EPA-600/2-76-104
July 1976
Environmental Protection Technology Series
NUTRIENT CONTROL BY
PLANT MODIFICATION AT
EL LAGO, TEXAS
Municipal Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into five series. These five broad
categories were established to facilitate further development and application of
environmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL PROTECTION
TECHNOLOGY series. This series describes research performed to develop and
demonstrate instrumentation, equipment, and methodology to repair or prevent
environmental degradation from point and non-point sources of pollution. This
work provides the new or improved technology required for the control and
treatment of pollution sources to meet environmental quality standards,
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-76-104
July 1976
NUTRIENT CONTROL
BY
PLANT MODIFICATION
AT
EL LAGO, TEXAS
by
B. W. Ryan
Harris County WCID No. 50
Seabrook, Texas 77586
E. F. Barth
Wastewater Research Division
Municipal Environmental Research Laboratory
Cincinnati, Ohio 45268
Grant No. 11010 GNM
Project Officer
E. F. Barth
Wastewater Research Division
Municipal Environmental Research Laboratory
Cincinnati, Ohio 45268
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Municipal Environmental Research Labora-
tory, Environmental Protection Agency, and approved for publication. Approval
does not signify that the contents necessarily reflect the views and policies
of the Environmental Protection Agency, nor does mention of trade names or
commercial products constitute endorsement or recommendation for use.
n
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FOREWORD
The Environmental Protection Agency was created because of
increasing public and government concern about the dangers of pollution
to the health and welfare of the American people. The complexity of
the environment and the interplay between its components require a
concentrated and integrated attack on the problem.
Research and development is that necessary first step in problem
solution and it involves defining the problem, measuring its impact,
and searching for solutions. The Municipal Environmental Research
Laboratory develops new and improved technology and systems for the
prevention, treatment, and management of wastewater and solid and
hazardous waste pollutant discharges from municipal and community
sources, for the preservation and treatment of public drinking water
supplies, and to minimize the adverse economic, social, health, and
aesthetic effects of pollution. This publication is one of the products
of that research; a most vital communications link between the researcher
and the user community.
This report shows that control of nutrients in wastewater discharges
can be effectively accomplished at municipal facilities.
Francis T. Mayo, Director
Municipal Environmental Research
Laboratory
ill
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ABSTRACT
The Harris County Water Control and Improvement District #50 has constructed
and operates an advanced wastewater treatment process at its El Lago, Texas,
facility. Funds for the demonstration project were shared by the District
and Environmental Protection Agency.
The need for advanced waste treatment at El Lago is based on the requirements
of the Texas Water Quality Board to protect the receiving water, Clear Lake,
from excessive pollution by organic carbon, suspended solids, ammonium nitro-
gen oxygen demand, and phosphorus. The nitrogen removal portion of the demon-
stration is not keyed to Clear Lake requirements, but is intended as a demon-
stration of the capability of this process.
All existing facilities of the nominal 0.3 mgd plant were utilized in the
advanced waste treatment design. The processes control phosphorus by metal-
lic salt addition to the primary settler, carbonaceous removal by trickling
filters, nitrogenous oxygen demand by suspended growth second stage activated
sludge, nitrogen removal via attached growth column denitrification, and
tertiary solids removal fay granular media filtration. These processes are
operated in series.
Process evaluation shows that an effluent with the following residual concen-
trations can be obtained at the design flow of 0.3 mgd.
Biological oxygen demand, 5 day 4 mg/1
Chemical oxygen demand 25 mg/1
Suspended solids 2 mg/1
Total phosphorus 1 mg/1
Total nitrogenous content 2 mg/1
This project demonstrated the feasibility of modifying an existing small trick-
ling filter plant to control nutrients in wastewater discharge.
IV
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CONTENTS
Page
Disclaimer n
Foreword i "•i
Abstract 1v
List of Figures V11
List of Tables 1x
Acknowledgments xl
Sections
I Conclusions '
II Recommendations
III Introduction 3
IV Preliminary Studies
V Phosphorus Control ^
Design and Construction
Operation and Results 15
VI Nitrogen Control 22
9?
Design and Construction
Operation and Results, Nitrification
40
Operation and Results, Small Media
Denitrification Towers
4fl
Operation and Results, Large Media
Denitrification Towers
VII Discussion of Modified Plant Operation and Results 56
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CONTENTS (continued)
Page
VIII Costs 69
Capital Costs 69
Operational Costs 69
IX Problems Encountered 72
X Publications and Patent Disclosures 74
XI Abbreviations 75
XII Appendices 78
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FIGURES
No. Page
1. Original El Lago Plant 6
2. Phase I Construction 12
3. Installed Chemical Storage Tanks and Pumps 13
4. Interior of Pump House 14
5. Sand Drying Beds with Digested Sludge 20
6. Phase II Construction 24
7. Nitrification Reactor and Sump 26
8. Centrifugal Blowers 27
9. Intermediate Clarifier and Air Lift Pumps 28
10. Sump and Vertical Turbine Centrifugal Pumps 29
11. Methyl Alcohol Storage Tanks and Pumps 31
12. Packed Bed Denitrification Towers 32
13. Small Sand Media Packing 33
14. Plastic Media Packing 34
15. Tertiary Granular Media Filter 37
16. Chlorine Contact Tanks 39
17. Laboratory and Control Building 40
18. Percent BOD5 and COD Remaining 61
19. Cumulative Frequency Data on 6005 in Final Effluent 62
20. Cumulative Frequency Data on COD in Final Effluent 63
21. Percent Suspended Solids and Total Phosphorus Remaining 64
vn
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FIGURES (continued)
No. Page
22. Cumulative Frequency Data on Total Phosphorus in Final Effluent 65
23. Percent of Various Forms of Nitrogen Remaining 66
24. Cumulative Frequency Data on Total Nitrogen in Final Effluent 67
vm
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TABLES
No. Page
1. Calculated Loadings for the El Lago Facility 7
2. Average Values for El Lago Raw Wastewater and Primary and Final 8
Effluent
3. Percent Removal Efficiency of the El Lago Plant through June 1972 10
4. Effectiveness of Phosphorus Removal, August-October 1972 16
5. Effectiveness of Phosphorus Removal, September 1974-February 1975 18
6. Average Values for Anaerobic Digester Samples Before and After 19
Chemical Treatment
7. Specifications for Nitrification Reactor 25
8. Design Specifications for Fine Sand Media Denitrification Towers 35
9. Design Specifications for Plastic Media Denitrification Towers 36
10. Tertiary Filter Specifications 38
11. Nitrification Performance 42
12. Conditions for Evaluation of Small Media Denitrification Towers 44
13A. Initial Evaluation of Small Media Denitrification Towers 45
13B. Evaluation of Small Media Denitrification Towers 46
14. Small Media Denitrification Performance Following Backwash 49
15. Conditions for Evaluation of Large Media Denitrification Towers 5"1
16A. Initial Evaluation of Large Media Denitrification Towers 52
16B. Evaluation of Large Media Denitrification Towers (31 days) 53
16C. Evaluation of Large Media Denitrification Towers (41 days) 54
17. Tertiary Filter Performance 5^
IX
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TABLES (continued)
No. Page
18. Coliform Content of El Lago Wastewater Samples 59
19. Final Effluent Residual Objectives Compared with 68
Demonstration Results
20. Chemical, Electrical and Labor Costs for Removing 71
Phosphorus and Nitrogen
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ACKNOWLEDGEMENTS
At various times during the grant period, the Board of Directors of Harris
County Water Control and Improvement District #50 included S. Lamprose (Presi-
dent), H. Nobles, E. Crum, J. Corbin, R. Ingles, W. LeCroix (President), R.
Tokerud, W. Wilson, S. Markham, N. Swennes, R. Robson, H. Jenkins (President),
E. Allan and G. Hanks.
The interest of H. Yantis (Texas Water Quality Board), G. Putnicki {EPA Region
VI), and Bob Casey (Congressman, 22nd Congressional District, Texas) is appre-
ciated.
Lockwood, Andrews and Newnam, Inc., Houston, Texas, performed the detailed engi-
neering design with E. Munson as principal design engineer. J. Hostettler and
D. Roberts provided additional engineering services during change order modi-
fications. J. Smith (EPA's Municipal Environmental Research Laboratory in
Cincinnati, Ohio) provided design guidelines for the denitrification process.
J. Cohen (MERL - Cincinnati) helped in the initial development of the scope of
work, and E. Earth (also MERL - Cincinnati) conceived the process seqjence
described in this report.
J. Winter (MERL - Cincinnati, Analytical Quality Control Laboratory) furnished
chemical reference samples for laboratory evaluation.
The phosphorus removal facilities were installed by George C. Cox, Inc., as
general contractor. The nitrogen control facilities were installed by Don Love,
Inc., as general contractor. Both firms are located in Houston, Texas.
F. Adams, J. HcPherson and D. Baker operate the Harris County Water Control and
Improvement District #50 facilities. 0. Cornett was plant superintendent until
his retirement in December 1972.
Secretarial services for the District were performed by Mrs. J. Dirnberger and
Mrs. A. Kleabonas.
B. Ryan, District General Manager, served as project engineer.
XI
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SECTION I
CONCLUSIONS
1. A small municipal facility can be converted to an advanced wastewater
treatment plant with no disruption of services.
2. Existing capital equipment can be retained and utilized as useful com-
ponents of an advanced waste treatment facility.
3. High quality effluent can be produced by the proper combination of chemi-
cal - physical - biological processes to meet effluent requirements for
biological oxygen demand, suspended solids, phosphorus, and nitrogenous
pollutants.
4. A series designed and operated stage system lends itself to flexible op-
eration.
5. A full-time resident engineer is needed for plant startup and for initial
evaluation of plant processes.
6. Operators can adapt to advanced waste treatment control processes.
7. Attached growth microbial denitrification in packed columns has been demon-
strated on a full scale.
8, Dosing of metallic salts for phosphorus control did not interfere with an-
aerobic digestion or overload the installed sand drying bed capacity at
El Lago, Texas.
9. Tertiary filtration of wastewater effluent to control particulate matter
enhances the visual qualities of the final product.
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SECTION II
RECOMMENDATIONS
Because the full scale feasibility of simultaneously controlling the major
wastewater pollutants such as organic carbon, suspended solids, phosphorus,
and nitrogenous material, by a combined biological-chemical process has been
firmly established at El Lago, Texas, it can be instituted at other sites,
where the need exists.
Due to the flexibility of the stage treatment concept designed into this
facility, several alternate operational schemes could be studied.
The basic operational mode could be optimized to produce lower effluent resid-
uals.
Eventually limited reuse of the effluent could be approached by converting one
of the column denitrification systems into a carbon adsorption process.
Long term evaluation of the operational manpower requirements, operational
cost, and effluent residual variability is recommended.
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SECTION III
INTRODUCTION
On July 6, 1970, the Board of Directors of Harris County Water Control and Im-
provement District #50 (HCWCID #50) made application to the United States En-
vironmental Protection Agency (EPA) for a Research, Development and Demonstra-
tion Grant. The impetus for the application was Proposed Board Order No. 69-9
of the Texas Water Quality Board, dated March 27, 1969. This proposed order
provided an implementation plan for protection of Clear Lake from excessive
eutrophication. Two options were permissible. Plan I called for diversion of
effluent discharges from Clear Lake. Plan II allowed discharge into the lake
if "The implementation of advanced waste treatment techniques which would ef-
fectively limit the nutrients (nitrogen and phosphorus) being discharged into
the lake ..." were instituted.
Clear Lake is fed by a watershed of 260 mi2 and has a surface area of 1,542
acres. It is connected to Galveston Bay by a 1 mi long channel which is about
200 ft wide. The lake is normally 2 to 12 ft deep and is subject to tidal
variations.
In July 1970 there was sparse information available on either diversion plans
or treatment techniques upon which the Board could make a cost effective de-
cision between Plan I or Plan II. Due to the fact that approximately 20 sep-
arate municipalities and water districts discharge wastewater treatment plant
effluent to the Clear Lake basin, a regional or diversion plan would pose
legal, right-of-way, and taxing complications. Also a diverted flow might re-
quire additional treatment in any case. The Board elected to pioneer advanced
wastewater treatment at their small municipal facility in order to implement
an action plan for compliance with the .Texas Water Quality Board order and to
collect information on alternate Plan II which could be used for future decis-
ions.
The EPA was receptive to the grant application because the Board of Directors
and other residents of the District were technically oriented due largely to
the close proximity of the Lyndon B. Johnson Space Center, and also because the
daily volume of wastewater was large enough to be classified as full scale op-
eration, but small enough that huge capital outlays would not be necessary. In
addition, there existed a need for a national demonstration of nutrient control
technology, because there was no single facility in operation that was speci-
fically designed and successfully operated for phosphorus and nitrogen removal.
Personnel from the EPA and the District met and agreed on a conceptual design,
analytical evaluation, operational schedule, period of performance, and project
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objectives. The main objective would be the production of a final effluent
that had the following nominal pollutant concentrations:
Five Day Biochemical Oxygen Demand (8005) 5 mg/1
Chemical Oxygen Demand (COD) 30 mg/1
Suspended Solids (SS) 10 mg/1
Total Nitrogen (TN) 2 mg/1
Total Phosphorus (TP) 1 mg/1
The grant started on September 15, 1970, and was for a period of 3 years.
Three time extensions changed the period of performance to 4 years and 11
months, terminating August 15, 1975.
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SECTION IV
PRELIMINARY STUDIES
The HCWCID #50 covers an area of 300 acres and serves a population of 3,000
with 700 tax accounts. Aside from single family dwellings, the District in-
cludes the following:
2 - Apartment complexes
3 - Service stations
2 - Small grocery stores
3 - Boat and marine supply dealers
1 - Appliance and auto parts store
1 - Fraternal lodge
1 - Church
1 - Real estate brokerage office
1 - Insurance office
The District supplies both drinking water and wastewater treatment services.
As of 1975 the monthly charge for water was $2.75 for 5,000 gallons minimum
and $0.55 for each additional 1,000 gallons and the sewer charge was a flat
$4.25 per month.
Figure 1 is a schematic flow diagram of the El Lago wastewater treatment plant
as it existed in September 1970. The facility consisted of two side-by-side
plants. Plant #1 is a 200,000 gpd trickling filter plant constructed in 1962.
Plant n is a 300,000 gpd trickling filter plant constructed in 1969. Influent
to the treatment process is from a common wet well, and the flow to each plant
is controlled to provide proper residence time in the two slightly different
size facilities; therefore, loading parameters can be calculated on the summa-
tion of the dual plant capacity. Table 1 gives the calculated loadings for
this municipal trickling filter facility. The loadings on the plant processes
are in the upper range of a typical low-rate trickling filter design.
The second column in Table 2, titled Raw Wastewater, gives the pollutional
characteristics of El Lago wastewater calculated from data accumulated over
a 3 year period. Each value was determined from analytical results of approxi-
mately 40 samplings. The values indicate a typical domestic strength waste
with high and low extremes influenced by moderate infiltration as evidenced
from the average dry weather flow compared to the wet weather flow.
The performance of the plant before starting the advanced waste treatment
demonstration is tabulated in the third and fourth columns of Table 2. These
show the quality of the primary effluent applied to the trickling filters and
the quality of the final effluent discharged to Clear Lake prior to July, 1972.
5
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Influent
Interceptor
Sewers
200,000 gpd
Plant 1
J
Primaryl
Settlerj
~r
Sludge
Digester
Primary,
Settlerl
-r
Sludge
Digester
Plant 2
300,OGO gpd
Final Effluent,
to Clear Lake
Figure 1. Original El Lago plant.
= Main flow
— = Sludge
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Table 1. CALCULATED LOADINGS FOR THE EL LAGO FACILITY*
Average Maximum
dry weather dry weather Vet weather
Unit/Measurement (ADW) (MOW) (WW)
Influent flow, mgd
Primary settler
Detention time, hr
Surface overflow
rate, gpd/ft2
Trickling filter"1"
Organic load, „.
lbs/day/1000 ft-*
Hydraulic load,
Spd/ft2
Final clarifiert
Detention time , hr
Surface overflow
rate, gpd/ft2
Chlorine contact tank
Detention time , hr
0.3
3.4
524
17
92
5-4
320
1.0
0.5
2.1
873
—
155
3.0
530
0.6
1.0
1.0
1,745
—
310
1.5
1,060
0.3
*The El Lago facility serves a population of 3,000.
Anaerobic digester volume (non-mixed, non-heated) is 8,830 ft
7.
or 2.9 ftr per person.
"Natural rock (4- in. dia), 6.5 ft depth. Recirculation is con-
stant at 0.3 mgd during dry weather.
and wood flight scrapers.
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Table 2. AVERAGE VALUES FOR EL LAGO RAW WASTEUATER
AND PRIMARY AND FINAL EFFLUENTS, mg/1*
Measurement
BODc
5 Avg
Range
COD
Avg
Range
Suspended solids
Avg
Range
Total phosphorus
Avg
Range
Ammonium nitrogen
Avg
Range
Organic nitrogen
Avg
Range
Oxidized nitrogen
Avg
Range
Alkalinity, as
calcium carbonate
Avg
Total oxygen demand
Avg
pH units
Median
Range
May '70- AUK '73
Raw
wastewater
161
93-223
287
89-654
195
18-256
13.6
3-7-27
24
2.4-4-9
13.5
2.4-25
0
345
456
7.6
7.0-8.1
May '70-Jun
Primary
effluent
121
70-140
229
119-260
56
30-106
13.6
10-20
15-7
14-17
3.5
2-5
0
315
7.2
6.9-7.8
'72
Final
effluent
12
5-25
67
52-80
12
4-20
13,8
8-19
5.5
5-10
2
1-2
11
5-12
101
7.5
7.0-8.0
*Except pH
8
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Normal treatment at El Lago during this earlier period included the use of
Nalcolyte 603 polymer, injected into the wet well, for aid in settling sus-
pended solids in the primary clarifier. In comparing the values for primary
effluent and final effluent, the efficient operation of the trickling filter
secondary system is evident. The existing plant facilities were adequate for
the control of BODc, suspended solids and COD to meet secondary standards.
However, essentially no removal of phosphorus was achieved. Because of the
mild climate in the El Lago area and the conservative design of the trickling
filters and final clarifiers, partial nitrification was accomplished. Total
oxygen demand (TOD) was greatly reduced. TOD values given in Table 2 were cal-
culated by summing the COD values and the oxygen equivalent of ammonium nitro-
gen and organic nitrogen. The value of 4.5 was used as the oxygen equivalent
of the nitrogen species. A summation of the nitrogen value shows that there
was only very slight removal of total nitrogen after primary treatment.
There was very little change in pH through the process due to the buffering
action of the rather highly alkaline water.
Table 3 gives the efficiency of the plant during conventional operation in
terms of percent removal of pollutants from raw wastewater through primary
treatment, and an overall removal based on the average values for raw and
final waste streams. The degree of phosphorus removal was so slight that
calculations based on average values indicated essentially zero removal.
Digested sludge that accumulated in the anaerobic digester was periodically
discharged to sand drying beds. This wet sludge had a total solids content
of 8 percent and an ash content of 68 percent. After drying, the cake was
raked off the beds and used by local residents for soil conditioning or
spread on the fringe areas of the treatment plant grounds. The filtrate
from the sand beds and the supernatant from the anaerobic digesters were
both recycled to the influent wet well.
The above tabulations reflect the fact that the El Lago facility was producing an
acceptable effluent in terms of the usual pollutants that were of major concern
when the facilities were originally designed and placed into operation; however,
Board Order 69-9 proposed control of phosphorus and nitrogenous pollutants. A
study of the nitrification capabilities of the plant was done for a short 2
month period. The trickling filters were operated in series, rather than in the
normal paralled operation to see if nitrification could be increased. No improve-
ment in nitrification capability was noted. This finding influenced the design
considerations necessary to implement nutrient control into the El Lago plant.
Due to the good operation of the facilities, all existing unit processes were
retained in the advanced waste treatment design. The design, construction and
operation of the additional facilities were carried out in two phases. Phase
I involved phosphorus control, and Phase II involved phosphorus and nitrogen
control.
The goal of the El Lago project was to provide full scale demonstration of nu-
trient control process capability, not to build a research facility for collec-
tion of design data. Conservative design values, from numerous pilot plant in-
vestigations, were selected for the construction.
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Table 3. PERCENT REMOVAL EFFICIENCY OF THE EL LAGO
PLANT THROUGH JUNE 1972
Raw wastewater to Raw wastewater to
Measurement primary effluent final effluent
BOD5 25 92
COD 20 77
SS 71 94
TP 00
TN 48 51
TOD 31 78
10
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SECTION V
PHOSPHORUS CONTROL
DESIGN AND CONSTRUCTION
The construction and installation of the capital equipment for phosphorus con-
trol started in August 1971. The process selected was chemical precipitation
by metallic salt and polymer addition into the influent wastewater for removal
of the phosphorus in the primary settler. Figure 2 is a schematic showing
Phase I additions to the plant.
Construction consisted of general earthwork, concrete pad and dike for chemi-
cal storage tanks, concrete pad for pump house, laying of chemical dosing
pipe, increased electrical capacity, installing electrical motor control lines,
erection of pump house, and miscellaneous related tasks.
To allow for economic purchase of liquid metallic salts, two chemical storage
tanks (Western Fiberglass) were provided. These are of fiberglass construction,
and each has a 4,000 gallon capacity. A horizontal configuration was necessary
because of height limitations on structures in the community. Figure 3 is a pic-
ture of the installed tanks.
The pump house (Warminster Fiberglass Co.) is also of fiberglass construction
for chemical resistance.- The prefabricated structure, which measures 8 x 8 x
6.6 ft, houses two metal salt dosing pumps and two polymer pumps and tanks.
Experience has shown that a larger building would offer more comfortable operat-
ing conditions.
The dual-head metal salt pumps (Wallace & Tiernan, Series 748) have a combined
pumping capacity of approximately 20 gal/hour at 12 strokes/min and a 10:1
range in delivery rate by manual adjustment of stroke length. Each pump motor
is connected to one of the wet well pump circuits and a metal salt pump oper-
ates when its respective wet well pump is in operation. The metal salt solu-
tion is added to the raw wastewater at a point between the intakes to the two
wet well pumps.
Two polymer pumps deliver diluted polymer solution in the waste stream as it
flows through the riser pipe from the wet well to the primary settlers. Each
polymer pump (Wallace and Tiernan Series A-745) has a capacity of 30 gal/day
with a 10:1 adjustment range.
Like the metal salt pumps, the polymer pumps are connected to the wet well pump
circuits. The polymer solution is made up in 50 gallon polyethylene tanks
equipped with electric mixers. Figure 4 is a picture of the interior of the
pump house.
11
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200,000 gpd
Plant 1
Influent
1
Primary)
Settler,
T
Sludge
Digester
Interceptor
Sewers
Chemical Tanks
Dike
Polymer and
Pump House
Final Effluent,
to Clear Lake
Figure 2. Phase I construction.
= Main flow
= Sludge
= Chemical
12
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Figure 3. Installed chemical storage tanks and pumps
13
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Figure 4. Interior of pump house
14
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Within each chemical dosing system the respective storage reservoirs and pumps
are interconnected so that solutions can be pumped while one unit is off-line
for filling, cleaning or making repairs.
In a small facility such as this, it is not feasible to dose metal salt in pro-
portion to both flow and concentration. The arrangement of connecting the chem-
ical pump motors to the two wet well pumps allows chemical to be added in rela-
tion to flow. Since recycle flows of digester supernatant, said bed filtrate,
and filter backwashes also enter the wet well, they also create a demand for
chemical addition.
Phase I design for phosphorus removal was not intended for highly efficient
removal. Utilization of the existing facilities placed several constraints on
the phosphorus process selection. The advanced nutrient control design was a
multi-stage system with the first stage being the existing El Lago trickling
filters for carbonaceous oxidation. Therefore, metallic salts could not be
added to the first stage biological process, as is usually done when suspended
growth systems are employed. Dosage of metal salts to the trickling filter
underdrain for efficient phosphorus capture was not possible because the ex-
isting final clarifiers were to be converted to immediate stage clarifiers in
Phase II construction. Removing the major fraction of the phosphorus by add-
ing metal precipitants to the planned second stage suspended growth nitrifica-
tion reactor was not considered good practice due to the need to control the
biological solids sludge age in this process to assure nitrification. This
approach would build up inert solids in the reactor due to the sludge produc-
tion that occurs from the phosphorus-metal precipitation.
Under these circumstances it appears that the best approach was to add metal
salt and polymer in the primary stage for the removal of the bulk of the phos-
phorous and associated sludge ahead of the other unit processes, in spite of
the fact that organic and polyphosphates would not be efficiently removed. To
compensate for this and obtain the 1 mg/1 phosphorus goal, Phase II provided
for a polish dose of metal ion at the nitrigication reactor and another dose
of polymer immediately prior to final filtration.
OPERATION AND RESULTS
Table 4 provides data from a 3 month period (August, September, October 1972)
when ferric chloride and Dow A-23 polymer were injected into the wet well and
riser pipe, respectively. The total phosphorus concentration of the raw waste-
water was in the range of the typical values given in Table 2. Eighty-three
percent of the influent phosphorus was soluble. This rather high soluble con-
tent probably explains the very negligible removal of the phosphorus by the
El Lago facility during conventional treatment. Ferric chloride and polymer
injection was about 80 percent effective in both insolubilizing the phosphorus
and coagulating the precipitate to cause removal with the primary sludge. The
weight and mole ratios given in Table 4 are similar to other reported experience
to obtain 80 percent removal in a primary treatment process. Very slight addi-
tional removal was obtained through the trickling filter secondary process. When
the values for soluble phosphorus in the primary effluent and final effluent are
15
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Table 4. SZPSCTIV^HEoS OP FHOoPHOHUS REHOVAL*
AUGUST - GC^OE^S. 1972.
Primary influent
Haw (after recycle Primary Final
Measurement wastewater flows) effluent effluent
Phosphorus, mg/1
total 14.9 13.0 3-0 2.8
soluble 12.3 1.5 1-3 1.8
Percent soluble 83 12 43 64
Ferric chloride
as iron ng/1 — 35 — —
Weight ratio
iron/total
phosphorus 2.2 2.5 —
Hole ratio
iron/total
phosphorus 1.2 1.4 — —
A-23 Polymer,
mg/1 ~ 0.21
Cumulative
percent removal
of total
phosphorus — — 79 • 8 81.2
* Each value represents the average of 55 individual
analyses.
16
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compared, there is an indication that small amounts of previously insolubilized
phosphorus reverted to a soluble form during secondary treatment.
The plant efficiency for BODs, COD and SS removal remained essentially the same
during this chemical dosing period as for conventional operation as reported in
Table 3. No reduction in the pH of the primary effluent was noted in response
to the introduction of the acidic ferric chloride.
Table 5 presents phosphorus removal data from three later periods during oper-
ation of Phase II nitrification and denitrification facilities. The dosing
of ferric chloride and polymer was continued during these periods, but the fer-
ric chloride dose was split about 2 to 1 between the wet well and the nitrifi-
cation reactor and the polymer dose was divided equally between the riser pipe
to the primary clarifier and the inlet piping to the final polishing filters.
During the first period for which data are shown in Table 5, the ratio of fer-
ric chloride to total phosphorus content of the primary influent was increased
36 percent above that for the August - October 1972 period. Removal of total
phosphorus between primary influent and final influent increased from 78.5 per-
cent to 96.8 percent. This increase in removal effectiveness was attributed to
the increase in ferric chloride and split dosing of both chemicals.
During the two following periods (31 days and 41 days), the ratio of ferric
chloride to total phosphorus content of the primary influent was the same as
that for the August - October 1972 period, but removal of total phosphorus
between the inlet to the primary settler and the plant discharge was increased
from the previous 78.5 percent to 93.6 percent and 94.0 percent, respectively.
Total phosphorus removal efficency increased about 15 percent, and it was as-
sumed that this was due primarily to split dosing of ferric chloride and poly-
mer since calculations indicated that wasting of bacterial mass from nitrogen
control facilities would account for very small amounts of phosphorus. Since
this data showed that the target residual of 1 mg/1 total phosphorus could
be obtained with a split dose of ferric chloride at a 2.5 to 1 weight ratio
between ferric iron and phosphorus, that dosage has become routine at El Lago.
Table 6 gives analytical values for anerobic digester samples. Primary sludge
cannot be sampled at El Lago because the settled primary sludge is transferred
through a submerged standpipe to the anaerobic digester by the difference in
hydraulic head between the settler and the digester. Digester supernatant at
this plant has always been a good quality, and the most notable change after
chemical treatment was the reduction in total phosphorus concentration. Mar-
ginal increases in COD, SS and alkalinity were noted. The pH remained in a
satisfactory range. The most striking change occurred in the phosphorus con-
tent of the digested sludge. Before chemical treatment, digested sludge con-
tained 0.7 percent phosphorus by weight. After chemical precipitation in the
primary settler the phosphorus content increased to 4 percent. A thicker sludge
was also produced, as evidenced by the increase in total solids from 8 percent
to 9 percent. Alkalinity and pH of the digested sludge remained within the nor-
mal range; and good digestion, both before and after chemical treatment, is in-
dicated by the high ash content of both samples. Figure 5 is a view of the well
drained and cracked iron phosphate digested sludge on the sand drying beds.
17
-------
Table 5. EFFECTIVENESS OF PHOSPHORUS REMOVAL, SEPTEMBER 1974 - FEBRUARY 1975
00
Period
9/23/74
to
ll/ 8/74
(47 days)
11/16/74
to
12/16/74
(31 days)
I/ 5/75
to
2/14/75
(41 days)
Avg
Range
Avg
Range
Avg
Range
Ferric iron dose*
Fe*3 Weight Mole
mg/1 ratio ratio
41 3.4 1.9
20-79
27 2.5 1.4
14-43
25 2.5 1.4
14-57
Total phosphorus, mg/1
Prim
infl
12
8.1-16
11
6.0-14
10
5-9-12
Prim
effl
3.4
1.3-4.5
5
2.6-10
4.0
2.8-5.4
Denit
effl
3.0
1.0-4.5
2.4
1.6-4.4
2.4
1.7-3.9
Final
effl
0.39
0.15-
0.77
0.7
0.28-
1.3
0.6
0.29-
1.2
Soluble phosphorus, mg/1
Prim
infl
2.1
<0.01—
5.7
3.0
1.2-10
1.1
0.41-
2.0
Prim
effl
1.0
•cO.Ol-
2.2
1.9
0.71-
6.5
0.50
0.33-
0.70
Denit
effl
0.39
0.01-
0.90
0.6
0.27-
1.5
0.50
0.40-
0.58
Final
effl
0.38
0.13-
0.74
0.6
0.25-
1.3
0.53
0.27-
0.91
TP
removal
96.8
93.6
94.0
•Weight ratio and mole ratio are ferric iron to total phosphorus in the primary influent wastewater.
-------
Table 6. AVERAGE VALUES FOR ANAEROBIC DIGESTER SAMPLES
BEFORE AND AFTER CHEMICAL TREATMENT
Measurement
COD, mg/1
SS, mg/1
TP, mg/1
Alkalinity, mg/1
Digester supernatant
Before After
291
194
23
866
381
290
11
1,048
Digested sludge
Before
-
-
683
1,593
After
-
-
3,670
1,760
calcium carbonate
Total solids, %
Ash, %
pH, median
Number of
samples
6.6
10
6.9
13
8.0 9.0
67.5 64.4
6.4 6.8
3 12
19
-------
Figure 5. Sand drying beds with digested sludge
20
-------
During Phase I of the project, both alum and ferric chloride were evaluated
for phosphorus control. Equal mole ratios of Al+3 and Fe+3 worked equally
well from the standpoint of phosphorus removal and sludge handling character-
istics. The final choice of Fe+3 for more extensive evaluation was based on
the relative costs of alum and ferric chloride. Ferric chloride was much
less expensive in the Houston area where it is available as a by-product.
This phase of the project demonstrated that a low rate trickling filter plant
removing very little phosphorus under standard operation could be upgraded to
80 percent removal by addition of ferric chloride and polymer to the waste-
water; and routine removal of over 93 percent total phosphorus could be achiev-
ed by split dosing of the chemicals, followed by tertiary filtration.
21
-------
SECTION VI
NITROGEN CONTROL
DESIGN AND CONSTRUCTION
The construction and installation of the capital equipment for nitrogen control
started February 1972. The process selected was staged biological suspended
growth nitrification followed by attached growth biological denitrification
with tertiary filtration.
At the time of the initiation of the grant it was not clear whether the Texas
Water Quality Board would require nitrogen removal or elect to establish nitro-
gen control on a total oxygen demand basis. To benefit both parties of the
grant in relation to their financial interests, several compromises in design
criteria were made. The phosphorus removal, nitrification and tertiary fil-
tration facilities would be designed for a maximum dry weather flow of 0.5 mgd.
Design for denitrification would be for average dry weather flow of 0.3 mgd
since there was no established nitrogen removal standard. Flows in excess of
0.5 mgd could be routed around the nitrification and denitrification processes.
Within these confines all the processes required to meet the state standards
would be designed for maximum dry weather flow, and the experimental portion of
the design - denitrification - would be evaluated at average dry weather flow
and stressed to maximum dry weather flow. Wet weather flow in excess of 0.5
mgd occurs only about eight percent of the time at El Lago.
The preliminary studies had shown that, even in series operation, the existing
trickling filters did not produce a completely nitrified effluent. Therefore,
a suspended growth reactor was selected for Phase II. The feed to the nitri-
fication reactor is the direct underdrain from the existing trickling filters.
The final clarifiers were converted to intermediate clarifiers to separate the
nitrification mixed liquor.
Attached growth denitrification was selected in contrast to the suspended growth
nitrification process. Two media were chosen for comparison. One set of de-
nitrification towers has large plastic media, and the other set of towers has
fine sand media.
Tertiary filtration was deemed necessary to ensure meeting Texas Water Quality
Board requirements and to produce a clear effluent for aesthetic reasons.
Construction consisted of general earth work, construction of the concrete ni-
trification reactor and nitrified effluent sump storage, installation of four
22
-------
air lift pumps in the intermediate clarifiers, construction of concrete pads
for the denitrification towers, erection of the two fine media towers and the
two large media towers, installation of two air blowers, installation of two
five-stage centrifugal pumps and electrical flow control system, installation
of two methyl alcohol dosing pumps, installation of process and backwash piping
and valving, installation of the tertiary filter, installation of electrical
wiring, laying of chemical feed lines, construction of a laboratory and control
building, and miscellaneous related tasks. Figure 6 shows a schematic of Phase
II additions to the plant.
The nitrification reactor and nitrified effluent sump occupy a rectangular tank
which is divided into three bays by two common walls. The nitrification reac-
tor, consisting of one or both of the first two bays, receives the trickling fil-
ter underdrain and was designed for biological oxidation of ammonium nitrogen
to nitrate nitrogen. Separation into two bays gives flexibility to vary deten-
tion time for study of the nitrification process rates. The third bay serves
as a sump for the nitrified effluent after it has passed through the intermed-
iate clarifiers and before it is pumped to the denitrification towers. When not
used for nitrification, the smaller of the first two bays can be interconnected
with the third bay to double the sump capacity. This increased storage capacity
helps equalize the flow to the denitrification towers. Design specifications
for the nitrification reactor and the sump are given in Table 7. Figure 7 shows
the two aeration bays of the nitrification reactor on the right and the sump on
the left. The two centrifugal blowers (Lamson Div. of Diebold, Inc.) shown in
Figure 8 are used to provide air for the aerobic nitrification process, for op-
eration of air lift pumps and for air scouring of the small media denitrifica-
tion towers. Each blower has a capacity of 450 ft3/min and only one is used at
a time. Routine operation is to switch units each day. Air from the blowers
is discharged into the nitrification reactor through diffusers (Eimco Div.,
Envirotech Corp., Assembly No. 209). Figure 9 shows one of the two intermediate
settlers with the air lift pump piping and header that returns settled nitrifi-
cation sludge to the nitrification reactor inlet channel. Nitrified effluent
flows from the section of the settlers seen in the foreground and enters the
pump sump shown in Figure 10. The vertical pumps seen in this picture are five-
stage industrial turbines with semi-open impellers (Goulds, Model VIT). Each
can deliver 210 gpm at a total pumping head of 115 ft. The pumps are variable
speed direct drive, and they are controlled by an Autocon Class 1900 Reacto-
speed Duplex Drive that receives a signal from an Autocon Model 174 Proportion-
al Range Sensor and a self purging Bubbletrol system. The lead pump is alter-
nated automatically each 24 hours. These pumps serve as feed pumps to the de-
nitrification towers and as prime movers for the backwash of these towers.
Following an initial evaluation period, two constant speed, four-stage turbine
pumps (Fairbanks Morse, Model 6977) were added in parallel with the variable
speed pumps. The new pumps each have a capacity to deliver 250 gpm at a total
pumping head of 120 ft. These pumps commence operation after the water in the
sump has risen past the level at which both variable speed pumps are at full
speed. The combined pumping capacity of all four pumps is approximately 900
gpm.
Immediately downstream from the pump manifold, the discharge line is tapped to
permit the injection of methyl alcohol into the nitrified wastewater before it
enters the denitrification towers. Two diaphragm pumps (Wallace and Tiernan,
Series A-747) with variable speed motors are used to dose the alcohol. Stroke
23
-------
200,000 £pd
Plant 1
Polymer and
Pump House
Intermediate
Clarifier
Media
w. ^x
J)enitrification
Large U Media
Methanol
Storage and
Pumps
Final Effluent,
to Clear Lake
Figure 6. Phase II construction.
= Main flow
= Sludge
= Chemical
24
-------
Table ?. SPECIFICATIONS FOE NITRIFICATION REACTOR
Section Volume Detention time, Detention time,
hr. ADW hr. MDW
Main Bay 56,988 gal 4.5 2.7
Second Bay 18,81? gal
Both Bays 75,805 gal 6.1 3.6
Nitrified
Effluent Sump 18,81? gal
Diffusers:
Two headers in main "bay 12.4 ft each, with diffusers spaced 1 ft,
One header in second bay with diffusers spaced 1 ft. All head-
ers located on south wall.
Compressors;
Two, 4-50 ftVmin capacity, alternately operated; to supply air
for nitrification bays, air lift pumps, and filter scour.
Air lift pumps;
Two each, located in each clarifier to return settled mixed liq-
uor to main nitrification bay.
Intermediate clarifiers:
As shown on Table 1 as final clarifier.
25
-------
Figure 7. Nitrification reactor and sump
26
-------
Figure 8. Centrifugal blowers
27
-------
Figure 9. Intermediate clarifier and air lift pumps
28
-------
Figure 10. Sump and vertical turbine centrifugal pumps
29
-------
length can be manually adjusted to vary the feed rate. Maximum capacity of
each pump is 25 gal/day at 15 psi. Initially, the speed of the alcohol pumps
varied in response to the speed of the vertical centrifugal wastewater pumps
controlled by the Autocon Duplex Drive. Experience soon revealed that the
flow of wastewater through the denitrification towers was not directly pro-
portional to centrifugal pump speed. This was due to changes in discharge
head associated with changes in flow rate and varying degrees of plugging in
the denitrification towers and the tertiary filters. As a result, higher al-
cohol dose rates occurred during periods of high flow and when tower and filter
plugging created substantial restrictions to flow. In order to make the alco-
hol pump speed, and the alcohol feed rate, proportional to the rate of flow of
wastewater, the controls were modified to accept a signal from a flow meter in
the denitrification line. Very uniform alcohol dose rates are provided by the
modified system. Figure 11 is a view of the two 500 gal. alcohol storage tanks
and the two alcohol pumps. The pumps are located out-of-doors to ensure that
alcohol vapors do not accumulate in the small pump house.
The denitrification towers are shown in Figure 12. The smaller front two towers
are a proprietary design of Dravo Corporation and contain 3-4 mm rounded sand
particles. The towers are operated downflow in series. Representative sand
particles are shown in Figure 13.
The two larger towers in Figure 11 were shop-fabricated and field erected steel
tanks designed specifically for this demonstration project. The media packing
for this set of towers are 5/8 X 5/8 in. cylindrical polyethylene Flexirings
(Koch Engineering, Inc.). These towers are operated upflow in series. The
smallest cylinder on the extreme right in Figure 14 is the type used in the
large towers.
To collect data on a realistic scale, each set of towers was designed for aver-
age dry weather-flow. Thus, only one set can be evaluated at any time. Design
specifications for the small sand media and the large plastic media towers are
given in Tables 8 and 9, respectively.
Figure 15 shows the tertiary filter installed at El Lago. The units were shop-
fabricated and field erected (Garchem Corp.). This filtration equipment was
built to the specifications listed in Table 10. Filtered effluent is discharged
to the chlorine contact tanks shown in Figure 16. The 150-lb. gaseous chlorine
cylinders are visible in the background. Effluent from the contact tanks flows
to Clear Lake after cascade aeration which occurs during a 6 ft drop from the
discharge weir to the inlet of the outfall pipe.
Phase II construction was finished by the completion of the laboratory and con-
trol building shown in Figure 17. All analytical work reported for this study
has been done by independent laboratory contract purchases. However, the build-
ing will have further utility if other grant studies are entered into and if
local operator training courses are conducted at the El Lago facility. One sec-
tion is also used as a visitor orientation room.
30
-------
Figure 11. Methyl alcohol storage tanks and pumps
31
-------
Figure 12. Packed bed denitrification towers
32
-------
Figure 13. Small sand media packing
33
-------
Figure 14. Plastic media packing
34
-------
Table 8. DESIGN SPECIFICATIONS FOR FINE SAND
MEDIA DENITRIFICATION TOWERS
Item
Specification
Vessels
Pressure test
Material
Diameter
Media height
Media type
Porosity
Empty bed contact time
Process hydraulic rate
at 0.5 mgd
at 0.5 mgd
Backwash water source
Backwash rate
Air cleaning rate
Freeboard
2 - connected in series, downflow
to 50 psi
steel tanks, sandblasted and shop
coated
6 ft
6.5 ft each tower
3-4 mm rounded sand of glacial origin
"
40 percent. Surface area 250 ft
15 minutes
7.4
12.3
nitrified effluent
20 gpm/ft2
8 cfm/f t2
30 percent bed expansion
35
-------
Table 9. DESIGN SPECIFICATIONS FOR PLASTIC
MEDIA DENITRIFICATION TOWERS
Item
Specification
Vessels
Pressure test
Material
Diameter
Media height
Vessel interior
Media type
Porosity
Empty bed contact time
Process hydraulic rate
at 0.5 mgd
at 0.5 mgd
Backwash water source
Backwash rate
Freeboard
2 - connected in series, upflow
to 50 psi
steel tanks, sandblasted and shop
coated
10 ft
10 ft each tower
divided into quarters by solid walls,
from the bottom head to the top of
the media - freeboard section common
to all quarters - separate influent
connections for each quarter — wire
mesh across top of media
5/8-inch Flexirings, polypropylene
92 percent - surface area 105 ft /ft*
60 minutes
1.5 gpm/ft?
-.1 gpm/ft
nitrified effluent
20 gpm/ft2
Not needed - 2 ft at apex of cone
above wire mesh
36
-------
Figure 15. Tertiary granular media filter
37
-------
Table 10. TERTIARY FILTER SPECIFICATIONS
Item
Specification
Vessels
Pressure test
Material
Diameter
Media height
Media type
Process hydraulic rate:
0.3 mgd
0.5 mgd
1.0 mgd
Backwash initiation
Backwash source
Backwash rate
Freeboard
Influent suspended solids
Effluent suspended solids
Inspection and instruction
Period of performance
2 - connected in parallel, downflow
to 30 psi
steel tanks, sandblasted and shop
coated
8 ft
6 inch gravel subfill; 3 ft media,
each filter
sand; 91 percent less than 0.8 mm
and 91 percent greater than 0.3 mm
Both filters in operation:
2.2 gpm/ft2
3.5 gpm/ft2
7.0 gpm/ft2
manual - time clock - pressure
chlorinated final effluent
15 gpm/ft , single filter
30 percent bed expansion
40 mg/1
less than 10 mg/1
Competent person to inspect construc-
tion and instruct operational
personnel•
Six months to demonstrate capability,
38
-------
Figure 16. Chlorine contact tanks
39
-------
Figure 17. Laboratory and control building
40
-------
OPERATION AND RESULTS, NITRIFICATION
In order to obtain a high efficiency of total nitrogen removal by biological
denitrification, a high degree of nitrification capability is needed. Table 3
shows that the existing trickling filters partially nitrified the wastewater;
but to insure as complete as possible conversion of ammonium and organic
nitrogen to nitrate nitrogen, the above described nitrification reactor was
considered essential. This reactor was placed into operation in January 1973.
Influent was the underdrain from the trickling filters. The concentration of
BODs ™ tn"js influent proved to be too low to provide flocculant growth in the
nitrification reactor. Consequently, most solids in the effluent were carried
on through the intermediate clarifiers instead of settling out and being re-
turned to the reactor by the airlift pumps. This problem was corrected by
diverting a slip stream of primary effluent into the reactor from March 12 to
March 26, 1973, along with the underdrain flow. Operational personnel were
cautioned not to waste any nitrification solids from the clarifiers until the
nitrification mixed liquor had a high solids content. By March 26, 1973, the
suspended solids in the mixed liquor had increased from 40 mg/1 to 1,000 mg/1
and the slip stream was discontinued. By June 1973, the mixed liquor had
reached an almost steady state level of 2,500 mg/1 total suspended solids and
1,000 mg/1 volatile suspended solids. With a volatile solids content of 1,000
mg/1, a flow of 0.3 mgd, no sludge wasting and a suspended solids content of
30 mg/1 in the clarified effluent, a sludge age of about 10 days was maint-
tained. Since January 8, 1974, the nitrification reactor has been operated
with only the main bay in use.
An example of the overall nitrification performance is given in Table 11. It
is impossible to gauge the unit performance of the nitrification reactor in
this design because at average dry weather flow nitrified effluent at a ratio
of 1:1 is recycled from the intermediate clarifier back to the rock trickling
filter. This, of course, dilutes the ammonium nitrogen and organic nitrogen
in the filter underdrain with nitrate nitrogen from the suspended growth reac-
tor so the rock filter has an apparent high nitrification capacity. The table
shows a loss of about 10 mg/1 of total nitrogen from primary effluent to the
nitrified effluent. This loss is to be expected as coincidental denitrifica-
tion occurs when the nitrified effluent is recycled to the primary effluent
before it passes over the trickling filter; and the filter underdrain flows
in a closed channel to the nitrification reactor.
The combination of a low rate rock filter with a second stage suspended growth
reactor for two-stage nitrification has proved to be very stable. Even during
the months of February and March 1973, when solids were building up in the
aerator, good nitrification was obtained. Twice during the early operation-
al period, hydraulic washout of part of the aerator solids occurred during
storm events. Nitrification capability was possible within two days, due to
the seeding action of the trickling filter underdrain. The plant is now oper-
ated so that when storm flows in excess of 0.5 mgd occur a portion of the
flow is routed around the nitrification and denitrification facilities.
Within two weeks after starting the practice of dosing a portion of the fer-
ric chloride into the nitrification reactor,the suspended solids of the mixed
liquor increased to 4,500 mg/1 and the volatile fraction to 1,800 mg/1. This
41
-------
Table 11. NITRIFICATION PERFORMANCE, mg/1'
Raw Primary
Constituent wastewater effluent
NH.-N
* Avg 15.4 15.1
Range 3.9-24.6 4.0-24.0
Org-N
Avg 14.6 10.6
Range 10.0-15.4 8.0-11.5
NO,-N
Avg
Range - -
Trickling
filter
underdrain
2.3
0.8-3.4
3.1
1.4-5.4
15.6
7.3-22.9
Nitrified
effluent
1.0
0.3-2.3
1.6
0.5-5.3
13-6
5.9-23.8
*From 33 sampling periods in July and August 1973
42
-------
soon made it necessary to deliberately waste sludge from the reactor to pre-
vent a high fraction of inert solids buildup and to alleviate a solids over-
load on the intermediate clarifiers. Solids are now wasted on an almost daily
basis to keep settleable solids in the mixed liquor at about 160 ml/1. This
normally corresponds to about 3,300 mg/1 of total suspended solids and 1,300
mg/1 of volatile suspended solids. A sludge volume index (SVI) of 50 is
normal.
The air lift pumps which return solids from the clarifiers to the nitrifica-
tion reactors were operated manually for several months. Efforts were made
to adjust the air flow to the pumps to provide continuous return of solids to
the reactor. Lack of success with this procedure led to the practice of return-
ing solids for several minutes each hour that operators were on duty. This
proved to be quite satisfactory for about nine hours each day, but almost all
of the solids accumulated in the clarifiers during the fifteen hours when no
one was present to operate the air lift pumps. To correct this problem,
timers and solenoid valves were installed to provide automatic operation of
pumps. Solids are now returned around the clock by the four air lift pumps
which operate in rotation with each pumping about three minutes during each 20
minute cycle. All pumps are turned off for about one hour each day to permit
an accumulation of solids in the clarifier hoppers from which the excess is
wasted to the plant wet well.
OPERATION AND RESULTS. SMALL MEDIA DENITRIFICATION TOWERS
These towers were operated from May to mid-July 1973 for initial evaluation of
process capability. The columns were placed into operation by gradual in-
creases in the weight ratio of methyl alcohol to nitrate nitrogen. The ratio
was increased from 1:1, to 2:1, to 3:1 over a ten-day period. A two-week per-
iod was necessary to establish an acclimated denitrifying population on the
fine media. The towers are piped in series, and the lead column cannot be al-
tered in sequence. The biological denitrification process utilizing methyl al-
cohol as an organic supplement has a cell yield of 0.2 parts of cells produced
per part of alcohol oxidized. Since these fine media towers have a porisity of
40 percent, the growth of cellular material increases the resistance to flow
through the tower. It was found necessary to backwash the lead tower each day
in order to achieve satisfactory through-put. The second tower usually re-
quires backwashing on alternate days.
The efficiency of the entire plant during use of the small media towers was
initially calculated from data taken during the period from June 4 through
July 6, 1973. After modifications to improve methyl alcohol dosing, data were
again collected during operation of the small media towers from September 23
through November 8, 1974. Table 12 gives the general conditions at the plant
during these two periods; and Tables 13A and 13B show the residual concentra-
tions of pollutants through each unit process for these two periods.
It should be noted in Table 13A that suspended solids, as well as several other
constitutents, showed an increase in concentration in the primary influent as
compared to the raw wastewater. The substantial increase in suspended solids
is due to the precipitates formed as a result of ferric chloride and polymer
addition and to the return of solids from backwashing the small media denitri-
43
-------
Table 12. CONDITIONS FOR EVALUATION OF SMALL
MEDIA DENITRIFICATION TOWERS
Jun - Jul
1973
Sept - Nov
1974
Length, of study period:
Rain during study period:
Total
Peak day
Total flow to plant:
Average
Low day
High day
Flow to small media
denitrification towers:
Average
Low day
High, day
Wastewater temperature:
Total number of analytical
measurements:
33 days
12.2 inches
5.7 inches
0.307 mgd
0.160 mgd
1.000 mgd
0.254- mgd
0.160 mgd
0.420 mgd
78° F
433
47 days
2.5 inches
0.6 inches
0.255 mgd
0.202 mgd
0.386 mgd
0.282 mgd
0.084 mgd
0.384 mgd
78° F
1,081
44
-------
Table 13A. INITIAL EVALUATION OF SMALL MEDIA DENITRIFICATION TOWERS, mg/1
(34 days: June 4 to July 6, 1973)
Keasure-
ment
EOD,-
Avg
Range
COD
Avg
Range
TP
Avg
Range
3P
Avg
Range
S3
Avg
Range
Avg
Range
TKN
Avg
Range
NO,-N
5 Avg
Range
Methanol
dose
Avg
Range
Haw
wastewater
175
297
89-391
12.8
3.7-21.8
10.3
2.4-17.0
113
21-200
18.7
2.4-35.2
42.6
7.7-64.7
-
-
Primary
influent
222
220-223
488
244-720
15.4
4.8-22.8
4.7
0.9-12
289
98-754
21.7
16.2-26.2
38.6
30.8-49.3
-
-
Primary
effluent
-
181
101-240
8.4
5.1-15.6
4.1
1.6-6.9
72
37-114
21.5
16.2-23.9
30.2
29.3-31.6
-
-
Nitrified
effluent
65*
58-72
121*
51-224
7.3
4.0-16.1
3.4
2.1-3.9
37
8-57
0.9
0.4-2.2
3.7
0.8-10.8
15.2
5.4-24.8
47
20-81
Denitrified Final
effluent effluent
9
6-12
72
16-176
6.6
1.5-11.5
5.5
1.0-11.0
17
2-56
0.8
0.5-1.8
2.4
0.9-6.2
2.6
0-9.7
-
9
5-18
51
36-90
4.8
4.1-5
3.6
2.1-5
3
1-6
0.6
0.4-0
3.3
1.5-6
2.3
0-5.4
-
.4
.0
.7
.2
"Includes demand due to added methanol.
45
-------
Table 13B. EVALUATION OF SMALL MEDIA DENITRIFICATION TOWERS, mg/1*
(47 Dyas: September 23 - November 8, 1974)
Measure-
ment
BOD.
''Avg
Range
COD
Avg
Range
TP
Avg
flange
SP
Avg
Range
Avg
Range
* "4 Avg
Range
TKK
Avg
Range
NO,-N
•* Avg
Range
Pe"1"5 dose*
Avg
Range
Polymer
dose
Avg
.ttange
Methanol
dose
Avg
Range
pH
Median
Range
Primary
influent
_
-
12
8.1-16
2.1
-------
fication towers and the tertiary filters. Increases in BODs and COD are due
to recycle of digester supernatant and backwash water. The slight increase in
total phosphorus is considered to be due primarily to the insoluble phosphorus
backwashed from the final filters; and an increase in ammonium nitrogen is the
result of the decomposition of organic nitrogen compounds. Table 13B shows no
values for raw wastewater since emphasis during the final evaluation period
was shifted more to the nitrification reactor and the denitrification towers.
In order to better evaluate the denitrification process, sampling was commenc-
ed between the two towers in'series. These samples were analyzed for suspend-
ed solids, nitrate nitrogen, pH, BOD5 and COD.
During the initial evaluation period, high rainfall and concentration of ef-
fort on the startup of the denitrification process prevented optimum ferric
chloride and polymer dosing for phosphorus removal; consequently, only 63 per-
cent removal was achieved to produce a final effluent containing an average of
4.8 mg/1 of total phosphorus. During the final evaluation of small media tow-
ers, ferric chloride and polymer dosage was more consistent and total phospho-
rus content was reduced from an average of 12 mg/1 in the primary influent to
0.39 mg/1 in the final effluent. The average total does of metal salt was
41 mg/1 of Fe+3. This application was split approximately 2 to 1 between the
wet well and the nitrification reactor. The overall dose of metal salt was al-
most a 2 to 1 mole ratio of iron to total phosphorus in the primary influent.
Suspended solids reduction across the primary settlers was sufficient to pre-
vent the overload of downstream processes. During the first period, the small
media towers produced an effluent containing 17 mg/1 of suspended solids which
was somewhat higher than anticipated but was partly due to backwashing the
towers with feedwater which contained 37 mg/1 of solids. Effluent from the
small media towers contained 41 mg/1 of suspended solids during the final per-
iod. This was a marked increase over that for the first period; but the in-
fluent, also used for backwashing, contained 78 mg/1 suspended solids, which
was more than twice the concentration during the earlier period. Another prob-
able cause of high solids in the effluent was intermingling of the different
layers of supporting gravel with the fine media which resulted from improper
backwashing. However, this created no serious problem since, even in the de-
sign stage, tertiary filtration had been deemed necessary as a backup solids
removal system. The tertiary filter proved very capable of producing a pol-
ished effluent containing an average suspended solids residual of 3 mg/1 dur-
ing the first period; and after addition of facilities for adding polymer to
the filter feedwater, the suspended solids in the effluent dropped to an aver-
age of 1 mg/1 during the final evaluation. The tertiary filter effluent is of
such quality that the floor of the chlorine contact tank is usually visible
through a sidewater depth of almost 7 ft.
The nitrogen species behaved in a manner similar to the sequence given in
Table 11; there was a gradual hydrolysis of organic nitrogen to ammonium ni-
trogen in the treatment processes with a small organic nitrogen residual (2.7
mg/1 and 0.6 mg/1 in the first and second evaluations, respectively) passing
through the entire process. Nitrification was essentially complete with a re-
sidual ammonium nitrogen of less than 1 mg/1 appearing in the nitrified efflu-
ent. The nitrified effluent dissolved oxygen content was 6 mg/1 before dosing
with methyl alcohol and that of the tower effluent was 0.5 mg/1 as measured by
galvanic probe. The source of the backwash water is also important to the
47
-------
nitrogen removal efficiency of the process at El Lago because the backwash
water contains nitrate nitrogen, and the methyl alcohol pumps are turned off
during backwash; therefore, when the tower is placed back on-line, high con-
centrations of nitrate will be discharged in the beginning of the cycle. In
view of this and the short hydraulic detention time as shown in Table 8, the
towers performed in a very efficient manner. During the initial evaluation
period, the residual nitrate concentration in the final effluent was about
2 mg/1, the residual total nitrogen content was 5.6 mg/1 and total nitrogen
removal efficiency was about 87 percent. Comparison of methyl alcohol dosage
data in Tables 13A and 13B shows a somewhat lower average dose rate but it was
a much more consistent dosing. Improved alcohol dosing and a more uniform
flow of wastewater are considered to be primarily responsible for improved
nitrogen removal during the final evaluation period. Residual nitrate con-
centration in the final effluent dropped to 0.9 mg/1 while total nitrogen con-
tent was 1.8 mg/1. Nitrite nitrogen was not found to be present in signif-
icant concentrations. The estimated overall removal of nitrogen was 94 per-
cent. Ninety percent of the total nitrogen present in the influent to deni-
trification was removed prior to discharge. The data show that both towers
in series are necessary to accomplish efficient nitrogen removal.
The organic content of the wastewater, as evidenced by BOD5 and COD, was con-
trolled by the combined processes of primary settling, trickling filtration,
and aeration in the nitrification reactor followed by substantial polishing
by the tertiary filter removing the suspended organic material. The oxygen
demand values for the nitrified effluent in Tables 13A and 13B reflect the
contribution by addition of methyl alcohol prior to the denitrification pro-
cess. Lower effluent concentrations of both BOD5 and COD were observed dur-
ing the final evaluation as might be expected since the methyl alcohol dosage
was lower and more uniform during this latter period and suspended solids re-
moval was considerably improved. During this period the final effluent con-
tained an average of 2.9 mg/1 BOD5 and 17 mg/1 COD.
Recovery of denitrification efficiency following backwash was observed by de-
termining nitrate nitrogen concentrations at three points in the flow stream
immediately upon putting the towers back in operation and at 30-minute inter-
vals during the succeeding four hours. Nitrate nitrogen concentrations in
the influent to the first tower and in the effluent from each of the two towers
for that 4-hour period are shown in Table 14. Denitrification efficiency ap-
peared to be normal after 1 1/2 hours of operation following backwash of both
towers.
OPERATION AND RESULTS. LARGE MEDIA DENITRIFICATION TOWERS
The large media media towers were placed in operation in early July 1973.
After completion of construction, the vessels were wet tested and allowed
to stand idle for six months while filled with nitrified effluent. Initia-
tion of denitrification was rapid; and within three days, full denitrifica-
tion capability was achieved. An acclimated biological film had apparently
established itself on the plastic media surfaces during the idle interval.
The towers are piped in series, and the lead column cannot be altered. The
high void volume of 92 percent of the plastic media allows these towers to
48
-------
Table 14. SMALL MEDIA DEVITRIFICATION TOWER
PERFORMANCE FOLLOWING BACKWASH
Time followingNO?-N, mg/1
completion of Denit Denit #1 Denit #2
backwash, ar influent effluent effluent
0.0 17 11 10
0.5 17 4.8 3.4
1.0 18 2.7 1.3
1.5 14 1.6 0.6
2.0 15 2.0 1.1
2.5 18 2.4 0.8
3.0 17 2.2 0.9
3-5 17 2.3 1.0
4.0 14 2.5 1.1
49
-------
be operated without frequent backwash even though the biological denitrifica-
tion produces biological solids. Initially, six weeks of operation was pos-
sible before backwash was necessary. Then the routine procedure for months
was to backwash at wash was necessary. Then the routine procedure for months
was to backwash at 4-week intervals. The need to backwash was not related to
pressure drop through the towers, but arose to prevent excessive suspended
solids in the tower effluent. This was in contrast to the operational ex-
perience with the small media towers which required daily backwash due to
pressure drop. Late in the final evaluation period it was learned that de-
nitrification efficiency could be improved by more frequent backwashing even
though solids and pressure loss were not problems.
One important operational consideration was discovered during the initial ev-
evaluation of the large media upflow towers after they had been taken out of
service for two days and allowed to stand undisturbed. Upon resumption of
operation it was found that a large amount of solids had floated to the top
of each tower buoyed up by nitrogen gas bubbles. The effluent suspended sol-
ids completely blinded the down-stream tertiary filter. After that exper-
ience, routine operation provided for backwash before taking the towers off-
line and again immediately before placing them back on-line.
The efficiency of the entire plant when using the large media denitrification
process was evaluated from July 8 through August 31, 1973, to ascertain the
initial operational procedures that would have to be controlled for long term
studies. Following modifications to improve methyl alcohol dosing, further
studies were conducted to evaluate plant efficiency. These evaluation periods
were 31 days from November 16 through December 16, 1974, and 41 days from Jan-
uary 5 through February 14, 1975. The test plan originally provided for one
uninterrupted final evaluation period, but nonavailability of methyl alcohol
forced the shutdown of the denitrification process for 20 days. Table 15
gives the general conditions at the plant during these three periods.
Tables 16A, 16B and 16C show the residual concentrations of pollutants through
unit processes for the initial evaluation period and two final test runs, re-
spectively. Rainfall was less during the initial evaluation of the large
media towers than during the initial study of the small media towers. Also,
by the time of the first large media study, the operational sequence to keep
the multi-stage processes in operation simultaneously had been worked out with
experience gained in the previous five weeks. Total phosphorus removal im-
proved to 77 percent, but a residual soluble concentration of 2 mg/1 was pre-
sent. During the last week of the initial study of the large media towers,
the ferric chloride dose was split 2 to 1 between the wet well and the nitri-
fication reactor; but these few days of data did not significantly cKlter the
average phosphorus value compiled for the 55 days of the study period. Tables
16B and 16C show the effectiveness of this technique during the final evalua-
tion phases of large media denitrification. Suspended solids data for all
three periods show the same general trend as during the small media studies,
except for the concentrations in nitrification effluent and denitrification
effluent which are substantially lower than during the final small media
evaluation period.
50
-------
Table 15. CONDITIONS FOR EVALUATION OF
LARGE MEDIA DEVITRIFICATION TOWERS
Jul-Aug
1975
Nov-Dec
1974
Jan-Feb
1975
Length of study period:
Rain during study period:
Total rain
Peak day
Total flow to plant:
Average
Low day
High day
Flow to large media denitri-
fication towers:
Average
Low day
High day
Wastewater temperature:
Total number of analytical
measurements:
55 days
9.9 inches
2.5 inches
0.320 mgd
0.171 mgd
0.900 mgd
31 days
4.9 inches
1.4 inches
0.366 mgd
0.248 mgd
0.835
days
3.3 inches
0.9 inches
0.410 mgd
0.267 mgd
0.790 mgd
0.315 mgd
0.171 mgd
0.632 mgd
81°F
0.363 mgd
0.037 mgd
0.555 mgd
75°F
0.366 mgd
0.160 mgd
0.538 mgd
73°F
1,254
473
573
51
-------
Table 16A. INITIAL EVALUATION OF LARGE MEDIA DENITRIFICATION TOWERS, mg/1
(55 days: July 8 - August 31, 1973)
Measure-
ment
Avg
Pange
COD
Avg
Range
IP
Avg
Range
SP
Avg
Hange
S3
Avg
Range
' 4 Avg
Range
TKN
Avg
Range
NO,-N
Avg
Range
Methanol
dose
Avg
Range
Raw
waste water
143
60-260
248
136-380
12.3
6.2-18.5
10.3
3.3-15.9
102
43-219
16.3
3.9-24.6
29.7
13.9-40.0
-
-
Primary
influent
156
86-243
336
111-590
13.1
5.5-22.1
3-1
0.5-9.6
231
104-456
14.6
3.1-29-3
31.8
19.3-46.2
-
-
Pririary
effluent
87
47-124
167
97-329
6.7
1.0-17.4
2.4
0-6.5
63
17-136
14.4
6.2-20
26.7
16.2-35.4
-
-
Nitrified
effluent
43*
11-66
107*
50-207
-
-
43
2.0-90
0.9
0.3-2.3
2.6
0.8-7.6
13.6
5.9-23.8
34
16-69
Denitrified
effluent
15
3-38
52
23-182
-
-
19
2-71
1.2
0.1-3.0
2.5
0.5-6.1
0.9
0-3.0
-
Final
effluent
8
0.8-20
38
20-63
2.8
1.0-6.2
2.3
0.5-6.2
4.5
0.4-24
0.9
0.3-1.8
1.7
0.9-3.5
0.6
0-3.5
-
•Includes demand due to added methanol.
52
-------
Table 16B. EVALUATION OF LARGE MEDIA DENITRIFICATION TOWERS, mg/1
(31 days: November 16 - December 16, 1974)
Measure-
ment
BODq
-^Avg
Range
COD
Avg
Range
TP
Avg
Range
SP
Avg
Range
SS
Avg
Range
NH..-N
* Avg
Range
TKN
Avg
Range
NO,-N
^ Avg
Range
Fe*5 doset
Avg
Range
Polymer
dose
Avg
Range
Methanol
dose
Avg
Range
pH
Median
Range
Primary
influent
—
—
11
6.0-14
J>
1.2-10
20?
98-304
_
—
-
27
14-43
0.21
0.00-0.29
—
7.4
7.3-8.0
Primary
effluent
_
_
5
2.6-10
1.9
0.71-6.5
64
51-88
16
3.4-21
21
11-27
-
—
-
_
7.3
7.3-7.8
Nitrified
effluent
35+
16-42
69+
43-97
_
•
_
36
22-63
0.7
0.3-1.7
2.7
1.7-3.6
11
6.7-15
-
_
36
20-49
7.8
7.5-7.9
Denitrified
from
1st tower
20
8.5-38
47
28-97
_
_
28
7-91
.
..
5.6
2.1-8.8
_
_
_
7.7
7.6-7.8
effluent
from
2nd tower
11
2.7-24
32
16-70
2.4
1.6-4.4
0.6
0.27-1.5
13
2-57
0.5
0.1-1.9
1.7
0.8-3.6
2.6
0.6-7.0
_
0.16
0.00-0.26
_
7.7
7.5-7.9
Final
effluent
4
1.3-11
25
8-40
0.7
0.28-1.3
0.6
0.25-1.3
2
1-6
0.5
0.2-1.7
1.1
0.6-2.8
3.0
0.1-7.0
«•
.
•*
7.4
7.3-7.6
*Except pH
•••Includes demand due to added methanol
jDose split approximately 2:1 between primary influent
reactor
and nitrification
-------
Table 16C. EVALUATION OF LARGE MEDIA DENITRIFICATION TOWERS, mg/1*
(41 days: January 5 - February 14, 1975)
Measure-
ment
30D5
Range
COD
Avg
flange
TP
Avg
Range
SP
Avg
Range
SS
Avg
Range
Avg
Range
TKN
Avg
Range
NO,-N
Avg
Range
Fe*5 doset
Avg
Range
Polymer
doseAvg
Range
Methanol
dose
Avg
Range
PH
Kedian
Range
Primary Primary
influent effluent
— — •
-
10 4.0
5.9-12 2.8-5.4
1.1 0.50
0.41-2.0 C.33-0.70
251 72
1^6-404 48-134
16
10-20
21
15-26
-
25
14-57
0.22
0.15-0.32
— —
7.4 7.3
7.1-7.6 7.1-7.5
Nitrified
effluent
55+
2,3-87
100*
56-150
""*
~
36
17-65
0.6
0.2-1.4
4
2.2-16
14
9.7-18
—
-
44
33-55
7.7
7.6-8.0
Denitrified effluent
from from
1st tower 2nd tower
24 13
13-50 1.8-47
57 38
31-110 12-99
2.4
1.7-3.9
0.50
0.40-0.58
24 13
3-70
-------
The nitrogen transformations were similar to those previously observed, and
essentially complete nitrification was obtained as evidenced by an average
residual ammonium nitrogen of less than 1 mg/1 in both nitrified effluent and
final effluent during all three study periods. Biological denitrification was
more complete during the initial evaluation of the large media than during
small media studies even though the ratio of methyl alcohol to nitrate nitro-
gen content of the nitrified effluent was significantly lower. Nitrate reduc-
tion was 93 percent with a 2.5:1 weight ratio of methyl alcohol to nitrate
nitrogen. This higher efficiency was probably due, at least in part, to the
more uniform methyl alcohol dosing since the large media towers did not develop
large pressure losses that had such a pronounced effect on the original al-
cohol dosing system. Data from the two final evaluation phases, shown in
Tables 16B and 16C, include analytical results of samples taken between the
two towers being operated in series. The levels of nitrate nitrogen, BODs
and COD show that considerable denitrification was occurring in the second
tower which is considered essential to efficient operation. Data from the
last two study periods failed to confirm the higher efficiency of the large
media towers as compared to the towers with small media. During the first
of the two final evaluation periods, 76 percent reduction in nitrate nitrogen
was attained with a 3.3:1 weight ratio of methyl alcohol to nitrate nitrogen.
The last evaluation showed 80 percent reduction in nitrate nitrogen with the
methyl alcohol dosing being slightly reduced to a weight ratio of 3.1:1. The
improved efficiency during the last evaluation period may be the result of
backwashing more frequencly than in the earlier runs. The towers were back-
washed 7 times during the last 15 days in an attempt to prevent channeling
which could have been caused poor denitrification by reducing effective de-
tention time. The improvement of denitrification with more frequent back-
washing tends to support this channeling theory, but experience is too limit-
ed for a firm conclusion.
55
-------
SECTION VII
DISCUSSION OF MODIFIED PLANT OPERATION AND RESULTS
Plant operation and evaluation were complicated by reliance upon a succession
of commercial laboratories for analytical services. Several of these were
found to be unsatisfactory due to excessive time required for reporting ana-
lytical results and to poor performance in analysis of EPA reference samples.
Unreliable analytical results led to delays in optimizing chemical dosages
and operating procedures as well as to discarding data covering several per-
iods of evaluation. Data presented in this report were provided by laborator-
ies which reported acceptable values for EPA reference samples. In addition,
the laboratory which provided analytical services for final study phases of
denitrification was also evaluated by comparing their analytical results on
both plant and EPA reference samples with those of a local referee laboratory
and two competing laboratories.
The wide range of values for each of the various pollutant concentrations is
evident in Tables 13A, 13B, 16A, 16B and 16C. This is typical of the occur-
rence of wastewater constitutents at a small domestic treatment plant with a
short lateral and interceptor system. Recycle flows within the plant also
contribute to this variability. Such wide ranges in pollutant concentrations
make it difficult to achieve maximum efficiency in processes requiring stoich-
iometric addition of chemicals. Since the El Lago facility is manned on the
day shift only, chemical dosing pumps must be set to deliver a dose based on
average concentration of pollutants. In the case of phosphorus, peak concen-
trations will not be insolubilized and inefficient removal will occur. For
denitrification, the average dose of methyl alcohol is inadequate for optimum
removal of nitrate nitrogen during periods of maximum concentrations of that
constitutent. Moreover, during periods of low nitrate nitrogen concentration,
the average does provides an excess of methyl alcohol which passes through the
denitrification towers. Since no aerobic biological process follows denitri-
fication at El Lago, any excess methyl alcohol could cause a high organic con-
tent (COD and BOD5} in the final effluent. A tertiary carbon adsorption bed
would not correct this problem, since methyl alcohol is hydrophilic and very
polar and does not adsorb onto activated carbon,
There are two possible solutions to this problem of variation in pollutant
concentrations. One would be to provide an equalization tank for the primary
influent flow, including digester supernatant, sludge drying bed underdrain,
solids wasted from the nitrification reactor, and backwash from denitrifica-
tion towers and tertiary filters. Another solution would be the implementa-
tion of automatic analytical determinations of phosphorus and nitrate nitro-
gen with the on-line analyzers and plant flow meters providing signals for
56
-------
control of the chemical dosing pumps. Neither of these appears economically
practicable for a small facility like El Lago.
While both large and small media towers provided high degrees of biological
denitrification, the better performance of the small media towers would appear
to justify the additional effort and expense required for daily backwashing if
nitrate nitrogen must be reduced to the order of 1 mg/1. Furthermore, the
data on small media denitrification tower performance following backwash in-
dicate that greater removal of nitrate nitrogen could be achieved if provision
were made for recycling the denitrification tower effluent for the first hour
following backwash.
The performance of the tertiary filter system during the three final evalua-
tion periods is summarized in Table 17. These filters are considered essen-
tial in meeting project goals for final effluent concentrations of suspended
solids, total phosphorus, total nitrogen, BODc, and COD. While no significant
reduction in ammonium nitrogen and nitrate nitrogen can be attributed to these
filters, the reduction in organic nitrogen by removal of biological solids en-
abled the plant to produce an effluent containing less than 2 mg/1 total nitro-
gen during the final evaluation of the small media denitrification towers. It
is also evident that substantial quantities of insoluble phosphorus was remov-
ed by the filters and an appreciable reduction in BODs and COD accompanied the
suspended solids removal.
During evaluation of the small media denitrification towers, the tertiary fil-
ters received an influent containing an average of 41 mg/1 suspended solids at
a 1.9 gpm/ft2 average filter rate. The average filter run was 5.9 hours with
the controls set to initiate a backwash cycle by time clock once each day and
by pressure when head loss reached 28 feet of water. Backwash water returned
to waste was 17.3 percent of filter influent.
Since the El Lago plant is attended only during daylight hours, the chlorine
feed to the contact tanks is normally adjusted twice daily to maintain 1 to 3
mg/1 residual after contact time of 78 minutes at average dry weather flow.
Lower residuals occur during peak late morning and evening flows while higher
residuals appear in the very early morning effluent when flow is lowest. Con-
tact time during maximum wet weather flow is 23 minutes; therefore, the Texas
Water Quality Board requirement of at least 1 mg/1 of residual chlorine after
20 minutes contact time is consistently met.
Prior to the grant period, no microciological assays for the coliform content
of the final effluent had been performed. Determination of coliforms during
the period from June 19, 1974, to February 14, 1975, resulted in data shown in
Table 18. It is significant to note that all samples of final effluent had an
MPN of less than 2.2 coliforms per 100 ml. This disinfection was obtained
with an average chlorine dosage of 10 mg/1. The high degree of disinfection
with this quantity of chlorine is related to the chemical and physical qual-
ity of the El Lago effluent. After the operational sequence of the biological
and chemical processes, the effluent from the tertiary filter has a low ammon-
ium nitrogen and suspended solids content which is conducive to efficient dis-
infection by chlorine.
57
-------
Table 1?. TERTIARY FILTER PERFORMANCE
in
00
Period
Sept 23 - Nov 8,
1974
Nov 16 - Dec 16,
1974
Jan 5 - Feb 14,
Avg filter Avg filter Backwash Suspended
Denit rate ? run water solids, in
towers used gpm/ft hr % of flow mg/1
small media
large media
large media
1.9 5.9 17.5 4-1
2.5 5,0 15.8 13
2.5 6.1 12.9 13
Suspended Suspended
solids, out solids
mg/1 removal, %
1 98
2 85
2 85
1975
-------
Table 18. COLIFOHM CONTENT OF EL LAGO VASTEWATER SAKPLES*
MPN/lOOml
Process
Primary
effluent
Tertiary filter
effluent
Chlorine contact
effluent
Total coliform
7,4-00,000
60,000
0
Fecal coliform
—
—
0
* Each, value is the geometric mean of results from 16 samples,
March 1974 - February 1975-
59
-------
Figure 18 shows percent 8005 and COD remaining in the process stream follow-
ing nitrification, settling and addition of 40 mg/1 of methyl alcohol during
the final evaluation of the small media denitrification towers. 6005 and COD
data were not taken on raw wastewater, primary settler effluent and trickling
filter effluent during this period. Cumulative frequency data on BODs and COD
in final effluent are shown in Figures 19 and 20, respectively.
Percent solids and total phosphorus remaining in the process stream are shown
in Figure 21. Data on percent solids in nitrified wastewater were taken after
intermediate settling for separation of nitrifying bacteria. Cumulative fre-
quency data on total phosphorus in the final effluent are shown in Figure 22.
Percentages of various forms of nitrogen remaining in the process stream dur-
ing the final evaluation of the small media denitrification towers are present-
ed in Figure 23. Percent reductions in total nitrogen, organic nitrogen and
ammonium nitrogen are based on the content in the primary settler effluent as
100 percent since nitrogen data were not taken on raw wastewater during this
period. Nitrate nitrogen in the nitrified, settled wastewater was taken as
100 percent of that form of nitrogen. Organic nitrogen shows an appreciable
decrease between denitrification and chlorine contact chamber effluent due to
the removal of biological solids in the final polishing filter and is corre-
lated with the decrease in suspended solids shown in Figure 21. Cumulative
frequency data on total nitrogen in the final effluent are shown in Figure 24.
Table 19 compares the residual concentrations of pollutants chosen as para-
meters for defining the objectives for the demonstration in 1970 with the
average residuals of the pollutants found during the final small media study
period as reported in Table 13B. The objectives were met in all cases; and
the demonstration at El Lago showed that with proper operator attention and
rudimentary instrumentation an existing trickling filter plant can be modified
to produce effluent containing low residuals of pollutants.
60
-------
g
H
O
o
g
O
PQ
100 -
75 —
25 —
0
BOD,
COD
NOTE: NITRIFIED EFFLUENT BOD^ AND
COD INCLUDE THE DEMAND DUE
TO ADDED METHYL ALCOHOL
15
RAW
PRIMARY
SETTLER
TRICKLING
FILTER
NIT DENIT FILTER
CHLORINE
CONTACT
UNIT PROCESSES
Figure 18. Percent BOD^ and COD remaining, September 23 - November 8, 1974-
' (small media devitrification)
-------
30
(=\
O
25
20
10
0
0
• - LARGE MEDIA TOWERS - RUN 2
o - LARGE MEDIA TOWERS - RUN $
A - SMALL MEDIA TOWERS - RUN 2
20
30 4O 50 60 70 80
OP OBSERVATIONS < STATED VALUE
90
100
Figure 19. Cumulative frequency data on BOD^ in final effluent
-------
to
§
o
60
50
40-
20
10
0
« - LARGE MEDIA TOWERS - HUN 2
o - LARGE MEDIA TOWERS - RUN 3
A - SMALL MEDIA TOWERS - RUN 2
J L
10
J L
J L
20
30
60
70
80
% OF OBSERVATIONS < STATED VALUE
J I
90
100
Figure 20. Cumulative frequency data on COD in final effluent
-------
Ol
.£>
a
M
CO
§
O
02
O
PH
3
O
03
O
03
P4
03
100 —
50 —
o
RAW
SUSFEItfDED SOLIDS
TOTAL PHOSPHOHUS
PRIMARY
SETTLES
TRICKLING NIT
FILTER
UNIT PROCESSES
DEHIT FILTER
CHLORINE
CONTACT
Figure 21. Percent suspended solids and total phosphorus remaining,
September 2J - November 8, 1974- (small media denitrification)
-------
en
03
g
O
a
p-t
CO
O
£
PM
-=«{
^
O
1.30
1.20
1.10
1.00
0.90
0.80
0.70
0.60
0.50
0.40
0.50
0.20
0.10
0.00
« - LARGE MEDIA TOWERS - RUN 2
o - LARGE MEDIA TOWERS - RUN 3
A - SMALL KEDIA TOWERS - RIM 2
I
I
I
I
I
I
0 10 20 30 40 50
% OF OBSERVATIONS ,
60 70
STATED VALUE
80
90
100
Figure 22. Cumulative frequency data on total phosphorus
in final effluent
-------
en
100 —
H
H
75 —
50 -
0
TOTAL NITROGEN
,— ORGANIC NITROGEN
AMMONIUM NITROGEN
ooooooo NITRATE NITROGEN
RAW
PRIMARY
SETTLER
TRICKLING NIT
FILTER
UNIT PROCESSES
DENIT FILTER
CHLORINE
CONTACT
Figure 25. Percent of various forms of nitrogen remaining, September 25
November 8, 1974 (small media denitrification)
-------
o
g
H
EH
O
10 —
9 ~
8
5
4
3
0
0
• - LARGE MEDIA TOWERS - RUN 2
o - LARGE MEDIA TOWERS - RUN 3
A - SMALL MEDIA TOWERS - RUN 2
10
80
1
20 30 40 50 60 70
% OF OBSERVATIONS^STATED VALUE
Figure 24. Cumulative frequency data on total nitrogen in final effluent
100
-------
Table 19. FINAL EFFLUENT RESIDUAL OBJECTIVES COMPARED
WITH DEMONSTRATION RESULTS, mg/1
Objective/Result BOD^ COD SS TN TP TOD
Original objectives 5 30 10 2 1 -
July 1970
Demonstration results 2.9 17 1 1.8 0.39 21
Sept-Nov 1974-
68
-------
SECTION VIII
COSTS
CAPITAL COSTS
The construction costs for the El Lago facility as described in the previous
sections, including all change orders but exclusive of engineering costs, were
as follows:
Phase I - Phosphorus control - $ 36,400
Phase II - Nitrogen control and filtration - 276,038
(Including $65,460 for small
media denitrification towers
and $50,000 for large media
denitrification towers)
Total construction costs - $312,438
The Phase II cost of $276,038 included both small media and large media de-
nitrification towers so that the effectiveness of both types of media could
be evaluated. This redundancy would not be provided in a strictly operational
facility, and construction costs would have been approximately $60,000 less if
only small media towers had been installed. The reduction in cost would have
been due to elimination of $50,000 for the large media towers and to a reduc-
tion of $10,000 in costs of concrete slab and piping.
Construction costs of an operational facility with small media denitrification
towers would have been as follows:
Phosphorus control - $ 36,400
Nitrogen control and filtration - 216,038
Total construction costs - $252,438
OPERATIONAL COSTS
The chemical cost for phosphorus removal is based on an influent phosphorus
concentration of 12 mg/1, a 41 mg/1 dose of iron added as ferric chloride,
and a polymer does of 0.4 mg/1. Ferric chloride was purchased from Gulf
69
-------
Chemical and Metallurgical Co. for 25<£/lb of iron content plus transportation
charges of 40<£/ 100 Ib. of ferric chloride solution. Dow Purifloc A-23 poly-
mer was purchased in small lots for $2.80/1b.
The chemical cost for nitrogen removal is associated with the purchase of me-
thyl alcohol. The average nitrate nitrogen value of 14 mg/1 required 40 mg/1
of alcohol for denitrification. Methyl alcohol was purchased in 1,000 gal
quantities from McKesson Chemical Co. for 58<£/gal delivered to the site. Two
540-gal storage tanks were provided by the supplier at no charge to the Dis-
trict.
Electrical power costs for the advanced wastewater treatment are incurred in
the operation of centrifugal blowers, turbine pumps, tertiary filter backwash
pump, and small chemical dosing pumps. Power costs per 1,000 gal of waste-
water are approximately U for phosphorus removal and 2<£ for nitrogen removal.
Since HCWCID #50 operates the water system and maintains the storm sewers as
well as the wastewater collection and treatment facilities with the same crew
of three men, it is difficult to break out labor costs of advanced wastewater
treatment as a clearcut figure. However, labor costs for operation and rou-
tine maintenance are estimated at 1 it/1,000 gal for phosphorus removal and
3<£/l,000 gal for nitrogen removal.
Costs for chemicals, electrical power and labor are summarized in Table 20.
70
-------
Table 20. CHEMICAL, ELECTRICAL AND LABOR COSTS EOR REMOVING
PHOSPHORUS AND NITROGEN, cents/1,000 gal.
Item Phosphorus Nitrogen
Ferric chloride 10
A-23 polymer 1
Methyl alcohol — 3
Electrical power 1 2
Labor 1 3
Total for chemicals, 13 8
power and labor
71
-------
SECTION IX
PROBLEMS ENCOUNTERED
The El Lago facility was designed and put into operation as a unique, one-of-
a-kind facility, and problems of several natures were experienced. A topical
listing of the major problems that caused delay in construction and diffi-
culty in evaluation of performance follows.
Two natural events caused several weeks delay; these were hurricanes Agnes in
1972 and Delia in 1973. Both swept along the Gluf Coast. The effects at the
plant were immediate in that there was heavy rainfall and flooding, and pro-
longed in that vendors supplying equipment were temporarily out of business.
The chemical storage tanks had support piers which were so tall that the tanks
protruded above the plant fence. Plant neighbors complained, and the piers
had to be shortened.
Earth moving equipment used during Phase II construction severed the under-
ground metal salt chemical feed lines installed in Phase I.
A vendor supplied the wrong series of polymer dosing pumps; and during early
periods of Phase I, the proper quantity of polymer could not be dosed to the
primary influent flow.
The air lift pumps installed in the intermediate clarifiers could not be con-
trolled in a satisfactory manner to reduce the hydraulic flow through the ni-
trification tank, and periodic operator adjustments were needed. Time clock
actuated solenoid valves were installed to improve operation.
One of the centrifugal five-stage pumps was delivered with only four stages,
and the other pump had improper impellers.
The methyl alcohol injection line was installed into the wrong leg of the
branched centrifugal pump discharge line.
Methyl alcohol dosage became erratic, and it was found that the pump heads
supplied by the vendor were not compatible with methyl alcohol.
The tertiary filter was installed with only time clock actuated backwash,
and automatic backwash had to be added. The first set of pressure switches
failed rapidly since they were not exterior grade. New orifice plates and
valves were necessary to control excessive vibration during backwash. No air
relief valves were provided on the vessels.
72
-------
One of the two air blowers developed electrical problems shortly after in-
stallation.
A 4-inch pipe supporting one of the air diffuser headers in the main nitrifi-
caton tank snapped and dropped the header into the tank after only six months
of operation.
The original large media towers supplied were of the wrong gauge metal and ex-
hibited poor workmanship. The consultant would not take delivery, and new
tanks had to be fabricated.
Major construction activities proceeded rapidly, but when finishing punch list
items for final acceptance were discussed in the light of consultant-client-
contractor-vendor-federal interests, much time was consumed.
During the grant period two different elected Boards of Directors of HCWCID
#50 were seated, and revaluation of project objectives was necessary.
The 1972-1973 Houston area weather was the wettest period for several years,
influencing both construction and operation schedules.
Reliable contract laboratory analytical services were difficult to obtain.
73
-------
SECTION X
PUBLICATIONS AND PATENT DISCLOSURES
The essential points of the El Lago design were presented at an Advanced Waste
Treatment Seminar in Dallas, Texas, on July 27, 1971.
The objectives and design data for the El Lago Advanced Waste Treatment Facil-
ity were presented at the 2nd Annual Technical Conference, Southeast Section,
Texas Water Pollution Control Association in Houston, Texas, on December 6,
1972.
A report of the operational results of the initial evaluation period was pre-
sented at a Technology Transfer Seminar in Shreveport, Louisiana, on August 21,
1973.
A thesis for the Master of Science degree titled Process Development Studies
or^ the Biological Utilization of_ Nitrogen jn^ a Domestic Wastewater Treatment
System, based on early project data, was submitted to the University of Hous-
ton in December 1973.
A report on project progress was presented at the 3rd U.S./Japan Conference
on Wastewater Treatment in Tokyo, Japan, in February 1974.
An interim report titled Description of the El Lago, Texas, Advanced Waste-
water Treatment Plant was published by HCWCID #50 in March 1974.
A paper titled "Upgrading El Lago, Texas, Wastewater Treatment Plant to Pro-
vide Complete Nitrification" was presented at the 46th Annual Conference,
Water Pollution Control Association of Pennsylvania at University Park, Pen-
nsylvania, on August 8, 1974.
EPA office of Technology Transfer filmed a 28-nrinute documentary movie on
site in July 1975. The purpose of the film is to inform municipal and reg-
ulatory officials of current Wastewater treatment technology advances.
There have been no patent disclosures filed or anticipated as a result of
this demonstration project that covers the time period of July 6, 1970,
through August 15, 1975.
74
-------
ADW =
Avg =
BOD5 =
CaC03 =
cfm =
cfm/ft2
C =
COD =
denit =
effl =
EPA =
F =
Fe+3 =
ft =
gal =
gal/hr
g =
SECTION XI
ABBREVIATIONS
average dry weather
average
biological oxygen demand exerted in 5 days at 20°C
calcium carbonate
cubic feet per minute
cubic feet per minute per square foot
Centigrade
chemical oxygen demand (di chroma te method)
denitrified
effluent
Environmental Protection Agency
Fahrenheit
ferric iron
foot
square foot
cubic foot
square feet per cubic foot
gallons (U.S.)
gallons (U.S.) per hour
gram
75
-------
gpd =
gpd/ft2 =
gpm =
gpm/ft2 =
HCWCID #50
hr =
infl =
1 =
Ib =
MOW =
MERL =
mg =
mg/1 =
mgd =
mi =
mm =
NOa-N
Org-N
pH =
pri =
psi =
sq mi
SP =
SS =
gallons (U.S.) per day
gallons (U.S.) per day per square foot
gallons (U.S.) per minute
gallons (U.S.) per minute per square foot
Harris County Water Control and Improvement District No. 50
hour (sidereal )
influent
liter
pound (avoirdupois)
maximum dry weather
Municipal Environmental Research Laboratory (EPA)
Cincinnati, Ohio
milligram
milligram per liter
million gallons per day
ammonium nitrogen
mile (U.S., statute)
millimeter
nitrate nitrogen
organic nitrogen
negative logarithm (to the base 10) of the hydrogen ion
concentration
primary settler or clarifier
pounds (avoirdupois) per square inch
square mile
soluble phosphorus
suspended solids
76
-------
SVI = sludge volume index
TKN = Kjeldahl nitrogen
TN = total nitrogen content
TOD = total oxygen demand
TP = total phosphorus
U.S. = United States of America
WW = wet weather
<£ = cents (U.S.)
$ = dollars (U.S.)
77
-------
SECTION XII
APPENDICES
Page
A. Operational Data 79
B. Conversion Factors 110
78
-------
APPENDIX A
OPERATIONAL DATA
The following pages summarize operational data for evaluation
periods from June 1975 through February 1975*
The location of each sample point referred to is as follows:
Raw waste water - Sample is taken from manhole in sanitary
sewer main immediately before reaching the plant wet well;
it contains no chemical additives or plant recirculation.
Primary influent - Sample is taken from the distribution
trough in the primary settler; it contains metalic salt
and polymer which are added for phosphorus removal.
Primary effluent - Sample is taken from overflow trough
of the primary settler.
Denit influent - Sample is taken immediately prior to
entry into denitrification columns; the wastewater has
been through the trickling filters, nitrification reactor
and intermediate clarifiers. Methyl alcohol for denitri-
fication has been added, causing an increase in COD and
Denit effluent - 1 - Sample is taken immediately after it
has passed through the first of two denitrification col-
umns arranged in series.
Denit effluent - 2 - Sample is taken at exit from the
second denitrification column.
Plant effluent - Sample is taken at the effluent weir
of the chlorine contact tank and has undergone tertiary
filtration and chlorination.
79
-------
OPERATIONAL DATA - EL LAGO AUTP JUNE 1973
DATE
123*5
Rainfall, inches
Plant flow, MG
Denit flow, MG
PH
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
Suspended solids, mg/1
Raw wastewater
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
00
O Plant effluent
Phosphorus, mg/1 P
Total
Eaw wastewater
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
Filterable
Raw wastewater
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent 4.0 8.5 9.0 3.1 l.O
4
0.00
0.161
0.161
8.28
7.77
21
8
3
8.2
6.7
7.7
3.9
5
0.00
0.265
0.265
8.28
8.03
135
45
1
17.5
5-4
17.0
3.9
6 7
1.86 0.00
0.364 0.246
0.364 0.221
8.12 8.18
7.85 8.15
8.00 8.18
39 44
45 19
6 1
4.3
4.1
4.2
2.1
2.1
8 9 10
0.00 0.00 0.10
0.243 0.240 0.247
0.242 0.238 0.245
7.70
7.13
8.4O
8.10
8.10
251
61
24
10
2
4.8
5.8
8.7
0.9
1.9
11 12 13 1* 15
0.03 5.78 2.47 0.56 0.02
0.240 l.OOO O.?80 0.560 0.424
0.170 0.420 0.160 0.160 0.420
7.45
7.45
8.23 8.10
8.30 7.75
8.13 8.20 7.75 7.95
94
98
53
47 34 30
5 26
2 4
3.7
8.5
6.9
9.5 5.2 1.5
2.4
1.9
3.2
-------
00
Nitrogen, mg/1 N
Ammonium nitrogen
Raw wastewater
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
Total KJeldanl nitrogen
Haw wastewater
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
Nitrate nitrogen
Denit influent
Denit effluent - 2
Plant effluent
COD, mg/1
Raw wastewater
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
BODc, mg/1
Raw wastewater
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Final effluent
Methanol doseage, mg/1
35.2 21.6
0.4 0.6 1.2 0.6 0.8
0.7 1.8 0.9
60.1 37.7
5.0 2.3 5.* 10.8 5.4
6.2 2.3 1.5
15.8 19.9 11.0 15.4 11.6
3.5 0.0 0.1
338 391
96 51 77 77
142 176
478
173
90
2.4
0.6 0.4 0.7
0.6 0.9
0.4 0.7
7.7
2.9 5.6
1.8
2.2 6.2
12.3 12.0
0.1
1.5 5.4
244
141
163
85
89
54 70
5.6
2.7
10.0
0.1
78
47
56 76 66 46
64 66 47 47
33
-------
OPERATIONAL DATA -
16 17 18 19
0.00 O.OO 0.00 0.00
0.310 0.240 0.220 0.284-
0.308 0.238 0.21? 0.283
7.35
7.30
7.9O 8. 00
8.05 8.05
754
37
26 31
3 7
22.8
5.1
1.6
3.*
EL LAGO AWTF
20
0.01
0.256
0.255
7.70
7.60
8.00
8.10
7.60
256
63
36
3
2
16.0
7.5
5.2
3.4
5.4
21
0.16
0.248
0.24-6
7.15
7.50
7.85
7.95
344
71
35
21
13.0
7.1
3.5
3.9
JUNE 1973
DATE
22 23 24
0.01 0.00 0.03
0.238 0.242 0.240
0.236 0.240 0.238
7.23
7.28
7.88
7.90
170
114
36
2
20.3
12.4
12.4
6.9
25 26
0.06 0.00
0.202 0.251
0.200 0.250
7.85 8. 2O
8.10 8.25
7.55
38 39
7 9
2
16.1
5.9
27 28 29
0.00 0.00 0.00
0.266 0.268 0.234
0.265 0.267 0.233
7.85 7.80 7.88
7.95 8.10 8.20
8.10
200
50 57 51
25 56 14
6
21.8
11.5
14.0
30
0.00
0.257
0.257
Rainfall, inches
Plant flow, MG
Denit flow, KG
pH
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
Suspended solids, mg/1
Raw wastewater
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
Phosphorus, mg/1 P
Total
Raw wastewater
Primary influent
Primary effluent
Denit influent
Denit effluent- 2
Plant effluent
Filterable
Raw wastewater
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent 4.9 5-5 11.0
-------
00
co
Nitrogen, mg/1 N
Ammonium nitrogen
Raw wastewater
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
Total Kjeldahl nitrogen
Raw wastewater
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
Nitrate nitrogen
Denit influent
Denit effluent - 2
Plant effluent
COD, mg/1
Haw wastewater
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
Haw wastewater
Primary influent
Denit influent
Denit effluent - 2
Plant effluent
Methanol doseage, mg/1
1.2
0.6
16.2 24.6 16.9
21.6 23.7
1.8 1.4 0.7 0.8
1.1 0.8 0.5 0.5
58
6
27
40.0
39.3 29.3
30.8 30.0
2.8
2.0
6.6
0.0
2.6
1.8
5.4
1.5
2.0
2.0
12.3
3.9
3.0
2.8
15.0
9.7
2.0
1.4
22.0
9.7
713 396 436 720
101 159 178 225
117 124 89 115 66
39 16 35 75 23
35
20
223
65
5
30
15.4
48
35
0.9 0.8 0.5
0.9 0.5 0.5
4.5 3.0 4.6
3.0 2.0 3.5
14.1 18.5 19.4
0.9 5.3 0.9
150 ill 116
43 43 104
43
56 61 34
0.5 0.9
0.7 0.7
0.7
64.7
3.6 1.9
2.3 2.0
1.5
20.2 20.2
0.9 0.9
0.0
372
204 148
60 48
36
175
72
12
8
34 36
40
-------
00
Rainfall, inches
Plant flow, MS
Denit flow, MS
PH
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
Suspended solids, mg/1
Raw wastewater
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
Phosphorus, mg/1 P
Total
Haw wastewater
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
Filterable
Raw wastewater
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
7 8 9 10 11 12 13 14 15
0.00 0.00 0.00 0.00 0.50 0.66 0.10 1.85 0.01 0.00 0.00 O.OO 0.00 0.00 O.OO
2
0.00
0.2700
0.26*8
7.75
7.«>
7.95
8.07
7.95
295
41
40
14
1
13.5
6.0
7.3
2.7
1.6
6.8
3
0.00
0.2800
0.2718
7.38
7.50
7.85
8.03
7.75
179
81
23
11
1
20.9
15.6
4.1
8.2
5.3
3.9
4 5
o.oo 0.50
0.2500 0.2634
0.2450 0.2564
7.50
7.45
7.90
8.03
7.60
404
88
48
19
4
18.9
7.2
10.8
5.9
3.2
4.2
DAI
6
0.66
0.293*
0.287E
7.52
7.45
7.90
7.80
7.68
136
113
30
35
4
15.0
10.4
4.0
5.4
4.7
6.0
5.9
3.6
5.0
3.6
7.28
7.30
7.90
7.72
7.68
104
36
86
25
11
9.0
2.5
3.5
2.7
0.6
0.7
3.2
2.5
7.55
6.85
7.75
7.85
234
17
27
41
10.3
1.0
1.0
0.5
1.2
3.3
7.10
6.92
7.65
8.0O
7.4O
262
22
50
5.0
0.8
12.0
2.0
4.6
2.3
2.0
0.5
0.5
1.0
1.2
1.9
7.35
7.40
7.80
7.85
254
75
44
2.0
16.2
9.2
4.6
4.6
5-8
5-8
2.3
2.3
7.10
7.05
7.65
8.0O
263
50
42
8.0
14.9
5.9
3.6
1.3
0.5
0.6
1.0
0.8
-------
oo
tn
Nitrogen, mg/1 N
Ammonium nitrogen
Raw wastewater
Primary influent
Primary effluent
Denit influent
Dealt effluent - 2
Plant effluent
Total KJeldahl nitrogen
Baw wastewater
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
Nitrate nitrogen
Denit influent
Denit effluent - 2
Plant effluent
COD, mg/1
Baw wastewater
Primary influent
Primary effluent
Denit Influent
Denit effluent - 2
Plant effluent
BOD5, mg/1
Baw wastewater
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
Methanol doseage, mg/1
26.2
23.9
0.9
0.9
44.7
29.5
2.0
2.8
21.1
0.9
520
152
224
64
4O
21.6
16.2
2.2
1.4
30.8
0.8
0.9
15.8
4.4
388
219
123
100
46
41
41
58
20.8
23.1
1.2
0.8
49.3
31.6
1.9
1.4
24.8
1.8
714
219
104
46
38
220
18
51
25.4
21.0
0.9
0.9
37.0
29.5
2.6
2.6
11.4
4.4
276
240
156
132
60
53
29
10.7
12.3
0.5
0.4
21.6
19.3
2.3
1.9
16.7
0.9
111
ill
107
103
44
28
8.5
7.7
0.6
0.5
33.9
21.6
0.8
2.2
18.5
0.9
250
99
131
59
35
15.0
16.9
1.0
0.8
0.4
24.6
30.0
2.3
1.6
1.2
17.6
0.0
3.5
537
10?
99
44
32
111
47
29
2.9
2.5
22
8.5
12.1
0.7
0.8
30.8
30.0
1.8
1.4
8.5
2.5
4O3
157
97
35
26
9.2
15.4
0.4
0.1
26.2
29.3
1.4
0.7
23.8
0.0
422
119
108
35
28
47
-------
OPERATIONAL DATA - EL LAGO AWTF JULY 1975
DATE
16 17 18 19 20 21 22 23 2* 25 26 27 28 29 30 31
Hainfall, inches 0.15 0.00 O.OO O.OO O.OO O.72 O.OO 0.00 O.OO O.OO O.OO 0.92 O.OO O.OO 0.00 0.00
Plant flow, MG 0.2759 0.1712 0.26O8 0.2796 0.2726 O.3167 0.2544 0.2655 O.JIOJ 0.3109 0.2762 0.3632 0.2785 O.2495 0.2425 O.2702
Denit-flow, KG 0.2759 0.1712 0.2608 0.2796 0.2726 0.3167 0.2544- 0.2655 0.3103 0.3109 0.2762 0.3632 0.2785 0.2495 0.2425 0.2702
pH
Primary influent 7.30 7.23 7.65 6.95 7.28 7.35 7.40 7.40 7.22 7.50 7.50
Primary effluent 7.OO 7.05 7.30 7.10 7.50 7.O8 7.60 7.48 7.4O 7.80 7.60 7.60
Denit influent 7.65 7.90 7.78 7.72 7.72 7.85 8.00 7.74 8.00 7.58 7.96 8.10
Denit effluent - 2 7.9O 7.95 7.88 7.80 7.80 8.00 8.14 7.92 8.02 7.75 7.98 8.00
Plant effluent 7.70 7-70 7.65 7.58 7-89 7.95 8.00 7.57 7.98 7.90
Suspended solids, mg/1
Raw wastewater 102 116 196 91 126 45 159 114
Primary influent 220 230 188 338 128 456 192 202 129 253 120 22?
Primary effluent 1O4 99 42 36 70 114 1O6 56 46 69 59 107
Denit influent 60 67 90 50 10 34 32 42 2? 27 38
Denit effluent - 2 7.6 6.0 11 62 60 22 10 7.0 10 27 2.5 6.5
Plant effluent 4.5 6.0 24 4.0 8.0 4.0 13 5.5 0.4 2.5
Phosphorus, mg/1 P
Total
Haw wastewater 16.5 9.5 14.5 11.2 11.3 12.2 18.5
Primary influent 14.5 18.5 14.0 18.5 14.9 6.5 13.3 18.0 11.0 15.5 9.0 22.1
Primary effluent 8.0 13.0 5-0 10.4 5.6 6.9 11.4 6.0 5.4 7.0 5.6 17.4
Denit influent 9.0 5.0 7-5 5.0 3.1 2.4 4.8 4.0 4.6 3.4 5.4 6.6
Denit effluent - 2 3.5 2.O 2.0 6.3 3.1 3.1 4.2 4.6 5.4 4.4 5.0 4.2
Plant effluent 2.7 2.1 1.5 1.5 3.4 4.6 4.1 8.2 5.2 3.5
Filterable
Haw wastewater 15.9 9.6 11.0 8.8 10.5 7.0 15.9
Primary influent 2.5 7.5 5.5 0.9 0.5 3.6 2.4 l.l 3.3 1.9 2.0 8.4
Primary effluent 1.8 4.0 1.5 1.8 1.0 0.0 4.6 2.0 2.0 3.0 2.0 5.1
Denit influent 1.5 l.o 1.5 1.4 l.O l.O 2.4 1.9 2.4 2.5 3.5 2.5
Denit effluent - 2 3.0 1.5 1.5 2.3 1.5 2.1 3.1 4.2 4.2 3.1 2.9 3.2
Plant effluent 2.0 1.8 l.J 0.5 2.9 3.4 3.4 6.2 5.0 3.4
-------
00
Nitrogen, mg/1 H
Ammonium nitrogen
Haw wastewater
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
Total Kjeldahl nitrogen
Haw wastewater
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
Nitrate nitrogen
Denit influent
Denit effluent - 2
Plant effluent
COD, ag/1
Raw wastewater
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
BOD5, mg/1
Haw wastewater
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
Methanol doseage, mg/1
24.6
29.3
16.9
0.5
0.5
11.6
19.3
0.5
0.8
16.9
16.9
0.
.5
0.8
0.8
30.8
33.9
3.2
1.4
21.1
0.0
349
221
169
47
39
27.7
32.2
2.0
1.6
22.9
0.9
396
239
81
31
69
35.9
26.2
1.6
1.
1.
22.
1.
0.
384
161
123
54
46
134
86
64
24
17
44
6
2
9
8
9
13
11
0
0
o
38
27
3
3
1
17
.1
.6
.7
.8
.7
.5
.0
.6
.6
.4
.6
0.9
0.0
384
180
119
85
61
188
124
66
34
17
16
13
0
0
0
37
30
26
1
2
1
14,
.2
.9
.5
.8
.5
.0
.8
.2
.5
.7
.1
.2
1.8
0.0
293
428
178
83
48
36
178
82
27
38
2O
32
23
19
17
16
0
1
0
30
26
26
1
6
0
18,
0,
.3
.7
.9
.7
.6
.8
.8
.2
.2
.2
.1
.9
•5
.1
0.0
166
214
150
99
36
24
1O9
89
70
57
27
4.
54
5
21
27
2O
O
1
0
30
42
23
1
1
1
11
.8
.0
.0
.7
.1
.5
.8
.4
.9
.4
.6
.5
.4
0.7
0,
229
314
186
109
31
31
119
176
78
52
4.
3.
37
.0
7
4
15
.4
16.2
13
1
1
1
23
23
23
2
3
1
11
0
.9
.4
.5
.8
.9
.9
.1
.4
.1
.9
.4
.1
0.0
307
284
160
123
54
38
142
169
86
49
16.9
17
16
2
3
1
35
31
27
4
4
3
10
0
0
303
296
154
188
65
58
.7
.9
.3
.0
.5
.9
.6
.7
-7
.1
.5
.3
.1
.0
15
13
14
1
1
1
27
37
26
5
3
2
10
.4
.9
.6
.2
.2
.2
.0
.7
.2
.1
.2
.7
.0
0.1
0.0
252
361
140
124
54
39
9.2
6.9
37
53
63
17.7
13.3
16.9
0.5
2.0
1.8
33.1
33.9
26.2
1.5
3.1
2.8
13.2
2.5
2.5
241
256
186
50
58
31
116
66
84
11
4.3
8.5
0.0
18.5
17.7
18.5
0.5
0.4
0.4
27.7
33-2
32.3
1.9
1.8
1.6
13.3
5.0
2.5
318
590
229
93
27
23
146
206
110
4?
4.5
2.4
49
-------
00
00
Rainfall, inches
Plant flow, MS
Denit flow, KG
PH
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
Suspended solids, ng/1
Haw wastewater
Primary Influent
Primary effluent
Denit Influent
Denit effluent - 2
Plant effluent
Phosphorus, mg/1 P
Total
Haw wastewater
Primary influent
Primary effluent
Plant effluent
Filterable
Raw wastewater
Primary influent
Primary effluent
Plant effluent
Nitrogen, mg/1 IT
Amnonium nitrogen
Raw waatewater
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
OPEgAIPIOKAL DATA - EL LASO AVTP
1
0,00
0.2557
0.2557
7.02
6.97
7.81
7.92
7.98
116
139
1OO
44
15
*.5
11.3
12.8
4.6
3.9
9.0
1.0
1.7
5.7
18.5
21.8
19.6
0.3
0.5
0.5
2
2.46
0.9000
0.6324
6.73.
7.10
7.68
7.68
7.60
96
411
62
33
45
3.0
6.2
6.6
3.1
2.2
3.3
0.8
0.7
2.1
4.6
7-7
10.8
1.6
1.6
1.8
5
0.05
0.3470
0.3470
7.56
7.35
7.82
7.80
7.90
82
24?
47
28
1.6
0.8
7.4
6.8
3.3
2.6
6.6
0.8
1.2
1.1
8.5
11.6
3.9
1.5
0.3
0.4
456
0.00 0.00 0.64
0.2784 O.2724 O.2692
0.2784 0.2724 0.2692
7.65
7.60
7.82
7.90
8.00
143
71
26
5-5
0.8
10.0
7.0
5.6
9.6
6.5
5.2
24.6
19.3
0.9
0.9
1.1
AUGUST 1973
PATE
7
0.00
0.2775
0.2775
7.40
7.10
7.88
7.85
7.90
219
239
77
38
6.5
0.4
14.4
11.1
6.6
5.1
13.2
1.5
2.8
4.8
15.4
15.4
16.9
0.5
1.4
0.9
8 9
0.44 O.OO
O.J805 0.5669
O.J8O5 0.3669
6.92
7.03
7.58 7.78
7.80 7.60
7.68 7.90
89
277
38
39 54
5.0 3.2
1.5 1.6
16.0
11.5
2.7
3.5
10.0
1.0
0.5
2.3
13.9
16.2
16.9
0.4 0.0
0.9 o.o
0.8 0.5
10
0.66
0.5369
0.5369
7.78
7.72
6.92
35
6.0
0.8
1.4
1.1
0.0
0.1
0.0
11 12 15
0.12 0.00 0.04
O.J360 0.2999 0.3048
0.336O 0.2999 0.3048
7.30
7.25
7.48
7.90
7.52
ISO
262
64
60
71
3.6
7.5
16.0
6.0
1.9
4.3
1.5
2.8
1.8
17.7
18.5
7.8
0.9
0.8
0.7
14 15
0.00 0.01
0.3076 0.2766
0.3076 0.2766
15.5
19.0
6.5
1.6
8.0
4.5
3.3
0.8
-------
Total Kjeldahl nitrogen
Haw wastewater 30.0 13.9 19.3 33.9 26.2 33 9
Primary influent 35.* 19.3 23.9 40.8 30.0 30.8 35.'4
Primary effluent 28.5 16.2 19.3 33.2 27.0 27.0 28^5
Denit influent 1.2 3.8 1.8 3.2 2.7 2.3 1.4 7.6 *!2
Denit effluent - 2 2.0 4.3 1.6 2.4 2.2 1.6 0.5 2.0
Plant effluent 1.8 3.0 1.6 2.3 1.9 1.5 1.1 0.9
Hitrate nitrogen
Denit influent 14.4 8.6 10.6 10.8 8.6 5.9 11.2 10.0 13.2
Denit effluent - 2 1.4 2.1 0.6 0.3 0.1 0.3 0.1 2.5 0^3
Plant effluent 1.3 1.8 0.3 0.2 0.1 0.0 0.0 1.9 0 1
COD, mg/1
Haw wastewater 248 136 188 380 265 182
Primary influent 388 40? 236 281 306 341 407
Primary effluent 186 97 108 243 190 126 1X6
Denit influent 89 78 100 95 73 107 112 130 105
Denit effluent - 2 43 62 36 32 47 24 39 40 124
Plant effluent 31 35 32 32 43 20 34 36 35
BOD5, mg/1
Jg Haw wastewater 130 60
Primary influent 163 164
Primary effluent 101 55
Denit influent 42 54
Denit effluent - 2 5.6 IS
Plant effluent 4.5 0>8
Methanol doseage, mg/1 20 19 34 16 27 38 16 34 43 27 30 42 45 41 29
-------
OPERATIONAL DATA - EL LAGO AWTP AUGUST 1975
Rainfall, inches
Plant flow, MG
Denit flow, MG
PH
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
Suspended solids, mg/1
Raw wastewater
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
Phosphorus, mg/1 P
Total
Raw wastewater
Primary influent
Primary effluent
Plant effluent
Filterable
Raw wastewater
Primary influent
Primary effluent
Plant effluent
Nitrogen, mg/1 K
Ammonium nitrogen
Raw wastewater
Primary influent
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
DATE
16
O.OO
0.2591
0.2591
7.66
8.00
8.25
7-68
7.80
64
426
45
84
54
6.0
16.2
18.5
16.9
0.9
0.8
0.9
17
0.18
0.2662
0.2662
7.40
7.42
7.70
7.85
7.68
43
168
47
46
3.0
2.5
13.0
9.0
10.0
1.0
12.3
4.5
2.8
1.0
3.9
3.1
6.2
1.2
1.1
0.9
18 19 20
0.26 0.00 0.00
0.3252 0.3256 0.3331
0.3252 0.3256 0.3331
7-43
7.^8
7.88
7.90
7.60
72
334
37
2.0
22
2.0
6.3
10.5
3.5
3.1
5.8
2.5
1.0
5.0
21.6
20.0
14.6
1.1
1.4
0.7
21
0.00
0.3198
0.3198
7-38
7.42
7.88
7.80
7.75
85
182
63
42
7.5
2.0
11.4
18.5
6.7
2.8
10.0
7.6
4.3
2.7
16.9
16.9
15.4
1.2
1.5
0.8
22
0.00
0.3021
0.3021
7.23
7.60
7.90
7.80
7.68
87
214
44
42
8.0
3.0
11.5
14.5
5.8
2.3
10.5
5.0
3.6
2.3
20.0
13.7
13.1
1.2
1.6
0.9
23
0.00
0.2821
0.2821
7.55
7.28
7-72
7.80
7.65
62
232
48
6.5
5.0
7.5
14.0
15.0
5.2
1.0
12.5
3.7
2.6
0.8
3.9
6.9
10.8
1.4
2.0
1.2
24
0.00
0.2964
0.2964
7.41
7.52
7.75
7.69
7.55
59
109
51
56
37
1.2
11.3
8.8
7.2
1.7
9.6
4.5
3.6
1.5
4.6
8.5
10.8
1.6
1.9
1.6
25 26 27
0.00 0.00 0.00
0.2876 0.5453 0.2353
0.2876 0.3453 0.2353
7.45
7.50
7.98
7.95
7.78
94
118
53
50
35
3.5
13.5
13-5
5.7
2.6
13.2
3.5
4.0
2.5
16.9
17.7
14.6
1.6
1.9
0.9
28
0.00
0.3105
0.3105
7.88
7.30
7-72
8.00
7.85
86
198
61
38
25
6.0
16.2
14.5
7.0
2.5
14.6
5.5
3.5
2.1
22.3
11.6
1.1
0.9
0.4
29
1.16
0.4509
0.4509
7.52
7.48
7.84
7.90
8.00
103
362
64
55
22
4.0
7.6
11.5
4.6
1.2
6.7
1.3
1.3
1.2
13.7
13.7
0.7
1.2
0.4
30
0.22
0.3095
0.3095
7.35
7.25
7.65
8.00
7.62
97
278
136
53
9.0
2.5
11.5
12.5
4.6
1.6
11.0
3.0
1.6
1.3
15.4
13.7
0.7
0.8
0.3
31
0.00
0.2804
0.2804
7.20
7.28
7.83
7.80
7.50
68
182
57
39
12
8.0
18.1
12.8
5.8
1.7
17.4
5.1
3.3
1.3
20.8
17.7
0.7
0.9
0.4
-------
Total Kjeldahl nitrogen
Raw wastewater 30.8 27.7 32.3 34.7 25.4 23.9 28.5 34.7 40.0 27-7 31.6 32.3
Primary influent 38.5 27.7 37.7 33.8 31.6 28.5 29.2 46.2
Primary effluent 35.4 28.5 23.9 26.2 25.4 26.2 25.4 31.6 23.9 24.6 24.6 25.4
Denit influent 3.6 3.4 2.S 2.3 2.6 2.4 3.8 2.2 3.0 2.8 1.5
Denit effluent - 2 3.4 2.3 3-1 2.7 2.7 3.2 3-2 4.2 2.6 2.2 2.0 2.3
Plant effluent 1.5 2.0 1.5 1-9 1.5 2.2 2.3 2.4 1.1 1.2 1.1 1.5
Nitrate nitrogen
Denit influent 10.6 8.9 11.9 13.2 10.6 1O.6 18.0 12.6 14.7 12.1 13.3 13.8
Denit effluent - 2 2.2 1.5 0.4 0.4 0.4 2.0 0.7 0.1 0.1 0.7 0.2 0.4
Plant'effluent 0.1 1.2 0.0 0.1 0.1 1.3 1.0 0.0 0.0 0.1 0.0 0.1
COD, mg/1
•Haw wa3tewater 178 190 184 261 296 217 183 507 261 269 269 321
Primary influent 352 253 332 376 365 334 186 396
Primary effluent 158 329 150 157 188 1?1 132 211 166 154 150 189
Denit influent 75 63 207 134 96 74 116 115 127 95 83 87
Denit effluent - 2 63 32 46 31 58 23 50 73 182 4? 40 31
Plant effluent 55 24 31 38 42 27 4? 38 40 63 36 39
BOD-, mg/1
Raw wastewater 88 260 230
Primary influent 138 243
Primary effluent 86 122
Denit influent 27 57 28
Denit effluent - 2 14 8.6 9.2
Plant effluent 14 7-1 1'6
Methanol doseage, mg/1 46 26 33 33 21 24 24 18 30 41 26 . 41 40 36 40 34
-------
vo
ro
Rainfall, inches
Plant flow, MG
Denit flow, «G
PH
Primary influent
Primary effluent
Denit influent
Denit effluent - 1
Denit effluent - 2
Plant effluent
Suspended solids, mg/1
Primary influent
Primary effluent
Denit influent
Denit effluent - 1
Denit effluent - 2
Plant effluent
Phosphorus, mg/1 P
Total
Primary influent
Primary effluent
Denit effluent - 2
Plant effluent
Filterable
Primary influent
Primary effluent
Denit effluent - 2
Plant effluent
Nitrogen, mg/1 B
ImnoniuB nitrogen
Primary effluent
Denit influent
Dealt effluent - 2
Plant effluent
OFERATIOHA1 DATA - EL LAGO AWCT SEPTEMBER 1974
DATE
16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
O.OO 0.00 O.OO O.OO O.OO 0.00 0.00 0.00
0.2494 0.3236 O.2426 0.320O 0.270O 0.2930 0.2597 0.26O4
0.3469 0.4186 0.3237 0.3714 0.3458 0.3410 0.2958 0.3108
6.8
6.9
7.6
7.7
7.8
7.5
312
78
33
17
4
6.4
6.4
7.0
7.2
7.2
6.8
201
25
49
32
13
<1
6.9
6.9
7.4
7.7
7.7
7.4
276
41
75
48
63
<1
7.5
7.3
7.7
7.9
8.0
7-6
285
158
107
83
34
7
11
1.3
1.9
0.19
0.01
0.01
0.01
0.13
17
0.3
0.4
0.1
11
2.1
2.7
0.15
0.11
0.06
0.08
0.15
15
0.2
0.2
0.1
10
2.5
3.3
0.21
5.7
0.82
0.13
0.16
18
0.4
0.5
0.4
8.1
3.8
1.0
0.18
0.36
0.81
0.26
0.18
18
0.8
0.5
0.5
-------
UD
CO
Total Kjeldahl nitrogen
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
Nitrate nitrogen
Denit influent
Denit effluent - 1
Denit effluent - 2
Plant effluent
COD, ng/1
Denit influent
Denit effluent - 1
Denit effluent - 2
Plant effluent
BOD5, ng/1
Plant effluent
Methanol doseage, mg/1
Ferric iron doseage, ng/1
Polymer doseage, mg/1
22
0.9
1.2
0.6
15
2.7
0.2
2.2
9*
55
23
12
3.0
41
79
0.41
20
1.9
1.6
0.8
16
3.2
3.8
0.1
88
46
42
13
-------
OPEEMIOSA1 DATA - EL LAGO AVTF
OCTOBER 1974
Bainfall, inches
Plant flow, MG
Denlt flow, MS
PH
Primary influent
Primary effluent
Denit influent
Denit effluent -
Denit effluent -
Plant effluent
Suspended solids
Primary influent
Primary effluent
Denit influent
Denit effluent -
Denit effluent -
Plant effluent
Phosphorus, mg/1 P
Total
Primary influent
Primary effluent
Denit effluent - 2
Plant effluent
Filterable
Primary Influent
Primary effluent
Denit effluent -
Plant effluent
Nitrogen, mg/1 H
Ammonium nitrogen
Primary effluent
Denit influent
Denit effluent -
Plant effluent
BATE
7
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
O.OO 0.00 O.OO O.OO O.OO O.OO O.OO O.OO O.OO O.OO O.OO 0.00 0.00 O.OO 0.55
0.2687 0.2274 0.2242 O.2352 0.22O9 0.2420 0.2615 0.240J O.221J 0.2015 O.2215 0.2458 0.2565 0.2702 0.2977
0.292? 0.2B74 0.2642 0.3072 O.2929 0.3380 0.3455 0.2802 0.2453 O.2255 O.2693 0.2938 0.2685 0.2944 0.3217
7.3
7-3
8.0
8.1
8.2
7.7
190
47
26
8
1
9.9
2.8
1.6
0.34
0.89
0.82
0.38
0.33
19
0.3
0.4
0.4
1
2
1
2
2
2
2
7.2
7.2
7.7,
7.9
8.0
7.6
682
50
62
54
18
1
13
2.7
2.3
0.21
1.6
0.38
0.20
0.20
19
0.3
0.6
0.5
7.2
7.2
7.7
7.8
7.8
7.4
326
50
91
73
57
-------
Total Kjeldanl nitrogen
Primary effluent 27 25 27 26 22 21
Denit influent 2.6 2.4 3.1 3.6 2.2 1.7
Denit effluent - 2 1.3 1.9 1.9 1.8 1.6 0.9
Plant effluent 1.3 0.7 0.7 1.0 1.1 0.8
Nitrate nitrogen
Denit influent 16 15 16 14 15 14
Denit effluent - 1 1.5 5.2 1.4 0.8 1.4 1.2
Denit effluent - 2 1.2 2.7 0.2 0.1 0.5 1.1
Plant effluent 2.0 1.1 0.7 0.1 0.4 0.7
COD, jag/1
Denit influent 96 140 130 109 94 110
Denit effluent - 1 35 53 48 51 27 25
Denit effluent - 2 30 37 34 39 27 22
Plant effluent 18 14 2O 16 16 22
BOD5, as/I
Denit influent 83 78 38 46
Denit effluent - 1 37 16 12 10
Denit effluent - 2 2O 10 10 10
vo Plant effluent 1.4 3.0 2.6 2.9 2.7 <1.0
01 Methanol doseage, mg/1 39 38 39 38 41 41 40 40 37 4? 37 39 40 41 41
Ferric iron doseage, mg/1 51 45 50 43 52 40 41 36 46 48 56 20 53 33 41
Polymer doseage, mg/1 0.52 0.53 0.59 O.51 0.53 0.46 0.45 0.49 0.38 0.25 0-63 0.49 0.49 0.31 0.26
-------
OPERATIONAL DATA - EL LAGO AUTF
OCTOBER 1974
Rainfall, inches
Plant flow, MG
Denit flow, MG
pH
Primary influent
Primary effluent
Denit influent
Denit effluent -
Denit effluent -
Plant effluent
Suspended solids
Primary influent
Primary effluent
Denit influent
Denit effluent -
vo Denit effluent -
°* Plant effluent
Phosphorus, mg/1 F
Total
Primary influent
Primary effluent
Denit effluent -
Plant effluent
Filterable
Primary Influent
Primary effluent
Denit effluent -
Plant effluent
nitrogen, mg/1 N
Ammonium nitrogen
Primary effluent
Denit influent
Denit effluent -
Plant effluent
16
1?
18
19
20
21
DATE
22
23
24
25 26 2? 28 29 30 31
0.00 0.00 0.00 0.00 O.OO 0.00 0.00 0.00 O.OO 0.00 0.00 0.00 0.48 0.45 0.00 O.OO
0.24JO 0.2369 0.2466 0.240? 0.2406 O.2437 0.2172 0.2462 0.2305 0.2992 0.2401 0.2441 0.3O43 0.3860 0.2653 0.2455
0.2910 0.2969 0.2826 0.3O05 O.28S8 0.0835 0.2652 0.2702 O.29O5 O.3592 0.2881 O.28O1 O.1743 0.3O78 O.3133 O.2935
1
2
1
2
2
2
2
7.2
7.1
7.6
7.7
7.7
7.7
226
49
84
9*
54
1
12
3.8
3.2
0.25
2.2
0.61
0.31
0.25
18
0.5
0.3
0.3
7.2
7.2
7.5
7.7
7.7
7.6
230
42
83
5*
36
<1
12
*.5
3-7
0.33
L*
0.60
0.31
0.33
18
0.6
0.2
0.4
7.5
7.3
7.7
7.7
7.9
7.9
3J4
54
66
58
41
1
16
3.6
2.9
0.58
3.8
1.2
0.56
0.55
15
0.4
0.4
0.4
7.4
7.4
8.0
8.1
8.1
7-8
216
43
63
44
29
< 1
12
4.2
3.6
0.77
2.7
2.2
0.90
0.74
20
0.6
0.2
0.4
7.4
7.4
7.8
8.0
8.0
7.8
266
54
77
33
27
< 1
13
3-. 7
3.3
0.49
2.2
0.98
0.52
0.49
18
0.2
0.2
•£0.1
7.5
7.4
7.8
7.9
8.0
7.6
294
51
160
75
106
1
13
4.0
3.2
0.69
2.5
1.6
0.71
0.69
18
0.6
0.7
0.3
7.*
7.4
7.8
8.0
8.0
7.7
276
51
72
38
20
<1
11
4.3
3.6
0.58
2.8
1.7
0.53
0.56
17
0.5
0.4
0.2
-------
Total Kjeldahl nitrogen
Primary effluent
Dealt Influent
Denit effluent -
Plant effluent
Nitrate nitrogen
Denlt Influent
Denit effluent -
Denlt effluent -
Plant effluent
COD, ng/1
Denit Influent
Denlt effluent -
Denit effluent -
Plant effluent
BOD5, ng/1
Denit Influent
Denit effluent -
Denlt effluent -
Plant effluent
Methanol doseage, ng/1
Ferric iron doseage, ng/1
Polymer doseage, mg/1
2
1
2
1
2
1
2
n.
ngA
L
23
2.5
1.7
1.2
15
2.5
1.6
0.5
130
67
44
30
1.2
41
3*
0.39
25
3.9
1.0
0.8
14
2.7
0.5
0.1
140
47
35
16
3.*
40 41
3* 30
0.32 0.34
20.
2.0
1.8
1.3
11
0.7
79
48
32
20
2.8
39 *2 36
31 32 31
0.37 0.42 0.32
24
2.2
0.6
0.5
14
1.6
0.2
<0.1
100
40
28
16
2.3
43 41
32 28
0.28 0.19
24
2.0
2.2
0.6
16
2.0
1.6
1.0
120
33
33
14
69
17
15
3.3
41 40 40
30 32 28
0.34 0.36 0.37
26
5.4
15
2.8
110
55
82
24
-11.0
41 43
38 30
0.41 0.36
21
2.8
1.0
0.8
14
0.6
0.6
•^0.1
110
37
27
23
60
12
7
6.0
41 42
28 37
0.31 0.39
41
31
0.56
-------
OPERATIONAL DATA - El LAGO AWTF NOVEMBER 1974
DATE
1 2 3 4 56 7 8 9 10 11 12 13 14 15
Rainfall, inches 0.23 0.38 0.00 0.03 0.16 0.00 0.03 0.18
Plant flow, MG O.3275 0.4380 0.3292 0.3876 0.3791 0.3078 0.2820 0.3205
Denit flow, M& 0.2625 0.3019 0.3292 O.3279 O.3539 0.2510 0.2518 0.3205
pH
Primary influent 7-4 7.* 7-5
Primary effluent 7.3 7.3 7.4
Denit influent 7.8 7.9 7.9
Denit effluent - 1 7.9 8.0 7.9
Denit effluent - 2 7.9 8.0 7.9
Plant effluent 7.7 7.6 7.6 7.7
Suspended solids, mg/1
Primary influent 264 200 212
Primary effluent 49 41 64
Denit influent 84 77 83
Denit effluent - 1 55 48 45
10 Denit effluent - 2 19 94 21
Plant effluent 1 < 1 1 ^1
Phosphorus, mg/1 P
Total
Primary influent 15 12 14
Primary effluent 3-6 4.2 4.3
Denit effluent - 2 4.0 3.9 3.9
Plant effluent 0.60 0.65 0.54 0.41
Filterable
Primary influent 5.4 2.9 4.0
Primary effluent 1.1 l.B 1.6
Denit effluent - 2 0.59 0.66 0.74
Plant effluent 0.59 0.64 0.53 0.38
Nitrogen, mg/1 N
Ammonium nitrogen
Primary effluent 20 17 2O
Denit influent 0.5 0.5 0.7
Denit effluent - 2 0.4 0.4 0.6
Plant effluent 0.3 0.5 0.4 0.6
-------
Total Kjeldahl nitrogen
Primary effluent 23 22 26
Denit Influent 2.8 3.4 3.9
Denit effluent -2 1.2 3.4 2.O
Plant effluent 1.0 O.9 l.i 1.5
Nitrate nitrogen
Denit influent 14 12 12
Denit effluent - 1 4.2 1.4 0.5
Denit effluent -2 3.3 0.6 1.1
Plant effluent 1.6 <0.1 0.6 2.0
COD, ng/1
Denit influent 12O 96 10O
Denit effluent - 1 44 34 33
Denit effluent - 2 30 54 25
Plant effluent 24 12 jo lg
BOD-, ng/1
Denit influent 48
Denit effluent - 1 13
Denit effluent - 2 14
Plant effluent 3.3 8.3 1.6 7.0
Hethanol doseage, ng/1 42 35 40 41 58 39 40 38
Ferric iron doaeage, ng/1 33 23 33 28 26 39 35 36
Polymer doseage, ngA 0.34 0.28 0.24 0.26 O.26 O.31 0.40 0.32
-------
Rainfall, inches
Plant flow, TO
Denit flow, MG
pH
Primary influent
Primary effluent
Denit influent
Denit effluent - 1
Denit effluent - 2
Plant effluent
Suspended solids, mg/1
Primary influent
Primary effluent
Denit influent
Denit effluent - 1
O Denit effluent - 2
° Plant effluent
Phosphorus,, mg/1 P
Total
Primary influent
Primary effluent
Denit effluent - 2
Plant effluent
Filterable
Primary influent
Primary effluent
Denit effluent - 2
Plant effluent
Nitrogen, mg/1 N
Ammonium nitrogen
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
16 1? 18
1.01 0.25 0.01
0.297* 0.6870 0.4206
0.357* 0.5552 0.4806
7.*
7.3
7.6
7.6
7.5
7.3
236
69
37
31
14
3
9.0
2.6
1.8
0.28
2.2
0.96
0.27
0.25
10
0.3
0.3
0.5
19 20 21
0.03 0.11 0.00
0.3376 O.J427 0.2898
0.4536 0.3907 0.3138
7-3
7.3
7.7
7.7
7.7
7.4
196
51
31
20
5
6
11
4.1
1.7
0.46
1.9
1.5
0.41
0.42
16
0.5
0.6
0.4
DATE
22 23
0.00 0.00
0.2776 0.2908
0.3016 0.3148
7.5
7.4
7.8
7.8
7.9
7.6
152
54
29
21
9
<1
12
4.5
1.7
0.54
4.1
1.6
0.45
0.42
21
0.8
0.4
0.3
24 25 26 27 28 29
1.43 0.24 O.OO 0.00 O.OO O.OO
0.3201 0.8551 0.4855 0.3611 0.3263 0.3171
0.3681 0.0374 0.3536 0.4451 0.3983 0.3771
7.5
7.4
7.7
7.7
7.7
7.6
270
70
35
28
12
-------
Total Kjeldahl nitrogen
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
Hitrate nitrogen
Denit influent
Denit effluent - 1
Denit effluent - 2
Plant effluent
COD, ng/1
Denit influent
Denit effluent - 1
Denit effluent - 2
Plant effluent
BOD~, mg/1
Denit influent
Denit effluent - 1
Denit effluent - 2
Plant effluent
Methanol doseage, mg/1
7erric iron doseage, ng/1*
Polymer doseage, ag/1
• Average ferric iron doseage is shown for each of the days from 11-22-7* through 11-30-7*.
20
40
0.4?
15
2.8
l.O
0.9
9.0
7.9
4.1
5.4
62
43
23
15
38
20
12
5.8
21 21
14 25
0.17 0.23
19
3.6
1.3
1.0
9.7
5.3
1.1
2.6
57
34
23
19
4.5
22 23
28 26
0.32 0.38
27
1.7
1.4
0.8
14
5.7
0.9
-e.0.1
81
53
24
24
39
22
5.3
2.4
37 38 29
43 30 30
0.44 0.36 0.39
18
3.4
2.0
1.2
8.2
4.5
2.1
2.2
71
63
48
40
41
38
24
10
42 45 44 27 34 33 34
50 30 30 30 30 30 30
0.31 0.18 0.17 0.42 0.44 0.42 0.39
-------
OPERATIONAL DATA - EL LAGO AMTF
O
ro
Rainfall, inches
Plant flow, MG
Denit flow, MS
PH
Primary influent
Primary effluent
Denit influent
Denit effluent - 1
Denit effluent - 2
Plant effluent
Suspended solids, mg/1
Primary influent
Primary effluent
Denit influent
Denit effluent - 1
Denit effluent - 2
Plant effluent
Phosphorus, mg/1 P
Total
Primary influent
Primary effluent
Denit effluent - 2
Plant effluent
Filterable
Primary influent
Primary effluent
Denit effluent - 2
Plant effluent
Nitrogen, mg/1 H
Ammonium nitrogen
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
1 2
0.00 0.00
0.2758 0.2809
0.3478 0.3649
7.7
7.3
7.9
7.7
7.8
7.4
304
58
43
27
12
1
13
4.9
2.4
0.41
4.1
2.0
0.41
0.36
20
1.4
1.9
1.7
3 4
o.oo o.oo
0.2676 O.2478
0.3516 0.3318
8.0
7-8
7.9
7.8
7.8
7.5
98
6?
48
31
15
•^ 1
14
10
4.4
1.3
10
6.5
1.5
1.3
21
1.7
0.5
0.2
5 6
0.00 0.16
0.261? 0.2791
0.3217 0.3151
7-4
7.3
7.9
7.8
7.8
7.4
232
61
29
15
2
-<£!
20
0.5
0.4
0.4
BATE
7 8 9 10
0.00 0.00 O.OO 0.00
0.2740 0.2898 0.2905 0.2973
0.2980 0.3018 0.3265 0.3213
7.4
7.3
7.9
7.8
7.8
7.4
142
58
22
7
5
-Cl
12
5.5
2.9
1.3
2.6
2.6
1.5
1.3
17
0.5
0.3
0.2
11 12
0.96 0.00
0.4860 0.5989
0.4484 0.3117
7.3
7.4
7.8
7.7
7-7
272
59
33
16
7
10
4.1
2.7
2.5
0.71
0.91
18
0.4
^0.1
13
0.00
0.4180
0.4216
7.3
7-3
7.6
7.6
7.7
7.3
204
71
23
18
9
2
10
4.8
1.6
0.53
1.5
1.0
0.36
0.46
11
0.3
0.2
0.3
14 15 16
0.01 0.62 0.00
0.3746 0.5010 0.4845
0.3770 0.4626 0.4690
7.4
7.3
7-5
7.6
7-6
7.4
176
88
63
91
57
•^1
6.0
3.9
3.3
0.59
1.2
0.84
0.33
0.37
3.4
0.3
0.4
0.2
-------
O
<*>
Total Kjeldahl nitrogen
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
Nitrate nitrogen
Denit influent
Denit effluent - 1
Denit effluent - 2
Plant effluent
COD, og/1
Denit influent
Denit effluent - 1
Denit effluent - 2
Plant effluent
32
30
0.50
25
3.*
3.6
2.8
12
6.6
3.7
3.6
*3
28
16
8
1.3
33 35
30 30
0.50 0.*5
2*
2.8
1.6
1.2
11
8.1
7.0
7.0
55
31
31
23
16
1*
12
1.8
38
30
O.*0
25
2.8
0.8
0.5
13
*.7
1.6
3-*
8*
*2
30
26
*2
20
8.8
2.8
39 *9
30 30
0.33 0.*5
22
2.0
1.2
1.*
15
8.8
5.5
5.3
63
28
20
26
32
8.5
2.7
1.*
38 38 58
28 31 31
0.*5 0.*9 O.38
2*
2.8
0.9
11
5.9
1.3
87
38
2*
35
17
9.5
38 *3
31 23
O.2O 0.28
16
1.7
1.0
0.6
10
3.5
0.6
0.6
65
55
39
31
2.9
*5 **
17 1*
0.29 0.52
11
5.1
3.*
0.6
6.7
2.1
0.6
0.2
97
97
70
39
11
4* ** *0
1* 1* 1*
0.3* 0.37 0.36
Denit Influent
Denit effluent - 1
Denit effluent - 2
Plant effluent
Hethanol doseage, ng/1
yerric iron doseage, ng/1*
Polymer doseage, og/1
•Ferric iron doseages for periods 12-1-74 through 12-6-7*,
the respective periods*
12-8-71- through 12-10-7* , and 12-13-7* through 12-16-7* are averages over
-------
Rainfall, inches
Plant flow, KG
Denit flow, MG
pH
Primary influent
Primary effluent
Denit influent
Denit effluent - 1
Denit effluent - 2
Plant effluent
Suspended solids, mg/1
Primary influent
Primary effluent
Denit influent
Denit effluent - 1
Denit effluent - 2
Plant effluent
Phosphorus, mg/1 P
Total
Primary influent
Primary effluent
Denit effluent - 2
Plant effluent
Filterable
Primary influent
Primary effluent
Denit effluent
Plant effluent
Nitrogen, mg/1 N
Ammonium nitrogen
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
OPERATIONAL DATA - EL LAGO
34-56
0.00 0.00
0.536* 0.54*8
0.5019 0.4993
7.3
7.2
7.7
7.7
7.7
7.*
228
50
64
70
79
<1
9.9
3.4
3.9
0.52
1.1
0.70
0.44
0.42
11
0.5
0.3
0.5
AWTP JAKUAHY 1975
DATE
7 8
0.00 0.52
0.5683 0.5604
0.464J 0.3481
7.1
7.1
7.6
7.6
7.7
7.*
170
134
65
3*
10
1
9 10
0.00 0.56
0.4459 0.5200
0.4478 0.5175
7.1
7.3
7.7
7.6
7.7
7.5
426
89
26
28
22
<1
10
1.2
0.84
0.91
13
0.4
0.1
0.5
11 12 15
0.00 0.27 0.00
0.6958 0.5094 0.4623
0.2185 0.1944 0.2150
7.5
7.5
7.8
7.9
7.9
7.5
146
62
*5
15
8
2
5.9
0.78
2.0
0.63
10
O.6
0.5
0.7
14 15
0.00 0.00
0.4001 0.5469
0.1595 0.5772
7.4
7.5
7.8
7.8
7.8
7.6
188
67
50
22
12
1
11
0.76
0.41
0.57
16
0.5
0.3
0.2
-------
o
CJI
Total Xjeldahl nitrogen
Primary effluent
Dealt influent
Denit effluent - 2
Plant effluent
Nitrate nitrogen
Denit influent
Denit effluent - 1
Denit effluent - 2
Plant effluent
COD, rng/l
Denit influent
Denit effluent - 1
Denit effluent - 2
Plant effluent
BOD5, aig/1
Dealt influent
Denit effluent - 1
Denit effluent - 2
Plant effluent
Methanol doeeage, ng/1
Ferric iron doseage, Bg/1
Polymer doseage, ng/1
18
16
3.4
0.9
12
8.1
7.2
3.4
110
110
99
61
52
50
47
29
47 46 46 46 46
14 14 14 14 14
18
3.1
1.7
2.2
11
7.2
3.8
3.3
96
56
56
52
45 4?
14 19
15
3.4
2.0
9.7
5.1
1.0
150
75
*t-
36
74
36
18
7.2
55 52 55
19 19 19
20
2.8
1.7
1.1
13
7.7
3.0
3.2
70
83
47
47
23
27
26
21
54
19
O.Jl 0.31 0.39 0.26 0.30 0.32 0.33 0.41 0.36 0.30 0.40
-------
OPERATIONAL DATA - EL LAGO AVTP JANUARY 1975
DATE
16 17 18 19 20 21 22 23 2* 25 26 2? 28 29 JO 31
fiainfall, inches 0.00 0.00 0.18 O.O? O.OO 0.00 0.03 O.OO O.OO 0.00 0.00 0.00 O.OO O.OO 0.00 O.OO
Plant flow, MG 0.3052 0.3164 0.3695 0.4621 0.3624 0.3600 0.320B 0.2935 0.266? 0.2788 0.3113 0.3042 0.3197 O.2995 0.2725 0.3327
Denit flow, MG 0.3532 0.3524 0.4175 0.4512 0.4344 0.3293 0.3328 0.3175 0.2907 0.2908 0.3353 0.3522 0.3677 0.5235 0.2965 0.3447
PH
Primary influent 7.3 7.4 7.3 7.4 7.4 7.4 7.5
Primary effluent 7.3 7.3 7.3 7-5 7.4 7.3 7.5
Denit influent 7.7 7.7 7.7 7.9 7.7 7.7 7.3
Denit effluent - 1 7.8 7.8 7.8 7.9 7.7 7.7 7.8
Denit effluent - 2 7.8 7.9 7.7 8.0 7.8 7.8 8.0
Plant effluent 7.6 7.6 7.7 7.9 7.5 7.2 7.5
Suspended solids, mg/1
Primary influent 250 252 226
Primary effluent 73 43 61
Denit influent 33 23 17
Denit effluent - 1 22 18 3
Denit effluent -2 11 8 2 < 1 2 3 5
Plant effluent 3 2 <1 <-l <£1 2 2
Phosphorus, mg/1 P
Total
Primary influent 12 9-1 11 9.9 11 11 12
Primary effluent 5-4 2.8 4.3
Denit effluent - 2 2.1 1.9 1.7
Plant effluent 0.92 1.2 O.56 O.46 0.29 0.59 0.59
Filterable
Primary influent 0.59 0.39 1.1 1.4 0.79 1.9
Primary effluent 0.4? 0.52 0.33
Denit effluent - 2 0.58 0.58 0.40
Plant effluent 0.61 0.53 0.43 0.41 0.27 0.51
Nitrogen, mg/1 H
Ammonium nitrogen
Primary effluent 16 16 19 18 19 20 18
Denit influent 0.4 0.9 0.5 1.4 1.2 0.7 1.1
Denit effluent - 2 0.4 0.6 0.4 0.8 1.2 0.4
Plant effluent 0.2 0.2 0.5 0.3 0.5 0.6 0.6
-------
Total Kjeldahl nitrogen
Primary effluent 21 19 26 26 24 26 25
Denit influent 2.5 2.8 2.8 3.9 3.4 2.8
Denit effluent - 2 2.0 2.2 1.7 2.8 2.8 2.2
Plant effluent 1.0 1.4 1.5 1.7 2.8 2.2 2.2
Nitrate nitrogen
Denit influent 15 14 18 16 15 14 ie
Denit effluent - 1 8.8 7.3 6.1 6.4 4.7 4.6 4.1
Denit effluent - 2 3.2 1.0 1.2 0.4 0.2 0.4 0.2
Plant effluent 2.0 1.4 .2.7 2.3 2.2 0.2 0.1
COD, mgA
Denit influent 14O 120 115 110 78 100 9O
Denit effluent - 1 73 88 48 47 39 39 31
Denit effluent - 2 37 60 20 27 16 2J 12
Plant effluent 29 48 16 24 12 17 16
BODct ng/1
Denit influent 87 66 68 62 58 64 44
Denit Affluent - 1 42 42 14 24 15 18 14
Denit effluent - 2 18 15 5.1 6.0 1.8 6.7 2.4
Plant effluent 16 14 3.8 3.2 2.2 5.4 2.5
Hethanol doseage, mg/1 54 54 53 53 53 42 43 42 33 42 40 41 41 43 45 39
Ferric iron doseage, mg/1 31 31 31 31 31 27 31 31 3O 57 4? 43 32 38 37 32
Polymer doseage, ng/1 0.49 0.45 O.41 0.38 0.41 0.41 0.24 0.4? 0.41 0.38 0.37 0.4O O.44 0.31 0.45 O.37
-------
o
oo
Rainfall, inches
Plant flow, MG
Denit flow, MG
pB
Primary influent
Primary effluent
Denit influent
Denit effluent - 1
Denit effluent - 2
Plant effluent
Suspended solids, mg/1
Primary influent
Primary effluent
Denit influent
Denit effluent - 1
Denit effluent - 2
Plant effluent
Phosphorus, mg/1 F
Total
Primary influent
Plant effluent
Nitrogen, mg/1 B
Amonium nitrogen
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
Total Kjeldahl nitrogen
Primary effluent
Denit influent
Denit effluent - 2
Plant effluent
123
0.45 0.00 0.02
0.5300 0.7895 0.5868
0.4250 0.3288 0.3998
7.6
7-7
7.7
7.8
7.3
208
25
14
15
<£1
11
0.40
1.0
1.1
2.8
2.0
* 5
0.30 0.00
0.4141 0.4662
0.4501 0.5382
7.4
7.6
7.7
7.7
7.4
170
33
15
6
3
6.8
0.39
0.2
0.2
2.5
1.7
DATE
6789
0.00 0.00 0.00 0.01
0.3538 0.3340 0.3161 0.3129
0.3784 0.3820 0.3401 0.3489
7.4
7.6
7.7
7.7
7.5
286
49
57
43
5
10
0.31
0.6
0.3
2.8
1.7
10
0.00
0.3099
0.3339
7.6
7.6
7.7
7.8
7.1
180
26
8
2
1
9.5
0.52
0.5
0.4
0.5
2.2
1.7
11 12 13
0.00 0.93 0.00
0.3097 0.7225 0.4388
0.3337 0.4283 0.3893
7.5
8.0
8.0
8.0
7.6
378
43
21
10
3
9.4
0.78
0.2
0.3
0.3
2.5
1.7
14
0.00
0.3591
0.4161
7.3
7.4
7.8
7.8
7.9
7.6
4O4
68
26
8
3
<1
10
0.46
13
0.2
0.4
0.5
18
2.2
1.7
2.0
15
-------
Nitrate nitrogen
Denit Influent
Denit effluent - 1
Denit effluent - 2
Plant effluent
COD, ag/1
Denit Influent
Denit effluent - 1
Denit effluent - 2
Plant effluent
*»5» as/1
Denit influent
Denit effluent - 1
Denit effluent - 2
Plant effluent
Methanol doseage, mg/1
Ferric iron doseage, mg/1
Polymer doseage, ng/1
41
20
0.2*
15
4.5
1.6
3.7
56
40
28
12
35
24
14
7.9
40 40 35
20 20 20
0.21 0.22 0.31
12
4.5
0.8
0.4
87
43
24
24
52
15
10
4.9
38
23
0.23
17
6.6
1.2
1.6
67
67
61
22
2?
20
9.6
4.2
40 38 39 39
24 24 24 24
0.30 0.22 0.31 0.31
17
3.0
0.9
0.8
98
31
23
20
66
13
3.0
2.9
38
24
0.32
16
4.1
0.8
0.3
100
39
27
21
58
20
4.5
2.8
38 43
18 15
0.31 0.22
12
2.9
0.4
0.2
106
59
47
35
44
18
14
12
44 49
15 23
0.34 0.30
o
10
-------
Knylisk Unit
APPENDIX B
CONVERSION FACTORS
Multiplier
Metric Unit
cfm
cfs
cfs/;icre
cfs/sq mile
cu ft
cu ft
cu in.
cu yd
cu yd/inili!
cu yd/sq mile
°F
fathom
ft
ft-c
gul
gal
gpd/sq ft
gpm
Kpni/sq ft
lip
in.
Ib
Ib/day/aoro
Ib/dav/acre-ft
Ib/ 1,000 cuft
Ib/acre/day
Ib/day/cu ft
lb/day/c» yd
Ib/day/cu yd
Ib/day/sq ft
Ib/ft
Ib/mil gal
mgd
mgd/ acre
mile
ppb
pcf
,,sf
psi
sq ft
sq ft/cu ft
sq in.
sq miles
0.028
1.7
4.2
0.657
0.028
28.32
10.39
0.75
0.475
0.29
0.555 (°F - 32)
1.8
0.3048
10.764
0.003785
3.785
0.040S
0.0031
40.7
0.7457
2.54
0.454
11.2
3.G8
16.0
0.112
16
0.6
0.6
4,880
1.51
0.12
3,785
9,300
1.61
io-3
16.02
4.SS
0.0703
0.0929
3.29
6.452
2.590
cu m/mia
cu m/miu
cu m/min/ha
cu m/min/sq km
cu in
1
cu cm
cu m
cu in/km
cu m/sq km
°C
m
m
lumen/sq m
cu m
1
cu m/day/sq m
I/sec
1/miii/sq m
k\v
cm
kg
kg/day/lia
g/day/cu m
g/cu m
g/day/sq m
kg/day/cu m
kg/day/cu m
kg/day/cu m
g/day/sq m
km
g/cu m
cu m/day
cu m/day/ha
km
mg/1
kg/cu m
kg/sq m
kg/sq cm
sq m
sq ni/cu m
sq cm
sq km
110
-------
TECHNICAL REPORT DATA
(Please read lauructions on the reverse before completing)
t. REPORT NO.
EPA-600/2-76-104
3. RECIPIENT'S ACCESSION»NO.
4. TITLE AND SUBTITLE
Nutrient Control by Plant Modification at
El Lago, Texas
5. REPORT DATE
July 1976 (Issuing Date)
6. PERFORMING ORGANIZATION CODE
7. AUTHORIS).
and
B. V. Ryan *
E. F. Barth **
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORG \NIZATION NAME AND ADDRESS
•''Harris County WCID No. 50
1122 Cedar Lane
Seabrook, Texas 77586
10. PROGRAM ELEMENT NO.
1BC611
11. CONTRACT/GRANT NO.
(11010 GNM) S803099
12. SPONSORING AGENCY NAME AND ADDRESS
'"'^Municipal Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final 9/15/70-8/1S/7S
14. SPONSORING AGENCY CODE
EPA-ORD
15. SUPPLEMENTARY NOTES
E, F. Barth, Project Officer
68U-76H1
16. ABSTRACT
A project was conducted to demonstrate the feasibility of modifying
an existing small trickling filter plant to control nutrients in
wastewater discharge. All existing facilities of the nominal 0.3 mgd
plant were utilized in the advanced waste treatment design. The
processes control phosphorus by metallic salt addition to the primary
settler, carbonaceous oxygen demand by trickling filters, and nitrog-
enous oxygen demand by suspended growth second stage activated sludge.
Nitrogen is removed via attached growth column denitrification, and
tertiary solids removal is accomplished by granular media filtration.
These processes are operated in series.
Process evaluation shows that an effluent with the following residual
concentrations can be obtained at the design flow of 0.3 mgd.
Biochemical oxygen demand, 5 day 4 mg/1
Chemical oxygen demand • 25 mg/1
Suspended solids 2 mg/1
Total phosphorus 1 mg/1
Total nitrogenous content 2 mg/1
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Waste water*, Activated sludge
process, Nitrification*, Phosphorus*,
Chemical removal (sewage treatment),
Sludge digestion
Denitrification*,
Clear Lake ""(Texas),
Effluent standards,
Tertiary treatment,
Suspended solids,
Chemical dosing
system
13B
8. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReportf
Unclassified
20. SECURITY CLASS (Thispage)
Unclassified
21. NO. OF PAGES
123
22. PRICE
EPA Form 2220-1 (9-73)
111
U. S. GOVERNMENT PRINTING OFFICE: I976 — 657-695/5462
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