Mountain ranges begin about 5 miles to the southeast and about 20 miles to
the west and north, with many peaks rising to 4,000 and some to 6,000 ft
above sea level toward the southeast in the Appalachian system. Elevations
in the city range from 1,500 to over 1,700 ft.
The Johnson City area does not lie directly within any of the principal
storm tracks that cross the country, but comes under the influence of
-------
r
'"Rogersville
,./
VIRGINIA
""" /TEN~E"SSEE
HAWK.NS /' °NGSPORT
y A
f s \
GREENE
o
Greenevi
f
SULLIVAN
V Elizabethtont
JOHNSON CITY / O
I o
f Jonesboro
{WASHINGTON x
/WASHINGTO^X \ x
\XUNICOI/C>^OV
^Tx^
CARTER
TEMNESSEE
10 15
1 1
Miles
Figure 1. Map of the Johnson City-Kingsport-Bristol, Tennessee area.
4
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storm centers that pass along the Gulf Coast and then up the Atlantic
Coast toward the northeast. Table 1 gives meteorological data for the
calendar years 1967 and 1968, for the Bristol, Tennessee, station of the
U.S. Weather Bureau at the Tri-City Airport, 9 miles northwest of the
USPHS-TVA Composting Project plant. Table 2 gives the normals, means, and
extremes for this station. Since August 1967, temperature and rainfall
records have been kept at the composting plant. Figure 2 shows the recorded
high and low temperatures for the months through July 1969. Figure 3 shows
the monthly rainfall recorded at the plant over the same period.
Johnson City, with an area of 15 square miles (Figure 4), had in 1969,
an estimated population of 35,300. The city and county had an estimated
population of 68,500. The trading area had an estimated population of
180,000 and the area within a 50-mile radius had an estimated population
of 635,000.
The average income per family in Johnson City was $8,482 in 1968.
About 36 percent are employed in manufacturing, the remainder in trade,
finance, government, transportation, service jobs, etc. In the rural
area, about 28 percent occupy farms. Of this population, 30 percent
are engaged in manufacturing. Washington County has about 3,000 farms,
averaging 55 acres each.
Tobacco is the most important crop of the area. Corn and some small
grains are grown in support of the important dairy industry. Raising of
beef cattle has increased in the last 20 years to become a significant
part of the economy.
In the seven counties of the area, there are about 320,600 acres of
cropland and 281,800 acres of pasture.
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TABLE 1
METEOROLOGICAL DATA FOR JOHNSON CITY AREA
Tri-City Airport (Bristol, Tennessee, Station), latitude 36° 29' No, longitude 82° 2Ur W., ground elevation
feet above sea level.
196?
Month
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
YEAR
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NUV
utc
YEAR
Temperature
Averages
I
\
11
48.6
43.5
63.8
71.2
69.4
80.3
79.4
81.4
76.6
69.3
53.5
51.3
65.7
43. u
41.1
60.4
67.2
72.5
62.7
87.7
86.5
80.4
69.6
55.5
46.3
66.1
a
!>. S
a ~t
a 1
27.8
23.9
36.5
44.2
46.0
57.4
60.1
60.0
48.6
42.9
31.8
30.2
42.6
23.3
19.1
33.4
44.3
50.0
58.8
63.9
64.5
53.7
45.6
34.8
24.1
43.0
^
i
1
38.2
33.7
50.2
57.7
56.7
66.9
69.6
70.7
62.6
56.1
42.7
40.6
54.2
33.2
30.1
46.9
55.8
61.3
70.8
75.8
75.5
67.1
57.6
45.2
35.2
54.6
Extremes
1
1
72
67
79
81
85
68
87
87
87
80
73
71
88
62
64
60
62
35
93
94
94
87
83
75
65
94
1
26
1
27+
16
27
17
24
3
20
16+
11
21
JUN.
17
31
1
21
20
24
30
21 +
23+
24+
13*
2 +
19
AUG.
23 +
8)
j
14
- 1
15
30
36
48
48
51
34
27
17
14
- 1
1
4
18
31
35
47
55
48
44
27
17
6
1
fl)
i
12
25
18
29
10
2+
5
14
30
29
29
24
FEB.
25
8
22
14+
16 +
7+
1
5
30+
13
30
21
16
JAN.
6
.
3 .
jj
1
621
868
455
218
216
29
12
2
107
271
662
745
4406
979
1U04
553
276
137
1
0
4
19
245
590
920
4728
Precipitation
1
2.00
4.14
3.02
2.80
6.29
2.14
4.87
3.66
2.59
1.99
3.73
5.62
42.87
3.58
0.75
4.95
4.12
3.83
2.69
2.89
2*32
0.93
2.51
1.39
2.13
32.79
S
B
S jj
S J=
6 s
0.75
1.47
1.11
1.26
1.26
0.88
2.06
1.15
1.29
0.62
1.03
1.73
2.06
U.95
0.45
1.54
1.49
0.93
0.87
1.40
0.99
0.46
1.12
0.78
0.77
1.54
S
S
27
17
6-7
26
14-15
31-1
28-29
22
28
25
1-2
18-19
JUL.
28-29
3-4
23-29
9-10
23-24
26-27
7-8
31
10-11
9-10
18-19
6-7
22
MAR.
9-10
Snow, Sleet
1
4.6
4.8
T
0.0
0.0
0.0
0.0
0.0
0.0
0.0
T
4.1
13.5
12.1
6.3
1.0
0.0
0.0
U.O
0.0
0.0
0.0
T
2.9
l.u
23.3
S
"m
1 j
o S
4.0
3.1
T
0.0
0.0
0.0
0.0
0.0
0.0
0.0
T
2.6
4.0
4.5
4.8
3.2
0.0
0.0
0.0
0.0
0.0
0.0
T
1.4
1.0
4.6
o>
&
19
7
20 +
29 +
28
JAN.
19
!3-24
29
29-1
29 +
11-12
14-15
FEB.
29
Relative
humidity
1
AM
7
AH
1
PM
7
PM
Standard
time used:
EASTERN
82
76
74
68
94
91
95
93
92
66
79
85
85
86
79
81
78
94
93
96
94
95
95
65
89
89
63
62
48
46
67
60
69
68
56
55
53
70
60
66
63
52
51
70
68
75
77
71
64
60
74
66
1968
78
58
71
78
82
87
87
**7
84
79
78
70
78
81
66
79
86
88
90
90
92
89
84
82
73
83
65
43
.6
55
60
56
53
58
49
51
56
52
54
68
42
52
55
67
64
67
69
62
60
65
56
61
Wind -
Resultant
c
g
i
25
27
27
28
28
07
26
36
03
24
27
33
28
01
28
27
28
27
30
01
34
03
33
28
26
29
"8
I
2.6
4.4
2.1
3 0
1.6
1.3
1.5.
0.4
1.0
0.7
3.4
0.9
1.5
0.9
4.7
3.5
1.4
1.9
1.0
0.7
0.8
0.9
0.7
2.3
3.7
1.6
1
0.
s
1
5.4
7.2
6.6
7.3
6.2
5.7
5.1
3.9
3.6
4.5
6.0
5.1
5.6
5.7
7.2
6.7
5.6
5.2
4.6
4.1
3.5
3.7
5.0
5.9
7.4
5.4
Fastest mile
«
28
30
35
32
16
21
15
29
18
25
25
35
24
21
32
35
24
31
26
17
16
17
29
40
40
g
i>
&
24
30
25
29
31
26
27
31
25
31
27
25
10
30
24
23
30
31
30
28
29
23
30
24
24
S
S
27
16
7
17+
8
18
29
10
21
25+
22
12 +
MAR.
7
13
21 +
22
4
1
11
2
10+
10+
28 +
19
28
DEC.
28
1
"o o
II
ll
h
II
i
1 1
.6
.9
.8
.4
.7
7.6
6.7
4.4
5.1
5.4
7.0
6.2
7.1
5.7
6.2
6.6
7.0
6.3
6.7
5.9
5.7
5.8
8.1
7.2
6.5
Number of days
Sunrise to sunset
U
6
6
11
6
7
2
4
16
10
11
6
94
6
8
6
7
3
8
5
8
8
9
2
5
75
j* v
II
9
6
6
4
13
11-
12
7
13
10
7
112
6
11
11
7
11
8
11
12
10
8
8
10
113
13
&
16
16
14
21
10
18
15
7
8
9
18
159
19
10
14
16
17
14
15
11
12
14
20
16
178
S
o
C B
O B
a 5
~ x
0, 0
11
B
11
8
17
10
17
11
5
7
11
13
125
13
5
11
16
15
12
11
10
6
11
12
9
133
£
1 I
W j-
Is
1
2
0
0
0
0
0
0
0
0
2
5
4
2
0
0
0
0
0
0
0
u
1
0
7
1
2
o
c
3
0
0
3
11
5
7
4
1
0
2
1
36
0
0
3
4
8
6
11
8
3
2
0
0
45
S
r
1
9
1
1
0
5
2
5
8
4
10
1
4
50
4
0
2
4
6
8
10
8
4
4
5
2
57
Temperatures
Maximum
*o
d o
" a
8J5
nl
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2
11
12
0
0
0
0
25
^ *
o
c? "Si
Co JJ
1
3
0
0
0
0
0
0
0
0
0
3
7
6
7
1
0
0
0
0
0
0
0
0
4
18
Minimum
1 *
O
a 2
22
21
14
2
0
0
0
0
0
6
16
20
101
26
27
17
2
0
0
0
0
0
4
14
26
116
"S *
fl
0
1
0
0
0
0
0
0
o
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
Unless otherwise Indicated, dimensional units used In this bulletin are: temperature In degrees F.;
precipitation. Including snowfall, In Inches; wind movement In miles per hour; and relative humidity
In percent. Degree day totals are the sums of the negative departures of average dally temperatures
from 65' F. Sleet was Included In snowfall totals beginning with July 1946. Heavy fog reduces visibility
to 1/4 mile or less.
Sky cover Is expressed In a range of 0 for no clouds or obscuring phenomena to 10 for complete sky
cover. The number of clear days Is based on average cloudiness 0-3: partly cloudy days 4-7- and
cloudy daya 8-10 tenths.
ln»te"d ?! !««« In direction column Indicate direction In tens of degrees from true North;
'i 2?"El8tl 18:South- 27-we«, 36-North, and 00-Calm. Resultant wind Is the vector sum of
wind directions and speeds divided by the number of observatlona. If figures appear In the direction
column under "Fastest mile" the corresponding speeds are fastest observed 1-minute values.
-------
WBLE
METEOROLOGICAL DATA FOR JOHNSON CITY AREA
NORMALS, MEANS, AND EXTREMES
Tri-City Airport (Bristol, Tennessee, Station), latitude 36° 25" No, longitude 82° 2ii' W., ground elevation
feet above sea level.
f
1
(a)
J
F
H
A
H
J
J
A
S
0
N
0
YR
Temperature
Normal
e
>. .5
1 1
(b)
46.8
50.0
56.5
66.2
77.6
84.5
86.4
85.4
80.6
70.1
56.7
47.1
67.5
E
>. 1
11
(b)
29.7
30.0
35.5
44.9
53.7
61.9
65.4
64.1
57.5
45.9
35.1
29.5
46.1
^
3
1
(b)
38.3
40.0
46.0
56.6
65.7
73.2
75.9
74.8
69.1
58.0
45.9
36.3
56.8
Extremes 0
'S g
KJZ
7
72
76
81
85
92
95
94
95
92
84
80
73
95
S
1967
1965
1963
1963
1962
1966+
1963
1965
1965+
1964+
1961
1966
JUN.
1966+
58
oc.2
7
-15
- 4
12
21
30
38
48
48
34
20
15
- 9
-15
1
1966
1965
1965
1964
1963
1966
1967 +
1968
1967
1962
1964
1962
JAN.
1966
S.
a
8
5?
-o
*
g
1
(b)
828
700
598
261
68
0
0
0
51
236
573
828
4143
Precipitation
1
1
o
Z
Kb)
3.69
3.56
3.98
3.16
3.45
3.38
5.55
3.80
2.62
2.15
2.51
3.21
41.06
1 »-
g 1
X C
i I
23
9.18
7.29
9.56
5.59
9.71
6.68
9.73
7.07
6.19
5.65
5.90
6.75
9.73
1
1957
1956
1955
1949
1950
1957
1949
1966
1962
1959
1948
1961
JUL.
1949
1 *
1 -
i i
1.85
0.75
1.33
1.38
1.31
1.14
0.79
0.82
0.93
0.07
1.07
0.21
0.07
o
1955
1968
1957
1963
1966
1964
1957
1954
1968
1963
1953
1965
OCT.
1963
I a
is s
s .s
2.34
1.87
3.10
2.32
2.44
3.10
2.90
2.50
2.95
3.65
2.55
2.03
3.65
1
1950
1954
1963
1956
1958
1954
1946
1963
1962
1964
1957
1958
OCT.
1964
Snow, Sleet
3
c
1
31
4.9
3.8
2.7
T
T
0.0
0.0
0.0
0.0
T
1.4
2.7
15.5
S ^
I 5
X C
a o
2 B
22.1
17.2
27.9
0.6
T
0.0
0.0
0.0
0.0
T
18.1
12.9
27.9
1
1966
1947
1960
1962
1963
1968+
1952
1963
MAR.
1960
1 1
1 £
x £5
IS -
25
9.7
9.7
13.0
0.6
T
0.0
0.0
0.0
0.0
T
16.2
7.5
16.2
1
1955
1958
1960
1962
1963
1968+
1952
1963
NOV.
1952
Relative
humidity
1
AH
7
AH
1
PM
7
PM
Standard
time used :
EASTERN
76
71
70
73
85
66
88
88
85
81
79
78
80
80
76
77
82
90
90
91
91
89
87
84
80
85
61
57
51
51
57
57
61
61
54
51
57
62
57
65
59
55
53
62
63
67
69
66
60
65
67
63
Wind
|
11
6.5
7.0
7.5
7.3
5.3
4.6
4.1
3.9
4.5
4.7
5.8
5.9
5.6
OI
c z.
'a '?.
\l
£5
WSW
NE
WNW
WSW
WSW
NE
WSW
NE
NE
NE
W
WSW
WSW
Fastest mile
w
1 3
40
46
40
40
50
31
40
46
29
35
35
40
50
e
B
s
1 3
25
25
25
23
32
31
23
34
31
28
29
24
32
1
1965+
1961
1952
1961
1951
1966
1961 +
1962
1967
1965
1965
1968 +
MAY '
1951
, o
So
c.3
Sg
S3
20
7.1
6.9
6.7
6.5
6.2
6.0
6.4
5.9
5.3
4.8
6.2
6.8
6.2
Mean number of days
Sunrise
to
u
re
0
31
6
6
7
7
6
6
5
7
11
13
9
7
90
unse
9-S*
II
31
7
7
7
9
12
12
13
14
9
e
7
7
112
o
1
U
31
18
15
17
14
13
12
13
10
10
10
14
17
163
0)
o
.2 g
f-5
ll
23
14
12
13
12
11
10
12
11
7
8
11
11
132
S
c
*1
II
2
1
0
0
0
0
0
0
0
1
5
a,
n
0
E
S
1
25
*
1
2
4
7
9
10
8
4
1
»
*
46
?
>.
1
25
3
3
1
1
3
3
5
7
4
5
3
3
42
Tempe
Mav
ax.
D
-SJ
7
0
0
0
0
1
4
4
3
2
0
0
0
15
1*
. J
7
5
3
*
0
0
0
0
0
0
0
*
4
13
ratures
Min
mm.
B*
, J2
7
25
21
14
3
0
0
0
0
4
12
23
101
|
J5
o
c
O
7
1
*
0
0
0
0
0
0
0
0
0
ft
2
0 For period Hay 1961 through the current year.
Maaos and extremes In the above table are from the existing or comparable location(s). Annual extremes have been exceeded at other locations as follows:
Highest temperature 102 in July 1952.
() Length of record, year a,
(b) Cllmitologlcil mndard normals (1931-1960).
* Leoa than one half.
+ Also on earlier datei, months or years.
T Trace, an amount too small to measure.
Below-zero temperaturea are preceded by
mlnua sign.
The prevailing direction for wind In the Normals.
Means, and Extremes table Is from recorda
through 1963.
Sky cover Is expressed In a range of 0 for no clouds or obscuring phenomena to 10 for complete sky
cover. The number of clear days Is based on average cloudiness 0-3; partly cloudy days 4-7; and
cloudy days 8-10 tenths.
-------
go
80
70
60
50
40
30
20
10
I I I I I I I II I I i I i ir-ri
i i i i i i i i i i i i i i
i i
i
i i i
A S 0 N 0 J F M A M J J
1967 1968
A S -0 N D J F M A M J J
1969
Figure 2. Average high and low temperatures recorded at the plant for the period
August 1967-July 1969.
8
-------
5.00
4.50
4.00
(5 3.50
«x
u_
| 3.00
CS
m 2-50
h
1
I 2.00
LU
ac
1.50
1.00
.50
0-
.
-
1
1
.
ASONDJFMAMJJASONOJFMAMJJ
1967 1968 1969
Figure 3. Monthly precipitation recorded at the plant for the period August 1967-
July 1969.
-------
.
-------
Residential wastes of 31,200 persons and 40 percent by weight of
the commercial wastes are collected weekly in Johnson City by the Sanita-
tion Department using five threeman crews with compactor trucks. Sixty
percent of the homeowners, however, burn some wastes in their backyards.
Others employ private collectors to provide supplemental service once a
week. Street sweeping and brush are collected by the Street Department
and are deposited in the city's landfill.
Industries in Johnson City generate about 130 tons of solid wastes
weekly. The majority of these are hauled to disposal sites by employees
of the industries. The Sanitation Department collects from seven indus-
tries, totalling about 9 tons per week.
Wastes collected by the Sanitation Department are delivered to a
transfer station. Here they are transferred to either a 53 or a 65 cu
yd compaction trailer for hauling to the compost plant or the landfill.
One load per day of commercial material, about 95 percent paper, and
averaging about 10 tons, is routinely hauled to the landfill. Hospital
wastes and some yarn wastes from an industrial establishment also do not
reach the composting plant. When the compaction trailers are out of serv-
ice for any reason, the 16 cu yd packer trucks used for residential
collection deliver their refuse to the composting plant.
For the period January 1968 through June 1969, the compost plant
received an average of 33.8 tons of refuse per day for 5 days per week.
This collection with the 10 tons per day sent directly to the landfill,
is about 2.8 Ib per capita per day on a 5-day-week basis and 2 Ib
per capita on the 7-day-week basis. The low figure probably does not
11
-------
represent the true per capita generation of refuse in Johnson City.
Composition of the Municipal Refuse. Two studies of the production
of refuse per capita and the composition of that refuse have been made in
the same residential area of Johnson City. The first was performed by
the Division of Technical Operations, Bureau of Solid Waste Management,
in October 1967, and the second by the staff at Johnson City in July 1968.
The first study showed a production rate of 1.1 Ib per capita per day
of residential waste and the second showed a rate of 1.4 Ib per capita per
day (Table 3).
The composition of these samples was found by manually sorting the
refuse into ten categories (Table 4). This refuse was higher in food
wastes and lower in paper wastes than the averages usually reported since
it was collected from a residential district. The refuse received daily
at the Johnson City plant probably has a greater paper content. As
previously mentioned, one load of commercial waste, with a very high
paper content, is not received at the compost plant but is hauled directly
to the landfill.
. USPHS-TVA Composting Project
Description of the Project. The joint USPHS-TVA Composting Project
has been for demonstration and research to study the feasibility of
composting as a possible answer to the problem of increasing quantities
of municipal solid wastes produced by municipalities. The major
responsibilities of the principals are as follows:
12
-------
TABLE 3
MUNICIPAL REFUSE PRODUCTION
Johnson City, Tennessee
(Residential Area)
October 1967 July 1968
Refuse production (Ib/capita/day) 1.1 1.4
Number of homes sampled 136 144
Population sampled 519.8 550.0
Population density (people/home) 3.82* 3.82*
Weight of refuse collected, Ib
(wet weight basis) 4,003 5,400
Sample period, days 7 7
*Based on 1967 study.
13
-------
TABLE 4
COMPOSITION OF REFUSE
Johnson City, Tennessee
Category
Paper products
Food wastes
Metals :
Ferrous
Nonferrous
Combined
Glass products
Plastics
Leather and rubber
Yard wastes
Cloth and synthetics
Brick, rock, dirt, etc.
Wood
Total
Wet weight
October
1967
1,820.4
1,036.5
433.0
436.1
67.0
40.0
63.5
56.0
39.0
11.5
4,003.0
, pounds
July
1968
794.5
788.5
211.5
24.5
236.0
206.0
76.5
55.5
53.0
47.0
3.5
18.5
2,279.0
Percent of
October
1967
45.5
29.5
10.8
10.9
1.7
1.0
1.6
1.3
1.0
0.3
100.0
total sample
July
1968
34.9
34.6
9.3
1.1
10.4
9.0
3.4
2.4
2.3
2.0
0.2
0.8
100.0
14
-------
1. USPHS pays all costs incurred in the design, construction,
operation, and maintenance of the plant and conducts research
related to the process of composting, the nature of compost,
the health aspects of compost, and the efficient operation of
the composting plant.
2. TVA designs, constructs, operates, and maintains the
compost plant and conducts research on the feasibility of
commercial and agricultural use of the compost produced,
on a reimbursable basis.
3. The city of Johnson City provides the site for the plant,
mixed refuse from its collection system, and raw or digested
sewage sludge from its sewage treatment plant.
While TVA operates and maintains the composting plant, USPHS has the
responsibility for technical direction, which includes developing schedules
for certain operations, monitoring the physical and chemical characteristics
of the maturing compost, and altering schedules and procedures where these
characteristics dictate such changes. The USPHS is studying plant operation
and sanitation methods to avoid the production of odors and the propagation
of flies and rodents and, in close collaboration with the TVA agriculturist
assigned to the project is studying the improvement of composting methods
and compost. East Tennessee State University, under contract with USPHS,
and a microbiologist on the project staff, studied the survival of pathogens
throughout the composting and curing periods.
As part of the feasibility study, USPHS and TVA are studying the
economics of the plant operation on the basis of detailed cost records
that TVA maintains.
15
-------
Since TVA operates the National Fertilizer Development Center (NFDC) at
Muscle Shoals, Alabama, one of the world's largest institutions for research
and development of fertilizer, TVA has important resources for testing and
demonstrating the value of compost as a soil amendment and for studying
the marketing of compost. The principal use of compost is.expected to
be as a soil builder and conditioner with potential for application on
lawns, gardens, parks, golf courses, and truck or specialty farms. Tests
may show how compost fortified with nitrogen, phosphorus, and potassium
can be used to produce an organic-base fertilizer. Disposal of the compost
has been a major factor in the success or failure of many composting plants.
Marketing, therefore, should be an integral part of the demonstration
project and the study of the economics of composting.
The Division of Agricultural Development, TVA, has a number of test
plots and demonstrations under study by the project agriculturist in the
Johnson City area. Test plots have also been established at the NFDC,
Muscle Shoals, Alabama. Such factors as the rate of application and
effect of compost, on various crops, etc., are being studied. Greenhouse
studies will be made, and some work has been started with the use of
compost on bare areas, such as abandoned strip mines and highway cuts,
for revegetation and erosion control.
Description of the Composting Plant. The composting plant began
operating on June 20, 1967, to demonstrate composting of municipal solid
wastes by the windrow method.
The plant was designed to process during a 5-day-week raw refuse and
sewage sludge of 33,000 people, approximately the present population of
Johnson City. Nominal capacity is 60 tons per day for an 8-hr shift.
16
-------
Figure 5 shows an overall view of the plant. Figure 6 is a schematic
layout of the processing steps, and Table 5 lists the plant equipment and
specifications.
Refuse is delivered to the plant, 5.4 miles distant, in 53 and 65
cu yd compaction trailers from a central transfer station in Johnson City.
The refuse is weighed and then dumped into a hopper in the receiving
building or onto the paved apron to be later moved into the hopper by a
front-end loader (Figures 7 and 8). Items such as mattresses, bed
springs, bicycle frames, wire, which might block or entangle the
equipment, are removed. A 6-ft wide plate conveyor, forms the bottom
of the hopper and advancing at a rate of 2 to 10 ft per minute, carries
the refuse under a vertical leveling gate and drops it onto a 3-ft wide
elevating belt that carries it into the processing building. The
receiving building is roofed and enclosed on three sides. The belt
conveyor is covered between the receiving and the processing buildings
(Figure 9).
The processing building is 40 ft by 60 ft and houses all of the
refuse processing operations, the sludge thickener, and the refuse-sludge
mixer. The elevating belt conveyor from the receiving building becomes
horizontal after it enters the upper level of the processing building.
It carries the refuse past a picking station at a rate of 60 ft per min
(Figure 10). Two or more pickers manually remove bulky paper, rags,
glass, plastics, metals, and other noncompostable material. The refuse
placed in paper or plastic bags may arrive at this point with the bag
still intact. Either the pickers must discard the entire bag or permit
17
-------
00
JOINT. U.S. PUBLIC HEALTH SERVICE
TENNESSEE VALLEY AUTHORITY
COMPOSTING PROJECT
JOHNSON CITY TENNESSEE
1967
I
Figure 5 - Joint USPHS-TVA Composting Project
Johnson City, Tennessee
nson i
-------
GIVING HOPPER
RECEIVING HOPPER CONVEYOR
LEVELING & METERING GATE
ELEVATING BELT CONVEYOR
REJECTS HOPPER
MAGNETIC SEPARATOR
RASPER
GRINDER
MIXER
BUCKET ELEVATOR
GROUND REFUSE STORAGE BIN
SLUDGE THICKENER
SLUDGE COAGULATING TANK
SLUDGE HOLDING TANK
CHEMICALS MIXING TANK
HAND PICKING STATION
SHIPPING
WINDROWING
TURNING
COMPOSTING
-------
TABLE 5
DESCRIPTION OF MACHINERY AND EQUIPMENT
USPHS-TVA COMPOSTING PROJECT, JOHNSON CITY
Item
Description
Manufacturer
& model
Capacity
Power
Rating
Truck scale
Refuse feeder and
leveling grate
N3
o
Raw refuse elevating
conveyor
Raw refuse cross
conveyor
Rasping machine
Hammermill
Mechanical 10 x 34-ft platform scale with tare
beam and remote dial weighs incoming refuse.
Double-beaded 5 x 28-ft apron feeder in bottom
of hopper (fabricated at plant) moves refuse at
2-10 ft/min; vertical, hydraulically controlled
leveling gate regulates flow of refuse.
Rubber-covered belt 3-ft wide moves raw refuse
at 60 ft/min from receiving building to process-
ing building under cover and then to picking
station. Head pulley is permanent magnet
(field: 400 Gauss, 5 in. from face at center)
for removing ferrous metal.
Rubber-covered belt 3-ft wide moves refuse at
60 ft/min from picking station to grinders.
Arms on rotating vertical shaft force refuse
against rasping pins projecting from sides and
bottom of 18-ft-diameter housing until reduced
to less than 2-in. particles that drop through
perforated steel floor.
Mill with 44 chisel-point swing hammers (21 Ib
each) reduces refuse to particles that pass
grate openings 2 in. by 1.5 to 2.5 in.
Fairbanks, Morse, Inc.
Model 6507B
Websters Mfg., Inc.
Feeder and gate driven
by Falk helical-geared
speed changers, models
51BN2 and 224F2, re-
spectively.
Continental Conveyor
and Equipment Co.
Continental Conveyor
and Equipment Co.
Dorr-Oliver N.V.,
Amsterdam. Type
R.T.M. 55 V.S.T.D.
Gruendler Crusher and
Pulverizer Co.
30 tons
10 tons/hr 5 hp
10 tons/hr 2 hp
7.5 tons/hr 1 hp
7 tons/hr 40 hp
each, 2
motors
12 tons/hr 250 hp
-------
TABLE 5 (continued)
Item
Description
Manufacturer
& model
Capacity
Power
Rating
Ground refuse cross
conveyor
Ground refuse
conveyor
Sludge concentrator
Refuse-sludge mixer
Conveyor for ground
refuse=sludge
mixture
Rubber belt 2.5 ft wide moves ground refuse
from hammermill to ground refuse conveyor.
Rubber belt 2 ft wide moves ground refuse from
rasper to mixer at 200 ft/min.
Electric-motor-driven stationary sewage sludge
concentrator, traveling screen type, utilizing
gravity as the dewatering driving force. The
nylon filter cloth moves at a variable speed
of 1.5 to 4.5 fpm. The unit is designed to
dewater raw sewage sludge containing 3 to 5
percent solids and deliver a sludge cake with
approximately 15 percent solids. In addition
to the filter, there is a Wallace & Tierman
flocculant dosing pump and a Worthington
metering pump of the diaphragm type.
Rotary drum mixer, 3 ft in diameter and 10 ft
in length. Internal vanes are designed for
mixing the refuse and sludge and discharging
mixture at outlet.
Moves mixed refuse and sludge from mixer to
bucket elevator. Rubber belt type. 2 ft wide.
Fabricated by TVA
Continental Conveyor
and Equipment Co.
Permutit Co. Model
DCG-200
Designed and fabricated
by TVA
Continental Conveyor
& Equipment Co.
7.5 tons/hr 1 hp
7.5 tons/hr 1.5 hp
Designed
for 1200
gal/hr
Rated at
890 cu ft/
hr or 11.3
tons/hr at
belt speed
of 200 ft/
min
1 hp
-------
TABLE 5 (continued)
Item
Description
Manufacturer
& model
Capacity
Power
Rating
Conveyor for ground
re fus e-sludge
mixture
Conveyor for dis-
charge of ground
refuse
Bucket elevator
NJ
Storage bin
Bucket elevator
Vibrating screen
Replaces sludge-ground refuse mixer when mixer
is not in use. Belt is 2 ft wide and 15 ft
long.*
Used to transfer ground refuse to trucks when
bucket elevator and storage hopper not used.
Belt is 2 ft wide and 25 ft long.
Vertical centrifugal type. Electric-motor-
driven. Buckets are cast malleable iron, 14
x 7 in., 16 in. on center. Elevator used to
transfer ground refuse-to storage bin.
Cylindrical storage bin designed to hold
several truckloads of ground refuse. Discharge
to truck through horizontal sliding gate. Bin
is 12 ft in diameter at largest dimension.
Electric-motor-driven, vertical bucket,
centrifugal discharge type. Used in moving
compost from feed hopper to vibrating screen.
Electric-motor-operated. Vibrating in-
clined screen with interchangeable wire mesh
screens of 1/4- and 1/2-in. openings. Used
to screen the compost.
Fabricated by TVA
Fabricated by TVA
Fairfield Engineering
Co. Model VCE, No. 147
Designed and fabricated
by TVA
J. B. Ehrsam and Sons
Mfg. Co. H-17
Link Belt
1 hp
2 hp
Rated at 3 hp
1650 cu ft/
hr (75% of
theoretical)
at chain
speed of
200 ft/min
About 110
cu yd
Rated at 3 hp
1715 cu ft/
hr (75% of
theoretical)
at chain
speed of 221
ft/min
-------
TABLE 5 (continued)
Item
Description
Manufacturer
& model
Capacity
Power
Rating
Compost grinding
hammermill
Windrow turner
u>
Swing hammer type with 30 hammers each weigh-
ing approximately 2-3/4 Ib. Electric-motor-
driven, heavy duty type. Used to regrind
compost.
Diesel-engine-driven, self-propelled. A
rotating drum turns the windrow as the
machine straddles the row. The drum has
teeth arranged so as to move the material
toward the center of the windrow as it is
turned. The material is picked up from the
ground, passed over the drum and redeposited
behind the machine. The machine moves
through the row at approximately 0.27 mph
and is capable of turning windrows approxi-
mately 8-ft wide and 5-ft high.
J. B. Sedberry, Inc.
5W-26
General Products of
Ohio, Inc. (Cobey)
Model 003
10 tons/hr 100 hp
rated, did
not grind
compost at
this rate.
500 tons/hr 100 hp +
(spec, claim (122 BHP
1500 tons/hr by specs)
of 700-lb/
cu yd ma-
terial)
Tractor shovel Rubber-tired, gasoline-engine-driven front-end
loader with general purpose bucket transports
refuse, ground refuse, and compost .
«.
International Harvester
Company, Model H-50
(Ser. C)
Lifting:
13,200 Ib
Bucket:
Heaped:
3-1/2 cu
yd
Struck:
3 cu yd
103 bhp
at 2,500
RPM
*In late 1969 the mixer was found to be too small for the capacity of the new Gruendler hammermill.
not being processed, the mixer was temporarily removed and replaced by this conveyor.
As sludge was
-------
ISJ
-p-
Figure 7 - Receiving building with a 65
cubic sards compaction trailer discharging
-------
T.gure 8 - The hopper in the receiving
building. Refuse is being wetted in
preparation for shredding in the rasper.
25
-------
to
Figure 9 - Receiving building on the left
and processing building on the right. The
covered conveyor which transports refuse
to the processing building can be seen
betwee^fche two.
-------
Figure 10 - The picking station inside the
processing building.The men are attempting
to remove noncompostable items and large
items which might damage equipment.
-------
some cans and bottles to pass since they cannot tear open all the bags.
The belt then passes around a magnetic pulley where cans and other ferrous
metal objects are separated from the refuse. Some plants may employ a
primary grinding operation prior to magnetic separation to reduce the amount
of compostable material that might be trapped by the ferrous materials
and removed with them. The rejected material, including that removed
at the receiving building, is weighed and hauled 4.6 miles to the Johnson
City landfill. About 27 percent of the incoming material was rejected
during the period of this report because no salvaging was practiced.
After removal of noncompostables the refuse proceeds to either a
hammermill or a rasping machine for comminution. These are so placed
that they can be used alternately for comparison of efficiency and costs
of operation and maintenance.
The hammermill (Figure 11) is of the swing-hammer type, having 44
chisel point hammers each weighing 21 Ib. The grate bars have 1-1/2-
and 2-1/2-in. openings. The mill is driven at 1,150 rpm by a 250
horsepower electric motor and has a rated capacity of 12 tons per hr.
The rasping machine (Figure 12) is similar to that developed by the
Dutch N. V. Vuilafvoer Maatschappij (VAM). It was imported from the
Netherlands where it was constructed by the Dorr-Oliver Company. This
machine consists of a covered cylindrical housing 18 ft in diameter and
8 ft 6 in. high not including the height of the conical cover. The
perforated floor is about 3 ft above the bottom of the housing. Revolving
arms attached to a vertical shaft in the center scrape the refuse against
projecting pins in the floor and on the wall of the housing, finally
28
-------
Figure 11 - The hammermill used to shred
or grind refuse. The man has his hand on
tha clean-out door of the tramp metal trap
-------
Figure 12 - The Dorr-Oliver Rasper.
-------
forcing it through the perforations. The arms are driven by two 40
horsepower electric motors.
Refuse as received has an average moisture content of 39 percent.
When using the rasper, water is added in the receiving hopper to presoften
cardboard. Water is also added in the rasper. When the hammermill is
used, water is added after grinding at a point ahead of the refuse-sludge
mixer. The ground refuse or refuse-sludge mixture is adjusted to a
moisture content of 50 to 60 percent by wet weight.
Raw or partially digested sludge containing 3 to 5 percent dry solids
is pumped to the composting plant from the nearby sewage treatment plant.
When using sludge from the same population generating the refuse, the
water content is greater than that needed to obtain the 50 to 60 percent
moisture content in the ground refuse-sludge mixture to be composted.
Thus, especially with an operation using a rasper, sludge dewatering
must be provided. For sanitary reasons it is impractical to add sludge
to the refuse at any point in the process ahead of those places where the
workmen must come into contact with the refuse.
Sludge is thickened in a Permutit Dual Cell Gravity (DCG) Solids
Concentrator (Figure 13) to a moisture content of about 85 to 88 percent.
This apparatus uses a revolving filter of fine-mesh nylon cloth. As a
"plug" of sludge revolves inside the filter it becomes dewatered, rolls
up, and is discharged. Special coagulants (polyelectrolytes) are used
to condition sludge for filtering. The filtrate is returned with other
liquid wastes to the sewage treatment plant where it is treated with
incoming sewage. The thickened sludge is discharged to a conveyor belt
which in turn discharges it to the mixer.
31
-------
U)
NJ
Figure 13. The Permutit Dual Cell Gravity
Sludge Concentrator used to dewater sewage
slu
-------
Refuse and thickened sludge are mixed in a horizontal cylindrical
mixing drum designed by TVA (Figure 14). As the drum revolves, internal
vanes carry the mixture to the discharge end. From the mixer the material
is carried to the ground refuse-sludge storage bin from which it is loaded
into dump trucks and transported to the windrow area.
The ground refuse-sludge mixture is composted in windrows on a 4.8-
acre area graded and stabilized with crushed rock. The windrows (Figures 9
and 15) are laid down so as to have a section as near to 9 ft wide and
4 to 4-1/2 ft high as possible. They can be as long as 230 ft. The
"haystack" shaped cross-section will shed rain and the mass of a windrow
so shaped will contain the heat of decomposition and can be aerated easily.
The field is arranged to receive 34 windrows. As the plant operates 5
days a week and onewindrow is laid down each working day, each windrow
can remain on the field for a period up to 45 days. The active composting
time in the field is 35 to 44 days.
During the time the material is being composted on the field it is
turned 8 or more times with a special turning machine (Figure 16). This
patented machine straddles a windrow, turning it with a rotating toothed
drum as it proceeds from one end to the other. Turning aerates the
windrows to supply the oxygen needed for aerobic decomposition. To
maintain the desirable 50 to 60 percent moisture content, water can be
added as needed before turning. Should rain cause the moisture content
to rise above the optimum, the windrows are turned as often as necessary
to dispel the excess moisture and return them to the proper wetness.
After the material has composted in the open field for a period of
6 to 7 weeks it is turned, taken from the field, and deposited in the
33
-------
Figure 14 - The cylindrical mixer for
intimately mixing dewatered sewage sludge
with the ground or shredded refuse.
-------
LO
Ui
Figure 15 - A windrow of ground or shredded
refuse.
-------
Figure 16. The windrow turning machine. The
machine straddles the windrow, turning it with the
drum as it passes through the windrow.
Cobey composter, front view.
ompQsti
-------
curing and drying shed (Figure 17). This shed is 60 ft by 200 ft and
provides a curing and drying period of 2 weeks, which is frequently
insufficient to adequately dry the compost for screening.
Following the drying period, compost is screened and reground as required
using a vibrating screen and a hammermill for this purpose. The screen
is equipped with interchangeable wire mesh screens of 1/4 in. and 1/2 in.
openings. The mill is of the swing-hammer type using hammers weighing
approximately 2 3/4 Ib each. A 100 horsepower electric motor drives the
mill at 3,540 rpm and the rated capacity is 10 tons per hr. The screening
installation is shown in Figure 18.
Compost is stored either in the unground and unscreened state or in
the finished condition in stockpiles.
Construction Costs. Construction of the composting plant began on
May 18, 1966, and was completed in June 1967. The total cost, including
that of modifications made since startup, is $958,375. Constructed as
a plant for both demonstration and research and including some duplicate
equipment for comparison, the construction cost is somewhat more than
would be required for a municipal plant.
Modifications Made Since Startup. Many modifications have been made
to the plant since operations began. Important ones are tabulated below
for the value they may have to future plant designers. They are given in
the sequence of accomplishment rather than in the sequence of the process.
1. Repairing and strengthening the drive of the drum mixer
and setting same in level position. Modification of vanes or
flights inside the mixing drums. It was found that the
37
-------
CO
'
17. The storing and curing shed (left) and processin
-------
Figure 18 - The final screening and grinding
equipment. Compost is lifted by the bucket
elevator and fed to the vibrating screen.
Screened material is being collected in the
kruck. Material not passing through the
:reen is ground in a hammermill and re-
Cycled to the screen.
39
-------
original inclination was not needed to carry the material
forward. The level setting alleviated a side thrust on
the supporting and rotating mechanism.
2. Addition of wipers to underside of conveyor belts
and installation of drip or catch pans under the belts.
3. Addition of a curb or coaming around the floor which
supports the DCG sludge filter and its appurtenances.
Spillage in this area had caused cleanup problems.
4. Laying of plywood flooring over the grating floor
at the picking station to prevent spillage to lower
level. This also gives more comfort to men who must
stand for long periods.
5. Covering conveyor belt drive motors to protect them
from dust and spillage.
6. Applying thermal tape to pipes and valves in the process
building to protect them against freezing. Installing heat
lamps at end pulleys of certain conveyor belts to prevent
freezing of belt to pulley during shutdown.
7. Removal of cover on cross belts from grinders to mix-
ing drum. Covers over belt are not necessary except where
they traverse an open area where the wind may cause a
problem.
8. Installing a vertical pipe loop in the sludge pipeline
between the metering pump and the sludge-flocculant mixing
tank to equalize the hydraulic head of sludge in the holding
40
-------
tank. It was found that the diaphragm sludge metering
pump would not operate satisfactorily with the high
positive head on the suction side resulting from the
elevation of the sludge holding tank.
9. Removal of strut across receiving hopper at level-
ing gate end thus removing a cause for jamming. There
should be no structural parts which catch refuse over or
alongside a hopper.
10. Modification of chute under the leveling gate. A
man must be able to dislodge refuse which may jam the
flow at this point.
11. Installation of dual controls for the leveling gate
and the plate conveyor at a station beyond the leveling
gate. This gives the man beyond the leveling gate an
opportunity to shut down this machinery when necessary.
12. Erection of targets or poles for aligning and posi-
tioning windrows. Ground refuse-sludge mix is deposited
by trucks and the drivers need some guide in getting wind-
rows in the correct position.
13. Adding pads to the bucket of a payloader to give clear-
ance between it and the stabilized rock base of the field
to prevent picking up rock with compost when it is being
removed or when windrows are being shaped.
14. Correcting the slippage of the elevating conveyor
belt by addition of weights for tension.
41
-------
15. Adding skirts to the sides of the elevating conveyor
belt to prevent spillage of refuse. This has saved much
cleanup time.
16. Installation of a larger discharge gate for the reject
bin. This bin discharges from the bottom. Gates must be
as large as possible to avoid arching above the constricted
lower part.
17. Installation of a larger discharge gate for the ground
refuse bin. As in Item 16, gates must provide larger open-
ings than those needed for grain, coal, or crushed stone.
18. Installation of a 12-ton-per-hr hammermill to replace
the original 7-1/2-ton-per-hr mill. This is discussed later
in the section on operations.
19. Back flow preventers were installed in the processing and
receiving buildings and the composting field to protect the
fresh water system from backflow from the sludge dewatering,
washdown operations, and other possible sources of contamina-
tion. In the case of the sludge dewatering installation, the
water supply piping was redesigned and reworked to enable one
back flow preventer, located in a loop of pipe above the
highest level of all other lines in the complex, to protect
the portable water system from back-siphonage from this opera-
tion.
Staffing. For two years, the Division of Research and Development,
Bureau of Solid Waste Management, maintained at the plant site a staff
42
-------
consisting of a Project Engineer, a Staff Sanitary Engineer, a Staff
Chemist, a Staff Microbiologist, and a Staff Assistant. Thereafter, the
technical staff was reduced to a Project Engineer and two part-time tech-
nicians. Laboratories, equipped for research and much more complete than
would be needed for simple process control, were established on site for
the chemist and the microbiologist.
The Office of Health and Environmental Science, TVA, is the official
liaison between the TVA and the Bureau of Solid Waste Management. While
this office has no resident staff at Johnson City, all interagency matters
are handled through its staff. This office also maintains surveillance
over the health of the TVA personsel at the plant with special attention
to possible occupational problems specific to composting.
The plant is operated by the Division of Reservoir Properties, TVA,
with the following on-site staff:
1 Foreman - in charge of daily operations.
1 Assistant Foreman - is in charge of the plant in the
foreman's absence and also works as an operating engineer
in some phases of the plant work.
2 Equipment Operators - these are classified as Operator
B employees. One operates the windrow turner and the
front-end loaders in addition to other duties. The other
operates the sludge dewatering machinery and heavy equip-
ment.
3 Truck Drivers - two work on the site or transport rejects
to the landfill. One operates a truck equipped with spread-
ing equipment and delivers compost to demonstration sites.
43
-------
4 Compost Plant Laborers - one laborer is stationed at the
leveling gate to do gross picking and to correct cloggings
which occur here. Two work at the picking station. The
fourth works where directed and presently performs the
task of weighing incoming refuse, rejects, and outgoing
compos t.
If the Public Health Service staff now at the plant did not furnish
this service, there would be a need for a clerk and laboratory technician,
one man may perform both duties. This clerk would relieve the one laborer
of weighing.
The Division of Reservoir Properties furnished higher-echelon super-
vision from its Morristown, Tennessee, office.
The Division of Agricultural Development, TVA, with headquarters in
Muscle Shoals, Alabama, has the responsibility for the utilization and
marketing studies and has one resident Agriculturist at the plant site.
Operations and Processes
Operating Schedules. At the start, the plant operated from 10:00 a.m.
to 6:30 p.m. in the period of daylight saving time and 8:00 a.m. to 4:30
p.m. in the period of late fall, winter, and early spring. The warm
weather schedule was adopted because of the lateness of the first delivery
of refuse from the city. In colder weather, the last load of the day was
held overnight to be on hand for the earlier start.
Later, changes were made in the city's delivery schedule to enable a
truckload to arrive at about 8:30 a.m. each morning. Also, it was found
44
-------
that the last load of the day could be held over to the next morning even
in warm weather if it was stored in the hopper and sprayed with an insec-
ticide. Since then the plant has operated from 8:00 a.m. to 4:30 p.m.
each day, summer and winter.
The plant does not usually process refuse after 3:00 p.m. The re-
maining hours of the day are devoted to the cleanup of the receiving and
processing area.
Production. As previously mentioned, the plant is designed to process
10 tons per hr or 58 to 60 tons in 6 hr, leaving the remaining 2 hr for
cleanup. It has been demonstrated that with refuse of favorable charac-
teristics, the plant can process at this rate. The average capacity,
however, is about 52 tons per day in 6-1/2 hr of grinding time.
The plant has been run as a research project. Although it normally
takes all of the refuse delivered by the Sanitation Department of Johnson
City, and there have been very few shutdowns, the plant has riot been
operated to full capacity for extended periods. Efforts are being made
to extend the contributing area to a nearby city. At the present time,
according to the city's Planning Office, the plant processes refuse from
31,200 persons.
Table 6 shows processing data for the period January 1968 through
June 1969. The plant received an average of 34 tons per day. Based on
the population served of 31,200, this is 2.17 Ib per capita per day
for the 5-day week and 1.55 Ib per capita for a 7-day week. The 10
tons of commercial waste, routinely delivered directly to the landfill,
brings the total tonnage collected to 44 tons per day. This indicates
45
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TABLE 6
PROCESSING DATA FOR JANUARY 1968 THROUGH JUNE 1969
USPHS-TVA Composting Project
1968
Jan.
Feb.
Mar.
Apr.
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Refuse
received
(tons)
554
587
698
640
578
220
866
932
427
544
458
661
Refuse
rejected
(tons)
142
163
178
174
168
57
220
214
111
154
130
178
Refuse received
per day (tons)
Average
26
28
33
34
32
31
39
44
36
39
35
31
Maximum
48
42
53
53
46
58
51
55
52
61
59
45
Processing
days
21
21
21
19
18
7
22
21
12
14
13
21
1969
Jan.
Feb.
Mar.
Apr.
May
June
Total
623
573
599
775
758
773
11,266
157
150
148
213
218
226
3,001*
33
29
30
36
36
37
34
50
39
43
48
50
53
19
20
20
22
21
21
333
*27 percent of incoming refuse.
46
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a collection of 2.81 Ib per capita per day for the 5-day week and 2.00 Ib
per capita per day for the 7-day week. As previously mentioned, this is
low compared to the national average. Street sweepings and brush are not
included in this quantity. Packing house and produce wastes are sold
to piggeries. Much of the industrial waste of the city is hauled privately
as is some of the household waste.
Of the incoming material, 27 percent was rejected as noncompostable
and disposed of in the landfill.
A seasonal variation in refuse exists, as would be expected, and
Figure 19 shows these variations.
Compost yield from the 11,266 tons of refuse received was about
5,650 tons (30 percent moisture content by wet weight). All of the
compost removed from the field was not weighed. Two studies of yield,
on which the above is based, are discussed in a following topic.
Receiving. The receiving hopper has a capacity equivalent to two
trailer loads of refuse. When the hopper is empty, the 53 and 65 cu yd
compaction trailers discharge a small part of their loads into the hopper
and then pull away to deposit the remainder on the paved apron in front
of the receiving building. A front-end loader is used to push refuse
from the apron into the hopper. This procedure allows an inspection of
the refuse, an opportunity to remove large items of noncompostables or
those which interfere with the movement of the material, and the breaking
up of compacted refuse. This latter treatment prevents serious bridging
in the hopper. When the hopper contains refuse, the whole trailer load
is deposited on the apron to be fed in as needed.
47
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40
30
20
= 10
Summer
Summer
CO
=>
ca
CO
en
CO
CO
Figure 19. Quantity of refuse received at the USPHS-TVA Composting
Project by seasons.
48
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On one occasion, refuse failed to dislodge from the rear door of a
16-cu-yd packer truck as it was raised over the receiving hopper. This
overbalanced the truck and the front end was lifted upward to almost a
vertical position where it was caught by the eaves of the building. Both
the truck's hood and the building were damaged. All packer trucks are
now required to unload on the apron.
Gross picking is necessary at the receiving hopper and at the station
behind the leveling gate.
Time records have been kept for the plate conveyor of the hopper and
the main elevating conveyor belt. Table 7 shows that this machinery is
capable of handling the design capacity of 10 tons per hr or more although
the overall average for the last 6 months of 1968 was 9.3 tons per hr.
On a day in which 58 tons of incoming refuse were processed, the machinery
handled 9.9 tons per hr. On other days the rate of feed might be higher
or lower depending on the characteristics of the refuse.
Operating difficulties since startup have been minimal. The drive
motor of the plate conveyor required rewiring and a bearing has been rebuilt.
Apparently the trouble was not caused by a condition of overloading with
refuse. The 328 bolts which fasten the pans of the conveyor to the driving
mechanism had to be replaced after some 26 months of operation. It was
difficult to keep them tight and the repeated loosening ruined the threads.
The new bolts have a finer thread and are installed with lock washers. An
improved program of lubrication has been initiated to reduce heating of
bushings, wear of bolts and other similar conditions.
49
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TABLE 7
PERFORMANCE OF RECEIVING MACHINERY
1968
July
Augus t
September
October
November
December
Total
June 5
October 30
November 27
Hours of operation
of receiving equip-
ment and main feed
belt
85
85
44
66
55
82
417
6
7
6'
Tons of raw
refuse moved to
picking station
866
932
427
544
458
661
3,888
58
61
59
Tons per hour
(average)
10
11
10
8
8
8
9
10
9
10
50
-------
Due to lack of stiffness the pans or segments of the leveling gate
became bowed by the pressure of nonresilient items in the refuse. From
time to time the clips attaching the segments to the drive chain broke
and had to be rewelded. After processing about 17,000 tons of refuse
during 26 months of operation, all of the pans were replaced with pans
having heavier bar stiffeners. ,
The elevating conveyor belt has given no trouble since installation
of the skirts to prevent spillage. Occasionally cardboard or other
material jams under the cover but this is easily removed.
Grinding. The imported rasping machine has performed satisfactorily
in the past 18 months of operation.
The manufacturer of the rasper states that it has a capacity of 7
tons by wet weight of picked raw refuse per hr. Time and tonnage records
kept over a 6-month period show the rasper to be grinding an average of
5.6 tons per hr of refuse from which noncompostables and other objectionable
material have been removed (Table 8).
The rasper must be run for about 10 min as refuse is fed to it before
ground material is produced. It then builds up to a maximum production
which can be maintained by keeping it full. After the feed belt is
stopped, the machine must continue to run at a decreasing rate of production
to process the grindable refuse remaining in it. If the rasper is emptied
of grindable material at any time during the day, this cycle must be
repeated. This characteristic of its operation is reflected in the average
tonnage per hr given above.
The character of the refuse has an effect on the rate at which it
can be handled. On one day when 61 tons of incoming refuse were processed,
51
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TABLE 8
AVERAGE PERFORMANCE OF RASPER
1968
July
Augus t
September
October
November
December
Hours of
operation
113
108
57
77
64
96
Tons of sorted raw
refuse ground*
646
718
317
390
327
482
Tons per hour
(aver age )t
6
7
6
5
5
5
Total 515 2,880 6
Rasper Performance on Days of Maximum Runs
June 5, 1968 6 43 7
October 30, 1968 8 44 6
November 27, 1968 6 43 7
One Hour Test Runs with Rasper Full
January 15, 1969 1 7
January 17, 1969 1 7
*Tons of sorted raw refuse averaging 39 percent moisture by wet
weight, or the weight of incoming refuse minus that of rejected material.
Actual weight of ground refuse produced is greater than this due to water
added to obtain a 60 percent moisture content.
tThe rasper must be run for about 10 minutes as refuse is fed into it
before it produces a ground material. It then builds up to a maximum pro-
duction which is maintained if the rasper is kept full. After the feed
belt is stopped, the rasper must be run for 20 to 25 minutes to finish
processing the grindable material still in the machine. Due to the sched-
ule of refuse deliveries or for other reasons the rasper usually cannot
be kept full throughout the day and the average production figures reflect
this situation. The character of the refuse can also affect the production
of the rasper considerably.
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the 44 tons of sorted (picked) refuse were ground at a rate of 5.3 tons
per hr. On another day, when 59 tons of refuse were processed, the
rasper's rate for the 44 tons of picked material was 6.9 tons per hr.
On test runs of one hr with the rasper full, a rate of 7.1 tons per
hr of sorted material received with a moisture content of about 39 percent
was observed. It appears that this machine can meet the manufacturer's
claims.
Water must be added during processing to obtain a moisture content
of 60 percent by wet weight in the material laid down on the field for
composting. In practice it is added first in the receiving hopper to
soften cardboard and again in the rasper as needed. The rasper is
equipped with spray nozzles for this purpose and will not grind dry
cardboard without operating difficulties. The actual weight of material
entering the rasper is, therefore, greater than its weight when received
at the plant. On the occasion of the rasper's grinding 7.11 tons per hr
(39 percent moisture), it was discharging 10.8 tons of ground refuse
with a water content of 60 percent.
At the end of the day, there always remains in the rasper some
residue. This includes material such as metal cans, items of nonferrous
metal, rags, bits of wood, and wire. This material must be removed at
intervals either manually or through the rejection opening.
When the refuse is difficult to grind, the rasper can become
overloaded by the buildup of material. To date this has not: caused any
mechanical trouble but it does consume time when it is necessary to
remove the excess material by hand.
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Very little maintenance has been necessary. Not long after startup
a bearing in one of the American-built motors required repair which was
done by the manufacturer. The main bearing of the shaft which carries
the rotating arms became overheated soon after operations were begun.
This was corrected by a modification of the lubrication of this part.
In March 1969, after 20 months of operation and the grinding of
8,720 tons of sorted refuse, the rasper bottom plates, pin plates, and
wear plates were removed and replaced. The 8,720 tons of picked refuse
represent nearly 12,000 tons of incoming refuse. In September 1969,
after 26 months of operation, two of the rasping arms broke at the point
where they are fastened to the rotor. These were rewelded with some
steel reinforcement by plant personnel. Three others, not broken, were
also strenghthened and such trouble is not expected to recur within 2
years.
The hammermill originally installed in the process building did not
produce the particle size desired or achieve the specified capacity for
grinding 7-1/2 tons per hr of raw refuse. Tests during the first 6
months of plant operation showed a capacity of 5.6 tons per hr. In late
1967 and early 1968, experiments were conducted with several grate size
combinations to see if a better particle size could be obtained. The
smaller the particle size produced, the greater were the operating
difficulties and the smaller the grinding capacity. In March 1968,
tests with the original grates showed a production of only 4.2 tons per
hr.
On every occasion of operating the mill for grinding refuse, stoppages
in the feed chute occurred. Before an arrangement was made whereby the
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mill could continue to run after the feed belt was stopped, the mill
jammed and could not be restarted until it had been opened and cleaned
out. After March 8, 1968, the use of the hammermill for grinding of
refuse was discontinued.
From March through December 1968, the hammermill was used only for
regrinding compost for use by the TVA agriculturist. Between March and
October 1968, a total of 624 tons of compost at least 6 weeks old was
ground at an average rate of 8.9 tons per hr. The range of production
was from 3.7 tons per hr to 15.6 tons per hr. The dryness and other
characteristics of the material and the speed with which it can be fed
into the mill affect the rate of grinding. Compost with a water content
over 30 percent by wet weight can give trouble by sticking and jamming.
Material that is very dry can create a dust problem.
In mid-October 1968, the hammers were replaced with a set which had
been refaced by a buildup of welding rod. A total of 288 tons of compost
was subsequently reground at the rate of 13.6 tons per hr.
The hammers taken out of the mill in October 1968 had been installed
in November 1967, and had been used for 102 hr. Of this time, 27.4 hr
had been for grinding refuse. Total weight of refuse for this period of
grinding refuse was not determined as it was the accumulation of several
short experimental runs.
Experience had shown that the hammers of this mill required refacing
after 40 hr of refuse grinding. After about 27 hr of grinding, they
would have had 13 hr of remaining usefulness for this purpose. Thus,
13 hr for refuse grinding were good for about 74 hr of compost grinding.
At this rate, a set of refaced hammers might serve for nearly 230 hr of
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compost grinding. This mill had ten 50-lb and four 15-Ib hammers
operating at 1,800 rpm, driven by a 125 horsepower motor. The grates
were of the bar type. The mill recently installed for regrinding compost
is a different type, having narrow hammers weighing about 2-3/4 Ib each,
designed to rotate at 3,450 rpm, and powered by a 100-horsepower motor.
It is intended for grinding compost that has been rejected by the vibrating
screen. Information obtained on the wearing of hammers on the larger
mill is not applicable to the new final grinder.
In February 1969, a new and much larger hammermill for refuse
grinding was installed. This mill is described in Table 5. During the
month of March 1969, it had been operated for 47-1/2 hr, grinding 275
tons of refuse, when the hammers were taken out for rebuilding. The
hammers were badly worn resulting in less efficient particle size
reduction and indicating that removal after approximately 40 hr of
operation seems to be necessary. Rebuilding after 30 hr will result
in less difficulty in refacing.
The short experience with the new hammermill has shown that the
pickers and the magnetic separator may miss large pieces of metal that
will give trouble. In one case, a steel ball bearing almost 3 in. in
diameter got into the mill. In another case, a large piece of metal
was thrown about in the mill with such force that the I/2-in. steel cover
was bent. A tramp metal trap, which is quite heavy, was installed.
This in turn necessitated the installation of a trolley hoist above the
hammermill to assist in removing the trap and cover during hammer changes
or for other reasons.
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Experience to date has been insufficient to evaluate the cost of
operating the new hammermill.
Addition of Sewage Sludge. On January 2, 1968, the routine addition
of sludge was attempted.
Sludge is pumped from the primary sewage treatment plant adjacent
to the composting plant into a 2,600-gallon holding tank. From this
tank it is transferred to a mixing tank by a diaphragm metering pump.
A anionic or cationic polyelectrolyte flocculant is introduced into the
line ahead of the mixing tank by a positive displacement feed pump.
After mixing, the sludge flows into the filter.
In January and February of 1968, subfreezing temperatures on eight
occasions made it impossible to process sludge. The processing building
was unheated and the freezing of pipelines and even dewatered sludge
was experienced. Wrapping of pipelines with thermal tape and the
installation of space heat in the building have corrected this problem.
When a breakdown of the sludge filter occurred, there was difficulty
in disposing of unneeded sludge due to the arrangement of the sludge
return lines. It was decided to add sludge on a 3-day-a-week basis in
order to carry on the essential pathogen survival studies.
In July 1968, the plant again attempted to process sludge daily.
Of the 103 days on which refuse was processed in the second half of 1968,
dewatered sludge was incorporated into ground refuse on 75 days.
Of about 348,000 gallons of sludge received from the Johnson City
sewage treatment plant, 261,000 gallons were processed through the filter.
The average number of gallons processed per day of filter operation was
3,480. On 13 days the plant was unable to process sludge because of
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downtime on the filter. Of the 75 sludge processing days, the filter was
operated only part of a day on 12 occasions on account of downtime. Over
the 6-month period the added sludge solids averaged about 3.9 percent of
the dry weight of the raw refuse-sludge mix laid down in windrows. On
occasion, greater amounts were added for specific experimental windrows.
The DCG filter is capable of dewatering sludge from a water content
of 96.9 percent to 85.0 percent of wet weight. The capacity (not
necessarily raw sludge) is specified as 1,200 gallons per hr. The
monthly average rate has ranged from 861 to 1,060 gallons per hr. The
maximum amount of sludge processed on any one day has been 5,643 gallons.
The equipment installed is not capable of handling all of the sludge
generated by the 27,000 population served by the city sewer system.
The flash mixing tank, where the sludge is mixed with a flocculant
before it enters the dewatering cells, is equipped with a DC motor, the
speed of which is controlled by a rheostat. This rheostat burned out
and the mixer was subsequently operated with an AC motor. This operation
must be intermittent, however, because the motor runs at too high a speed.
Permutit's attempts at obtaining a replacement rheostat have failed as
the company that manufactures the speed control unit will not sell parts
for it. An alternate solution is to install a gear reducer for the AC
motor. Permutit is to supply parts numbers for such a reducer.
The sludge inlet piping to the dewatering cells splits the flow
from a flash mixing tank into four parts by using a weir box. Rags and
other large materials tend to clog this box, requiring continual attention
to insure steady flow. The cause of this trouble lies partly in design,
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which Permutit intends to correct in future models, and partly in the
fact that the Johnson City sewage treatment plant does not have comminution.
Trouble was experienced with the displacement of the sprocket idlers
over the cells. When these came loose, the cell moved out of position
and became deformed and jammed. The manufacturer recognizes this
fault and will design a correction into a test machine being constructed;
it is not known if this correction can be applied to the apparatus in-
stalled in the composting plant.
The nylon mesh filter medium is stretched between rubber seals which
in turn are attached to a drive chain which imparts the rotary motion to
the cells. The seals were not strong enough to stand the stress of being
part of the drive mechanism and still support the weight of the sludge
roll between them.
Metal inserts in the seals to which the drive chains are bolted
proved to be too weak for the purpose. The machine was developed for
dewatering digested sludge which forms a smaller roll than the raw sludge
treated at the composting project. Raw sludge forms rolls in the order
of two to three times the size of those for digested sludge, overloading
the seals, and pulling out the inserts. Each time this happened the seal
had to be replaced before the operation could be continued, a rather time
consuming task.
Due to these troubles, the processing of sludge in the first half of
1969 was intermittent.
Permutit has redesigned the seals so that the new inserts have two
horizontal projections instead of one, the web is incorporated into the
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new seal as it is poured instead of being glued on later, and the new seal
is poured in one piece instead of, several short pieces. The result is a
unit construction which should be capable of carrying a much larger load
than the original seals. The manufacturer supplied the-project with a full
set of these new seals in the late spring of 1969, and one unit of the
filter was equipped with them. In July 1969, it was decided to temporarily
cease the processing of sludge in order to devote time and funds to other
investigations. The new seals have therefore not been tried in continuous
operation.
From the above discussion, it can be seen that the sludge operation
has fallen below expectations. In defense of the filter, which was still
in the developmental stage, there were times when other operations in the
plant or difficulties at the sewage treatment plant resulted in a short
day's run. There were times when the quality of the sludge as received
made it unmanageable and part of it had to be wasted back to the sewage
treatment plant. As it is sometimes drawn from the digester and at other
times directly from the primary settling basin, the quality of the sludge
has been variable. Furthermore, since .there is no comminutor at the sewage
treatment plant, rags, sticks, etc., may come through and clog the troughs
in the DCG. Raw sludge has better dewatering characteristics than digested
sludge.
Handling and Storage. The ground refuse-sludge mixture is moved by
conveyor from the mixer to a bucket elevator which lifts the material into
a 12-ft diameter cylindrical storage bin. The bin was designed to hold
several truckloads of material so that a truck could shuttle back and forth
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from this point to the windrow field. The bin discharged to the truck
through a horizontal sliding gate in the bottom. The bottom third of the
bin tapers toward this opening.
It was found that due to arching ground refuse would not: flow through
the gate after it builds up in the bin. A vertical screw feed was tried,
but was unsuccessful. The gate has been enlarged and now a truck can
load, make a short trip, and return to be loaded again without trouble.
If the truck does not return shortly, however, the bin will clog. The
conclusion is that bins should have straight sides and a live floor. A
common ensilage wagon with such a conveyor floor has been tried with
success in an experiment.
Windrow Maintenance. Although the windrow turning machine success-
fully mixes and aerates the composting refuse, structural and mechanical
troubles have caused it to have considerable downtime, this being only the
second such machine ever built by the manufacturer.
The machine as delivered tended to spread the windrows. The addition
of teeth to the rotor and changes in their inclination to the center im-
proved the capability to maintain the shape of a windrow. A vexing trouble
was the frequent breaking of the drive chain. Overheating of fluid in the
hydraulic transmission resulted in failure to transmit sufficient power.
In the spring of 1968, the manufacturer had a mechanical engineer
design some improvements and sent a mechanic to the plant to make modifi-
cations. Work on the rotor teeth resulted in a machine capable of shaping
windrows newly laid down by the dump trucks. A stronger drive chain with
an improved idler sprocket arrangement was installed. The hydraulic drive
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system was improved including cooling of the fluid, some repairs were
made to the rotor, and the chassis or frame was somewhat strengthened.
In August 1968, a shaft in the gear train broke on two occasions.
Since the motor produces over 100 horsepower (BHP 122 by specification)
and the reducing gear has a nameplate rating of 18 horsepower, TVA
operations staff installed a torque limiter to protect the gear train.
Despite the torque limiter, gear train troubles have persisted. Some
motor troubles were experienced but these had nothing to do with the design
of the turner.
In December, the axle and king pin of one of the rear (steering) wheels
broke. This was expected due to the light construction and the stress put
upon it by an unsophisticated steering arrangement. The steering has been
improved by the TVA and the stronger king pins installed.
After the modifications made by the manufacturer in April 1968, the
machine moves over the ground at 0.27 miles per hr instead of the 4 miles
per hr claimed by the manufacturer. This speed is not appreciably changed
in working through a windrow and the machine appears to be able to aerate
about 500 tons of compost per hr. Even at this slow rate, it is capable
of turning the 34 windrows in 4 to 5 hr. Rarely would it be necessary
to turn all windrows on the same day.
During composting, the windrows tend to slump. To maintain a desired
windrow cross-section, they must be reshaped. Before turning, the margin
or foot, where the side of the row meets the ground, must be picked up
and placed on top or at the end of the windrow to assure that this part
of the material will be subjected to the heat generated within the central
mass.
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Windrows must be kept at 50 to 60 percent moisture content at least
until the 28th day. If they become too dry, they must be wetted and
turned. Should they become too wet, turning can help to dry them. In
the summer of 1967, wet weather gave some trouble. The summer and fall of
1968, were much drier than were these seasons in 1967. Added to this,
Johnson City suffered a severe water shortage and asked users to practice
conservation as far as possible. The watering of windrows was cut to a
minimum and by the end of September, the use of domestic water for the
complete daily washdown of the plant was discontinued. Portable irrigation
pipe and a portable pump were brought in from a nearby TVA installation.
The pump was set up near the plant on the bank of a creek entering the
Watauga River and this supply was used for washing down operations. The
city put a new filtration plant into operation in mid-1969 and there is
now an ample supply of water.
Curing and Drying. As mentioned above, the water content of the
digesting refuse is kept between 50 to 60 percent by wet weight throughout
the first 28 days. By the 42nd day, the moisture content is usually
between 40 and 50 percent. Trouble has been experienced in air drying
this compost to the 25 to 35 percent moisture content desired for screen-
ing, regrinding, and final disposition. Except in very dry weather, the
2-week storage under cover of the curing shed does not accomplish this
moisture reduction. In wet weather, the moisture content can be static
for long periods. In dry weather, better results have been obtained by
leaving windrows uncovered on the field exposed to the sunlight. Experi-
ence indicates that for commercial production of compost in a climate
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similar to that at Johnson City, mechanical drying equipment may be de-
sirable.
Screening and Grinding. In the summer of 1968, regrinding was done
-»
in the hammermill originally installed for grinding raw refuse. No screen-
ing was done. In February 1969, a mill procured for regrinding and the
vibrating screen were installed. The winter had been wet and extreme
difficulty was experienced in obtaining material dry enough to screen or
regrind. It was not until late April that compost was dry enough for real
testing. None had reached the favorable moisture content of 25 percent.
The use of compost in agriculture is seasonal, in fall and spring.
It appears that compost will have to be screened and reground in late
summer and stockpiled for fall and spring use.
The compost as taken from the field is still quite hot but has been
reduced to an inoccuous, earth-like material with no objectionable odor.
The composting activity still goes on but at a slower rate. The heat is
dissipated slowly from the inner mass of stockpiles, but is reduced.
Drying reduces microbial activity and further enhances cooling. Decom-
position is not complete, but for many uses, it has reached a practical
point in large-scale composting.
Although the vibrating screen and a compost grinding mill were in-
stalled in February 1969, operating troubles and dry difficulties have
prevented a full evaluation of this phase of the operations.
The compost is first screened and that material which does not pass
through the screen is ground and then recycled to the screen. Considerable
trouble was experienced due to blinding with the 1/4-in. and 1/2-in. woven
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wire mesh screens first installed. A perforated plate screen with 7/16-
in. openings is now being used. This screen will pass about 50 percent
of fresh compost when the moisture content is between 30 and 35 percent
by weight. Production is 1 to 3 tons per hr, much less than the 10 tons
per hr expected.
The hammermill installed for grinding compost has proven inadequate
and has experienced excessive hammer wear. A set of hammers furnished
with the mill lasted for only 8 hours grinding at the rate of about 2 tons
per hr. Because of the excessive cost of replacing or rebuilding the
hammers furnished with the mill, hammers fabricated from strap steel are
now used and discarded when worn. About 80 tons are ground between changes.
Because of the disappointing performance of the small hammermill,
consideration has been given to replacing it with the Williams hammermill
formerly used for grinding refuse. This mill has shown a capability of
grinding more than 10 tons per hr of compost. A rotary, drum-type screen
is being considered to replace or supplement the vibrating screen.
Fly Control. On June 20, 1967, it became evident that flies were a
problem.
Through the Regional SWP Chief, Region IV, an inspection by an entomo-
logist of the National Communicable Disease Center was arranged. The
Division of Health and Safety, TVA, also arranged for a TVA entomologist
to visit the plant. It was the opinion of these two entomologists that
although flies were breeding on the windrow field, the greater number had
come to the plant in the refuse as eggs, larvae, and pupae. In the several
days that it takes for a windrow to reach an elevated temperature, eggs
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hatch, and larvae migrate to suitable places for pupation. After windrows
heated up and were turned twice a week during the first 14 days, breeding
was lessened because of the heat destruction of eggs and what breeding appeared
occurred mostly at the "toe" where turning is less efficient and temperature
is low.
Before the inspections by the entomologists, the receiving and process
buildings had been sprayed with a pyrethrum-piperonly butoxide space spray
and Dibrom in solution had been used on the walls and on the windrows.
Application was by a gasoline powered sprayer. Only partial control was
obtained.
The CDC entomologist recommended Dimethoate in an emulsifiable con-
centration for space spraying and as a mist or fog in the windrow area to
kill adults. For larvae, Dimethoate wettable powder suspension was recom-
mended for a residual on the walls of the receiving and processing buildings.
At the receiving building, larvae could be seen migrating from fresh refuse.
He further recommended that Dimethoate wettable powder be incorporated into
the ground refuse before it was laid down in windrows. This material was
obtained and tried as a residual and a mist. The equipment on hand did not
create a mist of the magnitude necessary and a spray was applied directly
to the windrows. Some abatement was accomplished but flies continued to be
a problem until cold weather set in. The recommendation for adding the
insecticide to the ground refuse was not followed because of the unknown
effects upon the flora carrying on the composting and upon the pathogen
survival study.
The inspecting entomologists pointed out the fact that the once-weekly
collection in Johnson City was related to the large number of larvae in
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every stage of development found in the incoming refuse. In their opinion,
two collections a week would probably aid in the control of flies at the
plant.
On July 5, the first significant fly population of the summer of
1968 was observed at the plant. Using a Dynafog Model 40 gph nonthermal
fogger or mister and an emulsion of 12 gallons of 23.4 percent Dimethoate
emulsifiable concentration in 38 gallons of water, control was effected.
This dosage is equal to the recommended 6 gallons of 50 percent Dimethoate
EC in 50 gallons of water. The speed of application was 4 miles per hr
and it was found that only the four youngest windrows on the field needed
fogging. The dosage was later reduced to 8 gallons of concentrate in 42
gallons of water with equal control being accomplished.
The receiving building and the apron were sprayed with a Dimethoate
emulsion for the residual effect. Although fly larvae could be seen mi-
grating from fresh refuse received at the plant, very few appeared to
pupate. On the composting field, there was some breeding of flies in the
toe of the windrows. This material is now picked up with a payloader and
placed on the top of a windrow or at the end before each turning.
Interviews with county agriculturists and health officials disclosed
that fly populations had been abnormally high on the refuse dumps in
nearby Elizabethton and Jonesboro and in dairy barns in the summer of 1967,
in contrast to abnormally low populations in the summer of 1968. The
rainfall for the area in the period July through September in 1967, was
11.14 in. (normal being 11.97 in.) with 19 consecutive days of rain in
July. In 1968, the precipitation for the area was 6.14 in. with a
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comparatively dry July. The experience of 1968, therefore, did not show
i
to what extent the controls practiced would have been effective in 1967.
In the period July through September in 1969, the rainfall in the
area was 14.60 in., as compared .to the normal of 11.97 with 8.18 in. in
July mostly occurring as thundershowers followed byr.sunlight.- At the plant,
where a rain gauge was being maintained, the rainfall was 9.65 in., with
the July precipitation well below that ,for the area. At no,.time during-. .
that summer did flies, become a problem, indicating- that the control measures
described above appear efficient.
Removal of Plastics and Glass. Plastics, particularly plastic film,
present a problem. Shreds of plastic film persist through composting and
are carried from the windrows by the wind, causing an unsightly appearance
of the grounds. Regrinding and screening reduce the size and amount of
the shreds to where they are unobjectionable in the finished product..
As it would be advantageous to remove plastic film before the refuse-
sludge mix goes onto the field, TVA has conducted experiments for film.re-
moval. Several arrangements of apparatus have been tried, using the prin-
ciple of separating the plastic film from the ground refuse solely by air
currents. Although these showed promise, a significant amount of film has
not been removed in this way.
Glass .particles are objectionable if they are not ground fine enough
or if sharp pieces remain after grinding. At Johnson City, when a rasper
is used, glass is not reduced to fine particles as it is in the two or
more stages of hammermill grinding used in most other plants.
Trials of a drum-type ballistic separator did not show sufficient
removal of glass. This apparatus consisted of a revolving drum on which
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the ground refuse falls, the glass and other dense materials being bounced
off with a trajectory different from that of the lighter organic materials.
TVA also unsuccessfully experimented with an apparatus consisting of
a rotating cone on a vertical axis, mounted inside a cylindrical tank.
The theory of operating this apparatus was that the refuse falling on the
cone, which had an apex angle of about 152 degrees, would be slung off.
An attempt would then be made to collect the glass and other dense particles
which bounced off the wall of the tank at a trajectory different from that
of the organic material. Beneath the cone, suction was to be used to
remove plastic film loosened from the stream of refuse by the motion
imparted by the cone.
PROJECT STUDIES AND INVESTIGATIONS
Composting Process Studies
Temperature Studies. In the first year of operation a considerable
body of information was accumulated on temperatures attained in the composting
refuse. Readings were taken with a portable single probe thermistor type
telethermometer. Figures 20, 21, 22, 23, and 24 show the results of
observations on 152 windrows at the 1-1/2-ft depth over the period June 20,
1967 to June 14, 1968. Temperatures over 140 F were recorded in all
series for a number of composting days. For the series of windrows 1 C
through 34 C, which spanned a period of very cold weather in January and
February 1968, a shorter period of high temperatures was observed than
for the other series of observations.
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160
150
140
130
.120
110
100
Windrows 1 - 44
June 20, 1967 - October 16. 1967
10 15
20 25 30
COMPOSTING TIME (DAYS)
35
40
45 50
Figure 20. Average temperatures at the 1-1/2-ft depth in windrows 1 thru 44.
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160
150
140
120
110
100
Windrows 1A - 34A
August 29, 1967 - November 28, 1967
10 15 20 25 30
COMPOSTING TIME (DAYS)
35
40
45
50
Figure 21. Average temperatures
at the 1-1/2-ft depth in windrows 1A thru 34A.
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N3
160
150
140
130
120
110
100
go
0 5
76°F
1 Day
Windrows IB - 34B
October 16,1967 - January 19, 1968
10 15
20 25 30
COMPOSTING TIME (DAYS)
35 40 45 50
Figure 22. Average temperatures at the 1-1/2-ft depth in windrows IB thru SAB.
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160
140
120
100
80
Windrows 1C - 34C
December 4, 1967 - April 1, 1968
15 20 25 30
COMPOSTING TIME (DAYS)
35
40 45
50
Figure 23. Average temperatures at the 1-1/2-ft depth in windrows 1C thru 3AC.
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-J
.p-
o.
s
160
140
120
100
80
60
40
6 Windrows
March 6 - June 14, 1968
10 15 20 25 30
COMPOSTING TIME (DAYS)
35
40
45 50
Figure 24. Average temperatures at the 1-1/2-ft depth of six selected windrows.
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In the period April 26 through June 26, 1968, continuous temperature
observations in a windrow were made with a YSI 12-point thermistor
temperature recorder. The recorder monitored each point for 5 min10
points within the windrow, one point for the ambient temperature, and a
point for a register mark. The instrument cycled the 12 channels once
every hr, recording about 11,000 points for the 42-day composting period.
Temperatures were recorded at depths of 5, 13, 23, 32, and 41 in. at two
stations 10 ft apart. The windrow height was 45 in.
The first 11 days of observations at Station 1 at various depths are
shown in Figure 25. Station 2 showed a similar pattern of data. In this
period the windrow was turned just before inserting the thermistor probes
and again on the 4th, 7th, and llth day. Immediately after a turning the
windrow has a uniform temperature, after which the various depths reach
different temperatures. This results in three groups of data over the
period illustrated. Figures 26 and 27 show the temperatures recorded
during the period 22 to 28 days for several depths for the two stations.
Figure 28 shows the curve for the 22- and 32-in. depths at Station 1 over
42 days. Station 2 exhibited a similar pattern. Breaks in the curve show
points of turnings. Interior temperatures change rapidly during the first
2 weeks of composting after which the interior temperatures show no great
fluctuations. Surface temperatures, however, vary considerably during the
entire composting period, depending upon season and weather conditions.
In the period November 4 through December 30, 1968, temperatures
were continuously recorded for another windrow at two stations. Figure 29
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70
60
50
40
30
T I I I I I I I I I T I I T
,(140° F)
14" Depth jfi
/&^- /
_/A >-"
! X
vx
^ -^ x 32" Depth
I
M = Midnight
N = Noon
AMBIENT TEMPERATURE
I 1 I I
AGE (days)
Figure 25. Temperature profiles of a selected windrow during the first 11 days of
composting.
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CJ
o
70
60
50
40
30
20
10
I I
22" Depth"
5" Depth
22 M 23 M
24 M 25
AGE (days)
26 M
27 M 28
Figure 26. Continuous temperature record of windrow 17E, 22nd to
day (Station 1).
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70
60
50
40
30
20
10
5" Depth
I
M 22 M 23 M 24
M 25
AGE (days)
M 26
27 M
28
Figure 27. Continuous temperature record of windrow 17E, 22nd to 28th
day (Station 2).
78
-------
VO
50 10 -I
32 0
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
AGE (DAYS)
32 33 34 35 36 37 38 39 40 41 42
Figure 28. Temperature profile of windrow 17E.
-------
oo
o
This curve is constructed from the
average of temperatures from
two stations.
14-10
8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33
AGE (DAYS)
Figure 29. Temperature profile of windrow 17H.
-------
shows the curve constructed from the averaged readings at mid-depth at the
two stations over 42 days of composting. Ambient temperatures were low,
reaching 5 F. The profile for this windrow, however, did not show the
depressed temperatures exhibited in Figure 23. Figure 30 shows the
relationship of position to temperature at various locations around this
windrow at a depth of 8 in. and at mid-depth in the period of 31 to 35
days of composting. The higher temperatures in the upper parts of a
windrow and the difference for the south and north sides are to be noted.
Conclusions to be drawn from these detailed observations of temperature
are:
1. Temperatures vary with depth in all windrows. Temperatures
above 140 F (60 C) are reached and maintained for significant
periods-of time in the inner mass of windrows.
2. These variations are more pronounced early in the composting
cycle.
3. Immediately after turning, the temperature at all channels
were found to be within 3.6 F (2 C) of one another.
4. After a turning, windrows quickly return to the temperature
existing before the turning (Figures 25 and 28).
5. Excepting the outside 8 in. of material, weather conditions
appear to have little effect on the windrow temperatures.
6. The surface temperatures at the apex of the windrows were
often observed to be as high or sometimes higher than the
mid-depth temperature.
81
-------
op oc
140 60
104 40
68 20
uj 32 0
Mid-depth
Southside
Probe 1
Probe 6
Probes 3 & 5
(average)
Probes 2 & 4
(average;
N M
31 DAYS
86 30
50 10
14 -10
8" Depth,mid-height
8" Depth, bottom
Ambient
Probes 2 & 3
(average)
Probes 4 & 5
(average)
33
M In M
34 35
Figure 30. Temperature profiles at the 8"
depth of windrow 17H (Nov. 4, 1968-Dec. 30, 1968),
82
-------
7. The temperature on the outside 8 in. of the windrow
decreased from the apex to the ground. This is considered
due to convection currents rising from the bottom to the
top inside the windrow. It is interesting to note that these
may aid in the aeration of the compost.
8. The surface temperatures on the north or shady side of
windrow 17H were observed to be lower than those on the south
or sunny side.
Effect of Windrow Turning Frequency. Ten windrows were studied for
the effect of various turning schedules. The number of turnings during
the 49-day cycle for these windrows was 0 to 14. Temperatures were taken
once a week throughout the test period. The relative degree of decomposition
attained was judged on the basis of appearance, odor, and the amount of
carbohydrate reduction.
The present windrow turning schedule is twice a week for the first
3 weeks and once a week thereafter. This routine was based on the higher
temperature pattern reached with this schedule, compared with the greater
cost of turning more often with lower temperatures resulting. The minimum
number of turnings which will result in satisfactory compost is once a
week for the entire cycle.
It was found that the best decomposition in the 49 days was obtained
by turning the windrow twice each week throughout the cycle. This windrow
did not show as good a temperature pattern as the one turned on the present
schedule (which attained the highest overall temperatures). It did,
however, attain temperatures higher than any windrows turned fewer times.
83
-------
The windrow on the present schedule showed the next best decomposition
and attained the highest overall temperatures.
Other windrows, turned less frequently, showed decreasing temperatures.
After turning these windrows, however, the temperatures rose 20 to 30 F
within 5 days and then declined. The temperature in the windrow not turned
rose to about 130 F in 14 days, then dropped steadily, throughout the remainder
of the test.
Effect of Composting Sewage Sludge with Refuse.' Assuming that:
1. a population generates refuse at the rate ,of 5 Ib per day per
capita (a figure near the national average) and that it is received
at the compost plant containing 35 percent moisture by wet weight,
and
2. that raw sewage sludge solids of the same population are
generated at 54 grams or 0.119 Ib per capita per day, dry weight,
and
3. That rejected noncompos tables will amount to 26 percent of the
incoming refuse, .
the percentage of dry compostable material (sludge and "picked" refuse)
represented by the dry sewage sludge solids is:
100 x n 11Q. /c' - ^7T =4-7 percent
0.119 + (5 x .65 x .74)
or about 5 percent. This is the proportion of sludge to refuse to be
normally expected from the same population producing the refuse.
At Johnson City, although the per capita production of refuse is lower
than average, the available sludge handling equipment limits the amount
84
-------
added to refuse to between 3 and 5 percent of the total dry weight of
the refuse-sludge mixture for normal operations. Obtaining a uniform
sludge content has not been possible. -
Using temperature as a parameter of composting activity, three pairs
of windrows were closely observed. In each case a pair consisted of one
windrow containing raw sludge and one of refuse alone. Figures 31, 32,
and 33 show the temperature profiles for pairs having windrows containing
2, 3-5, and 9 percent sludge solids, respectively. Temperatures were
taken at a depth of 1-1/2 ft. The conclusion drawn is that the amounts
of sludge being processed, and even up to 9 percent sludge solids, had no
significant effect on the temperatures reached in composting.
Figure 34 shows the pH profiles of a pair of windrows, one of which
contained 2 percent of raw sludge solids by dry weight. No significant
effect of sludge can be observed. Figure 35 shows the average pH values
at various ages for a number of windrows with 3 to 5 percent raw sludge
solids and a number of windrows without sludge. Figure 36 shows curves
for a pair of windrows, one of which contained 9 percent raw sludge solids.
Here a difference in the pH of the masses was observed, the value being
higher in the earlier stages in the windrow containing sludge. The effect
of the addition of sludge solids in amounts greater than would normally be
the case is treated below in a discussion of a special study.
Assuming 0.85 percent nitrogen in fresh ground refuse and 3 percent
in sludge solids, the use of sludge in the amount of 5 percent of the
85
-------
00
£ 120 -
o>
ex
I I I I
Windrow 18D, without sludge
Windrow 17D, with 2% sludge solids
&0
20 25 30
Age of Windrow in Days
Figure 31. Temperatures in windrows with 2 percent sludge solids (1-1/2-ft depth).
-------
oo
180
160
140
2 120
0>
100
80
60
I I I I I I
340, without sludge
Windrow IE, with 3-5% sludge solids
I
I
I
10 15 20 25 30
Age of Windrow in Days
35
40
45
\
50
Figure 32. Temperatures in windrows with 3-5 percent sludge solids (1-1/2-ft depth).
-------
00
00
180
160
. 140-
£D
O.
-------
9'
oo
Windrow 34D, without sludge
4 .'I
20 25 30
Age of Windrow in Days.
Figure 34. pH of windrows with 2 percent sludge solids (1-1/2-ft depth)
-------
10
I I
Without sludge
-With sludge (3-5 per cent raw sludge
solids by dry weight)
14 windrows with sludge
20 windrows without sludgei
I
I
I
I \
10 15
20 25 30
AGE OF WINDROW (days)
35 40 45 50
Figure 35. Average pH of windrows with 3-5 percent raw sludge
solids (1-1/2-ft depth).
90
-------
Windrow 16E, without sludge
r ^
1
L
I
10 15 20 25 30
Age of windrow in Cays
35
40
45
50
Figure 36. pH of windrows with 9 percent sludge solids (1-1/2-ft depth).
-------
sludge-refuse mixture (dry solids basis) would result in a finished compost
containing 1.05 percent nitrogen. This calculation assumes that the loss
in nitrogen and the loss in weight from sludge during decomposition is
similar to the loss from refuse.
The addition of sludge in the quantities used does not significantly
add to the quality of finished compost as gauged by the nitrogen content.
At Johnson City, actual observations show the compost made of refuse and
I
sludge to have a nitrogen content averaging about 1 percent by dry weight.
Although the carbon to nitrogen ratios of refuse and compost are
discussed under a subsequent heading, the observed effect of sludge solids
on this important relationship should be mentioned here. The initial C/N
ratios of a group of seven windrows containing 3 to 5 percent sludge
solids showed an average of 44.4. At 42 days of composting a similar
group of five windrows showed an average .of 33.9 and at 49 days two of
these showed an average of 31.9. A special test windrow prepared without
sludge showed an initial ratio of 44.4 and at 49 days a ratio of 33.0.
The observations of the rate of heating, the pH profile, and the C/N
ratios lead to the conclusion that the addition of sludge in the amounts
which would normally be available has no appreciable effect on the composting
process for refuse similar to that collected in Johnson City. For refuse
with a low organic content, the effect of the addition of this amount of
sludge may be greater.
Several experiments were made with sludge in appreciably greater
quantities than would normally be available.
92
-------
Sludge solids were added in the amount of 12 percent of the dry
weight to a portion of a windrow. The heating pattern was observed to
be normal. The initial nitrogen content of the control was 0.79 percent
and that of the test portion 0.86 percent. The 49th day nitrogen
content was 0.97 for the control and 1.02 for the test material.
Despite the low nitrogen content in these observations, the C/N
ratio at 49 days was 25.4, lower and more favorable than normally
observed at Johnson City. The texture and appearence of the compost
was improved.
Another windrow was prepared with portion containing 33 percent in
raw sewage solids from a neighboring city which uses a vacuum filter for
dewatering. Initial nitrogen content was 1.64 percent for the test
portion and 0.75 for the control portion. The final nitrogen content
for the sludge-refuse compost was 1.58 percent and 0.88 for the control.
Figure 37 shows that the temperatures rose along with those of the control
for the first week, dipped, and then again reached those of the control
in three weeks. Figure 38 shows the pH profiles of the test and the
control. The initial pH was high at 9.0, then fell and gradually rose to
well above that of the control at the same age.
The chemical oxygen demand (COD) of the control and the test portion
were:
Day
1
28
56
Test
940 mg/g
710
590
Control
890 mg/g
775
670
93
-------
VO
160
150
140
130
120
110
Control Windrow without
added sludge.
Wiindrow 30N containing 34% raw sludge solids, dry weight
2 3. '4
AGE (WEEKS)
o
Figure 37. Temperatures of a windrow with 34 percent sludge solids (1-1/2-ft depth)
-------
9.0
8.0
7.0
6.0
Control windrow without added sludge
Windrow 30N containing 34% raw sludge solids, dry weight
5.0
4.0
0 1
3 4
AGE (WEEKS)
Figure 38. pH of a windrow with 34 percent sludge solids
(1-1/2-ft depth).
95
-------
The rates of decomposition did not differ greatly as measured by the
reduction in COD. The final product benefited in nitrogen content from
the sludge but some nitrogen had been lost in the process. The compost
had a rich appearance.
A windrow was prepared with 50 percent partially digested sewage
sludge solids taken from a dried up sludge lagoon. The temperature profile
was similar to that of the control to the 2-week point after which
temperatures of the test portion lagged. Satisfactory temperatures were,
however, attained. The pH of the mass of test material showed a departure
from that of normal refuse on composting. No nitrogen determinations were
made (Figure 39).
It is concluded that sewage sludge solids can be successfully composted
with municipal refuse. In the amounts normally available, the proportion
of sewage solids to refuse will not greatly affect the rate of decomposition
or the quality of the finished compost as measured by nitrogen content.
Where greater amounts are available, the nitrogen content and appearance
of the compost can be improved.
Effect of Adding a Nitrogen Compound to Composting Refuse. Under the
supervision of the TVA agriculturist, urea-ammonium nitrate containing
about 27 percent nitrogen was incorporated into composting refuse in several
tests. The windrows were kept under observation for temperature as a
parameter of composting activity and the chemist performed the chemical
tests and the moisture determinations. The observed effects are discussed
as follows:
96
-------
160 I
1 AI
Temperature of control
Temperature of windrow
containing sludge
t
pH of control
10.0
9.0
8.0
110
7.0
pH of windrow containing sludge
Windrow with 50% sludge solids from a
sludge lagoon, dry weight
Control containing no sludge
100
I I I L
6.0
5.0
14,0
Figure 39. Temperature and pH of a windrow containing 50 percent
sludge solids (1-1/2-ft depth).
97
-------
Test 1. Enough urea-ammonium nitrate was added to a section
of windrow 8G on day 1 to bring the nitrogen content from 0.94 to
3.5 percent by dry weight of the mass. This windrow contained
raw sewage sludge and had a moisture content of 62.1 percent by
wet weight. The second section was left as a control. It was
immediately noted that the pH of the test portion was 8.2 against
the normal 6.6 in the control. The pH did not thereafter drop to
the low normal obtained in the control. At the llth day, when
the control was at pH 5.00, the test row showed a pH of 7.55.
By the 14th day the test row pH was over 8 while the control was
barely over 7. After 21 days the two remained close together
with a pH slightly over 8. This change in pH appeared to be
linked with the microbiological activity as the temperature in
the test row lagged well behind and never reached that of the
control.
Table 9 tabulates the data and Figure 40 shows the temperature
curves. Decomposition was slowed and although the test windrow
contained more nitrogen than did the control at 42 days, there
had been a significant loss.
Test 2. Urea-ammonium nitrate was added to a section of
windrow 17G to bring the initial nitrogen content from 0.93 to
2.46 percent by dry weight. This windrow contained raw sewage
sludge. Again the initial pH was elevated as in Test 1 but by
the end of 8 days was nearer that of the control than was
observed in the case of Test 1. By 18 days the control reached
a pH of 7 but the test portion was above 8. As in Test 1, the
98
-------
TABLE 9
Age in Days
0
1
4
5
8
11
14
15
18
21
28
34
35
39
42
Age in Days
1
3
7
8
10
11
14
17
18
21
28
35
38
42
COMPOST
FORTIFIED WITH NITROGEN
(Urea- Ammonium Nitrate)
Test 1
% Nitrogen
Control Test
0.94 3.50
3.47
3.68
3.11
2.70
1.14 2.75
Test 2
% Nitrogen
Control Test
0.93 2.46
1.01
2.34
2.51
2.04
1.85
1.82
- Windrow 8G (8/8/68)
Turning % Moisture
No. Control Test
61.1 62.1
1
2
3
4
5 43.2 43.2
6
7
8
9
10
11 49.6 38.6
- Windrow 17G (8/20/68)
Turning % Moisture
No. Control Test
1
2 72.3 72.3
3
4
5 58.5 57.0
6
7
8
9
10
Control
6.60
4.70
4.68
5.00
7.08
8.50
8.30
8.22
7.90
Control
6.22
4.60
6.00
7.00
PH
Test
8.20
7.10
6.08
7.55
8.08
8.35
8.25
8.17
8.18
PH
Test
8.10
5.30
7.90
8.40
1.52
99
-------
160
150
140
130
120
110
Control
Nitrogen added by dry^weight.
8/8/68 to 10/8/88
^ 0
10
20
30
40
50
60
.160
150
140
130
120
110
Control
TEST 2
Nitrogen added by dry weight.
8/20/68 to 10/7/68
0
10
20
30
40
50
60
AGE (DAYS)
(All windrows contained 2 to 5 percent raw sludge solids by dry weight)
Figure 40. Temperature of windrows containing urea-ammonium
nitrate.
100
-------
temperature of the test portion lagged and was not falling at
the rate of the control at 42 days. As in Test 1, nitrogen was
lost and microbiological activity was slowed as indicated by
the temperature (Table 9 and Figure 40).
Test 3. In this test the urea-ammonium nitrate was added
on the 21st day of composting in two windrows, 11M and 12M.
Neither of these contained sewage sludge. In 11M, where the
nitrogen content was raised to 2.35 percent by dry weight, the
pH was immediately elevated and the temperature of the windrow
dropped radically. By the 26th day the temperature had risen
to about 150 F and was about normal thereafter. The final
nitrogen content was 1.41 percent, showing a loss. In windrow
12M, the nitrogen content was brought up to 4.63 percent by dry
weight. The pH reacted similarly to that of 11M but the
temperature fell and remained low. The final nitrogen content
was 3.35 percent, showing a loss (Table 10 and Figure 41).
Nitrogen had been added in an earlier test to windrow 1H on the 23rd
day of composting, raising the nitrogen by about 1 percent of the dry weight
of the mass. This windrow had reacted similarly to windrow 11M and 12M.
It is concluded from these tests that the addition of urea-ammonium
nitrate in the amounts used appear to inhibit microbiological activity and
result in a loss of nitrogen.
Effect of Adding a Buffering Agent to Composting Refuse. The pH of
fresh refuse or refuse containing normal amounts of sewage sludge is about
6 and may drop to between 4 and 5 soon after being laid down for composting.
101
-------
TABLE 10
COMPOST FORTIFIED WITH NITROGEN
(Urea-Ammonium Nitrate)
Test 3 - Windrow 11M (7/10/69)
Percent Nitrogen
Age in days Content pH
20 6.8
21 Nitrogen added 2.35 8.1
24 - 8.0
28 7.8
35 7.8
42 1.41 8.1
Windrow 12M (7/11/69)
20 6.2
21 Nitrogen added r 4.63 8.3
24 8.2
28 - 7.9
35 8.0
42 3.35 8.2
102
-------
170
Urea-NH4N03 added,
1 1
7/31/69
1 1 1
160
5 Nitrogen at this point after
adding UAN, 2.4% by dry weight
150 -
Final nitrogen content,
120
Nitrogen at this point after
adding UAN, 4.6% by dry weight
Finalinitrogen content,
3.
140
130 _
AGE (weeks)
Figure 41. Temperature of windrows with urea-ammonium nitrate.
103
-------
Often in farm and gardening practice crushed oyster shells, crushed
limestone, or even lime is added to raise the pH at the start to accelerate
decomposition. At Johnson City, three trials were run using limestone.
In the first trial, 3/16 in. crushed limestone was added in the amount
of 21.2 percent of the total dry weight of the refuse-sludge-limestone
mixture. The pH was raised initially to 7.5 but fell to 6 by the 16th
day, after which it rose slowly to 8.5 on the 42nd day. * The control was
also atypical with respect to pH but exhibited the normal immediate "drop
from an initial 6 to 5.2 in 3 days after which it slowly rose to 8.5 on
the 42nd day. The temperature of the test windrow rose more sharply than
did that of the control but dropped after 10 days due to a deficiency of
moisture. Water was added and the temperature rose again but not as quickly
as would have been expected. The data for pH and temperature are shown
in Figures 42 and 43.
Limestone dust was added at the rate of 9 and 16 percent by dry weight
to two portions of a test windrow prepared from fresh refuse only. Figures
44 and 45 show the pH and temperature profiles of the test and control
sections. The effect in each case was to raise the initial pH and both
test sections showed an atypical rise and dip in pH in the first week.
Again the attainment of high temperature was accelerated.
Analysis for nitrogen showed the following:
104
-------
160
150
140
ra
o>
1.30
120
110
Control
Wjndrow 21-L containing 3% to
sludge solids and 21% Crushed
limestone, 3/16 inch size, by
dry weight - 6/6/69
AGE (WEEKS)
Figure 42. Temperatures of windrows with limestone and sludge added.
-------
9.0;
8.0
7.0
6.0
5.0
4.0
Windrow 21-L containing 3% to
sludge solids and 21% crushed
Iimestone, 3/16 inch size, by
.dry weight - 6/6/69
0
AGE (WEEKS)
Figure 43. pH of windrow with limestone and sludge added.
-------
130
120
110
Windrow 26-M composted with lime-
stone dust added by dry weight to
sections as indicated:
O None (control)
8/4/69
3 4
AGE (WEEKS)
Figure 44. Temperature of windrow with limestone dust added.
-------
g.o
8.0
O
00
6.0
'5/0
A
7.0'
Windrow 26-M composted with lime-
stone dust added by dry weight to
sections as indicated;
None (control)
4.0
' 3
AGE (WEEKS)
!5
Figure 45. pH of windrow with limestone dust added.
-------
Nitrogen content by % of dry weight
IT. , AJJ.^. 0 day 21st day 49th day
Windrow Additives 3 J J
Test No. 1
Control
Test
Test No. 2
Control
Test
Test
3 to
Same
3/16
None
5% sludge solids 0.81
as above with 21.2%
11 crushed limestone 0.74
0.84 0.82
9% limestone dust 0.73 0.76
16%
limestone dust 0.64 0.61
1.02
0.57
0.96
0.66
0.49
Although the temperature rise was accelerated, there was a considerable
loss of nitrogen which resulted in a poorer compost. The results of these
field tests are similar to those of the laboratory tests conducted by the
University of California at .Berkeley.2
Effect of Composting Other Wastes with Refuse. The TVA agriculturist
obtained quantities of cow manure, paunch manure, aged poultry (chicken)
manure, animal blood, and pepper canning wastes for incorporation into
composting refuse to investigate the possibilities of this method of
disposal of such wastes and to see if the finished compost was improved by
addition of them. As with the windrows to which urea-ammonium nitrate was
added, temperature was used as the parameter of composting activity. Tests
with the several wastes are discussed as follows:
1. Cow manure, in an amount making it 15.4 percent of the mixture
of manure and refuse by dry weight, was added on day 1 to a section
of windrow 17N. No sewage sludge was incorporated in this windrow.
109
-------
The initial nitrogen content of the mixture by dry weight was
1.12 percent and of the control 0.80 percent. Final nitrogen
content for the composted mixture was 1.14 percent as against
0.93 percent for the control. Temperature was slow to rise,
reaching in 4 weeks what had been reached in -2 weeks by the
control (154 F). The pH of the mixture initially was lower
than that of the control, 4.4 to 6.2. The pH of the control
dipped then rose characteristically to nearly 8 in 2 weeks at
which time the mixture also had reached the same value.
Decomposition of the mixture in this proportion, as indicated
by temperatures, appeared to be slowed and the mixture would
have to remain on the field longer than refuse alone (Figure 46)
2. Paunch manure from a local slaughterhouse, in an amount
equal to 14.9 percent of the mixture by dry weight, was added
on day 1 to a portion of windrow 13G. This windrow contained
between 2 and 5 percent raw sewage sludge by dry weight. The
initial nitrogen content of the mixture was 1.22 percent against
0.97 percent for the control. The paunch manure itself contained
2.48 percent nitrogen by dry weight. The temperature curves for
the 42 days of composting were identical for the test and control
portions. The 42-day nitrogen of the test row was 1.26 percent
and of the control 1.04 percent. Figure 47 gives the temperature
curve.
3. Chicken manure, in an amount equal to 21.2 percent of the
mixture by dry weight, was added on day 1 to a portion of
110
-------
160
150
140
130
120
110
/ Control section,
^untreated
Windrow 17N, jnth
cow manure added
I 1 1 h
9.0
Contro I section,
untreated
8.0
7.0
6.0
5.0
Windrow 17N, with
cow manure added
I 1
AGE (weeks)
Figure 46. Temperature and pH of refuse composted with cow manure.
Ill
-------
170
160
150
140
130
120
110
No appreciable difference in curves of treated
and untreated material
Windrow 13G
Paunch manure added
O Control, untreated
8/15/68-9/26/68
15
20 25
AGE (DAYS)
30
35
40 - -45
Figure 47. Temperature of refuse composted with paunch manure.
-------
windrow 19G. The chicken manure had been made available to
the project on the occasion of a cleanout of droppings from a
local farm. A portion of it had undergone decomposition for as
much as 6 months. Its nitrogen content was 2..40 percent, similar
to that of paunch manure, and the initial nitrogen content of the
mixture was 1.37 percent and of the control 0.84 percent. The
raw refuse contained between 2 and 5 percent sludge solids.
Although the initial nitrogen content of the two portions was
not greatly different from those of the paunch manure test, the
test portion reached its maximum temperature more quickly than
did the control. On day 16 the test portion had reached 165 F
while the control showed only 150 F (Figure 48). In this
experiment the control did not act normally but the chicken
manure hastened the activity in this particular batch of
compost. The 42-day nitrogen content of the test portion was
1.25 percent against the 1.05 percent for the control.
The experiment was repeated with fresh chicken manure in
windrow 15N with a concentration of 20.1 percent. This windrow
contained no sewage sludge. Initial nitrogen content was 1.19
percent for the mixture and 0.73 percent for the control,, Final
nitrogen contents were 1.32 for the experimental portion and 0.99
percent for the control. 'The temperature of the portion containing
the chicken manure approximately followed that of the control to
about the third week when the profile for the test row fell below.
By four and a half weeks the test portion was about 12 degrees
113
-------
170
160
150
140
130
120
110
Windrow 19G with chicken manure added
T
/^Control, untreated
10
20 JO
AGE(DAYS)
40
50
Figure 48. pH of refuse composted with aged chicken manure.
114
-------
below that of the control. It then began to pick up and
at the end of 6 weeks was again approximately that of the
control. The pH of the mixture reached 8.8 when the control
had reached- 8. At 6 weeks the pH of the mixture was still
somewhat higher than that of the control (Figure 49). The
fresh manure and the composting mixture released large amounts
of ammonia which accounts for the high pH and the lower
temperatures observed.
4. Beef blood from a small slaughtering establishment was
added on day 2 to a portion of a windrow containing about 3
percent sewage sludge solids. The 40 gallons of blood,
weighing 354 Ib, contained about 110 Ib of solids. The mixture
of refuse, sludge, and blood contained about 1.3 percent blood
solids by dry weight. Blood is high in nitrogen, 10 to 14
percent by dry weight,1* and this rather small addition was
estimated to raise the nitrogen content of the windrow from
0.91 percent to about 1.0 percent.
The addition of blood appeared to retard heating, as
compared to the control portion, in the first 25 to 27 days.
After that, the test portion exhibited temperatures exceeding
those of the control (Figure 50). The 42-day nitrogen content
for the test portion was 1.25 vs. the 1.05 of the control. This
experiment showed that slaughterhouse blood can be composted
with refuse without trouble and may have some value in enriching
the compost. The experiment was not repeated due to the difficulty
in obtaining blood.
115
-------
Windrow 15N, with
chicken manure added
AGE (weeks)
Figure 49.
chicken manure.
Temperature and pH of refuse composted with fresh
116
-------
170
160
150,
140
130
120
110
Control, untreated
of windrow containing blood
10
15
20 25
AGE (DAYS)
30 35 40 45
Figure 50. Temperature of refuse composted with slaughterhouse blood,
-------
5. A batch of the wastes of a pimento pepper canning factory,
consisting of the pepper cores, rejected peppers, and skins,
was incorporated into a portion of a windrow of refuse
containing abput 3 percent sewage sludge solids on day 3.
The pepper waste represented 14 percent of the total dry
weight of the mix. The pepper wastes contained 2.82 percent
nitrogen on a dry basis and the initial nitrogen content of
the mix was about 1.1 percent. The temperature profiles of
the test and control portions of the windrow were identical
during the composting period. The final nitrogen content of
the test portion was 1.3 percent.
This test was repeated using pepper canning wastes in
the amount of 6.3 percent of the total weight of the mixture
of refuse and pepper wastes. The pepper wastes contained
2.68 percent nitrogen in this case and the refuse (control
portion) showed a nitrogen content of 0.89 percent. The initial
nitrogen content of the refuse-sludge-pepper mixture was 1.04
percent. Figures 51 and 52 show the temperature and pH profiles
during composting. The final nitrogen content (at 42 days) was
1.10 percent for the tes.t row and 1.01 percent for the control.
Effect of Covering a Windrow with Plastic Sheeting. Half the length
of a windrow was covered with plastic sheeting in April 1968 and the other
half was left uncovered. The plastic was removed for turning and replaced
immediately after turning. Temperatures were taken of both parts in the
center and near the surface at a depth of 4 in. Some of these data are
listed below.
118
-------
160
150
140
130
120
(Windrow 7N containing 3% sludge
solids and 6.3% pepper waste
solids by dry weight' - 8/26/69)
3 4
AGE (WEEKS)
Figure 51. Temperature of sludge-refuse mixture composted with pepper canning wastes.
-------
to
o
8.0
7.0
6.0
5.0
4.0
Test windrow
Control
Windrow 7N containing 3%_sludge
solids and 6.3% peppe'f waster
solids by dry weight - 8/26/69
3 4
AGE(WEEKS)
Figure 52. pH of sludge-refuse mixture^^mposted with pepper canning wastes.
-------
Age of windrow Covered Uncovered
in days
0
7
14
21
28
35
Center
65°
116°
125°
135°
137°
143°
At 4" depth
65°
114°
124°
133°
134°
140°
Center
65°
144°
145°
150°
149°
152°
At 4" depth
65°
139°
120°
112°
131°
135°
As can be seen from this tabulation, in the covered portion of the
windrow the temperatures in the center of the mass lagged substantially
behind those in the uncovered portion. .However, after 7 days the surface
temperatures were considerably higher in the covered portion due to the
greenhouse effect of the plastic. The pH of both parts was about the
same. The odors of both parts after turning were about the same, the
part under the plastic not being offensive.
The effect of plastic covering for fly control could not be evaluated
as the fly population at the composting plant was nil and remained so
through the period of the experiment.
Effect of Covering Windrows with Old Compost. In cold weather a
retardation of heating has been observed in the windrows. To evaluate the
usefulness of covering the new windrows with old compost, three windrows
were thus treated.
Windrow 14J was covered with a 12-in. layer of old compost for half
its length on zero day. The covered portion showed a steeper rise in
temperature at the interface between the old and new than did the control
near the surface. It reached 106 F in 3 days, while the control required
4 days to reach this temperature. At 5 days, the control had reached
121
-------
116 F against the 108 F of the covered portion. On the seventh day, the
control was at 112 F and the covered portion at 108 F. Thereafter they
both cooled, the control to 107 F and the covered portion to 98 F, by the
ninth day, showing need for a turning.
In the center of the mass, windrow 14J reached a higher temperature,
108 F, than the control by the third day. It thereafter became cooler.
The center of the control reached a temperature of 110 F in 5 days, 142 F
at 9 days, and then began to cool for lack of aeration.
Windrow 16J was covered similarly on the third day. On that day,
immediately after covering, the test portion showed 56 F and the control
48 F at the interface and surface, respectively. On the fifth day, the
uncovered portion had reached 118 F against the -test portion's 103 F. At
10 days, the control was at 102 F against the test portion reading of
104 F.
The center of the mass of uncovered portion of 16J was 13 F lower
than that of the test portion on the day they were covered. By the fifth
day, the test portion had reached 95 F against the 114 F of the control.
By the seventh day, the test portion was only 92 F at its center while the
control was at 135 F. Both cooled thereafter for need of a turning.
Windrow 13J was similarly covered on the seventh day. Starting at
4 degrees apart on that day, they both had reached about 120 F on the next
day at the interface. From there on, the covered portion showed an
increase in temperature at the interface to the fifteenth day^ when it was
at 131 F. The control showed only 109 F.
In the inner mass, the control steadily rose from 116 F to 151 F on the
thirteenth day while the test portion had declined from 114 F to 104 F.
122
-------
The ambient temperature during this period was about 32 F. All rows
were turned before being covered.
It is apparent from these studies that covering windrows at these
times has an adverse effect on the temperatures in the center of the windrow,
with no significant advantage being gained with surface temperatures.
This was observed when they were covered with plastic, and is apparently
due to preventing the windrow from "breathing" although the effect of the
cover in compacting the underlying refuse may also be a factor. Extrapolating
from the results of the windrow covered at 7 days, it appears that the
time to cover a windrow to achieve thermal kill at the surface is after
it has reached its maximum temperature (2-3 weeks). Such a procedure is
under consideration but will require investigation.
pH Observations. Observations of pH changes with age revealed the
characteristic curve as shown in Figure 53.
The pH showed an acid condition for the first week generally with some
values below 5.0. As the pH rose above 6.0 to a range of 7.5 to 8.0 during
the second week, the temperatures also increased. The pH leveled off in a
range of 7.8 to 8.5 for the rest of the composting and curing time.
Microbiological and Fly Population Studies
Bacteriological Statistical Experiments. A series of experiments was
undertaken by the microbiologist to determine the variability of the
bacterial population counts of compost samples due to the inherent heterogeneity
of the material itself.
Experiment 1. This experiment was performed to evaluate
variation due to error in laboratory procedure. Ten grams of
123
-------
N5
5 10 15 20
25 . 30
AGE (DAYS)
35 - 40. 45 50
Figure 53. Average pH in windrows 1A d 34A (1-1/2-ft depth).
-------
zero day compost were homogenized in a 100 milliliter phosphate
buffer (pH 7.2). Five 1 milliliter aliquots were removed from
this homogenate, each was serially diluted, and the appropriate
range of dilutions was incorporated into pour-plates of tryptone
glucose extract agar. Plate counts were made at 48 hrs. Results
were as follows:
Sample 1 229 x 10^ cells per ml of homogenate
2 243
3 249
4 248
5 233
average = 240 x 104 cells per ml of homogenate
Since cell distribution should theoretically be Poissonian, the
standard deviation should be ± 15.5 cells per plate of the average
count, if the laboratory technique is adequate. None of the five
counts exceeded this range.
Experiment 2. A set of five 10-gram samples was drawn from
a zero day windrow; each was homogenized in 200 milliliters of
sterile phosphate buffer. Plate counts were made on each of
the five homogenates. In addition, the fifth homogenate was
plated in triplicate to determine plating variation. A set of
five 5-gram samples was drawn from another zero day windrow,
homogenized in 100 milliliter aliquots of sterile buffer, and
plated as above. Results were:
125
-------
Sample 1 51 x 105 per ml homogenate for the five
2 65 10-gram samples
3 150 ;
4 137
5a 105
5b 126
5c 122
Std. deviation = ± 42 percent for samples l-5a
Sample 1 66 x 106 per ml homogenate for the five
2 49 5-gram samples
3 182
4 62
5a 42
5b 66
5c 28
Std. deviation = ± 73 percent for samples l-5a
The above experiments were repeated with 49-day compost using
the same experimental procedure. The results were as follows:
Sample 1 62 x 10^ per ml homogenate for the five
2 56 10-gram samples
3 71
4 33
5a 93
5b 80
5c 81 .
Std. deviation = ± 35 percent for samples l-5a
Sample 1 52 x 105 per ml homogenate for the five
2 32 5-gram samples
3 281
4 33
5a 30
5b 22
5c 25
Std. deviation = ± 140 percent for samples l-5a
126
-------
The value of determining the standard deviation in this regard
is that the range in which 67 percent of the sample counts should
fall is defined. It is clear from the limited data presented here
that choosing 10-gram samples would give a more accurate and
reproducible estimate of the actual cell counts than the choosing
of 5-gram samples. Samples of up to 200 grams were used in the
project laboratory at Johnson City.
Survival of Mycobacterium -phlei,. The Staff Microbiologist conducted
studies of the survival in composting of Mycobacteriim phlei. Strain 41
obtained from Dr. George Kubica, National Communicable Disease Center,
Atlanta, Georgia. This strain, which is rather thermophilic, was used
rather than MyGobacterium tuberculosis. A non-virulent strain of the
latter was concurrently being used in survival studies by another investigator.
During preliminary experiments in the project laboratory, attempts at
the isolation of MyoobaoteTiwn phlei. from seeded raw ground refuse samples
by classical published methods proved unsuccessful. Therefore, all
insertions were of necessity made with cultures grown on Lowenstein-
Jensen (L-J) agar slants at 45 C for 3 days. All insertions were prepared
in duplicate and inserted on either zero day or day 14 at depths of 2 in.,
mid-depth, and in the toe of the windrow. At selected time intervals, the
duplicate slants were removed from the windrows. Subcultures were made by
washing each slant with 0.5 milliliters of sterile phosphate buffer. The
buffer-cell suspension was then transferred to a new L-J slant and incubated
for at least 10 days at 37 C. Viable cultures would usually produce
detectable growth within 3 days. A total of 136 sets of duplicate sample
(224 tubes) was inserted into 12 windrows.
127
-------
Table 11 gives the findings. No samples inserted at mid-depth on
zero day or day 1 were found to contain viable cells after 14 days of
composting. For the insertions at the depth of 2 in., viable cells
were found after 49 days where the temperature reached only 92 F. In
other windrows none were found at compost ages over 21 days where temperatures
subsequently reached 118 F. Where temperatures reached 128 F or over at
the 2-in. depth, no viable cells were found. This condition was usually
obtained by the 14th day. For samples inserted in the "toe" of the windrow,
viable cells were found to the point at which temperatures reached 134-
136 F. In one case, viable cells;were found, at midrdepth at a temperature
of 138 F on the seventh day of composting. Samples retrieved at greater
ages were not viable.
From the data obtained in these studies it appears that temperatures
as low as 128 F are sufficient to kill M. phlei provided the time of
exposure is sufficient. Seven days at 128 F should be sufficient with
shorter times for temperatures over 130 F. Insertions were made under
artificial conditions due to the fact that they were slant cultures and
not directly exposed to 'the compost. Temperature, therefore, was the sole
factor in their destruction. Where proper mixing is practiced and temperatures
of 140 F or over are obtained, M. phlei. would be destroyed.
Pathogen Survival Studies under Contract. The intensive studies on
the survival of pathogens and parasites in the windrow composting of refuse
and sewage sludge were carried out under two contracts (PHT86-67-112 and
PH-86-68-143) with East Tennessee State University in the period July 1967
through June 1969.
128
-------
TABLE 11
MYCOBACTERIUM SURVIVAL IN COMPOST
(Mycobacterium phlei)
Insertions into Windrows 18H (11/19/68) and 28H (12/10/68) on Day 14
Exposure
Time (days)
0
1
2
3
7
Exposure
Time (days)
0
3
7
17
21
Viable Cells
Detected
18H 28H
OH) OH)
(+-)
( )
(--)
( )
(--) (-)
(-_) (-_)
(--) (-)
( ) (--)
All samples removed
Insertions
Viable Cells
Detected
OHO
OHO
OHO
OHO
OHO
OHO
OHO
( )
( )
OH-)
(-- )
(--)
( )
Temperatures, °F
18H 28H
120 132
152
162
146
160
128 144
158 152
148 148
158 156
after 14 and 21 days exposure
into Windrow 21 (12/10/68) on
Temperatures, °F
34-40
46
40
44
98
78
50
152
160
126
142
150
114
Insertion
Location
2" and mid-depth
2"
mid- depth
2"
mid-depth
2"
mid-depth
2.1
mid-depth
were negative
Day 0
Insertion
Location
2", mid-depth, and
toe area of windrow
2"
mid-depth
toe area
2"
mid-depth
toe area
2"
mid-depth
toe area
2"
mid-depth
toe area
Insertions removed from all three insertion depths at 35 days
were negative*
129
-------
TABLE 11 (CONT'D)
Insertions into windrow 191 (1/7/69) on Day 0
Exposure
Time (days)
0
7
1*
21
28
Exposure
Time (days)
0
7
21
24
28
35
49
Viable Cells
Detected
(-H-)
(-H-) :
(-H-)
(-H-)
(-H-)
(-H-)
(-H-)
(-H-)
<-->
(-H-)
(-)
(-)
(-)
Insertions into
Viable Cells
Detected
(-H-)
(-H-) .
(-H-)
(++)
(-)
(-H-)
(-)
(-H-)
(--)
OH-)
(-)
G+)
(--)
Temperatures, °F
38
26
30
46
92
108
92
102
142
98
118
142
116
windrow 221 (1/13/69) on
Temperatures, F
34
52
50
76
130
90
140
96
148
104
132
92
126
Insertion
Location
2", mid-depth, and
toe area of windrow
2»
mid-depth
toe
2"
mid- depth
toe
2»
mid- depth
toe
2"
mid- depth
toe
Day 0
Insertion
Location
2", and mid-depth
2"
mid-depth
2"
mid- depth
2"
mid-depth
2"
mid- depth
2»
mid- depth
2"
mid-depth
130
-------
TABLE 11 (CONT'D)
Insertions into windrow 291 (1/22/69) on Day 0
Exposure
Time (days)
0
7
14
28
35
49
Exposure
Time (days)
0
7
14
21
All
Exposure
Time (days)
0
7
14
All
Viable Cells
Detected
(-H-)
(-H-)
(-H-)
(+f)
(*+)
(-)
(-)
(-)
(-)
(-)
(-)
Insertions into
Viable Cells
Detected
(-H-)
(++)
(+-)
(-)
(--)
(-)
(-)
samples removed after
Insertions into
Viable Cells
Detected
(-H-)
(-H-)
(-)
(+-)
(-)
(-)
(-*)
samples removed after
Temperatures, °F
36
102
122
88
110
144
152
122
142
110
142
windrow 24J (3/5/69) on Day
Temperatures, °F
62
96
130
146
128
152
134
21 and 28 days exposure were
windrow 26J (3/7/69) on Day
Temperatures, °F
40
122
142
110
140
150
118
21 and 28 days exposure were
Insertion
Location
2" , and mid-depth
2"
mid-depth
2"
mid-depth
2"
mid- depth
2"
mid-depth
2"
mid-depth
0
Insertion
Location
2", and mid-depth, and
toe area of windrow
2"
mid-depth
toe
2"
mid-depth
toe
negative
0
Insertion
Location
2", mid-depth, and
toe area of windrow
2"
mid-depth
toe
2"
mid-depth
toe
negative
Insertion culture contaminated
131
-------
TABLE 11 (CONT'D)
Insertions into windrow 4M (6/30/69) on Day 0
Exposure
Time (days)
0
2
7
10
Exposure
Time (days)
0
2
7
10
Viable Cells
Detected
(-H-)
(-H-)
(-H-)
(-H-)
(-)
(-)
(--)
(-)
(-)
(--)
Insertions into
Viable Cells
Detected
(-H-)
(-H-)
(-H-)
(-H-)
(-M
(-H-)
(-H*)
(-)
(--)
(-)
Temperatures, F
92
134
120
126
134
148
134
144
152
136 . .
windrow 8M (7/7/69) on Day 0
Temperatures, F
86
118
118
118
136
138
134
142
146
136
Insertion
Location
2", mid-depth, and
toe area of windrow
2"
mid-depth
toe
2"
mid-depth
toe
2"
mid-depth
toe
Insertion
Location
2", mid-depth, and
toe area of windrow
2"
mid- depth
toe
2"
mid-depth
toe
2"
mid-depth
toe
Insertion culture contaminated
132
-------
TABLE 11 (CONT'D)
Insertions into windrow 17M (7/22/69) on Day 0
Exposure
Time (days)
0
2
7
10
Exposure
Time (days)
0
4
7
10
Viable Cells
Detected
(-H-)
(-H-)
(-H-)
(-H-)
( )
( )
( )
( )
( )
<-->
Insertions into
Viable Cells
Detected
(-H-)
(+)
(-H-)
(-H-)
( )
(-*)
( )
( )
( )
(-)
Temperatures, °F
88
118
120
116
142
142
150
120
148
144
windrow 19M (7/24/69) on Day
Temperatures, °F
92
142
132
134
134
146
128
140
152
132
Insertion
Location
2", mid-depth, and
toe area of windrow
2"
mid-depth
toe
2"
mid-depth
toe
2"
mid-depth
toe
0
Insertion
Location
2", mid-depth, and
toe area of windrow
2"
mid-depth
toe
2"
mid-depth
toe
2"
mid-depth
toe
Insertion sample contaminated
133
-------
The first contract studied the occurrence and survival of pathogens
and parasites. The second covered the actual insertion of organisms with
the compost. The findings of the two studies have not yet been published
by Dr. William L. Gaby, under whose supervision they were made.
The organisms for which the search for occurrence was made included:
Coliforms
Fecal coliforms
Fecal streptococci
Coagulase positive staphylococci
Salmonella species
Sh-igella species
Enteroviruses (such as polio)
Pathogenic fungi
Parasitic organisms (protozoa, cestodes, and nematodes)
In this phase, 602 samples were taken from 30 windrows and from the
fresh refuse, sewage sludge, and fresh sludge-refuse mix on the days those
particular windrows were laid down. The sludge was raw or in a partially
digested state. The duration of the composting process at Johnson City is
49 to 56 days, 35 to 42 days of which are on the composting field and the
remaining 2 weeks in the curing stage, either in the open or under a shed.
Samples were taken from windrows at various intervals during the process
and on the terminal day. The samples also were taken from several positions
within the windrows.
The studies showed that there was a consistent, inverse relationship
between the number of total and fecal coliforms in compost and the windrow
134
-------
temperature. Temperatures of 120-130 F (49-55 C) were sufficient to reduce
coliform populations significantly, often to levels lower than the minimal
level of detection by the Most Probable Numbers Method. However, the
temperature decrease occurring at the latter stages of the composting process
allowed reestablishment of significant numbers (102-105/g) of coliforms.
Fecal streptococci did not appear to be as heat sensitive and maintained
populations as high as 10e/g even when temperatures reached 130-140 F
(55-60 C).
Salmonella species were frequently isolated from the raw sewage sludge;
however, no Salmonella or Shigella species were isolated from samples of
windrows over 7 days old. Coagulase positive staphylococci were isolated
only from raw refuse, never from sludge, and found in only one windrow on
the 49th day. All other samples were negative for coagulase-positive
staphylococci after the first day on the field. The studies under the ETSU
contract did not give conclusive results for pathogenic fungi. No
enteroviruses were ever isolated from sewage sludge, raw refuse, or any
compost sample at any time. In the parasite detection studies, 3 percent
of the total number of samples (total of 602) of fresh to 49-day compost
were positive for one or more parasitic ova or cysts. Of the 49-day samples
taken, 8 of 135 (6 percent) were positive for parasites. It is of importance
here that these positive findings are based on the identification of parasitic
forms which were morphologically intact and not upon actual viability tests.
Organisms used in the insertion studies included:
Bacteria: Esceridhia ooli
Salmonella -typhimurium
135
-------
Salmonella typhimuriwh
Shigella sonnet
Staphyloeoccus aureus (coagulese positive)
Parasites: Endamoeba his toly idea
Asoaris Iwribricoides (viable ova)
Endolimax nana
Neoatur americanus
Fungi: Histoplasma capsulation
Blastomyces dewnatitidis
Aspergillus fwnigatus
' Geotriahum oandidwn
Viruses: Polio virus, Type II
Spirochoetes: Leptospira Philadelphia
A total of 1,137 samples of bacteria, fungi, parasites, and viruses
was inserted in 24 windrows in the second phase. In conformity with the
first phase of the work, the samples were planted at various positions
within the compost and withdrawn at intervals during the process. Insertions
of bacteria were made both in sealed ampules and in such manner that the
cultures were in contact with compost. This was done to determine if
bacteria could survive the process despite the elevated temperatures and
the possible presence of antibiotic substances. Other organisms were
inserted in test tubes with screw caps.
In the insertion studies, all bacterial samples in the form of
impregnated discs in contact with compost removed after 25 days in the
136
-------
windrows were rendered nonviable. All samples of Shlgella sonnei and
Staphylococcus aureus removed at 14 days and thereafter were nonviable.
Samples of S. sonnei inserted in sealed ampules removed after 25 days
were nonviable and those of S. aureus, similarly prepared, removed after
35 days were destroyed. Only two samples of 18 of 5. aureus in ampules
removed between 25 and 29 days in the compost were positive. One sample
of Salmonella typhimuriwn in an ampule was positive after 49 days and showed
a reduction of cells from 2 x 108 to 1.6 x 102. This was a sample inserted
and kept in the bottom 6 in. of a windrow where temperatures are lower.
On turning, the compost was moved from the bottom but the sample was
reinserted in this cooler part of the windrow.
Of the 38 samples of the fungus Histoplasma capsulatwn, inserted in
capped test tubes, three were found to be positive on withdrawal. Withdrawals
were made from the seventh day to the 28th day. One positive had been in
the compost for 14 days, another 24 days, and the third for 26 days. The
14th and 24th day samples had been kept at the midpoint of the composting
mass and the 26th sample in the outer layer at the 2-in. depth.
All samples of the fungus Blastomyoes dermatitidis, withdrawn at
intervals up to the 28th day, were rendered nonviable.
Thermophilic fungi such as Aspevgillus fwnigatus are commonly
associated with the composting of various types of solid wastes. On-site
observations showed that A. fwnigatus could be consistently isolated from
composting material at Johnson City at all stages of the process. In the
insertion studies it survived for 28 days in capped test tubes. Inserted
samples of Geotriohum candidum survived for 24 days.
137
-------
All samples of Endolimax nana and Endamoeba histolytica were destroyed
after 8 days' exposure. All samples of Leptospira Philadelphia, withdrawn
at from 2 to 9 days of exposure were deactivated.
Ova of hookworm (Necatur americanus or Ancylostoma duodenale)
disintegrated after 7 days' exposure in the compost.
As with the occurrence studies, the insertion studies show that some
morphologically intact, parasite forms (AseariSj Trichuris, Neoatur^ Ancylostoma3
and Hymenolopis species) persisted to the end of the composting process.
Facilities were not available at ETSU and the Tennessee State Department of
Health for a determination of the viability of these parasite forms.
Of the 66 samples of an enterovirus (Polio II) assayed for active
virus particles after remaining for various lengths of time in the composting
mass, one 3-day and one 14-day sample were found positive. The number of
active virus particles recovered from each of the two positive samples
amounted to 1 percent of the original concentration inserted. No virus
sample was positive after exposure for more than 14 days. The.windrow
temperatures recorded for the two positive samples at the time they were
withdrawn were 133 F (56 C) and 147 F (64 C).
Concurrently with the studies carried on by the Public Health Service
and the research done under contract by Gaby of East Tennessee State
University, Morgan conducted a study of the survival of Mycobactevium
tuberculosis in windrows at the Johnson City Plant.5 The organism used was
an avirulant M. tuberculosis var horrrinis, obtained from Trudeau Institute,
Inc. The insertion technique was used and the samples were planted in the
compost during fall, winter, spring, and summer months. Results revealed
138
-------
that M. tuberculosis was normally destroyed by the 14th day of composting
where the average temperature was 149 F (65 C). In all cases the organisms
were destroyed by the 21st day. In the study with one windrow, all M.
tuberculosis organisms were killed by a temperature of 140 F (60 C) or less.
The negative results obtained in the search for pathogenic bacteria
(such as Salmonella, Skigella, and Staphy loco ecus') in compost would indicate
that windrow conditions at Johnson City will destroy such pathogens. The
results obtained in the pathogen insertion studies, which were supported
by the in-house work with Mycobacterium phlei, confirm this conclusion.
Of the fungi, Blastomyces dermatitidis samples withdrawn up to the
28th day were rendered nonviable. Although one of the inserted Histoplasma
capsulatum samples was found to survive 26 days of composting, the search
for this fungus in the compost was not successful. Aspergillus fumigatus,
occasionally pathogenic to humans, could be isolated in the compost itself
throughout the process. Histoplasma capsulatum has been isolated in garden
soils and Aspergillus fumigatus is ubiquitous. The literature does not cite
any references to fungal infection among sanitation workers in association
with the disposal of solid wastes. Present data do not permit any estimate
of the possible hazard of pathogenic fungi in this connection and the results
at Johnson City do not warrant any restrictions on the use of compost due to
these fungi.
Although morphologically intact parasite forms persisted through the
process, the data shown by the Belding6 show that the ova of Ascaris
lumbrocoideSj Trichuris trichuria, Necator americanus, Ancylostdma duodenale,
139
-------
and Hymenolopsis diminuta are killed at time-temperature conditions which
are less severe than those which obtain in composting. The work of Scott7
in composting bears this out for Asocan-s ova. It was concluded that the
forms found were nonviable although they were not tested with live animals.
Only two.of 66 samples of enterovirus (Polio II) were found positive
after 14 days in the compost. It is believed that these may have been
recontaminated during assay as only very low counts were found and these
organisms may be inactivated in 30 min at 122-130 F. No positive samples
were found on withdrawal before 14 days.
Evidence from the ETSU studies, the in-house studies at Johnson City,
and the work of others in the United States and Europe, indicates that
properly processed compost of municipal waste and sewage sludge as used in
gardening or agriculture does not constitute a public health hazard. For
proper processing, it .is imperative that all material ,in a given windrow
be exposed to temperatures in the range of 122-130 F for a period of at
least 7 days. To accomplish this the material in the toe area must be
picked up and piled on top or at the end of the windrow before turnings.
At Johnson City the temperature of each windrow is taken weekly to be sure
that the necessary temperatures are reached and held for 7 days. Actually,
.windrows which have not reached 140 F or over and remained for 7 days, are
condemned at Johnson City in order to have a factor of safety.
Cellulolytic Activity in Composting. Cellulases were extracted by
homogenizing 200-gram samples of compost in 2 liters of cold phosphate
buffer (pH 7.0). The homogenates were clarified by centrifugation, and
cellulase activity in the supernatant fluid was determined by measuring the
140
-------
liberation of reducing sugars (as cellobiose) from acetate-buffered
solutions of carboxymethylcellulose. The pH, temperature, ionic strength,
and substrate concentration optima were determined for this reaction. The
total free cellulase content of compost was measured in relation to the age
of the compost to determine the time of maximal production of cellulolytic
enzymes. The cellulolytic flora which produce these cellulases in compost
were isolated on microcrystalline cellulose-mineral salts agar and identification
of these organisms was initiated.
Detectable cellulase activity (as measured by its ability to liberate
reducing sugars from carboxymethylcellulose) increased tenfold at a
logarithmic rate during the 49-day composting cycle. Concurrently, the
cellulose content of the compost decreased from 50 to 30 percent. The pH
and temperature optima for the cellulolytic reaction were consistently 6.0
and 149 F (65 C) , respectively. Variation of ionic strength between 0.1
and 1.0 had little effect on the velocity of the cellulase reaction.
Maximal reaction velocity was achieved with a carboxymethylcellulose
concentration of 2.5 percent, a concentration which is near the limit of
solubility.
Three species of cellulolytic flora (designated as C-l, C-2, and C-3)
were isolated from compost homogenates. C-l resembled Aspergillus fumigatus,
grew rapidly at 95-113 F (35-45 C), and caused intense clearing of the
cellulose agar within 5 days. C-2, a Gram-variable sporeforming rod, grew
rapidly at 95 F (35 C), slowly at 113 F (45 C), and produced diffuse zones
of clearing on cellulose agar. C-3 appeared to be a thermophilic actinomycete
(rapid growth at 125-131 F); it produced wide zones of cellulose clearing
around colonies within 72 hr.
141
-------
During the 49-day composting process, total cellulolytic activity
increased tenfold while the cellulose content of the compost decreased from
50 to 30 percent. Consideration of temperatures which exist in the windrows
would indicate that the greatest portion of cellulolytic activity is produced
by the thermophilic actinomycete (C-3). This organism, which grows rapidly
at 131 F (and has an upper growth limit of 140 F) is the only species isolated
which seems compatible with windrow temperatures. This actinomycete might
be profitably exploited in various cellulose decomposition or transformation
processes. At the present time, studies are being performed to determine
production of cellulase in pure culture and the factors which affect this
production.
Fly Population Counts. As mentioned in the section on operations, an
extensive fly problem developed in the plant area in the summer of 1967.
Flies in all stages of their life cycle came to the plant with the refuse
being delivered in compaction trailers. Adult flies were widespread over
the plant area and were particularly concentrated on windrows just being
formed. Table 12 shows the adult fly counts obtained with the Scudder grill
from August 31 to September 15, 1967. It will be noted that fresh windrows
were the most attractive to the flies. Although many flies came in with the
refuse, there was some breeding in the plant at the foot of windrows.
Fly counts were taken in October 1968 to determine the comparative
attractiveness of the storage area and several other areas. The storage area
contained compost from 42 days old to more than 1 yr old. Table 13 shows
findings which indicate that the stored compost had no attractiveness under
the conditions which obtained. As would be expected, the greatest number was
142
-------
TABLE 12
ADULT FLY COUNTS WITH SCUDDER GRILL - 1967
Windrow
11-13
12
14-15
16-17
18-19
20-21
22-23
24-25
26-28
27
29
30
31
32
33
31-33
34
35
36
37
38
39
40
41
42
43
44
1A
2A
3A
4A
5A
6A
7A
8A
9A
10A
11A
12A
13A
14A
8/31
0
1
0
0
10
3
3
3
2
6
1
2
3
2
5
_
5
3
6
9
3
1
1
7
4
0
3
2
6
-
£
§
co
9/1
0
0
0
1
2
1
0
1
1
11
4
6
.
6
.
.
6
2
9
6
1
3
9
2
2
5
2
3
6
8
7
t
£
o
§
o
0
f^
9/6
.
0
4
0
2
1
9
2
0
5
3
3
4
3
.
5
5
3
0
2
5
3
2
15
7
8
3
3
5
0
2
12
120**
x
X)
g
o
§
^_
r^
!J
CO
9/7
-
.
.
1
2
1
3
1
7
4
3
2
6
1
.
1
3
1
3
1
6
4
9
10
9
9
1
2
4
4
2
2
3
72**
r-l
0
,_4
4J
t.
K
04
9/8
.
.
.
0
1
2
0
8
3
6
1
.
5
_
4
2
1
1
4
4
5
2
11
5
5
3
3
6
2
1
1
2
5
5
13**
.^
o
0
0
^
4J
cO
P4
9/11
_
-
.
0
0
0
0
3
6
3
1
-
1
_
2
5
0
2
3
4
4
3
4
6
3
2
1
2
4
3
5
4
10
4
5
28**
^
o
o
o
^
l-l
4J
M
(4
9/12
-
_
_
2
3
0
5
5
0
2
3
-
0
.
3
3
9
1
4
4
3
2
2
4
1
2
1
5
1
3
0
3
4
0
5
0
25**
M
0)
i-^
0
9/13
_
.
-
0
0
0
0
1
2
10
7
.
6
_
0
3
5
-
2
1
0
6
5
4
1
1
4
3
3
2
1
3
3
2
4
5
6
15**
w
0}
Q)
r-l
U
9/14
_
-
_
_
0
1
0
0
3
4
3
.
1
_
1
1
4
1*
8*
0
2
1
5
8
5
4
5
3
6*
7
0
3
0
2
0
5
10
4
21**
)4
(0
o>
I I
o
9/15
.
.
-
_
-
1
0
0
3
2
2
-
5
-
1
0
2
2
10
5
3
0
10
8
7*
4
3
7*
3
2
1
5*
2
0
7*
8
0
2
2
10**
M
0)
Q)
r-l
O
* Immediately after turning.
** Windrow formed on this day.
Note: Observations above the upper line within table were made in the
drying and curing shed.
143
-------
TABLE 13
FLY POPULATION DATA
Date
10/ 3/68
10/ 4/68
10/ 7/68
10/ 8/68
LO/ 9/68
10/10/68
10/14/68
10/15/68
Receiving
Building
No reading
No reading
1
10 -
4 -
7 -
5
3
3
No reading
11 -
7 -
3
20
0-di
Winch
26 -
5 -
30 -
7 -
20 -
24 -
26 -
5 -
?ly C<
iy :
row V
27 ,
7
22
22 '
9
17
13
30
>unt
J5-d£
/indi
7 -
3 -
3 -
2 -
0 -
0 -
3 -
3 -
iy
row
11
1
4
0
5
3
7
3
Storage
Area
0
0
0
0
0
0
0
0
- o ;
- o :
- o :
- o :
- o :
- 0
- o :
- o :
Cloud
Time Wind Conditions Temp.
2:30 pm Light Cloudy Cool
1:30 pm Light Clear Cold
2:45 pm Light Partly Warm
1:30 pm None Partly Warm
3:30 pm Light Partly Cool
4:15 pm None Cloudy Cool
3:15 pm None Partly Wa;
3:00 pm Strong Partly Warm
iTja
Count of flies resting on a Scudder grill in one minute.
Two counts made at each observation point. No distinction
made for species.
144
-------
found where raw, unground refuse was being handled. The observations were
made at the end of the fly season and may not be valid for a period of higher
populations. At no time in 1968 or 1969 did the fly population reach a
nuisance level at the plant.
Chemical and Physical Characteristics
Sampling Techniques. The chemist completed a series of studies
designed to discover a reliable sampling procedure for determination of
physical and chemical characteristics of compost.
Forty samples, each of 50 grams, wet weight, were collected from
windrow 6H immediately after turning on the 25th day of composting. The
windrow was of average cross-section and 120 ft in length. Samples were
taken at 6-ft intervals, 20 per side. These were all dried and then
ground in a Wiley mill (large pieces of glass, metal, and rock were
removed to prevent damage to the mill). The windrow was sampled two
additional times on the same day and each set composited. These
composited samples were ground wet in a W-W grinder, each was well mixed,
quartered, and dried. Randomly selected samples were taken from each
quarter of the two samples and ground in the Wiley mill. The 40
individual samples and the four quarters of the two composite samples
were then analyzed for nitrogen and ash. Results are summarized in the
table below.
Ash Nitrogen
Avg. % Std. Dev. % Dev. Avg. % Std. Dev. % Dev.
40 Individual Samples 19.11 3.46 18.1 .865 .083 9.6
Composite Sample I 26.04 1.61 6.2 .924 .017 1.8
(8 samples)
Composite Sample II 25.94 0.66 2.5 1.033 .021 2.0
(8 samples)
145
-------
The lower percentage ash for the 40 individual samples is due to the
fact that rocks, glass, etc., were removed prior to analysis.
Windrow 17D was sampled on the 2nd day of composting by taking two
large (5,500 grams) composite samples and preparing them in the manner
described above (W-W grinder, mixing, drying, Wiley mill). The windrow
had not been turned prior to sampling and was at its maximum heterogeneity.
Both composites were analyzed for nitrogen, lipids, ash, and pH.
ai 7 7
/o /o /o
Nitrogen Lipids Ash pH
Composite I 0.757 5.69 22.7 5.14
Composite II 0.739 5.75 23.5 5.01
From another windrow, 15E, 28 individual samples (about 120 grams
apiece) were taken at day 3 before turning. The moisture content of each
was determined. The windrow was turned, 30 more samples were taken, and
their moisture content determined. Results were:
% Moisture Variance Std. Deviation
Before Turning 57.11 18.98 4.36
After Turning 56.8 5.18 2.28
The two large composite samples taken from 17D before turning were
dried and their moisture content determined. Composite I contained 47.3
percent moisture and Composite II 47.1 percent, indicating a satisfactory
accuracy of the sampling method. As a consequence, all moisture
determinations are now made with a 2,000-4,000 gram composite sample
146
-------
taken after turning, the whole amount of which is dried for investigative
work. For routine work, about 400 grams is taken from this well-mixed
sample.
Two conclusions are evident from these data: (1) samples for
chemical analysis should derive from a large composite that has been
ground and mixed, and (2) sampling should be done, whenever possible,
after turning.
Fifty temperature readings were taken on three different windrows
at 18 in. Their ages were 8, 22, and 32 days. Results were:
Age of Windrow Avg. Temperature Std. Deviation Variance
8 days
22 days
32 days
134 F
160 F
161 F
6.75
5.48
3.94
45.40
30.00
15.27
These data indicate increasing homogeneous composition as the age
of the windrow increases. This can be ascribed to (1) decomposition by
the microorganisms, (2) periodic mixing by the windrow turner, and (3)
particle size reduction.
It can be seen that for consistent precision more measurements must
be taken when working with windrows in the beginning of the composting
cycle.
Moisture Content of Raw Refuse. With improved methods of sampling
for moisture determinations, the dry weights of a number of windrows (11)
were determined in the course of the work on the weight and volume losses.
Knowing the weights of the same material as received from the city, the
moisture content of raw refuse was determined. The moisture content by
wet weight as received ranged from 22 percent to 61 percent over the
147
-------
period August 8 to December 6j 1968, with an average of 39 percent. This
is in the neighborhood of the 35 percent which has been quoted on occasion.
Weight and Volume Losses in Composting. As previously mentioned,
from 20 to 30 percent (by wet weight) of the incoming refuse is not
compostable and is removed for burial in a landfill. Grinding then reduces
the volume of the refuse retained for processing. As digestion proceeds,
a weight loss in the form of the two principal products of decomposition,
carbon dioxide and water, occurs. This amounts to between 20 and 30
percent of dry weight.
A study of seven batches (windrows) of refuse through the 42-day
composting process at Johnson City showed the following relationship of
incoming weights and volumes to those of the compost. In this study the
amount of noncompostables was somewhat higher than the average of 26
percent observed at this plant.
Refuse, as
Received in Noncompost-
Compaction ables, Un-
Trailer compacted
Wet weight, tons
Volume, cu yd
Moisture, percent
by wet weight
Density, Ib per
cu yd at given
moisture content
Density, expressed as
the dry weight in
Ib per cu yd
100
433
39
463
282
28.8
168.4
39
342
209
Picked,
Ground
Refuse, with
Water Added
111.7
236.5
60
945
378
Compost in
Windrow at
End of
Process
50.4
172.6
30
584
409
148
-------
This study shows a compost yield of 50.4 percent by wet weight and
40 percent by volume. It is assumed that the compost will go down on
the field at the desired 60 percent moisture and that the finished
compost will be dried to 30 percent moisture.
Elemental Composition of Compost. Analyses for certain elements
were performed on samples of compost 42 days old or older. Wilson's
methods for the gravimetric determination of carbon and hydrogen in solid
wastes are given in Reference 8. Additional methods are available in
Appendix I. Table 14 shows the average values found, on a dry weight
basis. Table 15 gives the results for individual analyses made for six
important elements.
Nitrogen in fresh ground refuse ranged from 0.58 to 1.01 percent
by dry weight, averaging 0.85 percent. Carbon ranged from 34.4 to 43.6
percent of dry weight, averaging 39.8. For compost 42 days old or older,
the nitrogen content was found to be between 0.85 and 1.07 percent of dry
weight, averaging 0.93 percent. Table 16 shows the nitrogen content of
some organic materials and soil for comparison with that of finished
compost.
Analyses for Carbon/Nitrogen Ratios. A total of 37 windrows of
different ages (0-130 days) was sampled and analyzed for carbon and
nitrogen. The carbon analyses were made in the Research Services
Laboratory of the Division of Research and Development, Bureau of Solid
Waste Management, in Cincinnati. The nitrogen determinations were
performed in the project laboratory.
Figure 54 shows the average carbon to nitrogen (C/N) ratios of
composting refuse containing 3 to 5 percent sludge by dry weight for
149
-------
TABLE 14
ELEMENTS IN FINISHED COMPOST
Johnson City
1968
Percent Dry Weight
Element Average Range
Carbon 33.01 26.23 - 37.53
Nitrogen 0.93 0.85 - 1.07
Potassium 0.30 0.25 - 0.40
Sodium 0.42 0.36 - 0.51
Calcium 1.55 0.75 - 3.11
Phosphorous 0.26 0.20-0.34
Magnesium 1.61 0.83 - 2.52
Iron 1.18 0.55 - 1.68
Aluminum 0.94 0.32 - 2.67
Copper less than 0.05
Manganese less than 0.05
Nickel less than 0.01
Zinc less than 0.005
Boron less than 0.0005
Mercury not detected *
Lead not detected *
* Lower limits of detection: Mercury, 0.005 percent; lead, 0.05 per-
cent. Neither was found above these levels in any samples tested.
150
-------
TABLE 15
CONCENTRATION OF CERTAIN TRACE ELEMENTS IN SCREENED COMPOST
(Values expressed as percentage of dry weight unless otherwise noted)
Windrow and
17D -
17D -
5E -
2E -
5E -
Stockpile
-
22-23E -
22-23E -
Stockpile
8G -
42
49
42
42
42
1
56
77
130
2
36
with NH4N03
5E -
24-25E -
8G -
154
130
42
age
day*
day*
dayt
dayj
day§
dayU
day;j:
day|
dayU
added
dayt
day§
day§
Iron
1.38
1.19
0.89
1.07
0.97
1.24
1.35
1.68
1.47
0.55
Boron
<2ppm
<2ppm
-------
TABLE 16
NITROGEN CONTENT OF SOME ORGANIC MATERIALS AND SOIL
(1) Finished Compost
(2) Sewage Sludge (raw)
(3) Chicken manure
(4) Cow manure
(5) Peat moss
(6) Leaves (hardwood)
(7) Pepper canning wastes
(8) Tobacco stalks
(9) Soil
% Nitrogen (dry weight basis)
0.93
2.58
2.61, 2.40
3.42
1.91
1.34
2.82
1.41
0.1 - 0.3 (approximately)
152
-------
Ui
u>
50
45;
= 40
h
OC.
LLJ
CO
<=>
QC
^ 35
CO
1 30
25
(Verticle I ines show ranges)'
0
10
20
NOTE: Contains 3~5$ sewage sludge
solids. 24 windrows sampled.
30 40
AGE (DAYS)
50
60
70
80
Figure 54. Average carbon to nitrogen ratio of 24 windrows containing 3-5 percent
sewage sludge.
-------
various ages. Ranges are shown but the data, taken from 24 windrows,
does not represent a follow-through of all these windrows from 0 to 80
days. The initial C/N ratios of a group of seven windrows showed an
average of 44.4. At 42 days of composting a similar group of five
windrows showed an average C/N of 33.9 and at 49 days two of these
showed an average of 31.9.
Figure 55 shows the decrease of the C/N ratios with age in a
windrow especially sampled for this purpose. This windrow did not
contain sludge solids. The initial C/N was 44.4 and at 49 days the ratio
was 33.0. The similarity of Figures 54 and 55 will be noted.
The C/N ratios at the beginning and end of the composting on the
field were determined for several windrows containing additives (Table 17).
Windrows to which were added paunch manure and poultry manure showed lower
initial C/N ratios. The decreases in the ratios while composting, however,
were not as great as in normal windrows. The 42-day ratios were 28.8
for the material containing paunch manure and 24 for the chicken manure-
refuse mixture.
The C/N ratios for two windrows to which urea-ammonium nitrate was
added showed an increase rather than a decrease after composting. The
rise was due to the loss of nitrogen as ammonia as a result of mass
action from (1) the increase of pH in the system caused by the addition
of Urea-NH4N03, and (2) shifting of the equilibrium NH^ + OH"^0 + NH3t
to the right due to an increase of NH^ and OH~ ions.
Analyses for Chemical Oxygen Demand. A total of 22 samples of
compost of different ages (0-168 days) was analyzed for chemical
oxygen demand (COD). The results showed a steady reduction with age
154
-------
50
45
40
CO
_vx
<=>
35
30
25
20
Windrow 24 - 25E
0 20 40
NOTE: Contains no sewage .sludge.
60 80
AGE (DAYS)
100
120
Figure 55.
sewage sludge.
Carbon to nitrogen ratio of a windrow without
155
-------
TABLE 17
CARBON/NITROGEN RATIOS OF COMPOST CONTAINING ADDITIVES
Windrow and Age Additive C/N Ratio
136 - 1 day Paunch manure 31.2
42 days 28.5
19G - 1 day Chicken manure 25.8
42 days 24.0
8G - 1 day Urea-ammonium nitrate 9.8
42 days 12.9
17G - 1 day Urea-ammonium nitrate 17.7
42 days 22.4
1H - 43 days Urea-ammonium nitrate 29.6
56 days 22.8
30G - 54 days Animal blood 22.5
336 - 51 days Pepper canning waste 26.5
156
-------
from about 900 milligrams per gram for fresh refuse to about 750 milligrams
per gram at 56 days of age. A sample taken from compost 168 days old
showed a COD of about 300 milligrams per gram. The COD can be used as
a gauge of the degree of decomposition of refuse (Figure 56).
Cellulose, Starch, and Sugar Content. The average cellulose content
of refuse at Johnson City was found to be 49 percent on a dry weight
basis. After composting for 28 days, it was 43 percent and at 49 days
the content was 31 percent.
The average initial starch content was 4.0 percent and dropped to
less than 1.0 percent after 28 days of composting.
The average sugar content at the start of composting was 0.8
percent and dropped to less than 0.1 percent within 14 days.
Figure 57 illustrates the diminishing content of these constituents
of refuse and compost with age.
Calorific Value of Refuse and Compost. At Johnson City, the calorific
values for composite samples of composting refuse containing 3 to 5 percent
sludge solids were found to be initially 4,077 calories per gram, diminishing
to 3,669 on the 49th day of composting and to 2,947 calories per gram for
compost 1 year old.
Cost Studies
A system of cost accounting for plant operations and maintenance was
developed to provide accurate cost data for each phase of plant operation
for appraisal of windrow composting as a method of solid waste management.
Plant operations and activities were divided into various categories or
157
-------
900
800
CO
GO
700
600
CJ
i
CJ
500
400
300-
12 16
COMPOSTING TIME (WEEKS)
20
24
Figure 56. Chemical oxygen demand of composting refuse.
158
-------
Figure 57. Sugar, starch, and cellulose content of
composting refuse.
0.80
0.60
0.40
0.20
4.0
3.0
2.0
1.0
50
40
30
2 4 6
AGE OF WINDROW (WEEKS)
2 4 6
AGE OF WINDROW (WEEKS)
2 4 6
AGE OF WINDROW (WEEKS)
159
-------
units with an account number each. Cost data used to report the project
costs and provide the basis for projections to other windrow plants
were obtained from these monthly, quarterly, and year-end financial
statements of operations (Appendix II).
Capital Cost. The total construction cost for the plant, including
the modifications made since startup, is $958,375. Table 18 itemizes these
costs. On the basis of per ton daily capacity the.actual capital investment
costs* were $18,580. On a per-ton-refuse processed basis, the capital
investment cost is $12.98 (at 34 tons per day in 1968) (Table 19).
The average rate at which the refuse has been received at the
plant would permit the processing of 52 tons in a normal processing day
(6-1/2 hr for processing and 1-1/2 hr for cleaning operations). Projecting
the actual costs to the 52 tons per day basis, the capital investment
cost would be $6.88 per-ton-refuse processed (Table 19).
Operating Cost. Actual costs for operating the composting plant in
1968 were $18.45 per-ton-refuse processed (Table 20). The nature of the
operations (research and development) and the inability of the Johnson City
municipality to deliver enough refuse for operation at full capacity are
some reasons for this high unit cost. A cost of $13.40 per-ton-refuse
processed was projected for operating this plant at 52 tons per day
(Table 21). Some modifications were made for the. research work being
conducted.
*Capital cost calculations assumed straight line depreciation
over 20 years of buildings and equipment (excluding land) and bank
financing at 7-1/2 percent over 20 years.
160
-------
TABLE 18
CONSTRUCTION COSTS FOR THE USPHS-TVA
WINDROW COMPOSTING PLANT (52-Ton Per Day) -^
Construction or Equipment Engineering
Installation and/or Materials Design Total
Site improvements $ 78,059.88 - $ 10,032.00 $ 88,091.88
Buildings -,
Receiving building 90,381.82 %. 13,982.00 104,363.82
Process building 142,742.36 £/ 21,800.00 164,542.36
Office and laboratory 40,245.28 =)'. 7,883.00 48,128.28
Curing and drying shed 44,192.55 -' 7,111.00 51,303.55
Receiving machinery and equipment
Hopper conveyor and leveling gate 12,643.94 $ 24,865.72 5,800.00 43,309.66
Scale 8,058.67 4,266.00 1,112.00 13,436.67
Processing ,/
Elevating conveyor (sorting belt), w/magnetic separator 23,608.17 -J, 11,667.00 6,828.00 42,103.17
Reject hopper 7,118.70 -' 965.00 8,083.70
Rasping machine (grinder) 7,477.38 51,160.00 9,380.00 68,017.38
Hammermill (grinder) 3_/ 2,086.63 9,262.00 1,880.00 13,228.63
Chuting 8,152.52 1,838.19 1,570.00 11,560.71
Conveyors 7,851.69 5,801.00 2,418.00 16,070.69
Sludge filter and appurtenances, including sludge «,
holding tank 2,299.67 -' 23,273.10 4,320.00 29,892.77
Ground refuse-sludge mixer 3,029.34 6,527.77 1,490.00 11,047.11
Sludge piping 13,760.08 ,. 2,698.65 2,700.00 19,158.73
Power and control system 36,181.73 - 5,820.00 42,001.73
Bucket elevator 1,408.77 . 6,000.00 1,282.00 8,690.77
Loading bin and chute 11,602.99 -'. 1,324.00 12,926.99
Composting field, site preparation and waterlines 28,792.61 -r', 9,901.00 38,693.61
Regrlnding and screening 47,500.00-' 13,689.65 61,189.65
Gasoline dispensing installation 1,754.62 788.00 253.00 2,795.62
Mobile equipment, including front end loaders and turner 48,789.48 48,789.48
Tools, small equipment, etc. 6,738.74 6,738.74
Office and laboratory equipment J5/ 4,210.00 4,210.00
$618,949.40 $221,575.30 $117,851.00 $958,375.70
Estimated cost of site (9.5 acres) 7,600.00
$965,975.70
1. Based on one shift per day, 6% hours of processing and 1% hours for cleanup.
2. Contains all or part of required materials.
3. This mill is being replaced.
4. Includes installation, construction materials, and design costs.
5. Laboratory costs include only that for simple process control equipment.
-------
TABLE 19
YEARLY INVESTMENT COSTS FOR THE USPHS-TVA
WINDROW COMPOSTING PLANT
Item of Cost Cost ($)*
Construction 958,375
Land costs 7,600
Total 965,975
Depreciation/yeart 47,920
Interest/year t . 45,080
Cost per ton daily capacity , 18,580
Cost per ton refuse processed 12.98
(6.88)§
* Actual costs of plant as built at Johnson City. Plant operates on
1 shift day. Cost per ton based on 1968 level of 7,164 tons of refuse
processed.
t Straight line depreciation over 20 years of buildings and equipment,
excluding land. .
± Bank financing at 7 1/2 percent over 20 years. Yearly figure is
average of 20-year total interest charge. Land cost included.
§ Cost of Johnson City plant adjusted to design capacity of 13,520
tons refuse processed per year.
162
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TABLE 20
ACTUAL COST OF OPERATIONS FOR THE USPHS-TVA COMPOSTING
(7,164 tons processed in 210 days)
Receiving
Picking and sorting
21
Disposal of rejects
Grinding (rasper)
(hanmermill)
Composting
Hauling and handling
Turning and wetting
Curing
Storage
Operation and maintenance
Grounds, buildings, and
utilities
Cleanup of process and
receiving buildings
Office and laboratory
Other
Regrinding and screening
Sewage sludge processing
Salaries
and
Benefits
$ 6,905
8,116
7,351
3,211
39
5,930
4,615
982
2,477
9,556
6,123
1,712
4,293
3,350
$64,660
Super-
vision
$ 1,181
1,388
1,258
549
7
1,015
790
168
424
1,635
1,048
293
734
573
$11,063
Utilities
Electric (excluding Truck
power electricity) Use
$ 59 $ $
17
3,524
770
17
28 5,764
224
577
1,165
378 614
134 1,044
130 1,230
54
$2,618 $748 $12,363
Supplies
and
Materials
$ 28
319
38
327
291
9
123
800
4,519
782
$7,236
Miscel-
laneous Total
$ $ 8,173
9,840
12,171
4,530
63
50 13,114
21 5,717
1,383
48 3,526
1,165
11,314
144 9,107
624 8,326
6,387
4,759
$887 $99,575
PLANT (1968) -1
Salaries
and
Benefits
$ 974
305
620
2,134
231
3,073
2,342
45
4,506
846
2,970
$18,046
Super-
vision
$ 250
78
159
548
59
789
600
12
1,156
217
762
$4,630
Supplies
and Miscel-
Materials Repairs laneous Total
$ 661 $ 480 $ $ 2,365
30 413
56 835
2,925 5,607
290
677 140 4,679
1,548 783 5,273
15 72
509 68 6,239
409 1,472
1,395 218 5,345
$7,801 $1,636 $477 $32,590
Total
$ 10,538
10,253
13,006
10,137
353
17,793
10,990
1,455
3,526
7,404
11,314
9,107
8,326
7,859
10,104
$132,165
1. At plant site.
2. Includes cost of haulage to landfill (no landfilling costs).
-------
TABLE 21
ACTUAL ANNUAL COSTS OF
OPERATING THE USPHS-TVA PLANT
Receiving
Picking & Sorting
Disposal of Rejects -'
Grinding (rasper)
Composting
Curing
Storage
Operation & Maintenance of
Grounds, Buildings, &
Utilities
Cleanup of Process &
Receiving Buildings
Office & Laboratory '
Other
Regrinding & Screening
Sewage Sludge Processing
Administrative & Overhead
Salaries
&
Benefits
" $ 11,400
17,200
9,650
4,550
18,150
1,750
5,200
11,550
7,250
8,150
7,200
102,050
8,600
$110,650
Electric
Power
$ 145
40
1,530
55
1,430
465
870
140
4,675
$4,675
PROJECTED TO FULL
... OPFRATTON"? _..__.__.
Supplies
Truck &
Use Materials
$ $ 50
500
2,768 70
100
5,000 1,090
536 50
1,384 50
150
800
5,000
1,384 500
2,935
11,072 11,295
$11,072 $11,295
CAPACITY (1968) -
Miscel-
laneous Total
$ $ 11,595
17,740
12,488
6,180
75 24,370
2,336
50 6,684
200 1,630
11,700
800 9,315
1,000 6,000
10,904
10,275
2,125 131,217
8,600
$2,125 $139,817
Salaries
&
Benefits
$ 1,550
900
750
4,750
8,200
6,000
2,900
2,350
27,400
2,400
$29,800
Supplies
&
Materials
$ 500
100
75
5,000
1,600
650
300
1,250
9,475
$9,475
Repairs Total
$ 500 $ 2,550
1,000
825
9,750
950 10,750
25 25
6,650
200 3,400
250 3,850
1,925 38,800
2,400
$1,925 $41,200
Total
$ 14,145
18,740
13,313
15,930
35,120
2,361
6,684
8,280
11,700
9,315
6,000
14,304
14.125
170,017
11.000
$181,017
1. Production of 13,520 tons, based on 260 working days in year.
2. At plant site.
3. Includes cost of haulage to landfill but no landfilling costs.
4. Operations only. Does not include maintenance of building, etc.
-------
Table 22 summarizes the actual capital and 1968 operating costs
for the plant.
The construction cost of $958,375 for the plant is subject to
some qualifications. A high proportion (38 percent of plant cost) is in
buildings, partly because of the multi-story design, with equipment
installed on the second and third floor levels. More ground level floor
space and simpler framing, as used in common mill buildings, with
installation of equipment independently of the structure, would have
permitted less expensive construction. A case in point is the 150-ton-
per-day plant at Gainesville, Florida, where the cost of the buildings,
estimated at $150,000, is approximately 11 percent of the total plant
investment.
Labor Cost. With respect to the plant operating costs in 1968,
labor constituted about 75 percent of this cost. Based on 50 tons of
refuse processed per day, 1969 labor costs amounted to 78 percent of
operating expenses. Table 23 provides salary information of the TVA
working complement as of January 1, 1969.
Cost Data Projected to Other Plants. Estimates of the capital,
investment, and operating costs for various capacity windrow composting
plants were developed based on the actual costs recorded during the
report period at the USPHS-TVA plant (Tables 24, 25, and 26). The
projections indicate that the total yearly costs for various size
windrow composting plants will range from $19.77 per-ton-refuse
processed for a 50-ton-per-day plant to $10.71 per-ton-refuse processed
for a 200-ton-per-day plant on two shifts (Table 27).
165
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TABLE 22
SUMMARY OF ACTUAL COSTS FOR THE USPHS-TVA COMPOSTING PLANT
*
JOHNSON CITY, TENNESSEE
Capital cost-
Tons per day per-ton daily Cost per ton refuse processed
capacity Capital Operating Total
34 ^ $18,580 $12.98 $18.45 $31.43
(7,164 tons/year)
52 AJU 18,580 6.88 13.40 20.28
(13,520 tons/year)
* Based on actual costs of Johnson City composting plant with 1\ percen
bank financing over 20 years. Equipment and buildings depreciated over 20
years (straight line). Operating costs based on actual costs for calendar
year 1968.
** Actual processing for 1968 operations.
*** Operations projected to full capacity.
166
-------
TABLE 23
SALARIES OF TVA PERSONNEL
PHS-TVA Composting Project
January 1, 1969
ANNUAL SALARY
Foreman $9300
Asst. Foreman 7740
Equipment Operator (2) 7050
Truck Driver (3) 6885
Maintenance Mechanic (2) 8490
Laborer (4) 6100
The salaries shown are for an 8-hour day, with 8 paid holidays, and 20
paid vacation days. Added benefits amount to 16.75 percent of the salaries,
not including leave benefits. Overtime is paid at the rate of time and one-
half on regular workdays and double time on holidays.
167
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TABLE 24
oo
ESTIMATED CAPITAL COSTS FOR WINDROW COMPOSTING PLANTS
Item of cost
Buildings
Equipment
4/
Site improvement
Land cost
Total cost
Total cost per ton
daily capacity
Daily
52 T/D
(Johnson City , ,
Plant - 1 shift)^'
$368,335
463,250
126,790
7,600
$965,975
$ 18,580
plant capacity
50 T/D .
(1 shift) -'
$210,000
482,700
126,800
8,400
$827,900
$ 16,560
in tons per
100 T/D
(50 T/D
2 shifts) -'
$231,000
482,700
126,800
12,400
$852,900
$ 8,530
day (T/D)
100 T/D .
(1 shift) -'
$ 231,000
607,100
152,000
12,400
$1,002,500
$ 10,020
200 T/D
(100 T/D .
2 shifts) -'
$ 251,000
607,100
152,000
21,200
$1,031,300
$ 5,460
1. Actual cost of the research and development PHS-TVA Composting Plant at Johnson City,
Tennessee.
2. Based on Johnson City cost data adjusted for building and equipment modifications*
3. Estimates based on actual Johnson City cost data projected to the larger daily capacity
plants. (See Tables 28 through 33).
4. Includes preparation of composting field with crushed stone and needed utility lines.
5. Land costs are estimated based on approximate land values near Johnson City, Tennessee,
of $800 per acre.
-------
TABLE 25
ESTIMATED INVESTMENT COSTS FOR WINDROW COMPOSTING PLANTS (1969)
Item of cost
Construction
Land costs
Total
3/
Depreciation/year
4/
Interest /year
Cost per ton daily
capacity
Cost per ton refuse
processed
52 T/D
(Johnson City,
1 shift, ,.
7,164 tons, 1968) -'
$958,380
7,600
$965,980
$47,920
$45,080
$18,580
$12.98 ,.
(6.88) -'
Plant capacity^
50 T/D
(1 shift, ,.
13,000 T/year) -'
$819,500
8,400
$827,900
$41,000
$38,600
$15,560
$ 6.12
(5.3S)-7
in tons per day (T/D)
100 T/D 100
(2 shifts, ,, (1
26,000 T/year)^' 26,
$840,500
12,400
$852,900 $1
$42,000
$39,800
$ 8,530
$ 3.15
(2.76)^
T/D
shift, .
000 T/year) -'
$989,100
12,400
,001,500
$49,500
$46,200
$10,020
$ 3.68
(3.28)~7
200 T/D
(2 shifts, ,
52,000 T/year) -
$1,071,100
21,200
$1,092,300
$53,550
$51,000
$ 5,460
[1
$ 2.01
(1.73)^
1. Actual costs of plant as built at Johnson City. Plant operates on 1 shift day. Cost per ton based on
1968 level of 7,164 tons of refuse processed.
2. Based on Johnson City plant cost data adjusted for less elaborate equipment, buildings, and modifications.
3. Straight line depreciation over 20 years of buildings and equipment, excluding land.
4. Bank financing at 7% percent over 20 years. Yearly figure is average of 20-year total interest charge.
Land cost included.
5. Cost of Johnson City plant adjusted to design capacity of 13,520 tons refuse processed per year.
6. Estimated cost without sludge processing equipment.
-------
TABLE 26
ESTIMATED YEARLY OPERATING COSTS
Plant capacity (tons
of refuse processed/
day) (T/D)
52 T/D
1968 Johnson City
(7,164) *
50 T/D ...
(13,000)
100 T/D ...
(26,000)
100 T/D .,_.
(26,000)
200 T/D .
(52,000)
Number
of
shifts
1
1
2
1
2
Plant
Operations
$99,575 ^
(139,817)
133,950
213,795
197,850
.357,015
FOR VARIOUS CAPACITY WINDROW COMPOSTING PLANTS
operating costs
Maintenance
$32,590 ...
(41,200)
43,700
59,150
59,850
95,400
($)
Total
$132,165 ^
(181,017)
177,650
272,945
257,700
452,415
Operating costs
$18.45 *.
(13.40)
13.65
10.50
9.90
8.70
* Figure in parentheses is total tons of raw refuse processed in 260-day work year.
** Costs projected for operating PHS-TVA composting plant at design capacity of 52 tons per day
(13,520 T/year) in 1969.
*** Estimated costs based on PHS-TVA composting project operating cost data.
-------
TABLE 27
SUMMARY OF ESTIMATED CAPITAL, OPERATING AND TOTAL COSTS
FOR VARIOUS SIZE WINDROW COMPOSTING PLANTS -'
Yearly cost per ton refuse processed
Plant Capacity
tons/day
(tons /year)'
52 y
(13,520)
50
(13,000)
100
(26,000)
100
(26,000)
200
(52,000)
Number
of
Shifts
1
1
2
1
2
2/
Capital cost -
(per ton/day)
$18,580
$16,560
$ 8,530
$10,020
$ 5,460
Capital &
Investment
$6.88
$6.12
$3.15
$3.68
$2.01
3/
Operating -'
$13.40
$13.65
$10.50
$ 9.90
$ 8.70
Total
$20.28
$19.77
$13.65
$13.67
$10.71
1. Based on actual costs of Johnson City composting plant with modifications with
7% percent bank financing over 20 years. Straight line depreciation of buildings and
equipment over 20 years.
2. Includes land costs estimated at $800/acre (Johnson City, Tenn.).
3. Does not include costs for landfilling rejects. For an estimate of these costs,
add $0.88, $0.72, and $0.52 to the 50-, 100-, and 200-tons-per-day plants respectively.
Costs for landfilling refuse generated in a municipality the size of Johnson City
9 10
range from $2.00 to $5.00 per ton of refuse deposited. ' Using the average of $3.50,
the 12.5 tons of compost plant rejects deposited each day would cost $43.75 or $0.88
per ton of refuse processed. Corresponding landfill costs for cities operating 100-
and 200-ton-per-day composting plants are about $2.75 and $2.00 respectively per ton
9 10
of refuse deposited. ' Costs for landfilling the rejects from these plants would be
$0.72 and $0.52 per ton respectively.
4. Actual costs of the research and development PHS-TVA Composting Plant at
Johnson City, Tennessee.
171
-------
The cost estimates include equipment for processing sewage sludge.
Also included are costs for land, depreciation, and debt service. Because
use of compost is normally seasonal, the estimates include land area for
storage of 6 month's production of compost in rectangular piles 15 ft
high. Land costs were assumed at $800 per acreconsistent with land
values near Johnson City. If land costs were assumed at $1,500 per
acre, the capital cost for the 100- and 200-ton plants on two shifts
would increase by no more than one cent per ton of refuse processed.
For the 100-ton plant on one shift, the increase would be about 3 cents
per ton of refuse processed. . .
Details of the construction and operating costs projections to
these plants are provided in Tables 28, 29, 30, 31, 32, and 33.
Plant Income. None of the compost produced has been sold. Also,
salvaging of potentially salable materials has not been practiced.
Therefore, the project has not obtained cost data with respect to:
potential plant income from such sources. The potential income of
composting plants, other economic considerations and the potential of
windrow composting in solid waste resource management systems, will be
discussed in a report entitled "Composting of Municipal Solid Waste in
the United States."11
Demonstration and Utilization
None of the compost produced at the Johnson City plant has been
sold. Prior to March 1969, the Bureau of Solid Waste Management had
asked TVA to restrict the uses to which it was put pending the outcome
172
-------
TABLE 28
USPHS-TVA PLANT CONSTRUCTION COSTS
PROJECTED TO A 50-TON PER DAY PLANT *
Site improvements . $ 88,100
Buildings
Receiving building 75,000
Processing building 90,000
Open shed (6,000 square feet) 25,000
Office and laboratory 20,000
Receiving machinery and equipment
Hopper conveyor and leveling gate 43,300
Scale (automatic talley) 18,500
Processing
Elevating conveyor (sorting belt), with magnetic separator 28,500
Reject hopper 8,100
Rasping machine (grinder) 68,000
Chuting 9,000
Conveyors 10,400
Sludge dewatering apparatus, degritter, thickening tank and sludge pump 68,000
Ground refuse-sludge mixer 11,000
Sludge piping 19,100
Power and control system 42,000
Loading bin with bucket elevator 16,000
Ballistic separator - 20,000
Composting field, surface preparation (crushed stone) and water lines 38,700
Regrinding and screening 50,000
Gasoline dispensing installation 2,800
Mobile equipment, including front end loaders and turner 56,000
Tools, small equipment, etc. 7,000
Office and laboratory equipment 5.000
Construction Total $819,500
Land costs (10.5 acres at $800/acre) 8.400
Total $827,900
* Based on costs of Johnson City plant (1966-67), revised for lower building costs and
some changes in machinery and equipment. Plant would operate one shift of 8 hours each
day. To operate this plant on two shifts for 100 tons of raw refuse per day the re-
ceiving building apron would require enlargement and cover and the site would require
expansion to 15-5 acres. The added cost would be $21,000 for receiving area and $4,000
for land, bringing total to $852,900.
173
-------
TABLE 29
USPHS-TVA PLANT CONSTRUCTION COSTS
PROJECTED TO A 100-TON PER DAY PLANT *
Site improvements $ 90,000
Buildings
Receiving building 96,000
Processing building 90,000
Open shed (6,000 square feet) 25,000
Office and laboratory 20,000
Receiving machinery and equipment
Hopper conveyor and leveling gate 43*300
Scale (automatic talley) 18,500
Processing
Elevating conveyor (sorting belt), with magnetic separator 28,500
Reject hopper 10,000
Rasping machine (grinder) 136,000
ChutJJtig 12,000
Conveyors 12,500
Sludge dewatering apparatus, degritter, thickening tank and sludge pump 92,000
Ground refuse-sludge mixer 16,500
Sludge piping 20,000
Power and control system 45»000'
Loading bin 20,000
Ballistic separator 20,000
Composting field, surface preparation (with crushed stone) and water lines . 62,000
Regrinding and screening 50,000
Gasoline dispensing installation 2,800
Mobile equipment, including front end loaders and turner 6?,000
Tools, «man equipment, etc. 7*000
Office and laboratory equipment 5.000
Construction Total $ 989,100
Land costs (15-5 acres at $800/acre) 12.400
Total $1,001,500
Based on unit costs (1966-6?) at Johnson City, revised for less expensive buildings and
some changes in machinery and equipment. Plant would operate one shift of 8 hours each
day. To operate this plant on two shifts for a capacity of 200 tons of raw refuse per
day would require enlargement of the receiving building, enlargement of the sludge
thickening tank, expansion of the site to 26.5 acres, and the addition of one front end
loader and one windrow turner. Added costs would be $20,000 for receiving, $15,000 for
sludge handling, $8,800 for land, and $47,100 for mobile equipment, bringing the total
to $1,092,400.
174
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1ABLE 30
Receiving
Picking & Sorting
3/
Disposal of Rejects -'
Grinding (rasper)
Composting
Curing
Storage
Operation & Maintenance of
Grounds, Buildings, &
Utilities
Cleanup of Process &
Receiving Buildings
LI
Office & Laboratory -'
Regrinding & Screening
Sewage Sludge Processing
Other (including
Administrative & Overhead
Salaries
&
Benefits
$ 11,400
17,200
9,650
4,550
18,950
1,750
5,200
11,600
7,250
8,200
5,300
101,050
8,600
$109,650
USPHS-TVA PLANT
COSTS PROJECTEI
PER DAY PLANT
_-___. _OPFRATTflN<;_ _ _ _ .
Supplies
Electric Truck &
Power Use Materials
$ 130 $ $ 50
40 300
2,700 70
1,330 100
20 1,740 1,000
1,220 50
1,220 50
1,580
150
800
1,360 1,220 500
1,070 500
5,530 8,100 3,570
5,000
$5,530 $8,100 $8,570
ANNUAL OPERATING
) TO A 50- TON
(one shift) -'
Miscel-
laneous Total
$ $ 11,580
17,540
12,420
5,980
100 21,810
3,020
6,470
200 1,780
300 12,050
500 8,550
11,280
6,870
1,100 119,350
1,000 14,600
$2,100 $133,950
Salaries
&
Benefits
$ 1,650
1,000
850
4,750
8,200
6,450
3,000
1,900
27,800
2,400
$30,200
Supplies
&
Materials Repairs
$ 500
100
100
5,000
2,000
800
500
500
9,500
$9,500
$ 500
100
200
1,000
100
100
500
500
1,000
4,000
$4,000
Total
$ 2,650
1,200
950
9,950
11,200
100
100
7,750
4,000
3,400
41,300
2,400
$43,700
1. Plant capacity of 50 tons of raw refuse per day in one 8-hour shift. Costs are for 260 days of
operation for a total of 13,000 tons per year.
2. At plant site.
3. Includes haulage to a landfill site but no landftiling costs.
4. For laboratory and office functions only. Does not include cost of building maintenance.
Total
$ 14,230
18,740
13,370
15,930
33,010
3,120
6,570
9,530
17.000
$177,650
-------
TABLE 31
USPHS-TVA PLANT ANNUAL OPERATING
COSTS PROJECTED TO A 100-TON
21
Receiving -'
Picking & Sorting
3/
Disposal of Rejects -'
Grinding (rasper)
Composting
Curing
Storage
Operation & Maintenance of
Grounds, Buildings, &
Utilities
Cleanup of Process &
' Receiving Buildings
LI
Office & Laboratory -'
Regrinding & Screening
Sewage Sludge Processing
Other (including
Administrative & Overhead
Salaries
&
Benefits
$ 18,700
38,450
18,050
7,800
31,900
3,350
10,050
12,100
7,250
15,600
9,550
172,800
13,600
$186,400
PER DAY
Supplies
Electric Truck &
Power Use Materials
$ 195 $ $ 100
55 600
4,590 150
1,935 200
30 2,345 2,000
1,645 100
1,645 100
1,435
200
1,000
1,635 1,645 1,000
1,390 1,000
6,675 11,870 6,450
$6,675 $11,870 $6,450
PLANT (two shifts) -'
Miscel-
laneous Total
$ $ 18,995
39,105
22,790
9,935
200 36,475
5,095
11,795
200 1,635
400 12,700
600 8,850
19,880
11,940
1,400 199,195
1,000 14,600
$2,400 $213,795
Salaries
&
Benefits
$ 1,750
1,000
850
5,150
9,500
6,450
4,000
2,300
31,000
2,400
$33,400
Supplies
&
Materials
$ 1,000
200
200
9,550
4,000
1,000
1,000
1,000
17,950
$17,950
Repairs
$1,000
500
400
2,000
200
200
500
1,000
2,000
7,800
$7,800
Total
$ 3,750
1,700
1,050
15,100
15,500
200
200
7,950
6,000
5,300
56,750
2,400
$59,150
1. Plant of 50 tons of raw refuse capacity in one 8-hour shift working two 8-hour shifts.
Costs are for 260 days of operation for a total of 26,000 tons per year.
2. At plant site.
3. Includes haulage to a landfill site but no landfilling costs.
4. For laboratory and office functions only. Does not include cost of building maintenance.
Total
$ 22,745
40,805
23,840
25,035
51,975
5,295
11,995
9,585
17.000
$272,945
-------
TABLE 32
USPHS-TVA PLANT ANNUAL OPERATING
COSTS PROJECTED TO A
100-TON
PER DAY PLANT (one shift) -1
21
Receiving
Picking & Sorting
Disposal of Rejects
Grinding (rasper)
Composting
Curing
Storage
Operation & Maintenance of
Grounds, Buildings, &
Utilities
Cleanup of Process &
Receiving Buildings
4/
Office & Laboratory -'
Regrinding & Screening
Sewage Sludge Processing
Other (including
Administrative & Overhead
Salaries
&
Benefits
$ 16,150
29,250
18,050
7,300
29,550
3,350
9,750
11,600
7,250
15,600
6,550
154,400
13,600
$168,000
------- -OPERATIONS- ------
Supplies
Electric Truck & Mlscel-
Power Use Materials laneous
$ 130 $ $ 100 $
75 600
5,385 150
2,715 200
25 2,600 2,000 200
1,825 100
1,825 100
1,485 200
200 400
1,000 600
1,710 1,825 1,000
1,400 1,000
7,540 13,460 6,450 1,400
1.000
$7,540 $13,460 $6,450 $2,400
Total
$ 16,380
29,925
23,585
10,215
34,375
5,275
11,675
1,685
12,200
8,850
20,135
8,950
183,250
14,600
$197,850
Salaries
&
Benefits
$ 1,750
1,000
850
5,350
9,500
6,450
4,000
2,300
31,200
2,400
$33,600
Supplies
&
Materials
$ 1,500
200
200
9,550
4,000
1,000
1,000
1,500
18,950
$18,950
Repairs
$1,000
500
400
2,000
200
200
500
1,000
1,500
7,300
$7,300
Total
$ 4,250
1,700
1,050
15,300
15,500
200
200
7,950
6,000
5,300
57,450
2.400
$59,850
1. Plant capacity of 100 tons of raw refuse per day in one 8-hour shift. Costs are for
260 days of operation for a total of 26,000 tons per year.
2. At plant site.
3. .Includes haulage to a landfill site but no landfilling costs.
4. For laboratory and office functions only. Does not Include cost of building maintenance.
Total
$ 20,630
31,625
24,635
25,515
49,875
5,475
11,875
9,635
12,200
8,850
17.000
$257,700
-------
TABLE 33
USPHS-TVA PLANT ANNUAL OPERATING
21
Receiving -
Picking & Sorting
Disposal of Rejects -'
Grinding (rasper)
Composting
Curing
Storage
Operation & Maintenance of
Grounds, Buildings, &
Utilities
Cleanup of Process &
Receiving Buildings
Office & Laboratory -'
Re grin ding & Screening
Sewage Sludge Processing
Other (including
Administrative & Overhead
Salaries
&
Benefits
$ 29,550
62,700
35,700
13,100
52,200
6,500
19,600
12,000
14,700
29,000
9,950
285,000
22,700
$307,700
COSTS PROJECTED
PER DAY PLANT
------ -OPERATIONS- - - -
Supplies
Electric Truck &
Power Use Materials
$ 190 $ $ 200
105 1,200
9,185 300
3,730 400
30 4,950 4,000
3,470 200
3,470 200
1,400
300
1,200
2,220 3,470 2,000
1,795 2,000
9,470 24,545 12,000
$9,470 $24,545 $12,000
TO A 200-TON
(two shifts) -'
Miscel-
laneous Total
$ $ 29,940
64,005
45,185
17,230
400 61,580
10,170
23,270
400 1,800
500 12,800
1,000 16,900
36,690
13,745
2,300 333,315
1,000 23,700
$3,300 $357,015
Salaries
&
Benefits
$ 2,450
1,400
1,150
6,000
13,750
6,650
6,000
3,600
41,000
3,300
$44,300
Supplies
&
Materials Repairs
$ 3,000
400
300
19,100
8,000
1,200
2,000
3,000
37,000
$37,000
$ 2,000
1,000
800
4,000
400
400
500
2,000
3,000
14,100
$14,100
Total
$ 7,450
2,800
1,450
25,900
25,750
400
400
8,350
10,000
9,600
92,100
3,300
$95,400
1. Plant capacity of 100 tons of raw refuse in one 8-hour shift working for two 8-hour shifts.
Costs are for 260 days of operation for a total of 52,000 tons per year.
2. At plant site.
3. Includes haulage to a landfill site but no landfilllng costs.
4. For laboratory and office functions only. Does not include cost of building maintenance.
-------
of pathogen survival studies. These restrictions and the lack of a
finished product has limited the activity of the Division of Agricultural
Development, TVA, in its utilization studies.
The TVA agriculturist assigned to the project has, however, been
active in setting up demonstrations where the unfinished material could
be used and where owners of the sites agreed to abide by the restrictions.
The demonstation areas are on public lands or the land of private owners
who have agreed to allow the agriculturist to supervise the application
and to follow the progress of the plantings.
Due to the troubles experienced with the final grinding and
screening equipment which was not completed until February 1969, the bulk
of the material used in Fiscal Year 1969 was unfinished (unreground or
screened). It represents 80 percent of the compost produced in the year.
The demonstration sites include tobacco, corn, gardens, grass or
sod establishment, erosion control and reclamation, orchards, shrubs
and flowers, golf courses, soybeans, and miscellaneous. TVA experimental
test plots are in corn and grain sorghum, each involving 52 test plots,
12 x 30 ft each, in which various application rates are being examined,
some with fertilizers and some without. Another concerns an evaluation
of compost on Bermuda grass. Appendix III provides preliminary results
of the experiments.12
The rates of application on the demonstration plantings range
from 10 to 100 tons per acre for corn and 5 to 30 tons per acre for
tobacco. The agriculturist hopes to evaluate the merits of application
rates of 4 to 200 tons per acre and various rates of fertilization in
several seasons over the next 3-1/2 years.
179
-------
Three other demonstrations deserve special mention. Two of these
involve erosion control and reclamation of strip mine spoil bank areas,
one project in cooperation with the TVA Strip Mine Reclamation Section,
and one project in cooperation with the Southern Soil Conservation
Committee in Mercer County, West Virginia. Approximately 100 tons were
shipped to the Oak Ridge National Laboratory for use as a soil amendment
in a radioactive burial ground area being used for special ecological
studies.
In addition to demonstration and research with compost in the
vicinity of Johnson City, the Division of Agricultural Development
undertook research into the effect of compost on a planting of pine
tree seedlings at Holder, Citrus County, Florida. Because of the
distance and cost for shipment from Johnson City, arrangements were
made to obtain compost from the Gainesville Municipal Waste Conversion'
Authority plant at Gainesville, Florida. Through cooperation from the
Soils Department, University of Florida, compost was obtained at no
cost and advice and consultation were obtained from the staff. The
physical appearance of this compost compared well with the Johnson
City compost, but the moisture content
was about twice and the nitrogen
content 50 to 80 percent that of the compost as used in demonstrations
at Johnson City.
180
-------
REFERENCES
1. Mason, H. G. Extending life of disposal areas. Compost Science,
10(1-2):26-31, Spring-Summer 1969.
2. Reclamation of municipal refuse by composting. Technical Bulletin
No. 9. Berkeley, Sanitary Engineering Research Laboratory,
University of California, June 1953. 89 p.
3. Wiley, J. S., and 0. W. Kochtitzky. Composting developments in
the United States. Compost Science, 6(2):5-9, Summer 1965.
4. Gotaas, H. B. Composting-sanitary disposal and reclamation of
organic wastes. World Health Organization Monograph Series
No. 31. Geneva, World Health Organization, 1956. 44 p.
5. Morgan, M. 1., and F. W. Macdonald. Tests show MB tuberculosis
doesn't survive composting. Journal of Environmental Health,
32(1):101-108, July-Aug. 1969.
6. fielding, D. L. Basic clinical parasitology. New York, Appelton-
Century-Crofts, Inc., 1958. 469 p.
7. Scott, J. S. Health aspects of composting with night soil. World
Health Organization Expert Committee on Environmental Sanitation,
3rd session, Geneva, July 27-31, 1953. 8 p.
8. Wilson, D. L. Laboratory procedure for the gravimetric determination
of carbon and hydrogen in solid wastes (for methods manual); a
Division of Research and Development open-file report (RS-03-68-17).
[Cincinnati], U.S. Department of Health, Education, and Welfare,
1970. 35 p. [Restricted distribution.]
9. Muhich, A. J. Sample representatives and community data. T-n
Black, R. J., ^t _al. The national solid wastes survey; an interim
report. [Cincinnati], U.S. Department of Health, Education, and
Welfare, [1968], p. 7-25.
10. Sorg, T. J., and H. L. Hickman, Jr. Sanitary landfill facts. 2d
ed. Public Health Service Publication No. 1792. Washington,
U.S. Government Printing Office, 1970. 30 p.
11. Breidenbach, A. W., et al. Composting of municipal solid wastes
in the United States. Washington, U.S. Government Printing
Office, 1971. 103 p.
12. Mays, D. A., E. M. Evans, R. C. Dyram, and C. E. Worley. Excerpt
Forage Research Report No. 6. Summary of 1969 forage investi-
gations. Soils and Fertilizer Research Branch, Tennessee Valley
Authority, Muscle Shoals, Alabama.
181
-------
APPENDIX I
Methods Used for Chemical Analyses
Test for Moisture. Moisture contents were determined by oven
drying at 100 C using 2,000 gram or larger samples. In most cases a
drying period of 24 hr was used as the water content was rarely over
60 percent by wet weight. Moisture content was calculated by the
relation:
100 (loss in weight) . , ^ \
7 . " . = % moisture (wet basis)
(net wet weight)
Digestion of Compost Samples for Elemental Analyses. Digest from
2.0 to 3.0 grams of compost (dried, finely ground, and weighed to the
nearest milligram) in a mixture of 20 milliliters of concentrated
sulfuric acid and 50 milliliters of concentrated nitric acid in a
Kjeldahl flask for 2 hr or until clear, adding additional nitric acid
if necessary. Filter and dilute this to 500 milliliters in a volumetric
flask and save for further analyses.
Test for Nitrogen (Organic and Ammoniacal). The test used in
the project laboratory is a modification of the Kjeldahl-Wilfarth-Gunning
method described in Appendix A, Municipal Refuse Disposal^ American
Public Works Association, 2 ed., 1966.
Equipment - Kjeldahl flasks for digestion and distillation,
800 milliliter; exhaust hood and special stack
to outside for venting acid fumes during digestion;
183
-------
Kjeldahl connecting bulbs (use bulbs 5 to 6
centimeters in diameter, fit lower end with
rubber stopper, and connect upper end to a
condenser with rubber tubing); Erlenmeyer
flasks, 500 milliliter.
Reagents - Standard sulfuric acid, 0.1N; standardize by
any official method.
Boric acid solution, 40 g/1.
Sulfuric acid, 93 to 96 percent I^SO^, free
from nitrates and (NH^^SO^.
Mercuric oxide, reagent grade, free from
nitrogen.
Sodium hydroxide-thiosulfate solution:
dissolve 450 grams of NaOH, free from nitrates,
in water and allow to cool; add 80 grams of
Na2S203.5H20, keeping solution cool, and make
to 1 liter with water.
Methyl red indicator: dissolve 1 gram of methyl
red in 200 milliters of 95 percent ethyl alcohol.
Potassium sulfate, l^SO^.
Granulated zinc.
Procedure - Weigh to fourth decimal place 0.7 to 2.5 grams
of redried sample (indirectly from aluminum
sample container) into a piece of Whatman No. 1
filter paper (9 centimeters). Fold paper and
184
-------
introduce into digestion flask. Add 15 to 18
grams of I^SO^, about 0.7 grams of mercuric
oxide, and 25 milliliters of concentrated I^SO^.
Heat gently until frothing ceases, then boil
briskly, continuing digestion for about 2 hr
after the mixture is colorless or nearly so.
Cool, add 200 milliliters of water, and dissolve
cake. Add 1 gram of granulated zinc to prevent
bumping and 75 milliliters of alkali-thiosulfate
solution, pouring down the side of the flask so
that it does not mix at once with the acid
solution. Connect flask immediately to the
condenser by means of the Kjeldahl connecting
bulk, taking care that the tip of the condenser
extends below the surface of the standard acid
in the 500-milliliter flask, which acts as a
receiver. Mix the contents by shaking and distill
into 50 milliliters of the boric acid solution
until about 200 milliliters of distillate has
been obtained. The first 150 milliliters of the
distillate usually contains all of the NH3. It
is helpful to mark the receiving flasks at about
200 milliliters and distill to the mark. Titrate
with the standard acid solution, using the methyl
red indicator.
185
-------
Calculations - ml 0.10N E2SOi+ x 0.14
Weight of sample (grams) ° ° n
Determination of Carbon Content of Compost and Refuse. Determinations
for carbon content was made by the Research Services Laboratory, Division
of Research and Development, BSWM, in Cincinnati, where special procedures
were developed. The gravimetric method for determination of carbon and
hydrogen is described in an open file report.8
Test for Phosphorus. Dilute the previously digested sample to 500
milliliters in a volumetric flask and determine the phosphorous content
as in Standard Methods for the Examination of Water and Wastewater, 12th
ed., 1965, p. 234-236, with the following modifications:
1. Use only recently digested samples, no more than 1 week
old. Old samples give erratic, inaccurate results.
2. Dilute 5 ml of digested material to 100 ml for the
determinations.
3. Standard addition must be used with this method. Make
two additional preparations of each sample and add 0.05
milligrams and 0.10 milligrams phosphorus to each,
respectively. It was found that there is a color
suppressant in the compost that will result in low
values if the analyses are performed against a standard
curve. This interference is readily overcome with the
standard addition technique, giving accurate, reliable
results.
186
-------
Tests for Sodium, Potassium, Calcium, and Magnesium. Using
previously digested samples of compost, these elements are determined
by flame photometry using the methods as described in Dean, John A.,
Flame Photometry, McGraw-Hill, 1960, New York, p. 153-179.
Test for Boron. Using a digested compost sample, boron is
determined by two methods as given in Snell and Snell, Colorimetric
Methods of Analysis, Vol. 11A, D. Van Nostrand Company, 1959, Princeton,
New Jersey. Page 594 of this text describes a method using quinalizarin,
and page 596 describes a method using carminic acid (carmine red). Both
of these methods were found to be satisfactory; however, both methods
should be employed with each sample tested to assure accurate results.
Test for Copper. Add 4 milliliters of a digested sample (2 to 3
grams in 500 milliliters of water) to a separatory funnel, then add 5
milliliters of 10 percent hydroxylamine hydrochloride and 10 milliliters
of 30 percent sodium citrate. Add concentrated NH^OH by drops until
the pH is between 4 and 6. Then add 10 milliliters of 10 percent
neocuproine, mix and extract with 10 milliliters of CHCls. Let the
layers separate, draw off the chloroform layer and read the absorbance
in a spectrophotometer at 457 millicrons. Run standards with a range
of from 10 to 50 ppm copper. The reference for this test is Snell and
Snell, Colorimetric Methods of Analysis, page 75.
Test for Iron. Dilute the previously digested sample to 500
milliliters in a volumetric flask. Pipet 5.0 milliliters into a
separatory funnel, add 10 milliliters 5 percent KCNS solution and
extract the red complex with exactly 50.0 milliliters ether. Draw
187
-------
off the aqueous phase and read the absorbance of the ether phase in a
spectrophotometer at 440 millimicrons. For standards use 20, 50, and 100
ppm iron (Fe 3). Compute the concentration of the sample directly from
the standard curve in ppm. The iron content of the sample is determined
by the relation: ;
Concentration of sample (ppm) . ,.
:T.* rr: ~~ = /o Iron
2.0 x initial sample wt.
Fairly reliable results can be obtained by simply boiling the
sample in strong hydrochloric, nitric, or sulfuric acid (3N to 6N) to
dissolve the iron, filtering and washing the resultant mass, and diluting
the filtrate to 500 ml, then proceeding as above. This would eliminate
the digestion step, thus giving a more rapid analysis with results
accurate enough for routine analysis. The reference for the iron test
is Snell and Snell, Colorimetria Methods of Analysis, Vol. HA, p. 229-
231.
Test for Aluminum. Remove iron from the sample as described in
page 246 of Snell and Snell, Colorimetrie Methods of Analysis, Vol. II,
Van Nostrand, New York, 1949.
After removal of the iron is complete, determine the aluminum by
following the directions given on pages 48-50 of the above reference.
Tests for Manganese, Nickel, Zinc, Mercury, and Lead. These
elements are present in compost in trace amounts, and their upper limits
of concentration were set using methods as described in Feigl, Fritz,
Qualitative Analysis by Spot Tests, Elsevier Publishing Company, New York,
188
-------
1946. These elements can be quantitatively determined by atomic
absorption spectroscopy or by mass spectroscopy. Polarographic
techniques may also be used, but difficulty will be encountered since
the compost contains an abundance of elements with electrode half-
potentials similar to these, and special solvent extraction or masking
techniques would have to be used to achieve reliable results. Atomic
absorption spectroscopy is probably the easiest, most rapid and accurate
technique to employ for these elements.
Determination of Chemical Oxygen Demand (C.O.D.) The reference
used for this determination is Standard Methods for the Examination of
Water and Waste-water, 12th ed., 1965, p. 510-514, where the technique
and standardization procedure can be found.
Reagents - Potassium dichromate solution, l.OON.
Standardized ferrous ammonium sulfate.
Concentrated sulfuric acid.
Ferroin indicator.
Procedure - Weigh out 0.2 to 0.3 grams of finely ground,
dry, compost (2 millimeter mesh) to the
nearest milligram and place the sample in a
250 milliliter Erlenmeyer flask. Pipette
in exactly 50.0 milliliters of l.OON K2Cr207,
add 30 milliliters of water and 20 milliliters
of concentrated H^SO^. Place on a hotplate
and boil gently for 1 hr, adding water to
compensate for evaporation. Dilute to 250
189
-------
milliliters in a volumentric flask, mix well,
pipette 10.0 milliliters into a 500 milliliter
flask and add about 100 milliliters of water.
Titrate with standardization ferrous ammonium
sulfate (about 0.1 to 0.2N) using ferroin as
an indicator.
Calculations - _ _ (A - B) x C x 200 (in milligrams/gram
L..U.U. ,. ..
grams of sample
where:
A = milliliters of titrant used for blank
B = milliliters of titrant used for sample
\ C = normality of titrant
It is advisable to run a duplicate of the original sample and a
duplicate of each dilution. Good precision was found in duplicate assays,
indicating that the method is stable and reproducible for a given sample
of compost. This observation is further substantiated by the results
plotted in Figure 56, which show the COD in milligrams/gram of randomly
selected windrows versus age. Johnson City compost, at 8 weeks, showed
a COD of less than 700 mg/gram, as opposed to around 900 mg/gram for
fresh refuse.
Determination of Cellulose Content. Two methods for the determination
of cellulose content were used in the laboratory, the anthron colorimetric
method and the gravimetric method.
(Anthrone Method)
Reagents - Diluted H2sok (760 ml cone. H2SOtt + 300 ml water)
190
-------
Anthrone reagent: 1 gram anthrone in 500 ml cold
96% t^SO^. Let stand at room
temperature 4 hr before use.
Benzene
Pure cellulose standard
Procedure - Weigh out a finely ground and redried compost
sample to the nearest milligram, place in a
Soxhlet extractor, and extract with benzene for
8 hr. Dry the composite sample and weight it in
order to compute the percent material extracted
with benzene. Extract this sample again with
hot water for 8 hr. Dry the sample and weigh it
in order to compute the percent material extracted
with water. Take between 0.5 to 1.0 gram of the
composite sample weighed to the nearest milligram
and place it in a 250 milliliter beaker, wet it
with a few drops of ethanol, methanol, or acetone.
Pipet in 10.0 milliliters water, then 60.0
milliliters diluted sulfuric acid and stir to
dissolve the cellulose solution into a 500
milliliter volumetric flask and dilute to 500
milliliters. Pipet 1 milliliter of this into
a test tube, add 10.0 milliliters anthrone
reagent, mix, seal the tube and heat in a 100 C
bath for 15 min. Cool to room temperature and
191
-------
read the absorbance with a spectrophotometer
at 630 millimicrons. Run cellulose standards
to bracket the sample concentration and a blank
with each series of samples. A blank and standards
must be included with each group of samples heated
in the 100 C bath.
wc x (ioo - [% ^ + % EWD
Calculations - % cellulose = -: r
grams of extracted sample
where:
W = weight of cellulose found in grams
E, = benzene extract
E = water extract
w
Note: If all the sample can be recovered and used after the
benzene and water extractions, then it is unnecessary to. compute the
percent of extracted material. Simply know the initial weight of the
sample, the number-of grams found (from the anthrone standard curve) and
compute the percent cellulose from this. This is easily accomplished by
placing 0.5 gram to 1.0 gram of compost in a porcelain thimble with an
asbestos filter, capping with glass wool, extracting, and then washing
all the sample into a beaker and proceeding with the determination as
above.
(Gravimetric Method)
Reagents - Concentrated nitric acid
Glacial acetic acid
192
-------
Benzene
Ether
Methanol
Acetone
Procedure - Weigh out about 1 gram of redried, finely ground
compost to the nearest milligram, place in a 125
milliliter Erlenmeyer flask and add 6 milliliters
water, 24 milliliters glacial acetic acid, and 2
milliliters concentrated nitric acid. Bring to
a gentle boil on a hotplate for 20 min, cool
to about 80 C, add 50 milliliters benzene and
swirl vigorously to extract materials soluble in
benzene. Set up a Gooch crucible with an asbestos
filter on a suction flask, decant as much of the
benzene layer as possible into the filter (with
suction) taking care not to let the bottom layer
spill over. Then add 50 milliliters of ether to
the flask, swirl vigorously, let settle and decant
all the liquid into the crucible. Wash all the
solid material into the crucible with acetone,
taking care not to leave any behind. Wash the
filter cake thoroughly with successive portions
of hot benzene, hot methanol, and ether. After
washing, clean the outside of the crucible, place
in an oven to dry, cool in a desiccator, weigh to
193
-------
the nearest milligram and ignite at 625 C for
1 hr. Cool, weigh, and report the loss on
ignition.
Calculations - Loss on ignition x 100 n1 ..
=.:;;a :: . . ,_ = /<, Cellulose
Initial sample weight
Discussion Duplicate samples should always be run to assure
precision. Swirling the benzene with the hot
reaction mixture is necessary to assure rapid
filtering of'the successive solvents used. Compost
contains a tar-like material that plugs the filter,
and most of this is soluble in benzene.
An alternate approach is provided by combining the two methods.
Complete the solvent washings as in the gravimetric method, then
dissolve the entire sample as in the anthrone method and determine the
cellulose colorimetrically. This was done three times with a 0-day
composite compost sample, and the results were 49.4 percent, 49.4
percent, and 49.6 percent. The gravimetric method on the same sample
yielded 50.2 percent, 50.0 percent, and 50.3 percent. The higher results
indicate that some substances were not removed by the extractions (0.7%)
and were not cellulose, but were lost on ignition.
Analyses were performed on samples to which known amounts of
cellulose had been added to further check the gravimetric method.
194
-------
% Cellulose
0-day compost
56-day compost
found
theoretical
found
theoretical
50.3 55.1
55.2
24.3 37.6
36.8
60.6
60.5
29.4
28.7
65.4
65.4
60.9
61.5
, _ found 19.1 28.0 38.3 48.1 60.8
1-year compost theoretical 28>2 39>1 49>2 61>1
The gravimetric method is recommended because it is more rapid and
easier to perform than the colorimetric anthrone method.
Tests for Volatile Solids and Ash. This test was made in accordance
with the procedure described in Appendix A, Municipal Refuse Disposal,
American Public Works Association, 2d ed., 1966, p. 381.
Test for Lipids. Lipids content was determined by the ether
extract method described in Appendix A, Municipal Refuse Disposal,
American Public Works Association, 2d ed., 1966, p. 381.
Tests for Sugars and Starch. Extract a carefully weighed sample
(about 3-5 grams) with ether in a Soxhlet extractor for 6 hr. Remove the
ether, dry the sample, and extract with 95 percent ethanol for 8 hr. - Dry
the sample and extract again with water for 15 hr. Determine the sugars
in the ethanol extract and the starch in the water extract by the anthrone
method as described in the Determination of Cellulose, page 77, or in
Appendix A,, Municipal Refuse Disposal, American Public Works Association,
2d ed., 1966, p. 386.
Glucose alone may be determined by using a device known as a
"glucostat" manufactured by the Worthington Biochemical Company, available
from Matheson Scientific Company.
195
-------
TVA 5133 (DRP-6-68)
APPENDIX II
STATEMENT OF OPERATIONS
DIVISIOn OF RESERVOIR PROPERTIES
Per Cent of
F. Y. Expired 25%
EASTERN
DISTRICT
MONTH OF
SEPTEMBER
19 69
Account Title
USPHS-TVA. Composting Plant
Delivery and Receiving
Operation HRS YTD
11 - Salaries, ST 161.5 502.0
or 9.0 13.0
12 - Benefits
Total salary expense
26 - Supplies and materials
Total
Maintenance .
11 - Salaries, ST 124.0 200.0
OT 25.5 26.5
12 - Benefits
Total salary expense
25 - Tire repairs, loader repairs
26 - Supplies and materials
Total
Total Delivery and Receiving
Picking and Sorting
Operation
11 - Salaries, ST 184.5 575.5
OT . 3rO 5.0
12 - Benefits
Total salary expense
26 - Supplies and materials
Total
Maintenance
11 - Salaries, ST - 1.0
OT -
12 - Benefits
Total salary expense
26 - Supplies and materials
Total
Total Picking and Sorting
Grinding
. Rasper Operation
11 - Salaries, ST 125.0 340.5
OT .5 7.5
12 - Benefits
Total salary expense
26 - Supplies and materials
Total
Account
Number
012-01.11
012-01.12
012-02.11
012-02.12
012-03.11
Expense
This
Month
618
38
. 107
763
763
573
152
115
840
"l63
1,003
1,766
650
13
113
776
13
789
-
789
506
3
88
597
597
Fiscal Yea]
To Date
1,886
58
312
2,256
2,256
917
158
171
1,246
15
26k
1,525
3,780
2,029
22
352
2,403
. 38 .
2,441
4
1
5
5
2,446
1,393
36
241
1,670
1,670
Budget
Per Cent
Expended
,
J
1
1
1
196
-------
TVA 5133 (DRP-6-68)
STATEMENT OF OPERATIONS
DIVISION OF RESERVOIR PROPERTIES
Per Cent of
F. Y. Expired
EASTERN
DISTRICT
MONTH OF SEPTEMBER
19 69
Account Title
Grinding - Continued HRS YTD
Rasper Maintenance
11 - Salaries, ST 1.0 114.0
OT - 32.0
12 - Benefits
Total salary expense
26 - Supplies and materials
Total
Hammermill Operation
11 - Salaries, ST - 34.0
OT
12 - Benefits
Total salary .expense
26 - Supplies and materials
Total
^Bammermill Maintenance
^J. - Salaries, ST 16.0 33.0
OT - 1.0
12 - Benefits
Total salary expense
26 - Hammers, belts, miscellaneous
Total
Total Grinding
Sludge Thickening and Mixing
Operation
11 - Salaries, ST 6.5 89.0
OT - 2.0
12 - Benefits
Total salary expense
26 - Supplies and materials
60 - Mileage
Total
Maintenance
11 - Salaries, ST 17.5 77.5
OT 1.0 1.0
12 - Benefits
Total salary expense
26 - Supplies and materials
Total
Total Sludge Thickening and Mixing
Account
Number
012-03.12
012-03.21
012-03.22
012-04.11
012-04.12
Expense
This
Month
5
1
6
8
14
-
84
4
88
26
114
725
25
4
29
29
80
6
14
100
100
129
Fiscal Yeai
To Date
547
191
79
817
792
1,609
lUl
25
166
166
156
5
17
178
26
204
3,649
364
9
62
435
8
443
343
6
59
408
120
528
971
Budget
Per Cent
Expended
197
-------
TVA 5133 (DRP-6-68)
STATEMENT OF OPERATIONS
DIVISION OF RESERVOIR PROPERTIES
Per Cent of
F. Y. Expired 25_1_
EASTERN
DISTRICT
MONTH OF
19 69
Account Title
Composting HRS YTD
Hauling Operation
11 - Salaries, ST l4l.O 453.0
OT 2.0 4.0
12 - Benefits
Total. salary expense
26 - Supplies and materials
60 - Truck use
Total
Hauling Maintenance
11 - Salaries, ST 4.0 74.0
OT - 4.0
12 - Benefits
Total salary expense
26 - Supplies and materials
Total
Turning and Wetting Operation
11 - Salaries, ST 124.0 342.5
OT 1.5 1.5
12 - Benefits
Total salary expense
26 - Supplies and materials
Total
Turning and Wetting Maintenance
11 - Salaries, ST 37-5 93-5
OT -
12 - Benefits
Total salary expense
25 - Tire repairs
26 - Supplies and materials
Total
Total Composting
Curing
.Operation
11 - Salaries, ST 1.0 25.0
OT
12 - Benefits
Total salary expense
26 - Supplies and materials
60 - Truck use
Total
Account
Number
012-05.11
012-05.12
012-05.21
012-05.22
012-06.11
Eroe
This
Month
564
10
99
673
365
1,041
20
3
23
33
56
499
8
85
592
12
604
166
29
195
U5
240
1,940
4
1
5
5
nse
Fiscal Yeai
To Date
1,806
19
31U
2,139
3
948
3,090
366
24
47
437
67
504
1,395
8
240
1,643
79
1,722
426
70
496
35
423
954
6,270
101
19
120
8
128
Budget
Per Cent
Expended
'
198
-------
TVA 5133 (DRP-6-68)
STATEMENT OF OPERATIONS
DIVISION OF BESERVOIR PROPERTIES
Per Cent of
F. Y. Expired 25
EASTERN
DISTRICT
.MONTH OF SEPTEMBER
1969
Account Title
Curing - Continued HRS YTD
Maintenance
11 - Salaries, ST
OT - -
12 - Benefits
Total salary expense
26 - Supplies and materials
Total
Total Curing
Regrinding and Screening
Operation
11 - Salaries, ST 152.0 1*50.5
OT
12 - Benefits
^^k Total salary expense
^^E - Supplies and materials
60 - Truck use
Total
Maintenance
11 - Salaries, ST 137.0 185.0
OT 1.0 1.5
12 - Benefits
Total salary expense
26 - Supplies and materials
Total
Total Regrinding and Screening
Hauling Rejects
Operation
11 - Salaries, ST 151.5 481.5
OT 4,5 9.5
12 - Benefits
Total salary expense
26 - Supplies and materials
60 - Truck use
Total
, Maintenance
11 - Salaries, ST 5.0 149.5
OT
12 - Benefits
Total salary expense
^K> - Supplies and materials
^^ Total
Total Hauling Rejects
Account
Number
012-06.12
012-07.11
012-07.12
012-08.11
012-08.12
Expense
This
Month
-
5
661
97
758
62
325
1,1^5
666
6
89
761
34
795
1,940
603
22
106
731
~3M
1,072
25
4
29
11
4o
1,112
Fiscal Yeai
To Date
-
-
128
1,925
319
2,214
317
640
3,201
899
8
125
1,032
81
1,113
4,314
1,918
46
331*
2,298
15
907
3,220
702
" 82
784
155
939
^,159
Budget
Per Cent
Expended
199
-------
TVA 5133 (DRP-6-68)
STATEMENT OF OPERATIONS
DIVISION OF RESERVOIR PROPERTIES
Per Cent of
F. Y. Expired 25
EASTERN DISTRICT . MONTH OF SEPTEMBER 19 69
Account Title
Disposal of Nonmarketable Processed Mat'l
HRS YTD
11 - Salaries, ST oTTo 157.0
or 2.5 h.o
12 - Benefits
Total salary expense
60 - Truck- use
Total
Distributing Processed Material
11 - Salaries, ST 67.0 175.5
or .5 20.5
12 - Benefits
Total
26 - Supplies and materials, services
60 - Vehicle use
Total
General Expense
Operation of Grounds
11 - Salaries, ST 108.5 195.5
OT - 70.5
12 - Benefits
Total salary expense
26 - Supplies and materials
Total
Maintenance of Grounds
11 - Salaries, ST - 6vO
OT - ' .5
12 - Benefits
Total salary expense
26 - Supplies and materials
60 - Truck use
Total
Supervision
11- Salaries, ST 184.5 567.0
OT 20,0 84.0
12 - Benefits-
Total salary expense
21 - Travel expense
60 - Vehicle use
Total
Account
Number
012-09
012-10
012-19.11
012-19.12
012-19.21
Expense
This
Month
270
13
48
331
32
363
286
2
48
336
16
37
389
333
21
354
2
356
18
18
1,046
125
' 179
1,350
65
101
1,516
Fiscal Yeai
To Date
633
21
111
765
101
866
723
100
122
945
2k
227
1,196
645
317
75
1,037
2
1,039
25
3
4
32
30
62
3,187
536
543
4,266
86
255
4,607
Budget
Per Cent
Expended
j^H~
200
-------
TVA 5133 (DRP-6-68)
STATEMENT OF OPERATIONS
DIVISION OF RESERVOIR PROPERTIES
Per Cent of
F. Y. Expired 25
EASTERN
DISTRICT
MONTH OF
1969_
Account Title
Processing Building Cleanup
HRS YTD
11 - Salaries, ST 17575 507-5
OT 2.5 36.0
12 - Benefits
Total salary expense
26 - Supplies and materials
Total
Office and Lab Expense
11 - Salaries, ST 13.5 46.5
OT - 19.0
12 - Benefits
Total salary expense
25 - Contractual services
26 - Supplies and materials
60 - Trailer rental
62 - Office equipment use
Total
Utilities
11 - Salaries, ST b.O 33-0
OT
12 - Benefits
Total salary expense
23 - Power
- Water
- Telephone
26 - Supplies and materials
Total
Gasoline
26 - Gasoline purchases
Other
11 - Salaries, ST 261*. 0 1^5,0
OT 3.0 14.0
12 - Benefits
Total salary expense
21 - Travel
22 - Freight
26 - Supplies and materials
60 - Vehicle use
70 - Power Stores issues
1 Total
1 Total General Expense
Account
Number
012-19.31
012-19.41
012-19.51
012-19.61
012-19.71
Expense
This
Month
635
12
104
751
751
44
5
49
" 68
12
129
36
6
42
355
12
19
428
437
1,084
17
191
1,292
17
53
514
15
1,891
5,528
Fiscal Yeai
To Date
1,857
171
317
2,3^5
2,3^5
163
85
25
273
14
26
184
36
533
155
27
182
720
40
59
. &.
1,095
449
1,788
69
311
2,168
50
53
898
80
99
3,348
13,^79
Budget
Per Cent
Expended
201
-------
TVA 5133 -(DRP-6-68)
STATEMENT OF OPERATIONS
DIVISION OF RESERVOIR PROPERTIES
Per Cent of
F. Y. Expired 25
EASTERN 'DISTRICT
Account Title
HRS YTP
General Expense Distribution
86 - Gas and oil issues to TVA
Modification & Additions. to Plant Equip.
11 - Salaries, ST 90.0 324.5
OT 3.0 19.0
12 - Benefits
Total salary expense
22 - Freight
23 - Equipment rental
25 - Contractual services
26 - Supplies and materials
31 - Equipment
60 - Truck use
82 - Suborder costs
Total
Activity Totals - USPHS-TVA Compost Plant
11 - Salaries, ST 2368.0 66?8.5
OT 79-5 376.0
12 - Benefits
Total salary expense
21 - Travel
22 - Freight
23 - Telephone, util., equip, rental
25 - Other services
26 .- Supplies and materials
31 - Equipment
60 - Transp. Branch equip, use
62 - Office equipment use
66 - Reproduction
70 - Warehouse issues
82 - Transferred costs
Gross
86 - Distribution
Expenditures
50 - Income
Net
Account
Number
012-20.61
012-50
012
012-20
012-999
MONTH OF
Tthrpc
This
MOQTill
-153
448
18
78
544
4o
180
118
882
9,929
445
1,641
12,015
82
93
548
94
1,426
1,285
12
13
15,567
-153
15,414
-15,414
.
SEPTEMBER
inse
Fiscal Yeai
To Date
-420
l,6o4
116
243
1,963
40
180
"345
2,527
28,095
2,010
4,649
34,754
136
93
999
157
4,139
3,359
36
13
99
43,785
-420
43,365
-43,365
-
19
Budget
104,770
9,170
18,000
131,940
500
1,000
6,000
3,000
15,000
20,000
17,560
5,000
200,000
-5,000
195,000
-195,000
-
6Q
Per Cent
Expended
4m
«
27
22
26
26
27
09
17
05
28
19
22
08
22
22
-
202
-------
APPENDIX III
Preliminary Results of Agricultural Research on Compost
Corn Grain Research Project, Johnson City, Tennessee. This project
involves the use of refuse-sludge compost in the growth of corn on
agricultural soils. Application rates in fall or spring ranged from 0
to 200 tons per acre. The purpose of such a range in application rates
was to determine the soil and crop improvement resulting from various
amounts of compost and the maximum amount of compost that can be applied
before the effect is adverse or deleterious. The fall applications of
4, 8, 50, 100, and 200 tons per acre of unscreened compost were made in
November 1968, and plowed under shortly thereafter. Spring applications
were made in April 1969, and disked into the soil. Nitrogen rates of 80
and 160 Ib per acre were also compared alone and with 8 tons of spring-
applied compost. There was a total of 52 test plots with each plot
receiving phosphorus and potassium at rates adequate for maximum plant
growth. The corn was planted on May 2, 1969.
There was a slight reduction in germination on the plots that
received the three highest rates of compost (50, 100, and 200 tons per
acre) with the lowest percentage germination coming on the 200-ton-per-
acre rate. One factor that contributed to this reduction in germination
was the inability because of the bulkiness of the compost to prepare a
firm seedbed, especially on the plot receiving the 200-ton-per-acre
rate. Other factors that affected the overall number of plants on all
203
-------
plots were (1) the crop was damaged somewhat by birds, (2) extremely cool
temperatures occurred during the germination period, and (3) there was
also some damage caused by hail.
Nitrogen deficiencies developed in all plots that did not receive
supplemental inorganic nitrogen. Early growth was extremely poor on the
plots that received the three heaviest compost applications; however,
toward the middle of the growing season, the corn on these plots began
to make some progress. The first noticeable growth response came on the
50-ton-per-acre treatment followed in sequence by the 100- and 200-ton-
per-acre rates. The final results indicated that these three treatments
gave favorable results when compared to the plots receiving the 80- and
the 160-lb-per-acre nitrogen treatments with no compost. It was also
noted that the corn on the 200-ton-per-acre plot remained green longer
than any other treatment. These .early results would seem to indicate
that the heavy application of compost had a definite effect on the amount
of nitrogen being released to the soil in a form readily available to
the plant, the heavier the application of compost, the longer it took for
the corn to respond. It was approximately 7 months from the time the
compost was plowed under in the 200-ton-per-acre treatment before,there
was any visual growth response that could be cpnsidered a normal, .growth
pattern.
Final yield results of this first year observation showed that
grain yields increased from 55 bushels per acre without nitrogen.or
compost to 76 bushels with 80 Ib of nitrogen or with 100 tons of compost
and to 90 bushels per acre with 160 Ib of nitrogen plus 8 tons of compost.
204
-------
Four to 8 tons per acre of compost alone resulted in slight, if any,
increase in corn yields.
The value of compost on corn in terms of increased yields ranged
from a (minus) -$1.75 per ton on spring applied compost at a rate of 4
tons per acre with no supplemental nitrogen to a (plus) +$3.18 per ton
on spring applied compost at a rate of 8 tons per acre with 160 Ib of
supplemental nitrogen per acre. The value of compost when applied at
a 200-ton-per-acre rate with no supplemental nitrogen was $.08 (8 cents)
per ton, however, this does show that large amounts of compost can be
utilized on agricultural soils with positive results. Additional studies
will determine the residual effect of high rates of application of
compost over a period of years.
It was apparent during the first year of testing that a combination
of compost plus inorganic fertilizer produced greater yield than either
compost or fertilizer alone. The response from the corn on the plot that
received compost plus 160 Ib of nitrogen was evident throughout the
growing season as the corn stalks appeared greener and stronger than
stalks from other plots. When inorganic fertilizer was used without
compost, the yield on the 80 Ib per acre of nitrogen and the 160 Ib per
acre of nitrogen treatments was approximately the same which would indicate
that the excess over 80 Ib per acre of nitrogen was not efficiently
utilized by plant uptake. This situation can be partly attributed to
the relatively small number of plants per plot; however, when 8 tons per
acre of compost was used in conjunction with 160 Ib per acre nitrogen,
there was an approximate 20 percent increase in yield over the 160 Ib
205
-------
per acre of nitrogen alone or the 8 tons per acre compost with 80 Ib per
acre of nitrogen. It would appear that the compost had somewhat of a
synergistic effect on the inorganic nitrogen since it is very doubtful
that 8 tons of compost per acre would supply enough nitrogen or moisture
to bring about such an increase in yield.
There are some preliminary conclusions drawn from 1 year of testing.
More valid information can be gathered from results obtained from 4 or 5
years of continuous testing. Table 1 presents a summary of yield data
obtained from corn research at Johnson City during 1969.
Use of Compost for Sorghum Production. (Experiment 56, National
Fertilizer Development Center, Muscle Shoals, Alabama.)
Yields of dry sorghum forage increased from 5 tons/A without compost
or N to 7.5 tons with 82 tons of compost and to 8 tons with 160 Ib of
applied N. Thus, the value of the compost in terms of the N it supplied
was very low. Less wilting during dry periods on plots receiving large
applications of compost indicated that it increased the moisture holding
capacity of the soil. The results also indicate that agricultural land
will accept large amounts of compost with small positive yield effects.
Procedure. Unground compost from Johnson City, Tennessee, was
applied in fall, spring, or combination applications for Funk's 101F
forage sorghum at total rates ranging from 6 to 82 tons per acre. Fall-
applied compost was plowed under shortly after application, while spring
applications were incorporated by disking. Compost rates were compared
with 80 to 160 Ib/A of N, with three treatments supplying both N and
compost and a check treatment with no N or compost.
206
-------
TABLE 1
Compost Experiment--Johnson City
Ear Corn Yields - Acre Basis
1969
Ear Corn
1
2
3
4
5
6
7
8
9
10
11
12
13
Treatment
None
- 80 N
- 4T-Spring
- 160 N
- 8T-Spring
- 8T-Fall
- 4T-Fall
- 8T-Spring + 80 H
- 8T-Spring + 160 N
- 8T-Fall
- 50T-Fall
- lOOT-Fall
- 200T-Fall
L.S.D., 5% Level
Stalks
8230
8470
8230
8230
8710
8230
7745
8710
8470
8230
7745
7745
6775
N.S.
Pounds
3570
4960
3235
4750
4325
3810
3900
4900
5870
3780
4535
4990
4295
855
Bushels
55
76
49
73
66
58
60
«?
75
90
58
69
76
66
13
Compost contained 40% moisture; application rates
are on a dry basis. N was applied in spring as ammonium
nitrate. Pounds of ear corn are as harvested (Av. of
14.5% moisture); bushels are on the basis of 15.5%
moisture (70 pounds per bushel). The corn variety
was Funk's G-5757.
207
-------
Chemical components in the compost were as follows (%, dry weight
basis):
Application
Time
Fall 1968
Spring 1969
N P K C
1.2 0.24 0.80 34.2
1.3 0.40 0.96 26.8
Ca
3.6
6.4
Na
0.49
0.82
Mg S Zn
0.49 0.4 0.13
0.87 0.4 0.15
P and K were applied at rates thought to be adequate for maximum
plant growth. Forage sorghum was planted on April 23, and harvested on
July 28 and October 15.
Results and Discussion. Forage yields, percentages, N content and
N uptake are given in Table 2. Total yields of dry sorghum forage increased
v
in a generally linear fashion with higher compost rates. Yields ranged
from 10,814 Ib/A on the check plot to 15,032 with 82 tons of compost/A.
In contrast, 80 Ib of N produced 13,850 Ib of forage, while 160 Ib
produced 16,384 Ib/A. The highest yield, 18,823 lb/A., was produced by
160 Ib of N and 40 tons of compost. Forty tons of compost produced as
much forage as 80 Ib of N, but no compost rate was as good as 160 Ib of
N. In all cases, compost plus N produced more forage, than either material
alone.
At the first harvest, N contents of the forage were much higher
with N alone than with compost alone, but differences were small at the
second harvest. N uptake for similar yields was less from compost-treated
than from N-fertilized plots. The N content and uptake data indicated
that this was probably due largely to luxury uptake of N on fertilized
208
-------
TABLE 2
Response of Forage Sorghum to Applications of Compost and N
O
VO
N Uptake, Pounds/A
Dry Forage, Pounds /A
Compost Rate
Fall
Spring
Tons /A
0
0
0
0
0
8
4
0
0
8
16
32
16
0
0
6.2
0
12.4
0
6.2
12.4
12.4
12.4
24.8
49.6
24.8
N
Rate
Pounds /A
0
80
0
160
0
0
0
80
160
0
0
0
160
Cut
1
8155f
10205c
8696ef
11306f
9214de
8736ef
9035def
11717b
12158ab
8871def
9483cde
9773cd
12670a
Cut
2
2659e
3643de
2943e -
5076b
3434e
3158e
3411e
4138cd
5729ab
3531d
4340c
5258b
6151a
Total
10814g
13850de
11640fg
16384b
12649e
11895fg
12447f
15856bc
17888a
12403f
13825de
15032cd
18823a
N Content, %
Cut
1
.63
1.08
.66
1.33
.71
.65
.68
1.10
1.15
.72
.78
.88
1.20
Cut
2
1.08
.91
.95
1.13
1.03
1.00
.90
.99
1.06
1.06
.97
1.11
1.11
Cut
1
51.3
109.9
57.3
150.6
65.5
55.9
61.6
128.0
139.1
63.7
73.2
86.4
150.0
Cut
2
29.2
33.7
27.9
58.1
36.0
31.5
30.7
41.0
61.0
37.3
42.0
55.1
67.4
Total
80. 4g
143. 6d
85. Ig
208. Sab
101. 5f
87.3fg
92.3fg
169. Oc
200. Ib
101. Of
115. 3e
141. 4d
217. 4a
Increase
over no N
or compost
-
63.2
4.7
128.4
21.1
6.9
11.9
88.6
119.7
20.6
34.9
61.0
137.0
Note; In all yield tables means with the same letter are not significantly
different at the 5 percent level.
-------
plots. Observation of the sorghum during dry periods indicated that
compost contributed some moisture holding capacity to the soil. There
was always less leaf curling on plots treated with the higher compost
rates.
A slight stand reduction occurred on plots receiving 50 tons in the
spring. It was not possible to incorporate this amount of compost well
enough to provide the firm seedbed needed for good germination.
Value of compost per ton in terms of its contribution to yield increase
was lower with increasing application rates. Dry matter yield increases
per ton of compost ranged from 255 Ib at the 6 ton rate to 52 Ib at the
80 ton rate. The yield contributions were similar with and without N
additions. Assuming that sorghum forage is worth $10 per ton on a green
weight basis, compost was worth approximately $2.20 per ton at 8- to 12-
tons-per-acre application rates and approximately $1.10 at rates of 20
tons per acre or more. If, on the other hand, the value is based on the
amount of N needed to give equal yield, it was worth about $0.13 per ton.
As with the bermudagrass experiment (No. 57), this experiment showed
that large amounts of compost can be disposed of by application on
agricultural land without apparent yield reductions.
The compost used in these two experiments was unground and contained
plastic, both film and dense type, fairly large pieces of glass and metallic
waste. It would have been completely unsuitable for application to grazing
or hay land and was objectionable from an aesthetic viewpoint for most
surface application uses.
Evaluation of Compost on Common Bermudagrass. (Experiment 57, National
Fertilizer Development Center, Muscle Shoals, Alabama.)
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Yields of bermudagrass forage increased from 2.9 tons with no compost
or N to 3.5 tons with 12 tons per acre of compost. The corresponding yield
with 160 Ib per acre of N/A were 5.0 tons without compost and 5.2 tons
with 12 tons per acre of compost. The increases for compost were of
insufficient value to pay for application costs.
Procedure. Compost was topdressed on common bermudagrass sod in
November 1968, at rates of 0, 4, 8, and 12 tons per acre. In 1969, N
rates of 0 and 160 Ib per acre were superimposed on plots of each compost
rate. Half the N was applied in April and half after the second harvest.
The grass was cut four times. Results are presented in Table 3.
Results and Discussion. Without added N there was a slight but
consistent increase in total yield with increasing compost rates ranging
from 5,772 Ib per acre with no compost to 7,045 Ib with 12 tons per acre
of compost. Where N was applied the 4-ton-per-acre compost application
resulted in a slight reduction in yield, and 8 and 12 tons per acre in
slightly increased yield. The increase was greater with 8 than with 12
tons per acre of compost.
Although there were inconsistencies in yield response to compost, the
8-ton-per-acre rate at both N levels resulted in approximately 900 Ib
additional forage per acre. At $25.00 per ton as the market value for
bermudagrass hay, this compost would have been worth $1.25 per ton spread
on the field. This would hardly pay spreading costs let alone production
and transportation expense. However, this data does indicate that it
might be possible to dispose of significant amounts of compost by
spreading it on grasslands providing that it did not. contain solid material
Harmful to lives tock.
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TABLE 3
Response of Common Bermudagrass
To Compost and Nitrogen,
Treatments
Compost, T./A """H
4
4
8
8
12
12
0
0
I, Lbs/A
160
0
160
0
160
0
160
0
1969
Forage harvested,
Cut 1
2899
1663
3017
2025
2529
1628
3156
1732
Cut 2
2177
1826
2533
1943
2696
1992
2048
1436
Cut 3
1731
504
2031
574
1845
721
1961
535
pounds
Cut 4
3290
2644
3590
2211
3444
2702
3146
2069
Total
10,098a
6,639bc
ll,172a
6,755bc
10,515a
7,045b
10,312a
5,772c
Note; In all yield tables means with the same letter are not significantly
different at the 5 percent level.
ya72-l-08s
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