WATER POLLUTION CONTROL RESEARCH SERIES • 17O1ODYBO2/71
PHOSPHORUS REMOVAL AND DISPOSAL
FROM
MUNICIPAL WASTEWATER
ION AGENCY
RESEARCH AND MONITORING
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WATER POLLUTION CONTROL RESEARCH SERIES
The Water Pollution Control Research Series describes
the results and progress in the control and abatement
of pollution in our Nation's waters. They provide a
central source of information on the research, develop-
ment, and demonstration activities in the Environmental
Protection Agency, through inhouse research and grants
and contracts with Federal, State, and local agencies,
research institutions, and industrial organizations.
Inquiries pertaining to Water Pollution Control Research
Reports should be directed to the Head, Project Reports
System, Office of Research and Monitoring, Environmental
Protection Agency, Room 801, Washington, DC 20242.
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PHOSPHORUS REMOVAL AND DISPOSAL FROM MUNICIPAL WASTEWATER
by
University of Texas Medical Branch
Galveston, Texas 77550
for the
ENVIRONMENTAL PROTECTION AGENCY
Project #17010 DYB
Grant #WPD 223-01-68
February 1971
For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price $1.25
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EPA Review Notice
This report has been reviewed by the Water
Quality Office, EPA, 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.
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ABSTRACT
Biological and chemical precipitation of phosphorus was studied in
a 0.7 MGD activated sludge plant.
Biological precipitation removed 0-70% of phosphorus. Near complete
mix aeration, plus variations in COD and P loadings, precluded holding
solids, COD and DO at levels favorable to P enrichment of solids. With
biological uptake of P there was magnesium-phosphorus co-enrichment of
solids at mol ratios of about 0.3/1, Mg/P.
Injection of Fe(II) to raw influent at doses of 1.3/1 - 1.6/1,
Fe/P, fqr 80-90% removal, at chemical cost of $0.32/lb of P removed was
the most feasible treatment. Dosage efficiency for Fe(II) to primary
effluent was slightly less; for Fe(III) to primary effluent appreciably
less; for Fe(III) to raw influent, least.
Doses of Al(III) at 1.6/1 to 1.8/1, Al/P, to primary effluent removed
80% P, but to raw influent, only 70%.
Dosage efficiency dropped significantly in attempts to raise removal
above 90% by iron, or above 80% by aluminum.
Injection of a polyelectrolyte to aeration effluent raised removal from
80% to above 90% for a 2.5/1, Al/P, dose of Al(III).
Within the 70% over-capacity of the digester and drain beds the iron-
phosphate sludge digested and dewatered effectively. About 150% over
conventional design capacity was indicated for the alumina-phosphate sludge.
Whether iron or aluminum was used, phosphorus remained insolubilized
through digestion.
This report was submitted in fulfillment of Project Number 17010DYB,
Grant WPD 223-01-68, under the partial sponsorship of the Water Quality
Office, Environmental Protection Agency.
iii
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CONTENTS
Page
INTRODUCTION 1
Objective 1
Treatment Schemes 1
Premises for Treatment Schemes 1
TREATMENT PLANT 9
AUXILIARY FACILITIES 11
SAMPLING AND ANALYTICAL PROCEDURES 12
DEMONSTRATION PROCEDURES AND RESULTS 13
Removal by Activated Sludge, No Added Cations 13
Removal and Disposal of Phosphorus From Digester Liquor 23
Utilization of Iron in Primary and Aeration Processes 28
Limited Lime to Return Sludge, Then Raw Influent 39
Aluminum Cloride to Raw Influent and Primary Effluent 42
DISCUSSION 48
Removal by Activated Sludge, No Added Cations 48
Removal of Phosphorus from Digester Liquor 60
Removal and Disposal of Phosphorus by Use of Iron 64
Removal and Disposal of Phosphorus by Use of Aluminum Cloride 73
SUMMARY AND CONCLUSIONS 78
ACKNOWLEDGMENTS 85
REFERENCES 86
TABLES-
FIGURES
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INTRODUCTION
OBJECTIVE
In studies, 1967-1969, at a 0.7 MGD (2650 cu m ) activated sludge
plant, Texas City, Texas,the objective was to demonstrate by two treat-
ment schemes the effectiveness, feasibility and costs of biological and
chemical processes for removal and disposal of phosphorus.
TREATMENT SCHEMES
Treatment Scheme Number One
This was to adjust operation parameters for biological precipitation
of solids of highest possible phosphorus content. Anaerobically digest
the solids. Chemically precipitate released phosphorus from the digester
liquor. Drain and dry the digested and reprecipitated solids on sand
beds for land disposal or utilization.
Treatment Scheme Number Two
This was the same as the first except that biological precipitation
of phosphate solids would be supplemented by chemical precipitation in
primary and aeration processes.
PREMISES FOR TREATMENT SCHEMES
Biological Precipitation
Biological precipitation and removal of phosphorus is limited:
first, by organic material and nutrients for building cell solids;
second, by the phosphorus incorporated into cell solids, I.e., the 1 to
2% requirement for cell production during exponential growth (1,2,3,4),
or up to 5 - 7% (5,6) including "luxury" (2), "overplus" (7,8) or
"volutin" (9) storage of polyphosphate under nutritional imbalance unfav-
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orable to cell growth; third, by instability of high-phosphate solids,
i.e., release of phosphorus at low pH (2,10) or with deficiency of
oxygen, or surplus of substrate food (2,6,11); and fourth, by the particle
size and agglomerated or bioflocculated state (12), i.e., their settle-
ability or floatability.
The high phosphorus removal at San Antonio, Texas, observed by
Vacker, et. al.. (6), and by Witherow, Priesing, et. al. (11, 13), and
at other activated sludge plants observed by Levin and Shapiro and by
Witherow and Priesing, is attributed by Vacker, et. al., to biological
enrichment; by Levin and Shapiro to "luxury" metabolic uptake; by
Priesing (13), to sorption by cells; and by Menar and Jenkins (14) to
phosphorus enrichment of the sludge by calcium phosphate precipitation.
There were observations common to several of the investigations
(2,6,10,11,13). The rapid and almost complete uptake of phosphorus was
toward11 the end of the log growth substrate utilization phase into the
bioflocculation endogenous phase, with dissolved oxygen approaching or
exceeding 1 mg/1. Higher DO levels promoted phosphorus uptake, but if
extended, released phosphorus by endogenous lysing of cells. There was
release of cell enrichment of phosphorus when aeration was withdrawn
for considerable time, e.g., with slow movement of sludge through
secondary clarifiers; also, when there was reloading with substrate food,
e.g., with mixing of plant influent with return sludge. Effective re-
moval of a phosphorus load was attained most readily by batch treatment,
e.g., in bench-scale tests; or under "plug" flow, e.g., in the long
aeration tanks of the San Antonio, Milwaukee, and Baltimore plants, wherein
complete substrate utilization could be approached and adequate biofloc-
culation attained. And, high degree of phosphorus removal was realized
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only when there was non-return of high phosphorus digester liquors.
At the Texas City Plant #2, it was evident that, even with the wide
diurnal variations in plant flow and COD and phosphorus loadings, an
approach to plant-scale batch treatment was limited. The short length
aerator coupled with turbulent aeration produced a flow-through pattern
much closer to complete mix than to plug flow. And the return of high
phosphorus digester liquor precluded high degree phosphorus removal.
However, pre-demonstration observations revealed several favorable
treatment results. Influent COD and phosphorus loads and rates were
such, that sufficient high-phosphorus solids might be built to remove
80-90% of the phosphorus. COD to aeration solids loadings and aeration,
were readily controlled for effective substrate utilization and bio-
flotcculation. Sludge withdrawal from secondary clarifiers was sufficiently
rapid to prevent andxic release of phosphorus enrichment. There was
phosphorus enrichment of aeration solids. As high as 5% phosphorus was
observed. As low as 2 mg/1 soluble phosphorus in the plant effluent was
observed for short periods. In bench-scale batch treatment, 70-80% of
phosphorus was removed from portions of primary effluent aerated with
2000 mg/1 of return sludge solids. There was occasional one-day through-
plant removal of more than 30% of the phosphorus load, even though high.
phosphorus digester liquor was being recycled.
Therefore, treatment scheme number one was projected for demonstra-
tion of maximum possible removal of phosphorus by biological precipita-
tion, after chemical precipitation of phosphorus from return digester
liquor.
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Chemical Precipitation
For chemical precipitation of phosphate from wastewater, lime, and
the salts of iron and aluminum have been the chemicals of choice for pro-
cess development and practice.
Use of Lime.—Rudolfs (15,16), (1947), Sawyer (17), (1952), Karanik
and Nemerow (18), (1965), Rand and Nemerow (19), (1965), Buzzell and
Sawyer (20), (1966), and Albertson and Sherwood (21), (1967) have demon-
strated effectiveness and lime requirements for removal of phosphorus from
raw wastewater; and Owen (22), (1953), Malhorta, Lee and Rohlich (23),
(1964) and Wuhrman (24), (1964) for removal from secondary effluents.
J-
There were common observations. Phosphate precipitation was pH dependent.
Reduction of phosphorus to below 1 mg/1, or removal of more than 90% of
a 10 mg/1 phosphorus load, required that pH be raised to above 10. High
alkalinity consumed major proportions of lime doses, and entailed pro-
duction of large quantities of solids. Menar and Jenkins (14), (1967)
demonstrated precipitation of calcium phosphate from high calcium waste-
waters, with no added lime, through prolonged aeration for stripping out
carbon dioxide, thus raising the pH level.
The forms of phosphate precipitates and the mechanisms of reactions
are not fully known. Owen (22) presented the results 'of his studies on
a functional assumption that phosphorus was precipitated as calcium
tribasic phosphate. Stumm (25) has stated that in the alkaline pH range
hydroxylapatite, Ca-, n(PO, ) , (OH) „, is the only stable phosphate phase.
Clesceri (16) reports that "colloidal chemical studies have indicated
that at pH 11, the predominant calco-phosphate compound is hydroxylapatite,
which may be mainly microcrystalline particles and, therefore, somewhat
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difficult to sediment." Johnson (26), (1964) states "In the cold lime
softening process phosphates are efficiently removed by adsorption on the
precipitated lime sludge."
The simplest of chemical models for describing phosphate precipita-
tion in secondary effluents by lime treatment would include the following
ion components: Ca4"*, Mg4^, (HC03)~, (C03) = , (PC^)5 and (OH)~. In treat-
ment of raw wastewater, polyphosphates and organic phosphorus would have
to be considered. In treatment of digester liquor the nitrogenous com-
pounds, acidity, and solids components add to the complexity.
However, studies of mechanisms were not within the scope of the pro^
cess development demonstrations at the Texas City #2 plant. Complexities
of reactions were recognized. The approach was emperical. Within the
best understanding of relevant information, incremental doses of chemicals
were added to selected wastewater streams. Evaluations were made for
feasible applications of processes demonstrated.
Pre-demonstration bench-scale studies confirmed pH dependency and
lime requirements observed by other investigators, and pointed to objec-
tives and procedures for plant-scale demonstrations. Under treatment
scheme for reducing the phosphorus content of digester liquor before
recycling it to the activated sludge process, the liquor was to be treated
with the minimum of lime required to reduce phosphorus to below about
10 mg/1, with production of least possible amount of solids of best
dewaterability. Under treatment scheme number two, for supplementing
uptake of phosphorus by primary and aeration solids, precipitation by
lime was to be tested at two injection points. First, lime was to be
dosed to the return sludge stream, sufficient to induce incipient
precipitation of calcium phosphate, and sufficient to raise calcium content
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and pH to levels favorable for augmenting uptake of phosphorus by activated
sludge solids. Then, second, lime was to be dosed to the raw influent,
sufficient for partial removal of phosphorus in primary units, with carry-
over of soluble and precipitated calcium into aeration units, potentially
favorable to continuing precipitation of phosphate.
Use of Iron and Aluminum.— Sawyer (17) in 1952 proposed the use of
iron and aluminum salts for removal of phosphorus from wastewater. The
following have been used in treatment of raw wastewater: ferric chloride,
aluminum sulfate, and sodium aluminate by Sawyer (1952); aluminum sul-
fate by Curry and Wilson (27), (1955), by Neil (28), (1957), and by Rand
and Nemerow (19), (1965) ; and ferrous sulfate and ferrous chloride by
Wukash (29), (1967). The following have been used for tertiary treat-
ment of secondary effluents: ferrous, ferric and aluminum sulfate by
Lea, Rohlich-and Katz (30), (1954); aluminum sulfate by Mahlorta, Lee and
Rohlich (23), (1964), and by Gulp and Slechta (31); and ferric chloride
by Wuhrman (24), (1964). The following have been used for augmenting
uptake of phosphorus by aeration solids: ferric chloride by Thomas (32),
(1962) and by Wuhrman (24), (1964); aluminum sulfate by Tenny and Stumm
(12), (1964), and by Eberhardt and Nesbitt (33), (1967); ferric chloride,
aluminum sulfate and sodium aluminate by Earth and Ettinger (34) , (1967) .
Dosage efficiency has varied with species of salts used, points of
injection, % removal and residual phosphorus attained, resultant pH, and
with precision in proportional dosing. Effective mol doses—ratio of
mols of chemical applied to mols of phosphorus removed—include the follow-
ing: 7/1, Fe/P, by Sawyer (17) using ferric chloride for 91% removal of
P from raw wastewater, reduction from a level of 2.2 mg/1 down to 0.2
mg/1, no resultant pH reported; 3.7/1, Al/P, by Mahlorta, et.al. (23),
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using aluminum sulfate in secondary effluent, for 94% removal, reduction
from 7.6 mg/1 P to 0.5 mg/1, at pH 6.0; 3/1, Fe/P, by Wuhrman (24), using
ferric chloride in aeration liquor, for 88% removal, reduction from 6 mg/1
P to 0.5-1.0 mg/1, at pH 6.8-7.5; 1.9/1, Al/P, by Eberhardt and Nesbitt
(33) using aluminum sulfate in aeration liquor, for 93% removal, from
13.8 mg/1 P to 1.0 mg/1, at pH 5.5; and 1/1, Al/P, by Earth and Ettinger
(34), using sodium aluminate in aeration liquor, for 95% removal, reduc-
tion from 12 mg/1 P to 0.6 mg/1, at pH 7.2-7.5. The effective mol ratio
of 1/1, Al/P, observed by Earth and Ettinger was attributable to rigid
control of proportional dosing, to resultant pH being near optimum, and
to upwards of 40% of the removal being biological precipitation of
phosphorus.
Three different reaction mechanisms have been considered as operative
in precipitation of phosphorus with iron and aluminum: chemical precipita-
tion by ion combination at pH levels of minimum solubility, Tenny and
Stumm (12), (1965); physical adsorption with pH dependence, Lea, et.al., (30)
(1954); and complexation of hydrolytic products, also pH dependent,
Singley and Black (35), (1967).
The available information cited above, the considered operative
mechanisms of reactions, plus pre-demonstration bench-scale studies
pointed to best points of injection, process control, and mol doses for
most efficient use of iron and aluminum at the Texas City plant. Under
treatment scheme number one, for removal of phosphorus from recycle
digester liquor the effectiveness and feasibility of the use of ferric
and aluminum chlorides were to be compared with the use of lime. lUhder
treatment scheme number two, for supplementing uptake of phosphorus in
primary and aeration processes, four chemicals were to be tested: ferric
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chloride, ferrous chloride, ferrous sulfate and aluminum chloride.'.: In-
jection was to be into raw influent for limited removal of phosphorus in
primary units, with carry-over of soluble and precipitating iron and
aluminum for continuing precipitation in aeration units. The,n, injection
was to be into the aeration influent for augmentation of uptake of phos-
phorus by activated sludge.
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THE TREATMENT PLANT,
OPERATIONAL FEATURES AND LIMITATIONS
The treatment plant, Texas City No. 2, is a conventional activated
sludge plant of 0.7 MGD (2650 cu m/day) rated capacity. The plant lay-
out and flow schematic, including auxiliary facilities for chemical
treatment, are shown in Figure 1.
The wastewater from a resident population of about 5000, plus a
325 bed hospital, reaches the plant through 5000' of 24", then 1000' of
36" concrete sewer (1520 meters of 61 cm, then 305 meters of 91.3 cm).
These sewers were utilized as surge reservoirs for increased uniformity
of flow.
The wet-dry lift station includes two comminutors; a 500 GPM
(1.898 cu m/min) and a 700 GPM (2.66 cu m/min) pump for through-plant
flow; and a 2500 GPM pump (9.5 cu m/min) for by-pass during heavy infiltra-
tion. Automatic sequential pumping control is provided, but manual con-
trol prevailed for these demonstrations.
The aerated degritter was effective for coarse grit, but not for
fine silt of heavy infiltration. Troublesome quantities of silt and
sludge accumulated in primary and secondary clarifiers which entailed
periodic heavy aeration of clarifier bottoms and hoppers to facilitate
transferal to the digester.
Overflow rate of the primary clarifiers is 1040 gal/sq ft/day
(42.4 cu m/sq m/day). Overflow weir length is only 10 ft. (3.0 m) per
clarifier. Flow-through patterns were not quantitatively evaluated but
were evidently poor at mean to higher flow. Baffle improvisation ef-
fected improvement. One of the primaries was utilized as a waste sludge
thickener for considerable periods, leaving only one for primary clarifi-
cation.
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The secondary clarifiers, rated at 670 gal/sq ft/day, (27.3 cu m/sq
m/day) have 25 ft (7.5m) overflow weir length per unit. Baffle improvisa-
tion also gave improved flow-through patterns, particularly at high rates,
permitting through-plant flow as high as 1*3 MGD (493.0 cu m/day).
The two aeration tanks, 60' x 20' x 12' (18 m x 6 m x 36 m) afforded
216,000 gallons aeration volume (819 cu m), rated at 6 hours aeration
based on .7 MGD plant flow (2650 cu m/day). The aeration flow-through
pattern was much closer to complete mix than to plug flow, due to the low
length to width ratio, to high return sludge rate (50-100%) and to
turbulent mix.
•ij
A single speed, plus a two-speed blower afforded five-step air appli-
cation rates. The highest rate, 1600 cfm, (45.3 cu m/min) was marginally
adequate in hot weather, during periods of highest BOD and solids loading.
I The digester is 42' in diameter and 21 ' in depth to the top of
the conical bottom (12.6 x 6.3 m) equivalent to about 220,000 gallons
volume (834 cu m). On basis of a 6000 sewered population, this allows
approximately 4.7 cu ft (133 1) per capita. It is estimated that a 15
year accumulation of sand and silt has reduced the digester volume by at
least 30%.
Digestion capacity was adequate when augmentative iron was used in
primary and secondary treatment but barely 50% adequate when aluminum was
used. The eight separable 42' x 44' (12.6 m x 13.2 m) sludge drain beds
afforded adequate capacity during the 2-year demonstration, but marginally
so through prolonged rainy periods, and immediately following the 2-month
production of high alumina sludge. Drain bed liquors were recycled to the
plant influent. Digested sludge was utilized for land fill and soil con-
ditioning of plant grounds and adjoining areas.
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AUXILIARY FACILITIES FOR CHEMICAL TREATMENT
Digester liquor was drawn by siphon and pumps through a strainer,
from 4-6 feet depth, at 10-30 GPM. A 1 to 3 minute quick mix with lime
was effected through the slurrier box of a dry lime feeder. Precipita-
tion and solids conditioning were completed in a 1000-gallon (3.79 cu m)
tank by gentle but complete mix aeration. Dewatering of the conditioned
slurry was by subsidence and overflow drainage in a compartmentalized
42* x 44' section of the sludge drain bed. When aluminum or iron was
used, injection was into the digester liquor line to the flocculation
solids-contact tank. Dewatering was also on the sand drain bed.
Liquid chemicals were stored in neoprene-lined and glass-lined
steel tanks, 3500 gallons (13.27 cu m) total capacity. Feeding of liquid
chemicals was by means of chemical metering pumps. Transmission of chem-
ical feed to plant injection points was through small plastic pipe and
hose.
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SAMPLING AND ANALYTICAL PROCEDURES
For monitoring of around-the-clock parameter variations, process
samples (Figure 1, Flow Schematic and Process Units) were collected
as needed and appropriate tests made at the time, or samples were re-
frigerated for delayed analyses. Sludge settleability, and phosphorus
and; solids .content were measured three times daily. Temperature and
pH readings were made once to thrice daily. Dissolved oxygen readings
were made on the aeration effluent at least bihourly, by means of DO
probes in,situ.,L Survey DO readings were made at other process points
as needed. >,,>,._
For monitoring daily variations in COD, solids, phosphorus, nitro-
genous .components, chlorides, alkalinity, calcium, magnesium, iron and
aluminum, bihourly samples were collected and refrigerated, then
composited proportional to flow, at the end of each 24-hours.
The COD test was routine for measuring organic loadings and reduc-
tions. Sufficient BODr tests were made to show approximately a 10:6
ratio of COD:BODc on raw influent and primary effluent samples, and a
10:2 ratio on final effluent samples.
Calcium, magnesium and iron were measured by atomic absorption
The spectrophotometric method, published by Davenport (36) in 1949 was
used for simultaneous determinations of iron and aluminum. For total
phosphorus — inorganic plus organic — samples were digested to fumes of
sulfuric acid and to a colorless digestate, from a 1:4:5 by volume
solution of sulfuric acid, nitric acid and water. All other analytical
procedures were in accordance with "Standard Methods for the Examination
of Water and Sewage" (37).
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DEMONSTRATION PROCEDURES AND RESULTS
REMOVAL BY ACTIVATED SLUDGE
NO ADDFJ3 CATIONS
Plant-scale studies of operation at the Texas City, Plant #2, with
no cations added to primary or aeration processes, were initiated in June,
1968. At that time, and until January, 1969, there was evidence of
biological phosphorus enrichment of aeration solids. After that time,
there was none. Ranges of levels of removal of phosphorus for representa-
tive demonstrations periods, and of concurrent levels of other parameters,
are listed in Tables I-III. Data for some of the parameters are represented
graphically in Figures 2 to 8.
Basically, operation control was in line with the regime that had
been empirically developed by the plant operators, for maximum day-to-
day removal of BOD and suspended solids: first, accept flow up to maxi-
mum solids retention capacity of secondary clarifiers; second, clean,
skim, and withdraw solids from primary and secondary clarifiers for
cleanest, "freshest" conditions; third, return and waste sludge, apply
air and waste solids for best physical appearance and settleability of
aeration solids; and fourth, withdraw digester sludge to drain beds as
necessary to prevent excessive "black" solids being recycled to the sys-
tem with digester liquor. Operation records show that by this regime
an effluent goal of less than 20 mg/1 BOD and suspended solids was main-
tained when aeration solids (MLS) were within the range 1500-2000 mg/1,
and dissolved oxygen (DO) in the aeration tank effluents was as much as
1 mg/1.
In the demonstration periods (Tables I and II) operational control
included the following supplementary modifications and intensifications
over the regime of previous operation.
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a. Greater uniformity of through-plant flow was maintained by
utilizing the 6000 ft (1830 m) of influent trunk sewer as a surge line
during the daily peak flow periods.
b. A larger proportion of flow was accepted through the plant,
except experimentally, and somewhat of necessity, August 1 - September 3,
1968 (Table II). ,
c. Digester liquor was not recycled through primary and aeration
processes unless it contained less than about 30 mg/1 of phosphorus.
d. Wasting of activated sludge was directly to the digester instead
':•'..'- 'j ' . ''• - . -. • <•'.,.
of through the primary clarifiers. After December, 1969, one of the
r
primaries was used as a thickener for waste aeration solids (MLS), and
only one primary was used as a clarifier for raw influent.
; e. Hourly to bi-hourly readings of DO in the aeration effluents
were made for more rigid control of air application.
f. A more intensive monitoring schedule was maintained for all
control and index parameters.
Removal, when there was Phosphorus Enrichment of Aeration Solids
Pre-demonstration observations, July 1967 to May, 1968, revealed
that the phosphorus content of aeration solids often was as high as 4
to 5%, dry weight basis. Thus, a prime requirement of effective removal
of phosphorus was being met. Assay of 24-hour sample composites indicated
occasional through-plant removal of 30-40%, but on the average only
i
10-15%. The low removal was attributed to the operational practice of
recycle of digester liquor to the raw influent and wasting of aeration
solids through the primary clarifiers, thus, returning soluble phosphorus
to the system.
A first opportunity was afforded, June 2-9, 1968, to observe phos-
14
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phorus removal without recycle of digester liquor and with aeration
solids wasted directly to digester. On May 31, digested sludge was
withdrawn to about 6 feet below overflow level in the digester. By
June 2, sand bed draining had subsided, and it was not until June
9, that the digester was refilled to overflow level. Wasting of aera-
tion solids to primary clarifiers was interrupted June 1. Phosphorus
removal was at 59% and 51% on June 3-4, and ranged down to 21% and
back to 57%, June 4-9 (Table II, June 2-9, and Figure 2, June 3-5).
Composite samples on alternate days, June 11-17, indicated removal of
24 to 55%, with recycle of digester liquor but with no wasting of
solids to primaries. Phosphorus in aeration solids held at near 5%.
Multiple periods of heavy rainfall and excessive sewer infiltra-
tion, plus interrupting sewer cave-ins and equipment failures, afforded,
opportunely, wide variations in hydraulic, COD, suspended solids and
phosphorus loadings, and required improvisations of operation. Results
of operation under these conditions did not delineate, but pointed to
the significant limitations to adaptation of this and similar plants for
effective removal of phosphorus, without added cations; that is, the
normal and abnormal variations themselves.
Normal dry weather flow; no primaries; 70-80% loading — From June
24 to July 14, there was a 21-day interruption of operation of secondary
clarifiers. Aeration solids dropped to less than 400 mg/1, of less than
1% phosphorus content. Then, on July 16, 2 days after restoration of
secondary clarifiers, the primaries went out of service. Replacement and
repairs of equipment were not completed until November 28, 1968. Thus,
of necessity, but opportunely, operation was without primary clarifiers
for 134 days.
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By August 1, aeration solids had built to above 1500 mg/1, .of .'.<
2% phosphorus content. Normal dry weather flow prevailed for 34 days
(Table I, Columns 1-3; Table II, August 1 - September 3). Weather was
hot, and aeration capacity was deficient for maximum loadings. There-
fore, through-plant daily flow and loadings were limited to levels
that permitted an experimentally desired DO near 1 mg/1. Through-
plant flow was held close to 0.4 MGD (1515 cu m/day) 18-22 hours but
dropped,to about 0.3 MGD during mid-A.M. (Figure 3a). Minimum COD,
suspended-solids and phosphorus loadings were concurrent with minimum
flow, and maximum with peak total flow of early afternoon (Figures 3
and 3a). Sludge return rate was 80-90% of through-plant flow. Aera-
tion solids (MLS) were held at 1500-2000 mg/1, and DO in aeration efflu-
ent at 0.5-1.5 mg/1, average, 0.8 mg/1. COD to solids loadings, Ibs/COD/
day/lbs of MLS, were in the range of .22-.42, average, .32. COD to
phosphorus loadings, Ibs COD/lbs P were 21/1 to 50/1, average, 28/1.
Thus, for 34 days, there was an approach to a steady state of parameter
variations, of lowest possible amplitudes.
Daily levels of parameters are listed in Table I. Ranges and aver-
ages for the 34-day period are compared with those for other demonstra-
^
tion periods in Tables II and III. Daily to 8-hour variations are
represented graphically in Figures 3 and 3a. The 52% removal for 3 days
(August 14-16, Tables I and II and Figure 3a), and the average of 43%
for 15 days (August 10-24, Table I), indicated that control at about 50%
removal might be attained. But the failure to do so, even when levels
of parameters were of the same order of reproducibility, was evidence
that it would be difficult.
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Wet weather flow; no primaries; maximum possible loadings — Results
of the 34-day period, August 1 to September 3, indicated that higher
COD loadings and a lower DO level might be tolerated, with resultant
higher removal of phosphorus. It was so planned for September and
October. But recurrent heavy rainfall and infiltration precluded desired
control of loadings, DO, aeration solids and the phosphorus content of
aeration solids. For example, note the variations September 3-7, with
best efforts to hold daily loading at 80% of average (Table I, and Figure
3). Heavy rainfall September 3-4, raised total flow to 1.8 MGD.
Through-plant flow was held at .66 MGD September 4, because of evident
flushing of accumulation of solids, COD and phosphorus from sewers and
lift stations, but was raised to 1 MGD September 5-6, because of evident
dilution. Control of DO at the 1 mg/1 level was lost. Aeration solids
(MLS) dropped, due to dilution and to some loss to effluent. Phosphorus
content of solids dropped to 1.5%, attributed to loss of biological
phosphorus enrichment and to dilution by inorganic solids. Phosphorus
removal dropped to as low as 6 and 7%. See also similar variations
September 15-19, following heavy rainfall September 13-14 (Figure 3).
After September 7, 1968, for the duration of the Demonstration
Project, no further attempt was made for experimental limitation of raw
influent loadings of COD, solids or phosphorus. Total flow was accepted
through the plant except when infiltration raised flow to above the
hydraulic capacity for retention and removal of plant solids, or when,
on a few occasions, there was lift pump failure. From September 4 to
October 1, in spite of uncontrolled variations in raw influent loadings,
the desired increases of COD/MLS loadings and reduced aeration DO levels
were experienced, but on the average with no correlative increase in
17
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phosphorus removal. Compare, September 4 - October 1, with August 1 -
September 3, Table II; also Figure 3. Moderate infiltration from lighter
i' •.'"•'
rains of September 6, 13, and 20 brought considerable slugs, then dilu-
tion of COD, solids, and phosphorus, which affected control of DO and
reflected reductions in phosphorus removal. Heavier infiltration from
heavy rain of September 4 and 14-17 produced wider variations, arid
phosphorus content of solids dropped to below 2% (Figure 3). A minimum
3-day average of only 19% removal was registered September 15-17 (Table
II). Phosphorus content of aeration solids had built to 3.5% by Septem-
ber 25 and to 4.3% by October 1. Phosphorus removal was 69% September
25, 67% October 1, averaged 59% September 24-26, and averaged 51% for
the eight-day period September 24 to October 1 (Figures 3 and 4, and
Table II).
October 2-4, there was a 50-hour interruption of operation due to
a sewer cave-in. Aeration solids were held under gentle aeration arid
j
phosphorus content at 4%. Rainfall. October 5-6, brought increased
flow and loadings. There was some release of phosphorus from aeration
solids October 5, reducing net removal to 9% (Figure 5). Total flow
and loadings were accepted on October 7 and 8. There was some recovery
of phosphorus in aeration solids. More rain came October 8-9, very
s
heavy on October 9, raising sewer infiltration to a very high level
October 10, bringing much inorganic solids, flushing out accumulation
of organic solids from lift stations and sewers, and diluting and
"washing out" soluble phosphorus. There was essentially no loss of
aeration solids to the effluent through October 10. Aeration DO was
held close to 1 mg/1 October 5-9, but went out of control October
10. Phosphorus removal, October 7, 8, and 9 was at 78, 67 and 65%
18
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respectively. Materials balance measurements became tenuous with the
"wash out" conditions of October 10, but the indicated phosphorus remov-
al was only 20% (Figure 5).
The flood conditions of October 10-11, entailed complete shut-
down of the plant lift station pumping equipment, October 12-21. With
auxiliary pumps, an unmeasured through-plant flow of 0.2-0.4 MGD (760-
1520 cu m/day) was maintained October 13-20. Aeration solids were
held at 2100 mg/1 and DO at .9 mg/1. Phosphorus content of solids held
at 2.5 to 3.0%. Daily phosphorus removal averaged 43%.
Average flow; no primaries; near maximum loadings— From October 22
to November 29, with much less rainfall, it was possible to accept,
through the plant, 93% of the total flow. Average daily flow was close
^
to the design capacity of 0.7 MGD, and close to the "normal" average,
(Table II, October 22 - November 26, 1968). Daily COD/MLS loadings held
close to 0.4, an experientially indicated effective level. Aeration
effluent DO was varied from 0.4 to 2.0 mg/1. Per cent phosphorus in
aeration solids held close to 3.0% for the first 15 days, fell to 1.7%
during the next 15 days, then rose to 3.0% the last 6 days of the 36-day
period. The low phosphorus removal experienced—29% average for the
period, 14% for a low 3-day average, and only 46% for the highest 3-day
average (Figure 7 and Table II)—was attributed to accumulation of raw
grease-laden solids in aeration solids and in the secondary clarifiers.
There was increasing evidence of the raw "debris" in the aeration and
return solids early in the period. Aeration DO level was raised but
with no measurable improvement. Then, it was noted that a heavy
accumulation of silt- and grease-laden anaerobic sludge in the secondary
19
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clarifiers was releasing soluble phosphorus to the effluent and to
return sludge. The deposition was removed by brief periods of heavy
auxiliary aeration of the clarlfier hoppers and bottoms, with some loss
of solids to the effluent. The phosphorus content of return and aera-
tion solids had dropped to a low of 1.7%, and the 3-day low of only 14%
removal of phosphorus was registered (Table II, November 18-20).
Further accumulation of solids in the clarifier was prevented by daily
aeration of the clarifier bottoms and hoppers, during brief interruptions
of plant flow. Phosphorus in aeration solids rapidly recovered to 2.8%
and the 3-day high of 46% removal was registered November 24-26.
Primaries restored; wet-wet weather; 70-90% loadings — The primary
clarifiers were restored to service November 27-28. Operation with no
cations added to primary or aeration processes was continued through
January 19, 1969. Moderate to heavy rains recurred weekly to bi-weekly.
Total flow averaged 1.06 MGD0 Through-plant flow was .86 MGD, 81% of
total. Phosphorus content of aeration solids dropped to below 2% with
each succeeding increase of infiltration flow. COD/MLS loadings averaged
about .3/1. Aeration effluent DO was held in the range of 1 to 2.5 mg/1,
at an average of 1.3-1.4 mg/1 for maintenance of settleability of aeration
solids, and of low effluent COD. The maximum, minimum and mean 3-day
average removals of phosphorus were 37, 0, and 15% respectively (Table
II, November 29-January 19). These low levels of removal were attributed
to "wash out" of phosphorus enrichment of solids at times of high infil-
tration flow; to some loss of solids to effluent at peak through-plant
flow; and to endogenous destruction of solids by extended aeration of the
sludge of considerable age, 4 to 6 days.
20
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Removal when there was no Phosphorus Enrichment of Solids
Operation with no cations added to primary or aeration processes was
interrupted January 20, 1969, for a demonstration of the use of iron, but
was reinstituted for 30 days June 15, and later for three other periods
of 9-19 days (Table III). Dry, to dry-dry weather prevailed. Total flow
was accepted through the plant except for a few days July 1-14, when
failure of one of the through-plant lift pumps limited flow to 88% of
total. Only one of the primaries was used as a clarifier for raw influent.
The other was used as a thickener of waste sludge. The use of the influent
sewer as a surge line effectively levelled diurnal peak and minimum flow,
but not so effectively the COD, solids and phosphorus loading rates (See
typical diurnal flow and loading patterns Figure 8; also Figures 3a, 4,
14 and 15).
Digester supernatant liquor was recycled to the raw influent, in
that soluble phosphorus never rose above 30 mg/1 after the periods of
iron treatment in primary and aeration processes January 20 - June 13,
and aluminum treatment August 21 - October 15;, also, in that much of the
digester liquor was unavoidably recycled as drainbed liquor from fre-
quent and heavy digester draw-down during the dry summer month. Recycled
supernatant contained excessive solids for a few days October 18-November
14, therefore higher levels of suspended phosphates—50-100 mg/1 P, as
alumina-phosphate—but amounting to less than 1 mg/1 additional phosphorus
in the raw influent.
Average daily COD to aeration solids loadings, COD/MLS, for the
various periods (Table III) from .39/1 to .56/1, were appreciably higher
than for periods when there was evidence of phosphorus enrichment of
solids (Compare data of Tables II and III; see also Table I). Air
21
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application was at maximum capacity rate for diurnal peak loading period,
and at sufficient rate at low period to maintain, on the average, about
1 mg/1 aeration effluent DO. Sludge settleability was poor, as indicated
by the 30-minute test (Compare SVI data of Tables l-III). And yet,
solids retention and removal through secondary clarifiers were effective,
except at times of extended denitrification, eg, October 18-29, with
loss of more than 30 mg/1 solids during the period (See effluent suspended
solids, Table II). Effluent COD averaged slightly below 40 mg/1, except
October 24 - November 14, when there was excessive loss of solids to
effluent and recycle of abnormally high COD digester liquor.
At no time was there evidence of phosphorus enrichment of aeration
solids^ nor of effective uptake of phosphorus. Note: The 2 to 4%
phosphorus content of aeration solids June 15-30, and October 18-29, was
due to residual ferri-phosphorus and alumina-phosphorus content of the
solids from the immediately preceding periods of iron and aluminum
treatment, respectively, (Table II). Daily phosphorus removal never
exceeded 20%, and averaged only 10 to 15%.
Presumably the failure to attain higher phosphorus enrichment of
aeration solids, and thereby higher removal of phosphorus was due to the
absence of deficiency of micro flora or fauna capable of biological
phosphorus enrichment.
Even if such species were present, the combination of low flow-heavy
load, the diurnal variations in loadings, the near complete mix of aeration,
the long sludge age and endogenous degradation of solids imposed nutrient
balance conditions unfavorable to maintaining adequate biological
phosphorus enrichment (7, 8, 9).
22
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REMOVAL AND DISPOSAL OF
PHOSPHORUS FROM DIGESTER LIQUOR
To minimize recycle of phosphorus to plant treatment processes,
phosphorus was precipitated from digester liquor; the solids drained
on sludge drain beds; and the filtrate, containing less than 10 mg/1
P, returned to the plant influent. Hydrated lime was used through most
of plant operation when no cations were being added to primary or
aeration processes, July 1968 to January 1969. The effectiveness of
Fe(III) and Al(III) were studied for brief periods.
Precipitation with Lime
The flow and chemical injection, reaction and disposal processes
are indicated schematically in Figure 1. Liquor was drawn from a 3-4
ft depth in the digester, through a cylindrical strainer, 4" x 10", with
5/8" holes on 1" centers (10.4 x 26 cm with 1.62 cm holes on 2.6 cm
centers). Flow rates were varied from 10 to 30 gpm (38-114 1/m) with
most operation at 20-24 gpm. Full flow was taken through the slurrier
box of a dry lime feeder, for a quick mix-slurry time of 1 to 2 minutes;
then, by gravity to the top and over the edge of the 1200 gal (4.6 cu m)
neoprene-lined reactor tank. An underflow baffle extended to 1' of the
bottom on the outflow side of the reactor. Air agitation was maintained,
sufficient to keep the mass of solids suspended, but stratified into a
sludge blanket toward and into the outflow compartment. Reactor effluent
was from near the top of the reactor, by gravity, 200' (62 m) to the edge
and over the side of a 42 ft by 44 ft (13 x 13.6 m) section of the plant
sludge drain bed, for solids subsidence and draining, and for overflow
of supernatant to another section of the drain bed. All transmission
lines were 1%-in and 2-inch (3.9 and 5.2 cm) plastic (PVC) pipes, except
23
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the line from the slurrier to the reactor tank. This was replaced
by a 3^" x 3%" (9.1 x 9.1 cm) wooden trough to facilitate removal of
depositions of magnesium ammonium phosphate.
Intermittent operation of the process, 6-24 hours, 2 to 3 times
per week was sufficient to prevent overflow of untreated liquor from
the digester to the plant influent.
Lime dosage was at various levels, to determine the minimum
required to reduce the"phosphorus content to below about 10 mg/1; with
production of least quantities of solids of best drainability; also with
least solids deposition on slurry transmission surfaces.
Operational parameters and results for representative days of
operation are shown in Table IV. The periods are listed 1 to 11 in
ascending order of pH levels of reactor effluent, which, experientially,
was the best index for control of lime dosage.
The soluble phosphorus content of the liquor was regularly reduced
to about 10 mg/1, when the pH of the reactor effluent was maintained
as high as 8.5; optimally, not higher than about pH 9.0.
r
For the experiential phosphorus levels in the digester liquor, 80
to 250 mg/1, a major proportion of the lime dosage was consumed by car-
bon dioxide and ammonium bicarbonate; then, at increasing doses of lime,
by precipitation of calcium carbonate. Since acidity and alkalinity in
the liquor did not increase greatly with increased phosphorus content,
efficiency in lime usage increased with increased phosphorus content,
i.e., ratios of lime to phosphorus were lower (See AMR and EMR values,
Table IV).
At phosphorus levels above about 200 mg/1 there was rapid deposition
24
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of magnesium ammonium phosphate (Mg'NH/ 'FO^BH^O, as assayed) on the
walls, and on the outflow orifice and line of the slurrier, but such
deposition did not extend to the surfaces of the reactor tank or its
outflow line. The deposition was so severe in the slurrier outfall line
that operation had to be interrupted every 4-6 hours for cleaning. But,
by replacing the outfall pipe with a wooden trough the cleaning was
readily accomplished without interruption of operation.
Settling and draining of the solids of the reactor effluent were
rapid in the 42' x 44' section of sludge drain bed. It was not until
after several intermittent days of operation that a 10-12 hour operation
period would fill the bed with liquor to the 14-inch overflow level.
Overflow and drain-bed liquors were clear, only slightly colored, and
of slightly lower soluble phosphorus content than the reactor effluent
(Table IV).
Removal of solids from the digester liquor was complete. Removal
of COD was 60 to 80%, with no discernible correlation of phosphorus and
COD removals. Removal of ammonia was measurable only at operation pH
levels above about 9.0. There was evidence of escape of ammonia from
the reactor and drain bed surface during and immediately following
operation at the higher pH levels.
Drain-down of the bed was complete within 12 to 18 hours after
interruption of operation. And cracking of the sludge cake surface
would develop within 48 hours. Cracks would widen and deepen rapidly
when interruption of operation was extended as long as 6-8 days. Also
a heavy algal growth would develop over the surface and down into cracks.
At the end of drain down, with incipient cracking , the sludge would
be about 30% solids, dry weight basis. By the time cracks developed to
25
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full depth, solids content was about 60%. Figure la is a photograph of
the bed when moisture content was in a 20-30% range. With long standing,
under dry weather conditions, the solids dried to a friable cake of about
15% moisture content. Removal and disposal was demonstrated at the 40%
and 15% moisture content stages, by the spade-fork-truck process, for
fill and spreading on plant grounds. Representative analyses of the
solids, dry weight basis, was .15% nitrogen and 4.3% available phosphorus.
Spreading on plant grounds gave evidence of plant growth stimulation.
Best utilization of the solids would be on acid soils deficient in
phosphorus.
Precipitation with Iron and Aluminum
Opportunity was not afforded for extended plant-scale demonstration
of the use of iron or aluminum for precipitation of phosphorus from diges-
ter liquor. The studies of the use of lime extended into January, 1969.
By that time, the low phosphorus content of waste sludge, and considerable
pumping of thin sludge to the digester, had reduced phosphorus content
of digester liquor to less than 100 mg/1. Then, with injection of iron
into raw influent or primary effluent, initiated January 21, the phosphorus
content rapidly dropped to below 30 mg/1. At this level, further reduc-
tion for recycle was not deemed justifiable, and results of demonstration
studies were not representative for treatment of liquors of higher
phosphorus content.
Laboratory grade ferric chloride (FeCl3'6H 0) and an ore processing
by-product ferric chloride (10-15% available Fe(III)) were used in bench-
scale studies. The latter was used in plant-scale demonstrations. A
waste by-product aluminum chloride, from polystyrene manufacture (5%
26
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available aluminum) was used in bench-scale studies and in two 6 to 8-
hour plant scale demonstrations.
In bench-scale and plant-scale tests on liquors containing 30-60
mg/1 phosphorus, doses of Al(III) or Fe(III) at mol ratios of about
1.5/1 effected 95% removal. Flocculation and sedimentation were rapid,
but compaction of the alumina-phosphate floe was poor. Buchner funnel
filtration of total flocculated volumes was poor, particularly of the
alumina-phosphate. Filtration of supernatant volumes was rapid, which
pointed to the most feasible scheme for plant-scale dewatering on sand
drain beds.
In plant-scale tests, the ferric chloride, or aluminum chloride,
was injected into a 20-25 gpm (76-95 1pm) stream of digester liquor
through 30 feet of 1%"PVC pipe, with out-flow over the top of the
1200-gallon (45.5 cu m) reactor tank (Figure 1, refer also to lime
treatment, above). Gentle air agitation was maintained in the influent
compartment of the tank (about 3/4 of the volume), just sufficient to
keep the mass of the floe moving under the bottom of the baffle into
and through the outflow compartment. The reactor effluent was trans-
mitted through 2%-±nch PVC pipe to a 42 x 44 ft section of the plant
sludge drain bed. Subsidence was rapid in the influent areas of the
drain bed, to a 4-5% slurry of ferri-phosphate, or to a 2-3% slurry of
alumina-phosphate. The liquor drained with decreasing rapidity through
the accumulating settled sludge, but the supernatant drained very
rapidly at the creeping edge of the sludge. It was indicated, though
not adequately demonstrated, that by using a second compartment for
draining of the supernatant, as much as 12-15 inches of a 5% sludge of
ferri-phosphate or a 3% sludge of alumina-phosphate could be accumulated
27
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in the first compartment of a two-compartment operation—subsidence,
and overflow withdrawal and draining of supernatant liquor. The second
compartment would need to be no more than ^ the size of the first.
Bench-scale tests were made on digester liquor fortified to 350 mg/1
of phosphorus by addition of orthophosphate. Reduction to less than
10 mg/1 was effected by mol doses of 1.2/1-1-4/1} Fe/P or Al/P plus about
a 1/1 mol dose of lime to hold pH at 4.5-5.0 for iron and 5.0-5.5 for
aluminum. Thus, it was indicated that the use of iron or aluminum for
precipitation of phosphate from high phosphorus liquor would also entail
the use of lime, or other suitable alkali.
UTILIZATION OF IRON IN PRIMARY
AND AERATION PROCESSES
The initial project concept, and the key objective of treatment
scheme number two, was to utilize iron, lime, or aluminum for augmenting
phosphorus uptake by aeration solids. But it became evident that control
of biological uptake of more than 15% of the phosphorus load would be
i
difficult if not impossible. Therefore, for 80-90% removal, the aug-
mentation and the total removal would be approximately equivalent. Demon-
stration objectives were then set for determining the preferable chemical,
the best points of application and the best overall operational control
under variable flow and loadings for removal and disposal of 80-90% of
the plant phosphorus load.
For the use of iron this meant: first, the use of ferric or
ferrous iron; second, applied to primary effluent or to the raw influent;
third, at single or two-level diurnal dosage rates; and fourth, at the required
28
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daily mol dosages Fe/P, for uptake of 80-90% of the phosphorus by the plant
solids and for holding the phosphorus with the solids through digestion and
drain bed drying.
Ferric and ferrous chloride were procured from Gulf Chemical and
Metallurgical Company, Texas City, Texas. These were by-product, solutions
from ore processing, of satisfactory purity, ontaining 8 to 12% available
iron and very little excess acid. High purity ferrous sulfate pickle liquor,
5 to 8% available iron, was supplied by the Chemlime Corporation, La Porte,
Texas. Delivery prices in the Texas City - Houston area, during the project,
were $0.09-0.12 per pound of available iron.
Operation control of overall plant processes was close to that for
operation with no cations added to primary and aeration processes. It was
possible to accept a larger proportion of excess infiltration flow due to the
heavier, better settling high iron sludge.
Experimentally and inadvertently, dissolved oxygen (DO) in the aeration
effluents ranged from 0.3 to 3.0 mg/1 with indications that 1 mg/1 was
adequate, and near optimum. A slightly lower level gave better control of
denitrification, for minimum gas-floating of solids in the final clarifiers.
Experimentally, aeration solids (MLS) were varied from 1500 mg/1 to
4000 mg/1, with indications that overall treatment effectiveness was favored
at greater than 3000 mg/1, when aeration capacity was sufficient to keep DO
in aeration effluent as high as 0.5 mg/1.
Return sludge rate was at about 0.5 MGD (1900 cu m/day), equivalent to
90-100% of dry weather plant flow. Except for May 18-29 and December 20-31,
1969, and January 1, 1970, sludge wasting was to primary clarifiers, with
satisfactory thickening, with measurable but not highly significant uptake of
phosphorus and reduction of raw solids and COD. During May 18-29, sludge was
29
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wasted directly to drying beds for testing of drainability and open bed
digestion feasibility. December 20-31, 1969, and January 1, 1970, sludge
was wasted to one of the primaries operated solely as a sludge thickener.
Digester liquor was returned to the plant influent. After only about
5 weeks of iron application to primary and aeration processes, the digester
liquor contained less than 25 mg/1 of phosphorus, entailing no significant
recycling of phosphorus.
In a first period of studies of utilization of iron, 145 days, January
20 through June 13, 1969, there was continuing frequent and heavy rainfall,
with resultant heavy infiltration. The estimated average flow to the plant
for the 145 days was 1 MGD (3790 cu m/day), of which an average of .86
MGD (3260 cu m/day) was accepted through the plant. Daily concentration of
phosphorus ranged from 2 to 10 mg/1, at a weighted average of 6.3 mg/1 for
the period. (Tables VI and VII, compare total and through plant flow;
also, the raw influent phosphorus).
A second period, 54 days, November 15, 1969, through January 7, 1970,
included 22 days of low dry weather flow, averaging .53 MGD (2000 cu m/day)
of 13.5 mg/1 phosphorus. Thus, opportunity was afforded in the two periods
to test the mol dosage effectiveness over a wide range of influent phosphorus
concentration. Results indicated that a given mol dosage Fe/P was equally
effective for various influent phosphorus levels experienced at most
treatment plants.
Rigid proportional chemical dosing was not attempted, only single level
and two-level diurnal rates. A mol dosage, Fe/P, was selected for a period
of days. Then, based on pre-knowledge of daily phosphorus loads, e.g. appro-
!
ximately 45 Ibs on Saturdays and 65 Ibs on Mondays, etc., the required
volume of chemical solution was estimated for the respective days. Then, for
a given day, the required volume was fed either at a single level uniform rate,
30
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around-the-clock; or at a two-level rate, i.e. at a low rate approximately
proportional to the expected low phosphorus loading for 4 to 6 hours during
mid-A.M., and at a higher rate approximately proportional to the average
phosphorus loading during the remaining 18 to 20 hours (See flow and
phosphorus level patterns, Figures 9 - 12). Initially, and for 175 of
the 199 days of iron application, dosage rate was single level. The results
of a six-day period of two-level rate indicated significantly greater
efficiency over single level dosing of ferrous iron to the primary effluent.
A two-level rate for a 1.32 mol dose, Fe/P, effected 87% removal of phosphorus,
as compared to 79.70% removal by a 1.38 mol dose, applied at single rate,
under comparable conditions of operation (Table VIII, Fe(II) to primary
effluent, April 25-30 and 19-24, respectively). No comparison was made
for feeding of ferric iron to primary effluent, nor to the raw influent. A
greater efficiency would be expected for two-level over single-level dosing
of ferric iron.
The results of 17 days of two-level dosing of ferrous iron to the raw
influent indicated only slightly better efficiency of iron utilization over
single level dosing (Table V; Table VIII, Fe(II) to raw influent; also
Figures 10-12).
Ferric and Ferrous Iron to Primary Effluent
A moderately quick mix
of dosing chemical was effected by injection into the primary effluent just
as it merged with the turbulent inflow of return sludge (Figure 1, RS and PE),
and mixing was near complete before division of the combined stream to
the two aeration units. This was adequate for ferrous iron in that mixing
was complete before total oxidation and hydrolysis of the iron; but was
marginally so for ferric iron, due to considerable hydrolysis before
homogenity was attained. It is suggested that this is a partial explanation
for the observed less efficient utilization of iron from ferric than from
ferrous.
31
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Ferric iron was dosed to the primary effluent for 18 days, during
variable wet weather flow (Columns 1,2 & 5, Table VI) , and for 20 days
during prevailing dry weather flow (Columns 3, 4 and 6, Table VI;
also Fe(II) to Primary, Table VIII). All dosing of Fe(III) to the
primary effluent was, diurnally, at a single-level rate. Dosing of
Fe(II) to the primary effluent was for a total of 34 days, during variable
wet weather, at single level diurnal rates, except for six days (Columns
7-11, Table VI; also, Fe(II) to Raw Influent, Table VIII).
Attempts to carry out a series of experimentally desired incremental
mol doses were frustrated by extreme variations in daily flow and phosphorus
loadings. But, "after the record," it was possible to select 3-day to
11-day periods in which the daily doses, and the levels of other para-
meters for a given period, were sufficiently close to the averages of the
period, for the average iron dose to be meaningful; i.e. with respect to
phosphorus removal effectiveness of such an average mol dose, Fe/P. The
averages of doses, raw and effluent phosphorus levels, phosphorus removal
and of phosphorus insolubilization are summarized in Table VIII for six
such periods of dosing Fe(III), and five such periods of dosing Fe(II)
to the primary effluent. These data are compared with data for other
parameters in Table VI. Control and index parameters were not wholly
comparable from period to period, but sufficiently so to indicate better
removal efficiency by Fe(II) than by Fe(III). Mol doses (AMR, applied
mol ratios, Fe/P) of Fe(II) at about 1.3/1 effected about 80% removal of
phosphorus. Mol doses of about 1.6/1 were required for equivalent removal
by Fe(III).
Operation conditions particularly were non-comparable for the period
November 15-22, 1969 (Column 4, Table VI; also line 4, Table VIII). This
was a start-up period. It had been noted that upon initiation of iron treat-
32
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ment, insolubilizatiqn proportional to dosage was immediate, but adequate
flocculation was not attained until about the third day. Poor flocculation
persisted through the period, November 15-22, with resultant effluent solids at
an average of 35 mg/1, and phosphorus removal of only 58%, at the average
applied mol dose of 1.35/1. It was not until the sequential period,
November 23-30, at a mol dose of 1.16/1, did flocculation improve, effluent
solids decrease and phosphorus removal increase. This was attributed
to the continuing build up of phosphorus and iron content of the aeration
solids to about 4% and 10%, respectively, apparently critical levels, along
with a continuing mol dose of as high as 1:1, Fe/P (Re, Aeration Solids,
TSS and % P and % Fe, Table V; also Columns 3 & 4, Table VI).
It is noted—Table VI, section on P Removal, Effectiveness and
Efficiency—that phosphorus removal across primary clarifiers was nil to
negative. Wasting of aeration solids (MLS) to primaries effected, marginally,
a measurable reduction of soluble phosphorus across primaries, but, most of
the time increased the suspended phosphorus content of primary effluent.
The mass of the waste solids settled rapidly with some augmentation of
removal of raw solids. But there was partial deflocculation of the waste
sludge, and reflocculation was poor, resulting in carry over of fine to
lightly flocculated solids across the short length effluent weirs.
The phosphorus content of these solids was high, and COD low, as compared
to raw solids, thereby keeping net removal of total phosphorus low to
negative, but not significantly affecting COD removal across primaries.
There was little evidence that injection of iron to the aeration
process gave appreciable augmentation of overall treatment effectiveness.
It was possible to accept larger proportions of infiltration flow, without
33
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loss of solids to effluent. When doses were sufficiently high to attain
75% or more removal of phosphorus, settleability of aeration solids was
good, as indicated by sludge volume index values (Re: Aeration Solids, SVI,
Table VI; also TSS and COD values). But through-plant removal of
suspended solids and COD was only marginally better under comparable flow,
loadings and operation control, than when no cations were added to primary
or aeration processes. Dosing of iron to primary effluent was slightly
less effective in COD and solids removal than dosing of iron to raw
influent (Compare relevant control and index parameters, Tables I-III
and ,V-VII). '
Ferric and Ferrous Iron to Raw Influent
Two points of injection were tried for dosing Fe(III) to raw influent:
in the wet well close to the pump suction; and to the outfall of the
degritter chamber just ahead of the Parshall flume. Neither gave an adequate
quick mix, in that there was appreciable hydrolysis, and precipitation
before the dosage was homogeneously mixed. Dosing was for 13 days in
February and March, 1969, during prevailing wet weather flow; and 20 days
.December 5-15, 1969, and December 24, 1969, to January 1, 1970, (Tables
VII-VIII) , during a period of decreasing wet weather flow and increasing
influent phosphorus concentration. No opportunity was afforded at dry
weather flow, of highest phosphorus concentration. Diurnally, all Fe(III)
injection was at single-level rates.
There were two advantages of the wet well injection point over the
degritter outfall point. First, it was easier to estimate and apply a
desired mol dose to the total flow than to only the through-plant flow at
time of any by-pass flow. Second, by injecting into the total flow, any
34
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by-pass flow received an effective phosphorus insolubilization dose of
iron, rendering such by-pass portions of phosphorus less readily available
for promotion of organic growth in receiving waters.
In addition to experimental periods of dosing Fe(II) and Fe(III) to
the wet well and degritter points of injection, Fe(II) was conveniently
injected into a manhole about 300 ft (93 m) up-sewer from the plant lift
station. For these three points there were no discernible differences in
progression of reactions or in through-plant removal of phosphorus. There
was essentially no precipitation and flocculation of ferrous iron,
nor of oxidation to, and precipitation of ferric iron, until long after
homogeneous mix of the dosage, i.e., after entry to primary clarifiers.
Fe(II) was dosed to the raw influent 54 days, March to June, 1969,
including uninterrupted feeding May 1 through June 13; then, for 8 days,
December 16-23. Diurnal dosing was at single-level rate except for 17
days, May 1-17 (Table V). Prevailing variable rainfall afforded demonstra-
tions at an extremely low phosphorus level of only 2 mg/1 (Table V, May 15-
18), and up to slightly above 9 mg/1, December 16-23 (Table VII, Column
12, December 16-23), but not at 12-14 mg/1 of dry weather flow.
Daily values of various parameters are listed in Table V and represented
graphically in Figure 9, for dosing of Fe(II) through the month of May.
Bi-hourly variations are represented graphically in Figures 10-12, for
May 12 and 28, and June 3. Average doses, raw and effluent phosphorus levels,
and phosphorus removal and insolubilization are summarized in Table VIII,
for 7 representative incremental dosing periods of Fe(III), and 6 for
Fe(II). These data are compared with data for other parameters in Table VII.
Again, as for the periods of feeding Fe(III) and Fe(II) to primary
effluent, operation parameters were not wholly comparable from period
to period, but sufficiently so to demonstrate that feeding of Fe(II) to raw
35
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influent, at or ahead of the wet well afforded most effective and efficient
utilization of iron. Mol doses of 1.3/1 to 1.6/1, Fe/P, consistently
effected more than 80% removal, approaching 90%, even at single level diurnal
dosage rates, (Table VIII, Summary Comparisons). Effectiveness was appreciably
better than by feeding Fe(III) to primary effluent or to raw influent, and
marginally so than by feeding Fe(II) to primary effluent.
Removal of phosphorus across primaries by Fe(III) was above 10% for only
12 of 33 days, and by Fe(II) was nil to negative except 8 of 39 days (Table
!,
VIII, Section, P Removal; also, Section Flow, MGD). There was visual and
analytical evidence of precipitation of ferri-phosphate from the Fe(III)
dosing, but very little sedimentation except at diurnal periods of low flow.
The carry-through of deflocculated waste sludge also kept net removal at
low levels. The 15-26% removal, December 13, 1969, to January 1, was
attributable to decreasing through-plant flow, including diurnal low flow,
1-4 hours of less than .4 MGD rate; and to a change in sludge wasting process,
after December 19, i.e., using one of the clarifiers solely as a thickener
for waste aeration solids, MLS, thereby preventing carry-through of waste
solids.
Dosing of Fe(II) to raw influent resulted in appreciable precipitation,
flocculation and sedimentation of ferro- or ferri-phosphate only at diurnal
periods of low flow, still carrying some infiltration water having sufficient
DO to oxidize some of the Fe(II). These flow conditions prevailed in the
i
period of December 16-23, when there was 20% removal across primaries,
(Column 12, Table VII). Also, operation of one of the clarifiers solely as
a sludge thickener kept carry through of waste solids essentially to zero.
It is noted that the analytical data for suspended solids in raw
influent and primary effluent indicate for most of the demonstration periods,
very little removal to heavy increase in solids across primaries. This was
36
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attributable in part to carry-through of waste solids, but principally
to precipitation of iron in samples in the interim between collection
and assay, upwards of 24 hours, thereby giving a false indication (Table
VII, Section, TSS; Re, also Section, Flow, MGD). There was visual
evidence of removal of raw solids across primaries, also, of precipitation
and sedimentation of iron, but no feasible procedure was found for routine
measurement. Also, it is noted that removal of COD across primaries was
quite low for 9 of the 13 demonstration periods. Highest removal was only
about 30% (Table VII, Section, COD, Columns 3, 5, 12 and 13). At no time
did dosing of Fe(III) or Fe(II) to raw influent show significant augmenta-
tion of removal of raw solids or COD, across primaries.
Overall treatment control and effectiveness with iron treatment, with
respect to removal of COD and suspended solids, was better than with no
added cations, but only marginally demonstrable. The principal advantages were:
first, accepting more infiltration flow through the plant without loss of
solids to the effluent; second, with injection of iron into raw influent,
affording a phosphate precipitating dose to any by-pass flow; and third,
retention of removed phosphate with the digested solids, minimizing recycle
to primary and aeration processes. Iron treatment, particularly with injection
of Fe(II) to raw influent, afforded an "ironing-out" effect to overall
operational control and treatment effectiveness.
Sludge Production, Digestion and Dewatering
Wasting of the ferri-phosphate sludge to the primaries inhibited anaerobic
action and facilitated withdrawal and pumping of the combined waste and
primary sludge. Convenient scheduling of pumping was 1000-2000 gallons for
each 8-hour operation shift, totaling about 5000 gallons (19 cu m) per day,
37
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equivalent to approximately 1% of lowest dry weather flow of plant influent.
Solids content of the combined sludge was 20,000-30,000 mg/1, about 50%
ash. At 1.0 to 1.6 mol doses of iron Fe/P, total daily production was
800-1000 Ibs (365-455 Kg), (Table XIII, Representative Sludge Production).
Materials balance measurements and calculations gave no indication of
h
greater or lesser production of organic solids than when no cations were
added to primary or aeration processes.
The combined sludge digested and compacted effectively (Figure 18,
Profiles of Digester Solids). Reduction of Fe(III) to Fe(II) was complete
but over 95% of the phosphorus remained with the solids. Draining, cracking,
and drying was rapid and effective, favorably comparable to that for non-
ferri, non-phosphate sludge. The dried sludge contained 4-5% total
phosphorus (90% fertilizer-available) and 10-14% Fe. Total N by Kjeldahl
was .6%. The sludge was utilized for fill and soil conditioning at plant
site and adjacent areas.
Drainbed Digesting and De-watering of
Waste Aeration Solids
For 12 days, May 18-29, 1969, the total wasting of aeration solids
2 7
was directly to an 1850 ft (174m ) section of the sludge drain beds,
1/8 of the total area (Table V, May 18-29). In this period aeration
solids were being maintained at highest levels, 3350-4200 mg/1. For the
first four days aeration mixed liquor was wasted at 10-30 gpm (38-104 1/m).
Then, as the wasting rate exceeded draining rate, return sludge instead of
wasted
mixed liquor, was/at 5-15 gpm for 8 days. Water level on the bed did not
rise to a fixed 12-inch overflow depth until the sixth day of the 12-day
period. Solids subsidence and compaction was rapid, permitting essentially
no loss of solids to overflow. Deposition was at about a 10-inch depth
38
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at influent and about a 3-inch depth at overflow end of the bed at time
of discontinuation of the wasting. Active anaerobic digestion had
developed but the supernatant liquor and algal growth prevented escape
of odors. Within five days after interruption of wasting, compaction was
to about six inches and two inches at influent and overflow end respectively.
Surface cracking had extended to considerable depth. Heavy algal growth
had developed. But anaerobic digestion had progressed to odor nuisance
level. The bed was then flooded with plant effluentj and the flooding
repeated every 5-8 days. This permitted digestion to proceed to completion
within about 30 days, with no odor nuisance. Then, after about 10 more
days, with no retarding rainfall, the digested sludge had drained and
dried to a readily removable condition. Thus, within a 2-month period,
12 days of waste aeration solids were digested and dewatered on 1/8 of
the plant drain bed area. The dried solids were highly friable and
contained about 5% phosphorus; over 90% fertilizer available.
LIMITED LIME TO RETURN SLUDGE
THEN TO RAW INFLUENT
Occasion and Premises
Menar and Jenkins have demonstrated the precipitation of calcium
phosphate in activated sludge from high calcium wastewater (14),
attributing the precipitation to increase of pH from stripping out of car-
bon dioxide by aeration. Emperical evidence was the increased calcium
uptake from the substrate and increased calcium content of activated sludge,
with its concurrent increased uptake and content of phosphorus. Correlation
of uptake of magnesium was not observed. They pointed to calcium phosphate
precipitation as a plausible accounting for high removal of phosphorus at the
San Antonio, Texas, plants, observed by Vacker, et.al. (6) and by Witherow,
et.al. (11).
39
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The correlated uptake of phosphorus and calcium by activated sludge
observed by Menar and Jenkins was from wastewater of approximately the
same: calcium and magnesium content as the San Antonio wastewater, i.e,
about 90 mg/1 calcium and about 20 mg/1 magnesium. But the co-uptake
occurred at appreciably higher pH than the experiential levels of 7.7-7.9
for the even higher uptake of phosphorus at the San Antonio plants.
Since the studies at San Antonio did not include demonstration of the ex-
tent of uptake of calcium and magnesium, it was decided to measure co-uptake
of phosphorus, calcium and magnesium by activated sludge at the Texas City
plant. The calcium and magnesium levels in the Texas City wastewater were
only about 1/2 those of the Sam Antonio .wastewater, and the aeration
effluent pH was within a slightly lower range, ie, 7.5-7.8 as compared to
7.7-7.9. It was considered, therefore, that it would be necessary to in-
crease calcium and magnesium content and/or raise pH level, eg, by adding
lime, in order to demonstrate significant precipitation of calcium or
magnesium phosphate.
'Limited Dosing of Lime to Return Sludge
For five days, July 15-19, 1969, lime slurry was injected to the bot-
tom of the return sludge sump, near the point of pump suction. Doses
were limited to amounts that would raise pH of aeration influent mixed
liquor to above 8.0 but no higher than 8.5, expecting incipient precipita-
tion of calcium phosphate, without significant change in bioactivity of
the activated sludge. Experiential mol doses—mols of lime per mol of
phosphorus in the raw influent—were 1.7, 4.2, 3.8, 3.4 and 2.1 for the
respective five days (Table IX). Aeration influent pH levels of 8.1-8.4
fell to 7.6-7.9 through aeration. Calcium content of aeration solids in-
creased from 2% to about 5%, but there was no measurable increase in
40
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phosphorus or magnesium content. Daily phosphorus removal averaged 19%
as compared to 15% and 12% respectively in the 5 preceding and 9 suc-
ceeding days, with no addition of lime. Settleability of aeration solids
as indicated by the SVI test, was better, and the improvement extended for
several days after withdrawing lime treatment. However, effluent suspended
solids were not reduced below the 6 mg/1 average level being attained with no
added lime.
Dosing of lime to return sludge was interrupted after five days. Ex-
tension of the treatment to higher dose levels had been planned, even at
the risk of imposing upsetting changes of bioactivity in aeration. It was
decided not to take this risk until further observations could be made
without and with lime and other cations added to raw influent and primary
effluent. These Project priorities held precedence and opportunity was
not afforded for further experimentation with injection of lime to return
sludge.
Lime to Raw Influent
For 8 days, July 29 to August 5, 1969, lime slurry was injected into
the plant wet well at a point near the suction of the lift pumps. Doses
were objectively limited to partial precipitation of calcium phosphate
in primaries, controlling at levels that would result in carry-through
of precipitation, and raise the pH of the aeration influent mixed liquor
to no higher than 8.5. Dosing was discontinued when it became evident
that excess precipitation of "lime" sludge in the primaries might impose
upsetting changes in sludge digestion.
The incremental mol doses of lime were from 2.2 to 8.4, Ca/P
(Table IX). Primary effluent pH levels were raised to a range of 8.30-
9.15, aeration influent levels to 8.10-8.40, and aeration effluent levels
41
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to 7.60-8.05. There was no measurable increase in phosphorus, calcium or
magnesium content of aeration solids. Through-plant removal of phosphorus
reached as high as 42%, but practically all the removal was registered
through the primaries. Sludge volume index values were high but effluent
suspended solids remained low. Effluent COD was very low, averaging
21 mg/1 as compared to about 30 mg/1 in the previous 29 days. There was
no discernible effect on sludge digestion by the "high lime" primary
sludge.
ALUMINUM CHLORIDE TO RAW INFLUENT
AND TO PRIMARY EFFLUENT
The objective was to demonstrate dosage requirements of aluminum for
80-90% removal of phosphorus, when injection was into the raw influent, and
when into the primary effluent. Aluminum chloride solution was used, a
waste by-product in polystyrene manufacture, supplied by the Monsanto
Company, Texas City, Texas. It contained 5 to 6% available aluminum and
less than 1% free acid. There were no contaminants known to be inhibitory
to bioactivity. Injection was to the raw influent for 18 days, August
21 to September 8, 1969, and to the primary effluent for 37 days, September
9 through October 15, (Tables X-XII; Figures 1, 14-17). Diurnal dosing
rates were two-level, September 3-23, but at single-level for the remainder
of the time.
Dry weather prevailed except for light to moderate rainfall August
21-29 and October 9-13. Total flow was accepted through plant except for
only 70 to 80% for the first three days, August 21-23, and for August 28,
29, and 31. - v_
Digester supernatant and drain bed liquor were regularly recycled to
42
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the. raw influent. Aeration sludge return rate was about 100% of dry
weather plant flow. Aeration solids, MLS, were wasted to one primary,
used solely as a thickener for the first 8 days, August 21-28. For the
remainder of the time return sludge was wasted to both primaries, used
as clarifiers for raw influent. Aeration solids ranged from 1500-3000
mg/1, with indications that 2000-2400 mg/1 was optimal. Air application
was at maximum rate during diurnal high loading periods for maintaining
measurable DO in the aeration effluent, and at sufficient rate through
low loading periods to effect a daily average of 1.0-1.5 mg/1, exper-
ientially indicated required levels for best solids conditioning and
maximum removal of COD and suspended solids.
Daily averages of operation and index parameters are listed in Table
X. Averages for the 10 incremental dosage periods are listed in Table XI,
and summarized in Table XII. Averages, weighted proportional to flow, are
shown for periods when variations in flow imposed significant differences.
Representative around-the-clock variations for flow and for raw and
effluent phosphorus, at two dose levels, Al/P, are shown graphically in
Figures 14 and 15. Daily averages, August 8 through October 12, for flow,
aluminum doses, effluent COD and suspended solids, and for raw and effluent
phosphorus are shown graphically in figures 16 - 17.
Dosage to Raw Influent
Aluminum chloride was injected into the plant wet well, near the lift
pump suction, August 21 through September 8. Each daily dose was fed at
a single level rate through September 2. Then, September 3-8, daily doses
were fed at a two-level rate; during the low load period for about six
hours, approximately proportional to the average phosphorus level; and the
remaining time, at a rate approximately proportional to the higher average
phosphorus loading.
43
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After an initial period of 3 days, in which dosage was increased
from .46/1 to 1.23/1, Al/P, an attempt was made to hold at a fixed dose
through at least five days. This was not found to be possible. But
in retrospect, an average daily dose for a period of 4 to 8 days was
designated as the incremental dose for the period, in that it was not
greatly different from the high or the low on more than one day.. Thus,
there were three incremental dose periods when injection was to the
raw influent: 1.25/1, Al/P, August 24-27 and 2.04/1, August 28 to
September 2, dosed at single level rates; and 1.79/1, September 2-8,
dosed at two level rate.
Through-plant removal of phosphorus at these three doses was 68%,
69%, and 74% respectively, and insolubilization of phosphorus was 70, 71,
and 77%, (Tables X-XII). There was no removal of phosphorus through the
primary units at the lowest dose, August 24-27, which was attributed to
the use of only one primary as a clarifier, and to carry-over of de-floc-
culated alumina-phosphate solids from the clarifier being used as a
thickener for waste aeration solids. With the use of both primaries as
clarifiers, and wasting of aeration solids to both,August 28 to September
2, phosphorus removal through primaries was 30% and 40% for the respective
doses of 1.79/1 and 2.04/1, Al/P (Table XI, section, P removal). Dosage
efficiency was best at the lowest mol dose, 1.25/1, Al/P, affording an
effective mol ratio for removal of 1.84/1 (EMRr, mols of Al to mols of
P removed), and for insolubilization, an effective mol ratio of 1.79/1,
(Table XI, Effective Mol Ratios, EMRr and EMRi). Efficiency was quite
low, EMRr of 3.14/1, at the mol dose of 2.04, with diurnal dosing rates at
single-level. The two-level mol dose of 1.79/1 was more efficient, EMRr
and EMRi, 2.42/1 and 2.32/1, respectively. But it was evident from these
44
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limited demonstrations that more effective, quick mix of dosage, much
more rigid proportional feeding and more effective flocculation would be
required for efficient utilization of aluminum chloride, when injection was to
the raw influent.
Dosage to the Primary Effluent
From September 9 through October 15, 1969, aluminum chloride was
injected into the primary effluent at confluence with return sludge (Figure
1). Through September 23, diurnal dosage rates were two-level; after that,
at single-level.
The first incremental dose of 1.65/1, Al/P September 9-13, effected
81^ removal and 84% insolubilization of the phosphorus load (Tables X-XII).
The two sequential incremental doses (at two-level rates), 2.02/1 and 2.41/1,
September 14-18 and 19-23, removed 82% and 80% and insolubilized 87% and
92%, of phosphorus loads, respectively. The next incremental doses, fed
at single-level rate, September 24 to October 1 and October 2-6, were 2.41/1
and 2.20/1. Phosphorus removal was 80% and 82% and insolubilization 92%
and 92% respectively. A subsequent dosage period, of widely varying doses,
averaging 2.21/1, effected only 68% removal of phosphorus , but insolubilized
as much as 92%.
Dosing of aluminum chloride was more efficient when injected to pri-
mary effluent than to raw influent. But, even at two-level rate, daily
mol doses of 1.6-1.8 were required to attain 80-85% removal of phosphorus.
Higher doses gave no increased removal. Insolubilization reached a peak of
slightly above 90% at mol doses of 2.0/1 to 2.2/1.
Wasting of the alumina-phosphate aeration solids to primaries effected
only 5-10% reduction of soluble phosphorus. Net removal of total phosphorus
45
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across primaries was negative, attributable to deflocculatiori of the
sludge with resultant carry-through of high phosphate solids (Tables
X and XI). Wasting of the solids to primaries effected no measurable
increased removal of influent COD and suspended solids.
Through-plant removal of COD and suspended solids was at about
90% and 95% respectively for aluminum doses, Al/P, up to about 2/1. At
higher doses removals were as low as 80% and 75% respectively, attributable
to inadequate flocculation, resulting in high effluent solids (Tables X and
- . ii
XI and figures 16 and 17). Aeration pH levels were reduced to as low as
7.0-7.2, at the high aluminum doses, concurrent with the poorer flocculation
and higher effluent solids (Table XI).
Polyelectrolyte Coagulant Aid to Aeration Effluent
Demonstration results pointed to the need for the following: more rapid
mix of the aluminum chloride dose; rigid proportional feeding, Al/P; adjust-
ment of pH level; addition of a coagulant aid. Opportunity was afforded
only for demonstrating the effects of adding a polyelectrolyte coagulant.
For four days, October 7-10, a cationic polyelectrolyte (ST-260,
Calgon Corporation) was dosed to the aeration effluent at 1 mg/1, propor-
tional to plant influent flow (Tables X-XII). The average aluminum dosage
was 2.56/1, Al/P. Effluent solids averaged 6 mg/1. Phosphorus removal
was 90% and insolubilization was 92%. Since insolubilization of 92% was
attained at the lower aluminum doses of 2.2/1 to 2.4/1 (Columns 7-10,
Table XI), 90% removal might have been attained had the polyelectrolyte
been used; also as much as 95% removal of suspended solids.
Sludge Production, Digestion and De-Watering
Wasting of the high alumina-phosphate solids to primaries gave a
46
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combined waste and primary sludge of 1.5-2.0% solids, dry weight basis,
containing about 40% ash (Table XIII). Sludge pumping was conveniently
scheduled at about 2000 gallons each, for the three 8-hour operation
shifts, totaling 6000-7000 gallons per day (23-27 cu m per day); this,
without development of objectionable digestion in primaries.
Digestion was moderately rapid in the digesters, but compaction
was only to about 2.5% solids (Table XIII and Figure 18). This limited
digestion time, and entailed frequent drawing of "green" sludge. Draining
on the sand beds was slow, but digestion continued to completion within
10-15 days, without development of odor nuisance. After about 10 more
days, dry weather permitting, draining, cracking and drying, had proceeded
sufficiently for ready removal by a "spade-fork-truck" procedure. Upon
re-wetting and drying the solids were quite friable. The solids were
utilized for fill and soil conditioning in the treatment plant area.
47
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DISCUSSION
Treatment control efforts were for maximum removal of COD, nitro-
gen, phosphorus and solids, pointedly, for building, removing and dis-
posing of solids of high phosphorus content. Key control parameters
were those of material's balance considerations in production and manage-
ment of solids. For some of these, correlations with phosphorus re-
moval were closely measurable, eg., the added, and some of the influent
cations, and the phosphorus and cation content of aeration effluent and
digested solids. Interrelated effects often obscured individual effects.
Discernible effects and correlations afford guidance to interpretation
of results and point to means for more effective treatment control.
REMOVAL BY ACTIVATED SLUDGE
NO ADDED CATIONS
Model for Processing
In prospect and retrospect, proposed premises for removal of phos-
phorus by activated sludge included (6):
First, building of cell solids by microbial species capable of
biological phosphorus enrichment (7, 8, 9, 39).
. Second, sufficient nutrients for, and actual building and removing
of sufficient high phosphorus solids, eg, for 90% removal of 10 mg/1
of phosphorus by the building and removing of 180 mg/1 of solids con-
taining 5% phosphorus.
Third, phosphorus enrichment of cell solids occurs in the nutrient
imbalance or deficiency conditions (7, 8, 9) of declining growth and
endogenous phases and not when there is sufficient nutrients to promote,
predominantly, log growth of cells.
Fourth, aeration at least to measurable DO is necessary for promotion
of phosphorus enrichment.
48
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Fifth, anoxic conditions, and/or resupply of nutrients promote
release of phosphorus enrichment (2, 6, 13).
Sixth, extended aeration or anaerobic digestion releases most all
of the biologically contained phosphorus (6, 38).
Process and Operational Limitations
Biological Enrichment, Species Specific — The first
premise affords, plausibly, a principal explanation of
the very low phosphorus removal when there was no phosphorus enrichment
of solids (Table III). During these 73 days, over 700 samples of aera-
tion mixed liquor, return sludge and waste sludge were analyzed for
total and soluble phosphorus, the soluble phosphorus assay being made
on filtrates procurred at time of sample collection. Also, soluble
phosphorus analyses were made on 73 24-hour composites plus 130 bi-hourly
grab samples of plant effluent. The lowest observed level of soluble
phosphorus was 6.2 mg/1, this, in a stream of flow in which influent
total phosphorus had been only 8 mg/1. At no time was there indication
of more than 25% through-plant uptake of phosphorus. The weighted
average removal for the 73 days was 13.1%. The phosphorus content of
aeration solids, when there was no residual ferri- or alumina-phosphate
from previously added cations, was never as high as 2% (Table III, %P
in Aeration Solids).
No attempt was made for identification of microbial populations,
to see if predominant species included those demonstrated to have bio-
logical phosphorus enrichment capacity (8, 9). But, whatever the pre-
dominant species of aeration processes during the 73 days, (Table III),
there was no phosphorus enrichment. Therefore, it is assumed that such
species were absent, or always at very low population levels.
The hypothesis that biological phosphorus enrichment is species
49
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specific, points to an explanation of the variable and ever decreasing
phosphorus removal June, 1968, to January, 1969, (Table II, Re sequential
data for flow and % P in Solids; also, Table I). For each heavy infil-
tration, high flow period there was, not only some loss of aeration solids,
but more seriously, a loss of phosphorus enrichment of solids, followed
by a lower rate of re-enrichment. In the very heavy and frequent high
flow periods of December and January, there was complete "wash out" of
enrichment, and apparently of re-enrichment capacity. If biological phos-
phorus enrichment is species specific, this could have been a "wash out"
of the species.
Materials Balance Requirements—The second premise above, along with
phosphorus enrichment capacity of cell solids, point to another limiting
factor to high phosphorus removal at the Texas City Plant #2, and similar
plants treating similar sewage, ie, plants and processes of equivalent
solids building capacity. In the 15-day period, August 10-24, 1968,
(Table I and Figure 3a), flow and sewage characteristics were representa-
tive of dry weather conditions. Primary clarification was not being
applied, affording representatively highest COD entering aeration pro-
cesses at highest COD/P ratio, conditions favorable for maximum building
of solids and biological uptake of phosphorus (1, 6) (Tables I, II, &
III, COD and COD/P data). Operation control was near experiential best.
The average flow was .388 MGD (1470 cu. m) and average removal of phos-
phorus was 4.8 mg/1, or 43% of the 11.1 mg/1 influent phosphorus. Aver-
age phosphorus content of aeration solids was 3.5%. The average measured
wastage of solids of this phosphorus content was 450 Ibs/day (205 Kg/day)
equivalent to 139 mg/1 in the .388 MGD flow. For 90% removal, it would
have required a net building and wasting of 922 Ibs/day (420 Kg/day),
or 285 mg/1 in .388 MGD flow. If phosphorus enrichment of the solids
50
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had been at 5%, about the highest experienced at the Texas City Plant,
it would have required net building and wasting of 200 mg/1 of solids,
for 90% removal of phosphorus. This 200 mg/1 solids building-wasting
level is considerably above experiential levels, attributable to the
limiting nutrient(COD) level of influent sewage, and to somewhat extended
aeration, resulting in digestion of some of the solids built.
Complete Mix Aeration; Variations in COD and P Loading; Air and
Solids Management—There were three closely interrelated operational
factors limiting to phosphorus removal through biological enrichment of
aeration solids: first, the near complete mix of the aeration units; second,
the extreme diurnal variations in COD and phosphorus loading, characteristic
of small treatment plants; and third, cell destruction, resulting from the
aeration solids management—high sludge return rate, moderately high
aeration solids level (MLS) and sludge age, and the high rate of air
application—all, experientially essential for maintaining effluent BOD^
and suspended solids at desired low levels.
These operation conditions are in contrast to those of large plants
having very long, "plug flow", aeration tanks, also, having fine bubble
air diffusion , and greater flexibility in air application and solids
level control, eg, the San Antonio, Texas, plants (6, 13). In line with
the model—the six premises above—progression of solids building and
phosphorus uptake in such "plug flow" systems is envisioned as follows.
Log growth of cells is predominant through an entrance segment of aera-
tion until substrate utilization is near complete, with uptake of phos-
phorus limited to requirements for cell multiplication (1, 2, 6). Then,
in extended segments of aeration distance and time, in declining to
endogenous bioflocculation phases, with nutrient imbalance, the cells
store phosphorus to the extent of their enrichment capacity or to
51
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depletion of substrate phosphorus. As high as 7-8Z phosphorus in
aeration solids, and substrate depletion to less than 0.1 mg/1 have
been observed (6, 38). Dissolved oxygen levels above 1 mg/1 are
favorable for rapid and complete uptake of phosphorus, but recently,
Wells (38) has demonstrated high uptake at DO levels no higher than
0.2-0.3 mg/1. Aeration to higher levels in the effluent end of aera-
tion aids in preventing anoxic release of phosphorus through clarifiers
and in return sludge, but extended aeration promotes digestive release
of phosphorus. With entry of "plugs" of mixed liquor—return sludge,
plus influent with a fresh supply of nutrients—there is release of
phosphorus enrichment. Higher than 30 mg/1 soluble phosphorus in entry
portions of aeration units, have been observed, 2 to 4 times higher
than soluble phosphorus levels in the influent or return sludge (6, 38).
But as the "plug" moves through the log growth substrate utilization
phase into the declining growth bioflocculation phase, there is re-
uptake of the released phosphorus; then, in flow cycles, sequential
uptake of phosphorus, wasting of some of the high phosphorus solids,
but return of sufficient viable cells and of nutrients for building and
removing of more cells of high phosphorus enrichment.
This phase progession for efficient building and removing of high
phosphorus solids cannot be attained in small systems such as the Texas
City Plant #2, with its short length aeration units of turbulent
aeration, receiving highly variable loadings. Equilibria may be
envisioned through limited periods of effective uptake and removal.
And, evidently, such did occur for net removal, through 24 hours, as
high as 70-80% (Figures 4 and 5), and in 3-day periods, 50-70% (Figures
2, 3a, 5 and 7; and Tables I and II). But on days immediately preceding
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and succeeding, there were shifts to heavy release or lesser uptake,
resulting in low net removal. Note time-peak-trough patterns: Figure
2, June 3-5; Table I and Figure 3a, August 13-18; Figures 3 and 4,
September 24-October 1; and Figure 4, October 1.
In jar tests on grab samples of aeration influent mix liquor it
was possible to demonstrate anoxic release of phosphorus and/or release
by the fresh supply of nutrient COD; to levels 10-15 mg/1 above soluble
phosphorus levels in the influent or return sludge; then, aerobic uptake
to residual levels below 1 mg/1. But in the near complete aeration mix
of the plant,such levels of release were not registered, and only in-
frequently were such low residuals from uptake registered. Net effects
were reflected in the 8- to 12-hour time-volume flow-through patterns.
On June 3, 1968 (Figure 2), effluent phosphorus fell from 3 mg/1
to 0.1 mg/1, 12:00 a.m. to 6:00 a.m. then rose to 1.2 mg/1 by 8:00 a.m.,
and held at 1 mg/1 until 12:00 noon. In the preceding 8-12 hours, in-
fluent phosphorus had been at 6-8 mg/1 (June 2, not shown in Figure 2).
Thus, for the reduction of this 6-8 mg/1 to 3 mg/1, then to 0.1 mg/1,
equilibria evidently were favorably "on the uptake", for a net removal
of 75%. Or, during the low flow period through 8:00 a.m., with decreasing
loadings, there was an approach to "batch treatment", favorable to com-
pletion of the log-growth substrate utilization phase, with "nutrient
starvation of cells" (7, 8), and permitting extension into the declining
growth endogenous phase, for high-rate uptake of phosphorus. But the
increasing flow 8:00 a.m. to 12:00 noon, June 3, with its heavy load of
COD, imposed negating release of phosphorus enrichment, registering lower
net uptake. The flow-through patterns of influent COD and phosphorus
loadings, and of effluent phosphorus, June 4-5 (Figure 2), reflect
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further cycles, from effective to low, to even negative uptake of phos-
phorus, attributable primarily to variations in COD and phosphorus
loadings. But note also the cause- effect relations of air application
and DO levels (Figure 2, G, DO in Aeration Effluent). During these three
days, air application was held near constant rate. With decreasing
loadings, DO in the aeration effluent rose and held at a slightly higher
level until the effects of increased COD had extended through aeration
units. It is also noteworthy that DO ranged from 0.2 mg/1 to no higher
than 1.3 mg/1, evidently, levels sufficiently high for effective substrate
utilization (Figure 2, D, COD in Final Effluent), and for promoting high
uptake of phosphorus. It appears also—COD and solids loadings permit-
ting—that this DO range is optimal for minimizing aerobic digestive
release of phosphorus.
The variations in phosphorus uptake, normally reflected from
regular diurnal variations in COD and phosphorus loadings, were also
affected by changes at irregular intervals and to other factors. The
increase in effluent phosphorus 2:00 to 10:00 p.m., August 14 (Figure
3a)—a decreasing net uptake—was due primarily to high influent phos-
phorus, from a non-discerned source, 27 mg/1 in the 2:00 p.m. sample.
The low profile of removal August 25 to September 3, 1968, (Table I and
Figure 3) was attributed first, to anoxic release of phosphorus from
solids in the secondary clarifier, due to slow rate of withdrawal and
return, practiced for several days; and second, to aerobic digestive
release (Note DO and nitrate levels Table I). The very low profile of
phosphorus removal, September 3-23, including extreme variation, was
attributed to "wash out" of phosphorus enrichment by high flow, bring-
ing not only surges of phosphorus-releasing COD from sewer-flushing
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first rises, but also inorganic and silt dilution of phosphorus in
the aeration solids. Note (Table I and Figure 3, % P in Aeration Solids),
that phosphorus content of aeration solids ranged down to as low as 1.5%,
and did not recover to 3% until September 21. The very low net uptake
of phosphorus October 5-6, was also attributable to a slug of COD from
rising flow, reducing phosphorus in solids from 4% down to 3%, and
reducing net removal to 9% (Figure 5). Then, for three days with uni-
form flow of about 1 MGD, (3,790.cu m/day), even with, wide variations
in COD and phosphorus loadings, net uptake was high and daily average
removal, 70%. But the very heavy infiltration flow late October 9
through 10, produced a "wash out"" of phosphorus enrichment.
The very low phosphorus content of aeration solids and resultant
low ttfrottgh—plant removal, November 18-20 (Figure 6) was due primarily
to anoxic release of phosphorus from solids retained in and moving
through secondary clarifiers, but in part to aerobic digestive release.
Air application was heavy in the previous 3-4 days, in an attempt to
overcome anoxic conditions in the clarifiers. Operation without pri-
mary clarifiers (August, through November 26, 1968) plus silt-bearing
influent had resulted in build-up and deposition of "raw debris". These
accumulations were removed by auxiliary intermittent aeration of the
clarifiers and rapid withdrawal of solids, November 15-19. Phosphorus
content of aerations solids built rapidly back to above 2.5% for higher
removal November 24-26 (Figure 7).
Through December* 1968, to January 19, 1969, phosphorus content of
aeration solids could not be maintained above 2%, because of frequent
and heavy infiltration, flow. Phosphorus removal deteriorated to levels
experienced when there was no enrichment of solids (Table III).
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Digestive Release of Phosphorus—Another process factor limiting
to the removal of phosphorus was digestive release through extended
aeration. The lysing of cells releases not only phosphorus of enrichment,
but almost the total of biological uptake. Degree of nitrification is
pointed to as an index (Tables I-III, Nitrogen Section. Compare degree
of nitrification and denitrification before and after December, 1968).
Vacker, et.al (6) and Witherow, et.al (13) have noted reduced phos-
phorus removal by extended aeration and nitrification.
Again, it is noted that loss of phosphorus enrichment of solids,
and of enrichment capacity in December, 1968, and January, 1969, (Table
II) was attributed to frequent and heavy infiltration flow. But
aerobic digestive destruction of cells and release of phosphorus was
contributory to this loss.
In the demonstration periods, June to November, 1969, with no
added cations, aeration and nitrification was even more extended than
in December,1968, and January, 1969. And this, along with other
process differences as follows, is believed to have been contributory
to the absence of phosphorus enrichment and the very low phosphorus
removal.
Dry weather flow prevailed. Total flow was accepted, which, even
with primary clarifiers in service, brought heavier daily COD and phos-
phorus loadings to aeration, and sharper diurnal variations in loadings.
Aeration solids were held at about the same level, which, without primary
solids, kept a higher inventory of cell solids—greater sludge age.
Air application was at higher rates, holding DO at equivalent to higher
levels, essential for maintaining low effluent COD and solids, but
promoting nitrification and digestive destruction of solids. This was
evidenced by the higher nitrate levels and lesser net production of solids.
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For example, July 1-14, 1969, (Table III), nitrification was to a
daily average of 6.2 mg/1 nitrate nitrogen, 26 Ibs/day; and measured
wastage of aeration solids was .37 Ib/lb of COD, a total of 416
Ibs/day. Whereas, August 10-24, 1968, (Table I), nitrification was
only to 0.6 mg/1 nitrate nitrogen, 2.6 Ibs/day, and net production of
aeration solids was 0.45 Ib/lb of COD, 456 Ibs/day. Thus, the exces-
sive destruction of cells, including those of phosphorus enrichment capa-
city, along with near total release of contained phosphorus would,
in part, account for the non-enrichment of solids and the very low
phosphorus removal June to November, 1969. Further, based on the
experiential observations, but without presenting supportive specula-
tive theory, it is suggested that nitrifying bacteria have low phos-
phorus enrichment capacityj and/or that the biochemistry of nitri-
fica.tion negates cell populations of high enrichment capacity.
Control and Index Parameters
It was concluded that in a small (0>.7 MGD) activated sludge plant
such as Texas City #2, with its near complete mix aeration and extreme
variations in COD and pfeospfeonas loadings, high level phosphorus removal
is extremely difficult, if not impossible. But within the hyposthesis
that phosphorus enrichment is species specific, and in terms of process pre-
mises (Page 48, above), experience points to process and parameter
level requirements.
Materials Balance Requirements—There must be sufficient COD for
building of sufficient solids of sufficiently high phosphorus content,
eg, in the order of 360 mg/1 COD, for building of 180 mg/1 waste solids,
of 5% phosphorus content, for 90% removal of 10 mg/1 influent phosphorus.
Control of Solids Building by "Plug" Flow—The log growth substrate
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utilization phase of cell production must be brought to near comple-
tion, then no resupply of food be permitted until phosphorus
enrichment and uptake are at maximum, and the solids removed from
aeration. This can be attained in long narrow "plug" flow aeration tanks.
Limited Solids Levels and Air Application—Solids level and aera-
tion must be sufficient for high uptake of phosphorus, to promote bio-
flocculation and to prevent anoxic release in clarifiers, but limited
to prevent excessive sludge age and aerobic digestion of solids.
Solids Management—Aeration solids must be moved through secondary
clarifiers with minimum anoxic release of phosphorus enrichment and
minimum loss of solids to plant effluent. Reaeration of return sludge
must be limited to prevent extensive release of phosphorus by aerobic
digestion. And excess solids cannot be wasted through primary
clarifiers.
Solids Disposal—Disposal or utilization of waste solids must be
without recycle of released phosphorus to primary or aeration processes.
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Phosphorus and Magnesium Co-enrichment of Activated Sludge
To obtain information on calcium and magnesium uptake when no cations
were being added, analyses were made on representative samples of raw
influent, final effluent, aeration solids (MLS), return sludge and of
waste sludge, July-December, 1968, when there was evidence of varying
degrees of biological phosphorus enrichment of aeration solids. Then,
July 10 through August 5, 1969, analyses were made when there was no
evidence of phosphorus enrichment of solids, including 5 days when lime
was added to return sludge and 9 days when lime was added to the raw
influent (Table IX). Over 100 samples of aeration effluent (MLS) from
the east aerator, over 50 from the west aerator (Figure 1), and over 100
samples of return sludge and waste activated sludge were analyzed for total
and soluble phosphorus, calcium and magnesium. Assay for soluble com-
ponents was made on filtrates procurred at time of sampling.
Variations in calcium and magnesium content of the raw influent were
of such proportions, frequency and irregularity as to preclude precise
measurement of uptake from influent to effluent. But sampling of aeration
solids was sufficiently representative and analyses sufficiently accurate
and precise to measure changes in magnesium, and calcium content of
aeration solids. There were increases in magnesium content, but not of
calcium, somewhat in proportion to increase in phosphorus content.
The data for 109 samples of mixed liquor (East aerator effluent),
including samples of July 11 to August 3, 1969 (Table IX) were plotted:
first, Figure 13b, % phosphorus in solids (X) and % magnesium in solids (Y);
and second, Figure 13c, % phosphorus in Solids (X) and % calcium in solids
(Y). For the phosphorus magnesium relation the linear equation of best
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fit (A of Figure 13b) is y= .2691 x - .1181; correlation coefficient, +
.7674, at 1% level. Thus, it is indicated for each mol of phosphorus
enrichment above 1.5% content of the aeration solids, there was uptake
of about 1/3 mol of magnesium. For the phosphorus-calcium relation the
linear equation of best fit is Y = 3.1583 - .5487x; correlation coefficient,
-.3853. Thus, there is evidence that there was no increase of calcium
uptake with phosphorus enrichment of aeration solids, and no significant
evidence of release.
REMOVAL OF PHOSPHORUS
FROM DIGESTER LIQUOR
Precipitation with Lime
The demonstrated lowest chemical cost for precipitating phosphate
from digester liquor was $.12/lb of phosphorus removed. This was by
use of hydrated lime when the phosphorus content of the liquor was 249
mg/1 (Column 6, Table IV). At the optimal reaction pH of about 9.0 for
reducing phosphorus level to below 10 mg/1, the effective weight ratio
was 7.3/1, lime/P, for the precipitation of 242 of the 249 mg/1 of P.
For the 12,000 gal (45.5 cu m) 178 Ib (81 kg) of lime was used for
precipitation of 24.3 Ibs (11 kg) of phosphorus. At $30/ton, ($36/metric
ton) for lime this amounted to $0.12/lb of phosphorus removed ($0.26/kg).
The 249 mg/1 phosphorus content of the liquor on September 27, 1969,
was representative of production in the 12 preceeding days, when the
weighted average daily uptake and removal of phosphorus by activated
sludge was 17 Ibs, 41% of the 42 Ib daily phosphorus load. Materials
balance measurements indicated that an average of 18.3 Ibs of phosphorus
was transferred to the digester daily: 5580 gal/day (21.3 cu m); containing
1.64% dry wt solids; of 2.4% phosphorus content—5580 x .0164 x .024 x
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8.34 = 18.3 Ibs/day (8.3 kg/day). The chemical costs for re-precipitation
of the 17-Ib net removal of phosphorus was $2.04 per day. Thus, for removal
and disposal of 41% of a 10 mg/1 phosphorus load in 1 MGD, the chemical
costs would be $4.10/day.
Lime dosage efficiency improved with increasing phosphorus content
of liquor. No opportunity was afforded for plant-scale demonstrations
for liquor containing more than about 250 mg/1. But in bench-scale
tests on liquor fortified to about 500 mg/1 phosphorus, effective weight
ratios of less than 5/1, lime/P (EWRr), reduced phosphorus to below 10
mg/1. On this basis, the chemical cost would be $08/lb of phosphorus
removed. Then, if biological uptake and removal of phosphorus were
raised to 82% as compared to the experiential of 41%, also, if waste
sludge were thickened to the experiential 1.6% solids content, without
significant loss of phosphorus enrichment—the chemical cost could be as
low as $5.5/MGD. This is assuming 82% removal of a 10 mg/1 (83.4 Ib/day)
in 1 MG, and $.08/lb of phosphorus removed—(.82 x 83.4 x $.08 = $5.50).
Thus, the chemical costs for re-precipitation of the biologically removed
phosphorus would be only about 1/4 the chemical costs for removal and
disposal of 80-85% of phosphorus load by use of iron in primary and/or
aeration processes, (Re: $22.50/MGD, Use of Iron in Primary and Aeration
Processes, Discussion below). But it is again noted that this is on the
basis of 82% uptake by activated sludge and release of the phosphorus in
digester liquor to at least 500 mg/1. Further it is recognized that
applicatory considerations hinge on the over-all feasibility and costs of
the processes. These, in turn, hinge on equipment and operational costs
for application of chemicals and for dewatering and disposing of solids
produced.
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Demonstration experience in re-precipitation and disposal of 17
Ibs/day of phosphorus does not delineate, but affords guidance to
feasibility and costs considerations for a 0.5-1 MGD operation.
Chemical Feeding and Mixing—Digester liquor production was about
6000 gal/day (23 cu m/day). Batch treatment was conveniently scheduled
for 3-4 days of operation per week, 6-10 hours/day. Dry lime feeding,
directly into the treatment stream through the 2-3 minute slurry box of
the feeder, gave adequate mixing. Rapid deposition of magnesium ammonium
phosphate on slurry box effluent orifices and transmission line entailed
frequent cleaning. Substitution of the effluent pipe with an open trough,
facilitated cleaning without interruption of operation.
Completion of Reaction and Solids Conditioning—The 30-50 minute
gentle but near complete mixing in the 1200 gal (4.6 cu m) reactor tank,
by air agitation, completed precipitation and solids conditioning, optimal-
ly at pH 9.0, with no further objectionable scaling or solids deposition.
At higher pH levels there was excessive precipitation of non-phosphate
solids, with hard scaling of transmission line. Transmission of the
reactor mixed liquor—3500-5000mg/l solids—through 2-inch and 2^-inch
plastic pipe was without impairment to settling and draining of the solids.
Drain Bed Dewaterinfc—Subsidence and draining on a 42 x 44 ft (14 x
15 m) section of sand drain beds were rapid. For prolonged runs, when
influent rate exceeded draining rate, the clear supernatant overflowed to
an adjacent section for draining, with essentially no accumulation of
solids. Final draining, cracking and drying to a readily removable cake,
20-40% moisture, was fully as rapid and effective as for digested sludge
from a mixture of primary and activated sludge solids.
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Solids Production—Under best experiential operation—precipitation
of 97% of 249 mg/1 phosphorus—solids production per pound of phosphorus
removed was 0.15 cu ft of sludge cake of 60% solids content, and 15.3
Ibs (7 kg) of dry weight solids (Column 6, Table IV). These values
would probably be reduced by about 20% for precipitation of phosphorus
from liquors containing as much as 500 mg/1. It is estimated for a
1 MGD operation with 80-85% removal and disposal of phosphorus, three
drain bed sections of about 50 x 50 ft, totaling 7500 sq ft (67.5 sq m)
would afford adequate drain bed capacity.
Solids Utilization—The solids contained 4-5% fertilizer available
phosphorus. Best utilization was for spreading on acid soils deficient
in phosphorus.
Precipitation with Iron and Aluminum
Effectiveness and Chemical Costs—In the limited plant-scale tests
on digester liquor containing less than 100 mg/1 of phosphorus,mol doses
of 1.3/1 to 1.5/1 Fe/P or Al/P, were required to reduce phosphorus to
below 10 mg/1. In bench-scale tests on liquor fortified to 350 mg/1
phosphorus, mol doses of 1.3/1 to 1.5/1 also reduced phosphorus to below
10 mg/1, but only with the addition of about 1/1 mol dose of lime to hold end-
point pH at 4.5-5.0 for .iron and 5-5.5 for the aluminum dose. This entailed
weight ratio doses of about 2.5/1, 1.2/1 and 2.5, Fe/P, Al/P and lime/P
respectively. The market value for the "by-product" ferric chloride and
aluminum chloride was $0.10 and $0.10 per Ib of Fe(III) and Al(III)
respectively. The market value for lime was $.015/lb. Therefore, the
indicated chemical cost for each Ib of phosphorus removed was $0.29 for
use of aluminum. Thus, the use of iron or aluminum would not be competitive
with the use of lime. But, again, applicatory considerations hinge on
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overall feasibility and costs of processes.
Chemical Feeding, Flocculation and Dewatering—Equipment and labor
costs for feeding iron or aluminum are significantly less than for lime.
Costs of facilities and operation for flocculation and solids conditioning
would be essentially the same. Dewatering of the ferri- and alumina-
phosphate sludges, as for lime-phosphate solids, can be effectively
dewatered by subsidence, decanting and draining on .sand drain beds.
But the order of drain bed requirements would be about 3:2:1 for the
alumina-, ferri- and lime-phosphate solids respectively.
Dry Solids Production and Utilization—The final dry solids produc-
tion for alumina-, ferri-,and lime-phospnate solids would be in the
order of about 2:3:6. Best utilization of the alumina- and ferri-
phosphate solids would be for spreading on phosphorus deficient soil.
REMOVAL AND DISPOSAL OF PHOSPHORUS
BY USE OF IRON
Demonstration, objectives were to obtain guiding information on effective-
ness and economic feasibility of the use of iron in an activated sludge
plant for removal and disposal of phosphorus, i.e., applicable answers
to the following questions. Which is the better form of iron to use?
Ferrous (Fe II) or ferric (Fe III)? Should dosage be to the raw, or to the
aeration influent? How critical are the needs for quick mix of chemicals,
and for rigidly proportional feeding? How different are control and index
parameters for equivalent or better removal of COD, suspended solids and
nitrogen? What are the dosage requirements for removal and disposal of
80-90% of plant phosphorus loads? Over what range of influent phosphorus
concentrations? Does the iron hold the removed phosphorus with the solids
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through digestion, thereby obviating the need for reprecipitating the
phosphorus from digester liquor? What about the increased solids pro-
duction and dis.posal problems? What are chemical and overall costs?
Fe(II) to Raw at Single-Level Diurnal Rates;
Effective and Most Feasible
Dosage of Fe(II) to the raw influent at single-level diurnal rates
was quite efficient, and the most feasible mode of treatment at the
Texas City #2 plant, and probably would be for many similar plants. Consis-
tently, through-plant removal of phosphorus was more effective than by
equivalent dosing of Fe(III) to raw influent or to primary effluent, but
only marginally more effective than equivalent dosing of Fe(II) to primary
effluent (Tables VI-VIII).
Fe(II) vs. Fe(III); To Raw vs. to Primary Effluent—The lesser dosage
efficiency of Fe(III) was attributed principally to the very slow mix with
raw influent and to an inadequate quick mix when injection was to the primary
effluent. Hydrolysis of Fe(III) was extensive before homogeneity was attained,
thereby, even when dosage was proportional to influent phosphorus load,
resulting in formation of hydrolytic products low in phosphorus content.
Whereas for Fe(II), even with slow mix, homogeneity was insured before
appreciable oxidation, hydrolysis, phosphate uptake, and flocculation had
occurred. These proceeded in close sequence in the short length aeration
tanks, wherein high rate of sludge return and the near complete mix from
turbulent aeration had leveled out fluctuations of phosphorus concentration
of the plant flow. Thus, the need for proportional feeding was reduced.
Injection of Fe(II) to raw influent at two-level diurnal dosage rate
showed only slightly increased dosage efficiency over single-level rates
(Tables V and VIII, Ferrous to Raw Influent). A further advantage of using
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ferrous iron is that it can be supplied at lower cost. Additional
advantages of dosing to raw influent, Fe(II) or Fe(III), include:
first, sulfide is tied up in non-volatile form, reducing odor nuisance;
second, insolubilization of phosphorus in any by-pass portion is insured; and
third, daily phosphorus loads in the total flow can be estimated more closely
than the loads in the through-plant portion of flow.
Reactions through Primaries—Injection of Fe(II) to the raw influent
effected essentially no removal of phosphorus across primaries, and very
little, if any, increased removal of solids and COD (Table VII, Columns
8-13. Note; the indicated negative removal of solids was due to delayed
precipitation in samples between time of collection and assay). There
was immediate evidence of formation of colloidal to visible precipitate,
increasing through primaries, but at average to high flow, not to a
settleable form or quantity for appreciable removal of phosphorus. The
high alkalinity of the raw influent, 400-500 mg/1 at dry weather flow,
held pH within a range of 7.0-7.5, evidently non-optimal for precipitation
and flocculation of ferrous phosphate. At diurnal periods of very low flow,
and at times of oxygen-car tying water from infiltration, there was some
oxidation to Fe(III) with accompanying and somewhat proportional precipitation
and flocculation, but not enough settling to result in major removal of
phosphorus.
In contrast to injecting Fe(II) to raw influent, equivalent dosing of
Fe(III) resulted in considerably more settling of iron, and some more of
phosphorus, across primaries, but less through-plant removal of phosphorus.
At diurnal periods of low flow and concurrent low influent phosphorus con-
centration, precipitation and settling of iron and phosphorus approached
completion. Thus, at single-level dosing rate, there was settling and re-
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moval of iron carrying much less than its stoichiometric share of phosphorus.
This loss of excess iron to primary solids was sufficient to account for much
of the lower through-plant removal when dosing of Fe(III) was to the raw
influent.
Wasting of high ferrl-phosphate aeration solids to the primaries had
little effect on primary processes other than to thicken solids to a
uniform consistency for convenient scheduling of pumping of sludge to the
digester. The mass of the waste solids settled rapidly, with marginally
measurable reduction in soluble phosphorus. But partial deflocculation
resulted in carry-through of some of the high-phosphorus solids, often
registering a net increase of phosphorus through primaries.
Fe(II) to Raw Influent: Parameters near Optimal for Removal of
Phosphorus through Aeration—Bringing of almost the total iron dosage, still
as Fe(II), homogeneously mixed in primary effluent, then in the return sludge,
was favorable for high uptake of phosphorus, even at single-level dosage
rates. The near complete mix in the tanks dispersed the dosage before
the sequential oxidation, hydrolysis, phosphorus uptake and flocculation
were complete. Also, the complete mix plus high volume sludge return
leveled out variations in phosphorus concentration, affording approach to
proportional feeding. Thus, each newly formed ferric particulate, capable
of absorbing phosphorus, was afforded maximum opportunity of attaining its
stoichiometric requirement from available phosphate ions—whether by ion
combination (12), by physical adsorption (30), or by complexation of
hydrolytic products (35). The high rate of sludge return and maintaining
aeration solids at high level (2000-4000 mg/1), extended the contact
opportunity by the mass of high iron solids, through a net retention of 4-8
days. It was not possible to demonstrate precisely the extent of this con-
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tinued uptake. But the around-the-clock uniformly low level effluent
phosphorus was evidence that continued absorption of phosphorus was
appreciable (Figures 10-12).
The oxidation of Fe(II) to Fe(III) imposed no burden on air supply
(only 1 Ib of oxygen for 7 Ibs of iron). It was possible to hold DO in
aeration effluent near 1 mg/1, a level favorable for removal of COD and
suspended solids, also evidently favorable for precipitation and floc-
culation of phosphate solids (Table VII, Columns 8-13; Aeration Solids, TSS
and COD).
There was no way for discerning how much of the phosphorus uptake was
biological precipitation. It was assumed that it was no greater than the
10-15% in demonstrations with no added cations immediately preceeding and
following periods with use of iron (Tables II and III). But the augmentative
doses of iron for 80-90% removal of phosphorus were no greater than would
have been required to hold biologically released phosphorus with the digester
solids.
Flocculation and sedimentation of aeration solids were highly effective
as evidenced by the low SVI values, low effluent solids and COD, and by the
observed sparkling clarity of the effluent (Tables V-VII; Figure 9). Even
the high degree of denitrification was not inhibitory to the removal of the
high ferri-phosphate solids (Table V-VII, Nitrogen and TSS). The effective
flocculation and the heavy solids minimized the floating and carry-through
by evolving nitrogen.
The aeration effluent pH range of 7.3-7.6 evidently was favorable to
precipitation and flocculation of ferri-phosphate solids. The range was well
above 5.3, pointed to by Stumm (16, 25) as the pH of minimum solubility of
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phosphorus in equilibrium with ferric phosphate; above 6.0-7.0 observed
by Tenney, et.al.,(40) as the range for rapid formation of Fe(III)
hydrolytic products favorable for flocculation and conditioning of act-
ivated sludge: and well below 8.8, demonstrated by Wuhrman (24) as favor-
able for removal of phosphorus from secondary effluents by Fe(III), using
lime for pH adjustment. But within the experiential range of 7.3-7.6,
80-90% removal and disposal of phosphorus was effected, by mol doses of
1.3/1 to 1.6/1, Fe(II)/P, injected into the raw influent at around-the-
clock single level dosage rates.
Effective Doses; for 80-90%
Removal, 1.3/1 to 1.6/1. Fe(II)/P
Demonstration results indicated that a certain per cent removal
of the influent phosphorus load could be expected from a given mol
dose of ferrous iron, somewhat independent of the influent phosphorus
concentration, and through considerable variations in levels of
other parameters. Precise demonstration of this, on a day to day
basis, was not possible, since daily and diurnal variations in
flow and phosphorus load precluded prediction and application of
exact mol doses. Also, the daily dose effects, due to the 8- to 12-
hour flow-through period, were not reflected in the analyses of
24-hour composite samples. But averages of daily values for periods
of at least three days, when maxima and minima were not extremely
variant from the means of the periods, pointed significantly to the
effectiveness of specific mol dose. The selection of the demonstration
periods of Tables VI-VIII was on this basis. It is believed that
results were close to what would have been, had the average mol dose
of a respective period been applied each day of the period.
As a test of correlation of doses of ferrous iron with phoshorus
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removal, 3-day moving averages of applied mol doses (AMR, Fe/P)
were plotted against respective 3-day moving averages of percent
removal of phosphorus, for 75 days of dosing of Fe(II) (Figure 13a).
These included one-level and two-level dosing rates to raw influent,
but only one-level rates to primary effluent. Days were not included
when influent phosphorus dropped below 3mg/l, ie, at times of
extremely high infiltration when flow measurement and proportional
sampling became non-reliable (Table V). Also May 3, was excluded
because it was non-representative of controllable operation. Non-
attention permitted through-plant flow to rise to 1.5-1.6 MGD for
3 hours, about .3 MGD higher than could be tolerated without
excessive loss of solids to effluent. (Table V and Figure 9:
note effluent solids, TSS=141 mg/1; effluent P=8.3mg/l; and effluent
COD=108mg/l).
Effects of mol doses, AMR, were not linear, but closely so,
through the range of 1.0/1 to 1.6/1, Fe/P. The curve of linear best
fit presented in Figure 13a is for the equation, y=50.55+22.32X;
correlation coeffecient, +0.6975, significant at 1% level.
Limited observations at mol doses above 1.5/1, Fe/P, indicated
decreasing efficiency with increasing doses. This appreared to be
a limitation of insolubility rather than of flocculation and
settling. Thus, for removal of as much as 95% of phosphorus load,
adjustment of pH toward a level of lesser solubility might be
required, ie, toward 5.3, the pH of minimum solubility of phosphorus
in equilibrium with solid ferric phosphate (16, 25). Then, if
solid separation is not adequate for reducing effluent phosphorus
to a desired low level, eg, less than 0.5mg/l, the use of a
coagulant aid and/or effluent filtration would be indicated.
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Again, by inspection of over-all results, plus consideration
of the above test of correlation of AMR values with % removal, a
significant observation was that mol doses of ferrous iron of
1*3/1 to 1.6/1, somewhat independent of influent phosphorus consen-
tration, effected 80 to 90% removal of the influent phosphorus
load. This was sharply true for AMR values of 1.4/1 to 1.6/1,
within a. phosphorus range 4.9-9. 4mg/l.
Of the 73, 3-day moving averages of AMR values, 21 were in
the range of 1.40/1 to 1.60/1; average 1.50/1. The range of the
respective values for % removal of phosphorus was 80.3-90.3;
average, 85%. The influent phosphorus range was 4.9-904mg/l;
average, 7.3mg/l; median, 7.3mg/l. Therefore, for an influent
phosphorus range of 5-10mg/l, 85% removal of the phosphorus load
could be expected when a mol dose of 1.5/1, Fe(II)/P was applied.
Opportunity was not afforded for using ferrous iron at times
of low dry weather flow when influent phosphorus was as high as
12-14mg/l. Comparison of results (Table VII, Columns 8-13; Table
VIII, Ferrous to Raw Influent) at lower influent phosphorus, 4.5-
6.5mg/l, with results at levels of 7.5-9.5mg/l, indicate that only
slightly lower dosage efficiency might be expected at still higher
influent phosphorus levels.
Sludge Production, Digestion and Dewatering
Increased solids production by use of iron, in the activated
sludge process was close to the estimated production of hydrolytic and
phospho-products (Table XIII). Volume production was about 10% less
than with no cationic treatment. There was no significant indication
of change in production of organic solids. Digestion retention
time was reduced by about 25%, but digestion was rapid and effective.
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Compaction of solids in digestion was about the same as for digestion of
normal primary plus activated sludge, ie, to 5-6% dry weight solids. Drain-
ing, cracking and drying of the digested sludge on the drain beds, were
fully as rapid and effective as for digested solids from primary plus
activated sludge. The dry solids were appreciably more friable.
Digester and drain bed capacity was about 70% over conventional
design. This was evidently adequate for digesting and dewatering of the
high phosphate high iron solids.
Chemical and Overall Costs
On the basis of 85% removal of a 10mg/l phosphorus load in 1 MG(3790 c m)
of wastewater, by a 1..5/1 mol dose of iron, Fe(II)/P, and $0.10/lb for iron
the chemical cost was $032/lb of phosphorus removed; $22050/MGD; $225000/day
for a 10 MGD plant. Chemical costs constitute almost the total costs,
therefore from region to region the costs for iron treatment would be almost
directly proportional to delivered cost of iron.
For the design, procurement and installation at a local (Houston area)
1 MGD plant, of a 4000 gallon (15.1 cu m) rubber lined steel tank, a
double-head chemical metering pump, plus necessary piping the cost was $7000o
For a 20-year amortization, plus maximum expected repair and maintenance
the additional costs would not exceed $2050/MGD, thereby totaling about
$25/MG at a 1 MGD plant for chemical and equipment costs.
"Iron-handling" entails additional through-plant housekeeping and
maintenance but the over-all "ironing-out" of control of treatment process
compensates for the additional operational costs, including the disposal
of an additional 20-30% digested solids.
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REMOVAL AND DISPOSAL OF PHOSPHORUS
BY USE OF ALUMINUM CHLORIDE
To Raw Influent
Demonstrations were at only three incremental dose levels,
with injection to the raw influent: 1.25/1 and 2.04/1, Al/P at
single-level diurnal rates and 1.79/1 at two-level rates; effecting
68%, 69% and 74% removal of phosphorus; and 70%, 71% and 77%
insolubilization, respectively (Table XII, also X and XI).
It was readily evident that more rapid mix and more rigidly
proportional doseage would be required for greater dosage efficiency.
Hydrolysis was considerable before homogeneity was attained„
Flocculation was in evidence in the primary influent0 At diurnal
low flow, precipitation of aluminum and phosphate was near complete
across primaries, and flocculation and sedimentation, extensive„
Thus, during the 2- to 6- hour low flow low phosphorus periods
most of the phosphorus was removed with primary solids, but there
was excessive loss of hydrolyzed aluminum, carrying less than its
stoichiometric capacity of phosphorusi Dtiring the longer diurnal
periods of higher flow, controlled at near uniform rate, almost
the total of the dose of aluminum was carried through primaries, with
precipitation and flocculation still in progress.
Reactions were complete and flocculation effective in aeration
(Table X: note effluent total and soluble and TSS values).
But total removal of phosphorus did not reach even an 80% level,
attributable to loss in primaries of hydrolyed aluminum iow
in phosphorus content, which in turn was attributable to slow mix
and non-proportional dosing.
Aluminum to Primary Effluent
Dosage efficiency was better with injection into primary effluent.
But dosing at 2-level diurnal rates was only slightly more efficient
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than at single-level rates. The three incremental doses at
2-level rates, 1.65/1, 2.02/1 and 2.41/1, Al/P, effected 81%,
82% and 80% removal of phosphorus, and 84%, 87% and 92% insolubili-
zation, respectively (Tables X-XII, Sept. 9-23). Two incremental
doses, at single-level rates, 2.20/1 and 2041/1, removed 82% and
80% of phosphorus, and insolubilized 92% and 92% (Tables X-XII; Oct.
2-6 and Sept. 24-Oct. 1)= Thus, it was noted that an upper limit
of about 80% removal was reached at doses of 1.6 /I, 1.8/1, Al/P,
and an upper limit of about 90% insolubilization, at doses of
2.0/1, to 2.2/1.
Earth and Ettinger (34) attained 95% removal of 12mg/l
phosphorus by a 1/1 mol dose of sodium aluminate, added to aeration
liquor, with a resultant pH level of 7.2-7,5. This high dosage
efficiency was attributable to at least 40% of the uptake
being biological precipitation, to rigidly proportional dosing,
and to the aeration pH level being near optimum. Eberhardt and
NesKtt (33) removed 93% of 13.8mg/l of phosphorus, by a 1.9/1
mol dose of aluminum sulfate, added to aeration liquor with resultant
pH of 505; near 5.0, the level pointed to by Stumm (25) for minimum
solubility of aluminum phosphate. Wukasch (29) increased phosphorus
removal by Fe(II) through primaries, by use of polyelectrolyte coagulant
aid. Therefore, for increased dosage efficiency for Al(III) at the
Texas City plant No. 2, the following were indicated: greater
biological precipitation, more rigid proportional dosing, raising of
pH for improved flocculation, lowering of pH for reduced solubility
of aluminum phosphate and improved flocculation, filtering of
effluent for removal of alumina-phosphate solids, and/or better
flocculation and settling,, Opportunity was afforded only for
the last.
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There was no evidence that biological uptake of phosphorus
could have been increased above the 10-15% removal experienced
immediately before and after the demonstration of the use of aluminum.
The mix of the dosage in the confluent stream of primary
effluent and return sludge was not sufficiently rapid to prevent
considerable hydrolysis of aluminum before homogeneity was attained;
in effect, reducing proportional dosing, and thereby indicating
need for quicker mix. The slightly greater efficiency of 2-level
diurnal feeding rate over single level rates, indicated that
appreciably greater dosage efficiency would have been experienced
with rigidly proportional dosing.
Insolubilization of phosphorus increased with increasing doses
above about 1.7/1, Al/P, but poorer flocculation and settling prevented
increased removal above the 80-82% level (Table X-XII; note effluent
total and soluble P and TSS; also EMR values). The lower aeration
pH, 7o0-7.3 at the higher doses as compared to 7.2-7«5 at lower
doses, may have been sufficient to have accounted for the poorer
flocculation and settling. Laboratory filtration tests indicated
that sand filtration would reduce effluent suspended solids and
phosphorus sufficiently to augment phosphorus removal to 90% at
mol doses of 2/1, A1/P0
Bench-scale tests plus the 4-day plant-scale demonstration
of dosing a polyelectrolyte to aeration effluent indicated that
removal of phosphorus could be augmented to 90% from a mol dose of
aluminum as low as 2.2/1 (Tables X-XII, Oct0 7-10). The effective
dose of coagulant aid was lmg/1, based on plant influent flow, or
about ^smg/l based aeration effluent flow rate0
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Sludge Production, Digestion and Dewaterinfi
At the mol dose of 1.65/1, Al/P for 81% removal of phosphorus,
the daily volume of sludge pumped to the digester was about 20%
greater than for camparable operation with no cations added to
primary or aeration processes. The total weight of solids was about
50 % greater (Table XIII). During the 57 days of operation with
added aluminum, the average mol dose was about 202/1, approximately
the dose that would have effected 90% removal with the aid of a
polyelectrolyte coagulant. The weight of sludge at this average
202/1 mol dose was proportionately greater than at the 1.65/1
mol dose, but the volume production was only slightly greater.
Digestion proceeded rapidly in the digester but the residual
sludge failed to compact to more than about 2.5% solids, dry weight
basis (Figure 18). Therefore, retention time was reduced by about
50%, entailing the drawing of "green" sludge. Digestion proceeded
on the drying beds, with no odor nuisance, and with completion in about
15 days. The on-bed digestion with gas evolution left a final sludge
mass that drained, cracked and dried effectively, and was readily
removable and quite friable
The digester and drain beds were about 70% over-size of conven-
tional design capacity., It is estimated that an additional 100%
over-size would be required for digesting and dewatering such a
high alumina-phosphate sludge0
Chemical and Processing Cost
The market price of the aluminum chloride solution used was
$0.075/lb of Al, FOB Texas City, 0.10/lb delivered to most points
in the area» For 80% removal of 10mg/l phosphorus in IMG of waste
water, the chemical cost would be $.85 /lb of phosphorus removed;
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$12.30/MGD. The costs for chemical storage and feeding facilities,
including procurement, installation, repair and amortization
would be of the same order as for the use of Fe(II) or Fe(III), is
about $2.50 for a 1 MGD operation. The total costs for chemicals
plus storage and feeding facilities would be about $15/day for a 1 MGD
plant.
For 90% removal of 10mg/l phosphorus load by a 2.2/1 mol dose
of aluminum plus lmg/1 of a coagulant aid, the chemical costs plus
chemical storage and dosing facilities would be in the order of
$38/day for 1 MGD operation.
The requirements for additional digesting and solids de-
watering facilities are not closely enough known for determination
of these additional costs.
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SUMMARY AND CONCLUSIONS
In a 0.7 MGD activated sludge plant, demonstration studies were
made of effectiveness and feasibility of biological, chemical and
physical processes for removal and disposal of phosphorus.
BIOLOGICALLY RELEASED PHOSPHORUS
REPRECIPITATED FROM DIGESTER LIQUOR
To recover, and to prevent its recycle to plant processes,
released phosphorus in digester liquor was chemically precipitated,
dewatered on sand beds and spread on soil deficient in phosphorus.
Concurrent with this practice, 25-60% biological uptake of
phosphorus by activated sludge was experienced, producing waste
aeration solids containing 2.5 to 4.5% phosphorus. Anaerobic
digestion of these solids released 100-260 mg/1 of phosphorus to
digester liquor. At these levels, precipitation and recovery by use
of lime, Fe(III) or Al(III) was operationally and economically feasible.
For levels above about 150 mg/1 and based on comparative volumes
of sludge produced, dewaterability of the solids, and chemical costs,
the precipitants of choice, in order, were: hydrated lime, Fe (III)
and Al(III).
In a 12-day period phosphorus content of waste solids was 2.0-3.5%
Through-plant removal of phosphorus was 41%. Soluble phosphorus
digester liquor reached 249mg/l. Lime dosage of the liquor to pH 9.0,
requiring 7.3 Ibs of lime per Ib of phosphorus precipitated, reduced
phosphorus content of the liquor to 7mg/l, at a chemical cost of $0.12/lb
of phosphorus removed. Thus, when biological uptake by aeration solids
was 41% of 10mg/l phosphorus, the indicated chemical cost was $4.10/MGD.
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BIOLOGICAL REMOVAL OF PHOSPHORUS
BY ACTIVATED SLUDGE
As a premise for effective removal of phosphorus by activated sludge
it was recognized that phosphorus content of aeration solids would
have to be well above 1.5%, a level required for cell reproduction, and
that net building of cell solids would have to be high, eg, for 90%
removal of a 10mg/l phosphorus load, 5% phosphorus content and net
solids building of 180mg/l.
Through a first series of observations, totalling 158 days,
phosphorus content of aeration solids regressed from a high of 5% to
a low of 1.6%, with a periodic recovery to 3-3.5%. Net solids
building average less than 100mg/l, but through several 3-day periods
reached 130-170mg/l. Phosphorus removal regressed from about 50%
to a 3-day average of about 15%, but in two 3-day periods averaged
60-70%, also in one 3-day period fell to zero.
In a second series of observations, totalling 73 days, phosphorus
content of cell solids never exceeded 1.8%; net solids building
averaged about 100mg/l, with peak 3-day averages of 140-150mg/l; and
average phosphorus removal was 13%, with 3-day averages ranging from
-4% to 17%.
In the first series of observations (158 days), operation control
and lack of control, were characterized as follows. With the exception
of one month there was moderate to heavy rainfall, with proportional
infiltration, extended through the period. Primary clarifiers
were out of service through the first 106 days. Through-plant flow and
loadings experimentally, then, unavoidably, were limited to 70-90%
of total. Air application and solids management were for effective
removal of COD and suspended solids, for minimum anoxic release of phos-
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phorus, enrichment of solids, and except for the last 30 days, without
excessive aerobic digestion and nitrification. In addition to
regular diurnal and day-to-day variations in flow and loadings, there
were irregular extremes from infiltration. As compared with "plug
flow" the flow-through aeration pattern was near complete mix.
In the second series of observations, (73 days) low dry weather
flow prevailed. Total flow and loading were accepted. At the low dry
weather flow, diurnal variations in flow and COD loadings were
sharper. In proportion to flow, a higher inventory of aeration solids
was maintained. Air application was held at maximum capacity. Aerobic
digestion of solids, and nitrification, were extensive. Complete mix
in aeration was intensified by the lower flow, by a higher rate of
sludge return, and by the more turbulent mix of high rate air
application.
The inability to maintain high phosphorus enrichment of aeration
solids and high net building of solids, and thereby, high removal of
phosphorus, was attributed to complete mix aeration, to frequent and
variations in COD and phosphorus loadings, and to extensive aerobic
digestion of cell solids. Before log growth of cells and subtrate
utilization could be brought to near completion, and aeration extended
into nutrient imbalance of declining growth_conditions favorable to
biological enrichment of cell solids— a fresh supply of nutrients, con-
tinually and in slugs, entered the complete mix system. The new supply
not only reestablished log growth cell building, but also promoted
release of phosphorus enrichment from old cells. Then, the extended
intensive aeration of a high inventory of cell solids, promoted
digestive release of phosphorus and reduced the population of cells
capable of phosphorus enrichment.
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It was therefore concluded that in small activated sludge
plants such as Texas City #2, with complete mix aeration and wide and
sharp variations in COD and phosphorus loadings, high level phosphorus re-
moval cannot be maintained.
PHOSPHORUS AND MAGNESIUM
CO-ENRICHMENT OF AERATION SOLIDS
Assay of phosphorus, magnesium and calcium content of aeration solids
was made through extended periods when there was phosphorus enrichment;
also, when limited doses of lime produced increased calcium content of
the activated sludge but no increased phosphorus or magnesium content. It
was observed that for each mol of phosphorus enrichment above the 1.5%
level, there was uptake of about 1/3 mol of magnesium, but no increased uptake
of calcium. The results of these observations are considered as evidence of
biological phosphorus and magnesium co-enrichment of activated sludge solids.
FERRIC AND FERROUS IRON
TO PRIMARY EFFLUENT AND TO RAW INFLUENT
Demonstration objectives were to determine mol dose requirements,
Fe/P, of Fe (III) and Fe(II), to primary effluent and to raw influent,
for attaining 80-90% removal of phosphorus. Injections of Fe(III)
to primary effluent was for 38 days, and to raw influent for 33 days; of
Fe(II) to primary effluent for 33 days, and to raw influent for 49 days.
Dosing, diurnally, was at single-level rates, except at two-level rates
for 6 days of Fe(II) to primary effluent, and 10 days to raw influent.
Dosage efficiency for Fe(II) was better than for Fe(III), into primary
effluent or into raw influent. Dosing of Fe(II) to raw influent was
more efficient than to primary effluent. Dosing of Fe(II) to raw influent
two-level diurnal rates was slightly more efficient than by single-level
rates. Injection into the total flow of raw influent insured insolubilization
of phosphorus in by-pass flow at times of heavy infiltration; tied up
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sulfides into non-volatile form; and, along with feeding at around-the-
clock uniform rates, facilitated estimating and applying required daily doses.
Therefore, the demonstrated effective and most feasible process
was by dosing Fe(II) to raw influent at constant level diurnal rates.
Mol doses of 1.5/1, Fe/P, dependably removed 85% of the influent
phosphorus load. Through 44 days of such operation with daily phosphorus
at 4 to 10mg/l, averaging 7mg/l, doses of 1.3/1 to 1.6/1, averaging 1,5/1,
removed 83 to 88%, averaging 86%, reducing effluent phosphorus to l.Omg/1.
Effluent suspended solids averaged 7mg/l, for across-plant reduction of
95%; effluent COD, 29mg/l, for 85% reduction.
Influent mix of dosage was slow, but homogeneity was attained before
there was appreciable hydrolysis or phosphate precipitation of Fe(II), or
oxidation to Fe(III) and hydrolytic precipitation of ferric phosphate.
Removal across primaries by precipitation of ferrous or ferric phosphate,
was small. Most of the dosage reached the aeration units as Fe(II),
homogeneously mixed with return sludge, for sequential but rapid oxidation
to Fe(III), hydrolytic precipitation of ferric phosphate, and effective
flocculation with the activated sludge.
Increased sludge production was demonstrably close to the estimated
amount from ferri-hydrolytic phosphate precipitation. The combined
volume of waste and primary sludge was 10-15% less than when no cations
were added. The high ferri-phosphate sludge digested effectively in the
70% over-capacity digester. The iron was reduced to the ferrous state,
but over 95% of the phosphorus remained with the ferro-sludge. Drainbed
draining, cracking, drying and removing of the digested solids were
fully as rapid and effective as for digested solids from conventional primary
plus activated sludge.
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For 85% removal of phosphorus by a 1.5/1 mol dose of Fe(II),
at $0.10/lb for iron, the chemical cost was $0.32/lb of phosphorus re-
moved. For influent phosphorus at 10mg/l this would amount to
$22.50/day for a 1 MGD operation. For a 1 MGD plant in the Texas City-
Houston area, the estimated additional costs for the chemical storage
and dosing facilities, including design and installation plus 20-year
maintenance and debt amortization, would be $2.50/day.
ALUMINUM CHLORIDE TO RAW INFLUENT
AND TO PRIMARY EFFLUENT
Incremental doses of aluminum chloride of 1.3/1 and 2.0/1 Al/P,
to raw influent at single level diurnal rates, effected 68% and
69% removal of phosphorus. A dosage of 1.8/1, at two-level rates,
effected 74% removal. The high rate of hydrolytic precipitation during
slow mix, and continuing precipitation at non-proportional dosing,
particularly during low flow, resulted in appreciable loss of the dosage,
carrying less than its stoichiometric capacity of phosphate. From
these limited observations it was concluded that very rapid mix at
rigidly proportional dosing would be required for efficient use of
aluminum, when injection was into the raw influent.
Dosage efficiency was better with injection into primary effluent,
with slightly better efficiency at two-level than at single level rates.
But an upper limit of about 80% removal was reached at doses of 1.6/1 to
1.8/1, Al/P, and an upper limit of about 90% insolubilization of the
phosphorus load, at doses of 2.0/1 to 2.2/1.
For more efficient use of aluminum chloride at the Texas City
Plant No. 2, the following were indicated: more rapid mix of the dosage;
more rigidly proportional feeding; raising of pH for improved
flocculation; lowering of pH toward the level of least solubility of
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aluminum phosphate; filtration of the plant effluent; and/or using
a coagulant aid for better flocculation and settling. Only the last
process was verified.
Increased solids production was close to the estimated amount from
the alumina-hydrolytic phosphate precipitation. The combined volume of
waste and primary sludge was about 20% greater than when no cations were
added.
Sludge digestion was rapid but compaction was poor, thereby
limiting digestion time. Sludge drawings were "green," but on-bed
digestion was complete in about 15 days, without odor nuisance.
Final draining, cracking and drying were effective to a readily remove-
able and friable cake. It is estimated that the digestion and/or
drain bed facilities would have to be increased by about 100% (170% over
conventional design capacity), for effective digestion and drying of
the high alumina-phosphate sludge.
At $0.10/lb for contained aluminum in the aluminum chloride,
the estimated chemical cost for 80% removal of 10mg/l phosphorus would
be about $10/day for 1 MGD operation. Adding a $2.5/day cost for
procurring and maintaining chemical storage and feeding facilities, the
costs for chemical precipitation of phosphorus at an 80% removal
level by use of this low cost aluminum chloride would be about $12.50/MGD.
Sufficient experience was not obtained for estimating the cost of
providing and operating the additional digester and drain bed facilities.
For 90% removal of 10mg/l phosphorus by a 2.2/1 mol dose Al/P
of aluminum chloride, plus lmg/1 of a polyelectrolyte coagulant aid,
the cost for chemicals plus costs for procurement, maintenance and
debt amortization for storage and feeding facilities, would amount to
about $38/day for a 1 MGD operation.
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ACKNOWLEDGMENTS
This project was financially supported by grants from the Water
Quality Office, Environmental Protection Agency; the Soap and Detergent
Association; and the Galgon Corporation.
The city of Texas City made available their wastewater treatment
plant No. 2, with its operating personnel.
The Monsanto Company (Texas City Plant) supplied a glass-lined tank
and all of the aluminum chloride used in the project.
iS
Chemlime Corporation of La Porte, Texas supplied the waste
pickle liquor.
The National Lime Association, Texas Division, and the Round Rock
Lime Company, supplied the hydrated lime.
Johns-Manville furnished plastic pipe and fittings.
Dr. M. S. Rao of the UTMB faculty made the statistical studies
and analyses.
Mr. E. F. Earth was the Project Officer for the Water Quality Office,
Environmental Protection Agency.
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Presented at the Pacific Northwest Section Meeting of the Water Pollution
Control Federation at Yakima, Washington, October, 1967.
22. Owen, R. "Removal of Phosphorus from Sewage Plant Effluent with Lime,"
Sewage and Industrial Wastes, Z5(5):548, May, 1953.
23. Malhorta, S.K., Lee, G.F., and Rohlich, G.A. "Nutrient Removal from
Secondary Effluent by Alum Flocculation and Lime Precipitation,"
Intl. Journ. Air Water Poll. (Brit.), S/.487 (1964).
24. Wuhrman, K. "Stickstoff und Phosphor-elimination; Ergebuisse von
Versuchung in Technischen Massstab," Schweiz. Z. Hydrol., J26_:520-558, 1964.
25. Stumm, W. "Chemical Elimination of Phosphates as a Third Stage Sewage
Treatment," A Discussion. Int. Conf. Water Poll. Research, London,
Vol. II, Pergamon Press, New York, 216-230, 1964.
26. Johnson, W.H. "Treatment of Sewage Plant Effluent for Industrial Reuse,"
International Water Conference of the Engineers Society of Western
Pennsylvania, September, 1964, pp. 73-86.
27. Curry, J.J. and Wilson, S.L. "Effect of Sewage-borne Phosphorus on Algae,"
Sewage and Industrial Wastes, 27:1262-1266.
28. Neil, J.H. "Problems and Control of Unnatural Fertilization of Lake
Waters," Proc. 12th Ind. Wastes Conf. 94:301-316.
87
-------
29. Wukasch, R. F. "The Dow Process for Phosphorus Removal," Paper presented
at the FWPCA Phosphorus Removal Symposium, Chicago, June, 1968.
30. Lea, W.L., Rohlich, G.A. and Katz, W.J. "Removal of Phosphates from
Treated Sewage," Sewage and Industrial Wastes, ^6_(3):261, March, 1954.
31. Culp, G. and Slechta, A. "Nitrogen Removal from Waste Effluents,"
Public Works, February, 1966.
32. Thomas, E.A. "Process fdr Removal of Phosphates from Sewage," Swiss
Patent No. 361543, April, 1962, Chemical Abstracts, 5_8:1237 b , 1963.
33. Eberhardt, W.A. and Nesbitt, J.B. "Chemical Precipitation of Phosphate
Within a High Rate Bio-Oxidation System," Presented at 22nd Annual Purdue
Industrial Waste Conference, Lafayette, Indiana, May, 1967.
34. Earth, E.F. and Ettinger, M.B. "Mineral Controlled Phosphorus Removal
in the Activated Sludge Process," Journ. Water Poll. Control Fed.,
39(8):1362, August, 1967.
35. Singley, J.E. and Black, A.P. "Hydrolysis Products of Iron III," Journ.
Am. Water Works Assoc., 59(12):1549, December, 1967.
36. Davenport, W.H. "Spectrophotometric Method for Aluminum in Presence of
Iron by Complexation with Ferron," Analytical Chemistry, 21(6);710,
June, 1949.
37. American Public Health Association, Inc. "Standard Methods for the
Examination of Water and Wastewater," 12th ed., 1965.
38. Wells, W.N. "Differences in Phosphate Uptake Rates Exhibited by
Activated Sludges," Journ. Water Poll. Control Fed., ^1(5):765, May, 1969.
39. Borchardt, A.J. and Azad, H.S. "Biological Extraction of Nutrients,"
Journ. Water Poll. Control Fed., 40(10):1739-53, Oct., 1968.
40. Tenney, Mark W., et.al. "Chemical Conditioning of Biological Sludges
for Vacuum Filtration," Journ. Water Poll. Control Fed., 4£(2):R1, Feb, 1970.
88
-------
TABLE I. - REMOVAL OF PHOSPHORUS BY ACTIVATED SLUDGE WITH NO ADDED CATIONS
WHEN THERE WAS EVIDENCE OF BIOLOGICAL ENRICHMENT OF AERATION SOLIDS
Dally Average Operation and Index Parameters
August 1 - September 10, 1968*
Date Total Plant Total P mg/1 » in %
1968 Flow Flow Raw Final Aer Rravl
MGD MGD Inf 1 Effl Solids of F
Mg/1 SVI COD loading COD/ DO in Meldahl-N N03-N TSS COD
Aer mg/1 Ibs/day MLS** Aer ingA Final in in
Solids Effl Raw Final Effl Final Final
Infl Effl mg/1 Effl Effl
Mg/1 Mg/1
Aug
1
2
3
4
5
6
7
8
9
Av
(1-9)
10
11
12
13
1*
15
16
17
18
19
20
21
22
23
24
Av
(10-24)
25
26
27
28
29
30
31
Sept.
1
2
3
Av
(25-3)
4
5
6
7
8
9
10
Av
.550
.550
.545
.515
.515
.625
.550
.520
.490
.540
.495
.455
=.535
.490
.475
.475
.490
.465
.490
.475
.475
.475
.475
.750
.600
.508
.600
.530
.550
.540
.550
.510
.465
.560
.575
.700
.558
1.809
1.797
1.253
.818
.641
.708
.577
.943
.460
.433
.418
.417
.413
.415
.402
.419
.415
.421
.398
.405
.436
.419
.385
.355
.390
.376
.394
.375
.385
.380
.375
.369
.371
.388
.357
.378
.405
.406
.403
.420
.390
.360
.375
.425
.392
.659
1.047
.973
.768
.641
.708
.577
.768
10.4
10.3
10.0
9.7
10.8
9.5
8.7
10.6
12.0
10. 2
12.0
10.4
11.7
11.9
12.2
11.3
12.0
12.2
10.3
11.5
12.0
11.0
12.0
7.6
8.2
11.1
8.3
10.1
10.4
10.4
10.8
9.3
11.0
9.5
10.1
9.0
9.9
7.7
3.6
5.3
9.3
7.9
5.7
9.0
6.9
8.2
7.7
6.4
11.8
7.2
7.2
5.9
7.3
8.7
7.8
7.4
6.2
7.4
7.9
5.7
5.5
5.6
6.3
6.7
6.8
a. 2
6.7
6.4
5.3
3.1
6.3
7.9
6.2
7.7
7.4
7.2
6.9
6.7
7.2
6.2
6.9
7.0
6.4
3.2
3.2
6.9
7.4
5.3
5.5
5.4
2.1
2.2
2.0
2.1
2.3
2.5
2.7
2.8
2.8
2.4
3.5
3.5
3.4
3.2
3.1
3.8
4.1
3.4
4.0
3.9
3.5
3.4
3.3
3.3
2.9
3.5
2.4
3.0
2.7
2.8
3.0
3.0
3.0
2.8
2.9
2.7
2.8
2.4
1.8
1.7
1.5
1.5
1.9
2.1
1.8
21
25
36
39
33
24
32
31
28
30
38
40
37
34
53
51
53
48
35
41
32
39
47
30
62
43
5
39
26
29
33
26
39
24
39
23
28
17
11
40
26
6
7
39
21
1785
1780
1990
1750
1835
1825
1795
1795
1805
1818
1590
1575
1615
1680
1775
1540
1476
1630
1490
1570
1618
1676
1696
1842
1834
1640
1972
1922
1910
1850
1772
1626
1514
1450
1400
1332
1675
1420
1450
1350
1316
1294
1198
1202
1319
521
520
470
520
500
500
520
510
490
506
533
514
508
482
428
416
501
460
5OT
522
500
500
460
418
414
478
380
380
372
378
305
258
257
228
193
225
298
162
118
96
84
85
92
92
105
266
327
351
312
338
322
299
323
287
314
251
265
323
451
262
244
320
330
3O2
320
338
360
362
381
272
319
260
260
289
265
264
-
294
280
270
287
274
236
164
73
150
145
194
217
169
1018
815
1222
1086
1165
1114
1004
1129
994
1061
834
896
984
1576
842
724
1040
1036
995
1002
1082
1144
1021
1171
840
1012
775
820
977
885
890
-
955
830
844
1017
888
1298
1431
600
961
776
1146
1046
1037
.32
.25
.34
.34
.35
.34
.31
.35
.31
.32
.29
.32
.34
.52
.26
.26
.39
.35
.37
.35
.37
.34
.33
.35
.25
.34
.22
.24
.28
.27
.28
-
.35
.32
,33
.42
.30
.50
.54
.25
.40
.33
.53
.48
.43
.7
.5
.6
.7
.6
.6
.6
.4
.3
.6
.6
.5
.9
.9
.9
.9
1.0
.7
.7
.6
.5
.5
.5
1.1
1.3
.8
1.0
1.0
1.0
1.1
1.1
1.2
1.2
1.0
1.0
1.0
1.1
1.1
2.2
1.2
1.0
.5
.6
.9
1.1
_
30
30
29
26
28
26
26
26
28
32
29
38
30
31
29
-
33
32
32
24
26
28
22
23
29
26
24
25
28
28
-
30
31
32
26
28
26
10
13
20
20
21
22
19
_
21
19
18
16
12
12
12
15
16
10
11
13
18
12
11
-
12
14
12
10
12
12
2
8
11
8
4
4
5
5
-
5
5
5
7
5
7
3
3
10
17
15
15
10
-
.5
.6
.5
.2
.2
.4
.5
.5
.4
.8
.5
.4
.4
.4
.4
.2
.2
-
.4
.5
.9
.5
1.4
1.8
.6
1.7
1.6
1.2
1.2
1.3
-
2.4
3.6
4.0
-
2.1
1.9
2.2
2.3
.8
1.1
.6
.9
1.4
11
12
19
21
8
15
18
4
5
13
9
10
10
10
12
8
11
7
35
17
14
8
10
14
5
12
5
16
6
21
7
8
4
16
4
8
10
5
6
6
6
14
14
10
9
51
54
57
53
52
58
45
51
34
51
34
33
38
40
52
20
42
44
47
35
32
25
36
39
37
37
43
20
22
42
28
-
34
34
48
34
34
37
40
25
21
34
21
48
32
(4-10)
* There was no primary sedimentation during the period covered by this table.
**COD/MLS > COD load in pounds per day/pounds of mixed liquor solids under aeration.
89
-------
TABLE II.-REMOVAL OF PHOSPHORUS BY ACTIVATED SLUDGE WITH NO ADDED CATIONS
WHEN THERE HAS EVIDENCE OF BIOLOGICAL PHOSPHORUS ENRICHMENT OF AERATION SOLIDS
Operational and Index Parameters at Maximum, Miniaun,
and Mean Levels of Phosphorus Renewal
June, 1968 - January, 1969
Period of
Nia-ber of Days
Muaber of days for average
Dates
1. Total flow to plant, HGD
2. Flow through plant, HGD
3. P ID raw lotl, ng/1
4. P In final effl, -g/l
i. Z P In aeration solids (MLS)
6. Z P removed
7. Aeration solids (MLS), eg/1
8. Sludge volune index (SVI)
9. COD loading, ng/1
10. COD loading Ibs/day
11. Ibs COD/day/lbs MLS
12. COD/P ratio
13. DO in aeration effluent, ng/1
14. *KJeldahl H in raw infl, ag/1
15. 'KJeldahl N in final effl. eg/I
16. Nitrate H in final effl, ng/1
17. COD ID final effl, ng/1
18. Suspended solids, ng/1
* I deluding amonia
June 2-9
8
Max Hlu
**Rnvd Rnvd
June June
3-5 6-8
.85 .64
.74 .62
7.6 11.1
4.0 8.1
47 27
1414 1397
361 378
152 159
944 818
.37 .32
20. 14.
.6
18.3 21.5
9.8
1.1
29.
**Rmvd - Ri
Av
Rnvd
June
2-9
.68
.66
9.5
5.8
38
1425
371
158
875
.34
17.
20.6
30.
moved
Aug :
Max
Rnvd
Aug
14-16
.48
.38
11.8
5.6
52
1597
448
275
865
.30
23.
30.2
12.0
.3
38.
10.
L - Sept 3
34
Mln
Rnvd
Aug
25-27
.56
.38
9.6
7.3
24
1934
377
270
856
.25
28.
25.5
5.1
1.5
28.
9.
Av
Rmvd
Augl-
Sept3
.53
.40
10.8
6.9
36
1696
432
305
1024
.33
28.
32.9
11.4
1.0
40.
11.
Sept
Max
Ravn
Sept
24-26
.70
.58
8.9
3.7
59
1788
123
278
1352
.42
31.
23.3
14.6
2.8
57.
18.
4 - Oct 1
28
-Mln
Rmvd
Sept
15-17
1.10
.82
5.8
4.7
19
1772
70
174
1194
.37
30.
15.4
12.8
.7
69.
31.
»v
Rnvd
Sept4
Oct 1
.85
.66
7.5
4.9
34
1539
89
198
1130
.41
26.
19.8
12.4
2.1
54.
19.
Oct 22 - »
Max
Rnvd
3
Nov
24-26
1 L E
.65
.66
10.1
5.4
46
1894
373
247
1366
.40
24.
24.7
6.8
.6
37.
8.
36
Mln,
Rnvd
Nov
18-20
V E L
.70
.65
9.4
8.0
14
1680
135
207
1139
.37
22.
21.2
8.4
1.1
55.
11.
)V 26
Av
Rmvd
36
Oct22-
Nov26
g
.71
.66
9.3
6.6
29
1815
188
243
1360
.41
26.
22.6
7.2
1.2
44.
12.
Nov 29 - Dec 31
Max
Rnvd
3
Dec
2-4
1.30
.98
4.8
3.0
37
1361
117
119
1118
.40
25.
12.5
2.0
.7
20.
6.
33
Hln
3
Dec
11-13
1.00
.91
6.4
6.4
0
1955
473
154
1492
.33
24.
15.1
3.8
.7
76.
67.
Av
Rnvd
33
Nov29-
Dec31
1.10
.89
5.9
5.0
15
1665
306
141
1243
.29
24.
14.8
4.5
2.0
48.
27.
Jan 1 - 19
Max
Rnvd
3
Jin
17-19
1.25
.94
4.7
3.5
25
1539
159
106
832
.30
22.
11.8
1.8
4.1
30.
6.
19
Min
Rmvd
3
Jan
2-4
1.15
.85
5.2
5.1
2
1640
204
129
920
.41
25.
14.7
3.0
5.3
43.
22.
Av
Rmvd
19
Jin
1-19
.98
.81
6.1
5.2
IS
1806
211
150
1071
.33
25.
15.7
2.6
5.9
38.
20.
TABLE III. - REMOVAL OF PHOSPHORUS SI ACTIVATED SLUDGE WITH. NO ADDED CATIONS
WHEN THERE HAS HO EVIDENCE OP BIOLOGICAL PHOSPHORUS ENRICHMENT OP AERATION SOLIDS
Operational and Index Parameters at Maximum, Minimum.
and Mean Levels of Phosphorus Removsl
June - November, 1969
Period of
Number of Days
Inicber of days for Average
Dates
1. Total flow to plant, HGD
2. Flow through plant, HGD
3. P in raw infl, mg/1
4. P in final effl, mg/1
5. I P in aeration solids (MLS)
6. X of P rewed
7. Aeration solids (MLS), mg/1
B. Sludge volume index (SVI)
9. COD loading, mg/1
10. COD loading, Ibs/day
11. Lb» COD/day/lbs MLS
12. COD/P ratio
13. DO in aeration effluent, Bg/1
14. Kjeldahl N in raw infl, mg/1
15. IJeldshl H In final effl, mg/1
16. Nitrate N in final effl, mg/1
17. COD in final effl, mg/1
18. Suspend solids, final effl, ng/1
June 15 -
16
Max Hln
Unvd Rtsvd
t 3
June June
26-28 17-19
.63 .61
.63 .61
12.2 10.3
10.1 9.3
2.0« 3.5*
1409 1700
460 160
242 248
1270 1255
.50 .41
20. 24.
1.2 .8
25.5 21.3
10.1 10.1
7.0 1.9
23. 42.
3. 12.
• 30
Av
Rmvd
16
June
15-30
.69
.69
11.7
9.8
2.7*
16
1450
333
253
1453
.56
22.
1.0
21.9
9.1
3.2
39.
7.
July 1 -
Max
Rmvd
3
July
10-12
.62
.47
11.4
9.4
1.6
1434
467
267
1054
.41
21.
1.9
25.7
2.7
10.7
30.
5.
14
Hln
Rnvd
3
July
6-8
.57
.54
11.3
10.0
1.6
1428
480
260
1169
.45
23.
1.0
26.2
5.3
3.9
39.
5.
14
Av
Rmvd
14
July
1-14
.58
.51
11.4
9.5
1.6
1407
424
262
1125
.44
23.
1.3
24.0
4.8
6.2
38.
7.
July 20-28
Max
Rmvd
3
July
21-23
PAR
.51
.51
12.9
10.7
1.4
1728
113
270
1156
.37
21.
.9
29.0
2.5
10.6
30.
7.
9
Mln
Rmvd
3
July
25-27
A H E
.55
.55
11.9
11.2
1.4
1696
JOO
292
1333
.42
24.
.6
30.0
4.8
4.6
38.
4.
Av
Rmvd
9
July
20-28
T E R
.52
.52
12.3
10.8
1.4
1740
201
278
1214
.39
23.
.7
28.4
3.5
8.1
31.
6.
Aug 8 -
Max
Rnvd
3
Aug
10-12
LEV
.52
.52
14.3
12.0
1.8
1544
509
318
1391
.50
26.
1.1
30.4
5.8
7.4
41.
7.
13
Hln
Rnvd
3
Aug
16-18
ELS
.53
.51
12.3
11.8
1.5
1355
578
291
1239
.51
25.
1.2
28.3
2.9
7.6
SI.
11.
20
Av
Rnvd
13
Aug
8-20
.53
.53
13.1
11.7
1.6
1452
539
300
1330
.51
26.
1.1
29.2
4.1
6.9
40.
8.
Oct 18 - 29
Max
Rmvd
3
Oct
20-22
.47
.47
14.5
12.3
3.8"
1254
305
274
1080
.48
22.
.b
32.3
3.7
9.3
».
9.
12
Min Av
Rmvd Rmvd
3 12
Oct OcC
26-28 18-29
.40 .44
.40 .44
14.0 14.3
14.5 13.3
2.3** 3.2**
-4 7
1132 1236
633 458
319 283
1079 1039
.47 ,47
22. 21.
1.1 .9
40.0 35.4
S. 6 5.3
S.6 11.0
M. 55.
60. 32.
Nov
Max
Rmvd
3
Nov
6-8
.41
.45
14.7
12.2
1.8
^7
1387
436
308
1150
.46
25.
1.1
36.7
8.2
15.5
50.
1C.
6-14
9
Mln
Rnvd
3
Nov
9-11
.47
.47
14.5
13.0
1.8
10
1788
432
332
1310
.41
26.
.4
«0.5
716
12.2
5*.
6.
Av
Rnvd
9
Nov
6-14
.46
.46
14.5
12.5
1.8
1632
447
311
1212
.41
25.
.7
37.5
6.7
12.9
53.
8.
1 imifoal big* Iron-phosphorus solids from Iron dosing through June 14
' lesldnal bigh alumlnum-phosphorus solid, fro. aluminum dosing through October 17
90
-------
TABLE IV. _ REMOVAL OF PHOSPHORUS FROM DIGESTER LIQUOR WITH HYDRATED LIME
Average Operating and Index Parameters for One Day Runs,
In ascending order of resultant, final, pH of treated liquor
Column Number
Date 1968
Gallons of liquor processed
Digester liquor analysis
PH
Alkalinity as CaC03> mg/1
Acidity as CaC03, mg/1
Total phosphorus, mg/1
COD
Total nitrogen by Kjeldahl, mg/1
TSS
Lime Dosage, mg/1
Mol ratio, lime/P (AMR)
Weight ratio lime/P
Reactor effluent (filtered samples)
PH
Residual phosphorus, mg/1 of P
COD, mg/1 of P
Sand bed sedimentation and filtration
pH of supernatant overflow
Phosphorus in recycle liquor mg/1 of P
Removals & efficiencies, across reactor
% of P insolubilized
% of COD removed
Removals & efficiencies, total process
% of P removed
Effective mol ratio, EMRr, lime/P
Effective wt. ratio, EWRr, lime/P
Deposits
Soft deposits of Mg(NH^) (PO^ • 6H20
Sludge production per Ib of P processed
Pounds of dry solids
Cu ft of sludge at 30% solids
Cu ft of sludge at 60% solids
Pounds wet sludge at 60% solids
1
Nov 4
15,600
_
1500.
1000.
228.
359.
292.
348.
2000.
3.7
8.8
8,3
26.8
128.
8.3
7.2
88.
64.
97.
3.8
9.1
2
Nov 8
20,350
6.7
1510.
918.
214 o
447.
282.
356.
2300.
4.5
10.8
8.5
10.5
91.
8.7
6.4
95.
80.
97.
4.7
11.6
3
Sept 19
14,130
6.6
1340.
780.
162.
269.
214.
202.
1500.
3.9
9.3
8.6
11.4
112.
_
4.4
95.
58.
97.
4.0
9.5
4
Oct 26
24,180
6.7
1595.
1000.
234.
435.
298.
388.
2400.
4.3
10.3
8.8
8.2
124.
8.8
7.4
96.
72.
97.
4.4
10.6
5
Sept 24
9,600
6.8
1400.
885,
179.
341.
198.
304.
1700.
4.0
9.5
8.8
5.3
120.
8.3
6.5
97.
65.
96.
4.2
9.9
6
Sept 27
12,000
6.6
1470.
885.
249.
324.
218.
216.
1775.
3.0
7.1
9.0
4.2
112.
8.2
7.0
98.
65.
97.
3.1
7.3
7
Sept 6
18,080
6.8
1030.
_
131.
267.
_
168.
1725.
5.5
13.2
9.1
2.8
75.
_
3.1
98.
72.
98.
5.6
13.5
8
Aug 29
13,490
6.8
1010.
700.
131.
194.
125.
120.
1950.
6.3
15.1
9.4
2.0
101.
_
—
99.
48.
_
-
-
9
Oct 22
29,600
6.7
1634.
1000.
238.
371.
266.
260.
3000.
5.3
12.6
9.4
4.7
122.
9.2
6.9
98.
67.
98.
5.4
12.9
10
Oct 17
4,200
_
1600.
1000.
234.
327.
298.
184.
3230.
5.8
13.8
10.2
5.5
111.
10.2
10.4
98.
66.
96.
6.0
14.2
11
Aug 18
12,780
7.0
950.
-
102.
196.
150.
136.
2200.
9.1
21.7
10.4
.8
127.
9.7
1.7
99.
35.
98.
9.3
22.1
severe severe slight severe slight severe slight slight severe severe slight
16.4
.41
.14
25.
17.5
.49
.16
29.
14.5
.41
.14
24.
24.1
.67
.23
40.
20.2
.57
.22
39.
15.3
.43
.15
25.
21.8
.61
.21
36.
24.7
.69
.23
41.
25.8
.71
.24
43.
23.4
.65
.22
39.
-------
TABLE V. - REMOVAL OF PHOSPHORUS WITH FERROUS SULFATE INJECTED TO RAW INFLUENT
Daily averages of operation and index parameters - Hay, 1969
Dace Flow—!iCD Hoi COD Total P—ag/1 Sol P ne/1 Aeration Solids TSS Kjldl 1!» NOj-N X Removal P I P to Solids
May Thru By^ Dose "8/1 FEF FE+ ZP ZFe mg/1 Raw FE FE Thru Plant Thru Plant
1969 Plant Psd Fe/7 Raw FE* Raw PJ_« FE Bpr« FE Bps HLE * SVJ_* Dry p_ry_ FE TO/1 ne/1 me/I Plant + Bpa Plant + Bps
1
2
0.78 0.00
0.67 0.04
3" 0.84 1.0?
4
5
6
^
8
9
10
11
12
13
14
15
16
17
*
18
19
20
21
22
23
24
25
26
27
20
29
30
31
Av .
1.15 O.»l
1.06 0.34
0.33 0.20
0.82 0.10
0.84 0.12
0.82 0.08
0.84 0.12
0.7i 0.05
0.76 0.02
0.89 0.83
1.03 2.25
1.16 1.00
1.65 201
1.48 247
0.91 280
1.15 129
1.34 174
1.67 120
1.92 148
1.69 150
1.C8
i.!0 155
2./0 178
1.18 277
l.M 250
O.'l 76
1.18 172
24
22
108*
39
34
34
45
31
35
24
37
53
37
22
1.14 1.66 1.24 70 19
1.08 2.47 1.60 342 30
FE - 'ln»l Effluent; PE - Pr
1.11 1.20
0.93 0.90
0.38 0.57
0.87 0.34
0.86 0.25
0.83 0.14
O.'f. 0.12
l.e.'j O.W
0.87 n.C7
u.es o.o:
...iff O.J1
0.85 0.00
'-.12 :>.!•<••
0.8C t.rv
•'.«» .1
1.31 77
1.36 137
1.36 115
1.41 146
1.33 149
1.46 152
1.30 177
1.61 170
1.62 198
1.74 201
1.12 1E4
1.7C If)
1.21 190
1.20 224
1.4k 17*
25
25
18
16
22
?6
2b
24
25
31
24
43
30
15
K
7.3
8.7
* 5.6
3.5
5.3
5.4
5.3
5.1
6.7
8.2
5.9
8.7
4.9
2.3
3.0
2.4
imarv
2.8
'i.5
4.2
5.2
5.7
6.3
7 7
8.2
7.8
6. 1
7.r,
S.O
a.ti
•,.f
7,5
7.6
4.6
5.2
5.2
5.2
5.1
5.5
6.7
7.6
4.9
7.3
5.1
2.6
3.0
2.1
T"0 LEVEL DOSING
0.6 0.6 0.6 0.6
1.0 1.7
8.3**6.5
0.7 2.0
0.9 1.8
0.6 1.4
0.6 1.0
0.6 0.4
0.6 1.3
0.8 2.0
0.6 0.8
0.5 0.7
0.9 2.8
1.2 1.3
i.l 2.0
0.8 1.6
Effluent; Bps -
2.4
4.3
'..2
4.6
5.4
6.3
7.1
7.?
6.8
:..b
6. •
7.4
•j. '.
ONE LEVEL
0.8 1.9
0.8 2.5
0.6 1.6
0.6 1.8
0.7 1.8
l.i 1.7
1.3 '.I
1.3 1.5
l.f 2.2
O.C 1.8
\e n.s
:1.1 0.8
ONE LEVEL
1.5 1.3
1.7 1.7
) t J . 7
0.8 0.9
0.8 0.6
0.4 0.6
0.5 0.5
0.3 0.4
0.4 0.4
3.4 0.3
0.4 0.4
0.6 0.7
0.5 0.4
0.3 0.3
0.5 0.6
0.7 0.8
0.6 0.7
0.5 1.2
0.5 0.7
By Pass;
- HASTING OF RETURN SLUDGE TO BOTH PRIMARIES
2300 100 5.6 - 4 19.3 3.5 7.9
2200 111 5.5 12.0 6 21.5 5.8 6.1
2050 112 5.6 141**19.5 6.8 8.1
2100 100 4.7 9.8 8 15.0 3.9 4.0
2000 100 5.3 7 18.8 7.4 3.6
2050 105 5.0 11.8 6 16.8 4.0 2.7
2035 95 5.0 6 14.8 2.4 7.7
2020 110 5.1 - 4 16.5 6.8 5.3
2050 135 5.2 - 3 13.0 3.4 7.9
2185 155 5.2 14.4 4 22.0 4.8 5.9
2320 201 5.0 4 22.5 5.5 6.5
2200 209 5.3 13.8 5 25.5 4." 11.3
2260 161 4.8 - 14 15.0 3.0 10.9
!K> HASTING OF SLUDGE
2270 230 4.3 12.6 26 8.0 2.0 3.9
2400 141 4.1 15 9.5 3.8 4.6
2690 96 ».l 11.7 14 8.0 1.9 3.2
3000 107 4.1 24 7.5 2.3 3.0
;ILS - Mixed Liquor Solids; SVI - Sludge Volume
DOSITC - HASTING OF MIXED LIQUOR SOLIDS TO DRYING BEDS
0.5 0.5 3350 84 4.0 11.3 10 9.5 1.8 5.7
0.5 0.7
0.5 0.3
3670 100 4.0 8 15.0 3.1 3.6
3650 103 3.1 9.6 8 12.5 2.0 3.6
0.5 0.5 3576 120 3.8 - 6 13.3 2.9 3.6
PASTIME OF RETURN SLUDGE TO DRYING BEDS
C.6 0.6 3521 130 4.1 . 7 17.0 2.8 *.t
0.7 0.7
C.V i.O
f'.l 0.9
0. •> 0.5
0.5 0.5
0.6 0.6
0.7 0.7
DOSING -
1.2 1.2
1.5 1.5
.6 .7
3590 97 4.4 4 16.5 3.8 1.2
3650 136 4.4 11.2 11 19.0 3.8 6.0
260'? 113 4.(. 7 17.0 2.9 0.5
3720 101 4.3 3 23.0 2.0 9.0
4180 112 4.? 1 18.8 1.9 10.9
4210 117 4.8 9 18.5 2.5 7.0
4110 110 4.8 9 21.0 2.5 10.0
WASTING OF RETURN SLUDGE TO BOTH PRIMARIES
3730 93 4.0 9.3 5 20.5 2.8 13.9
3110 76 5.1 10.7 5 23.0 2.0 3.9
2896 122 4.7 13 16.7 3.5 n. 7
91.8 91.8
88.4 80.5
-48.0 -16.0
80.0 74.2
82.8 65.8
88.8 77.0
88.8 81.4
as. 4 92.1
90.3 79.0
J8.9 72.2
90.0 86.5
94.3 94.3
81.6 43.3
4G.O 21.7
63.3 34.0
91.8
90.8
85.8
88.8
90.7
94.6
94.1
92.4
95.3
91.5
91.5
96.5
89.9
69.7
80.0
91.8
89.7
89.3
88.2
90.7
83.6
92.3
94.1
93.4
90.3
93.2
96.6
87.8
65.2
58.8
66.6 25.3 79.0 50.0
41.8 15.8 73.8 63.1
Index;* Including Anmonla
71.6 32.1
82.3 44.4
85. 8 61.9
88.4 65.7
87.8 68.5
82.7 73.1
83.6 73. «
82.0 79.2
78.2 72.8
89.7 89.1
88.5 87.3
88.5 88.5
03.6 83.6
79.8 79.8
81.0 7u.
82.3
88.8
88.1
90.6
89.5
38.8
811. 8
87.4
93.9
93.7
91.3
90.0
85.0
82.0
88.3
12.0
84.4
92.8
90.3
89.5
•18.8
87.6
5)2.7
93.7
91.2
90.0
85.8
82.0
85.7
.» 0.69 .4b l.4ft 172 29 S.8 5.i- .0 1.5 ,& .7 2925 l."2 t. f 8 16.6 J.4 :>.6 ilA.i l*.2 68.'J 85.5
:lflv 1-31 but excluding May 1.
** do ".
-------
TABLE VI. - FERRIC AND FERROUS IRON TO PRIMARY EFFLUENT
Average Daily Values of Demonstration Periods
Single Level DOBing Rate Throughout Each Day, Except Where Otherwise Indicated
Ferrous
Column Number
Period
Number of Days
Flow, HGD
Total
Thru plant
Dose, mol ratio, Fe/P
CXMR)
Phosphorus, P, mg/1
Total, raw influent
Total, prim effluent
Total, final effluent
Soluble, final effluent
Phosphorus, P, Ibs/day
Total, raw influent
Total, prim effluent
Total, final effluent
P, Removal, Effectiveness and Efficiency
Across primary, Z
Across plant, Z
Across plant, Z insolubllized
Effective Mol Ratios
For removal (EMRr)
For Insolubilizatlon (EMR1)
TSS
Raw influent, mg/1
Prim effluent, mg/1
Final effluent, mg/1
Raw influent Ibs/day
Prim effluent, Ibs/day
Final effluent, Ibs/day
Removal across primary, Z
>val across plant, 2
DO, Aeration effluent
Av of daily peaks
Av of dally lows
Av of bihourly rdgs
pH Ranges
Primary Influent
Aeration Influent
Aeration effluent
Aeration solids
MLS, nig/1.
Sludge volume Index (SVI)
Phosphorus In solids , ZP
COD
Raw influent, mg/1
Prim effluent, mg/1
Final effluent, mg/1
Raw influent, Ibs/day
Prim effluent, Ibs/day
Final efflueot, Ibs/day
Removal across prlaary, Z
Removal across plant, 7.
Lbs/COD/day/lbs, aeration solids
Total N, raw influent, mg/1
**KJldl. final effluent, mg/1
N03-N, final effluent, mg/1
Total N, final effluent, mg/1
Removal, total N, ng/3.
Removal, total H, Z
* Two level dosing rate each day
1
Jan 29 -
>eb 1 '69
4
.74
.74
.28
9.2
8.8
8.3
5 7
56.7
54.3
51.2
4.
9.
49.
3.12
.57
85.
85.
98.
524.
524.
606.
0.
-15.
2.4
.8
•1 c
7.3-7.6
7.3-7.6
7 5—7 7
1280.
604.
3.4
235.
216.
114.
1468.
1350.
712.
8.
51.
.64
19.2
12.6
3.7
16.3
2.9
15.
2
Jan '70
2-7
6
.79
.77
.81
9.2
8.5
3.8
59.4
54.9
24.6
59.
67.
1.37
1:20
134.
100.
22.
861.
642.
144.
26.
83.
i.O
.3
2654.
137.
4.2
293.
219.
44.
1880.
1410.
281.
29.
83.
.30
26.0
16.0
.3
16.3
9.7
37.
3
Nov '69
23-30
8
.51
.51
1.16
14.1
14.9
3.7
60.0
63.4
15.7'
74.
80.
1.57
1.45
133.
110.
10.
566.
468.
43.
17.
92.
3.4
.2
7.5-7.6
-
2153.
258.
4.7
355.
280.
37.
1515.
1194.
158.
25.
85.
.39
36.0
4.0
15.7
19.7
16.3
45.
4
Nov '69
15-22
8
.56
.51
1.35
12.8
13.2
5.4
54.5
56.2
23.0
58.
70.
2.32
1.93
143.
77.
35.
609.
328.
149.
46.
76.
3.5
.2
7.4
7.1
2205.
362.
3.5
318.
256.
63.
1350.
1088.
267.
19.
80.
.34
32.0
4.5
13.2
17.7
14.3
45.
** Including am
5
Mar '69
8-15
8
1.05
.94
1.41
5.0
5.2
1.1
39.2
40.7
8.6
77.
85.
1.82
1.66
82.
62.
10.
643.
486.
78.
24.
88.
4.1
.3
7.4-7.6
7.3-7.4
2188.
104.
3.6
125.
100.
22.
973.
779.
171.
20.
82.
.25
12.6
1.8
5.0
6.8
5.9
47.
nonla
6
Dec '69
1-4
4
.45
.45
1.60
14.0
15.4
2.9
52.6
57.8
10.9
-10.
79,
82.
2.03
1.95
118.
118.
17.
442.
442.
64.
0.
86.
2.5
.2
7.4-7.6
7.2
1993.
190.
5.4
354.
272.
27.
1335.
1026.
102.
23.
92.
.37
35.3
4.3
13.0
17.3
18.0
51.
7
Jan '69
21-28
8
.89
.89
.28
6.7
7.0
4.4
3 9
49.7
52.0
29.0
-4.
38.
44.
.74
.63
63.
53.
22.
468.
393.
163.
16.
66.
2.2
.6
7.3-7.5
7.1-7.6
1408.
278.
2.6
196.
172.
49.
1450.
1270.
361.
12.
75.
.57
15.6
7.6
2.1
9.7
5.9
38.
8
Apr '69
5-9
5
.72
.68
1.17
9.2
10.5
2.3
1.3
52.2
59.5
13.0
-14.
75.
85.
1.56
1.37
80.
84.
19.
454.
476.
108.
-5.
76.
2.2
.2
.9
7.4-7.5
1843.
86.
5.6
238.
195.
40.
1326.
1086.
222.
18.
83.
.40
21.8
5.0
8.0
13.0
8.8
40.
9
Apr '69
25-30
*6
.87
.81
*1.32
7.9
8.1
1.0
0.7
50.0
50.6
6.2
8?!
91.
1.51
1.44
106.
76.
7.
663.
475.
43.
28.
93.
2.0
.2
7.2-7.6
2439.
97.
5.4
227.
169.
31.
1544.
1150.
211.
18.
86.
.35
26.5
4.8
7.3
12.1
14.3
54.
10
Apr '69
10-18
9
1.64
.92
1.32
5.5
6.6
1.1
0.6
42.5
50.5
8.4
-19.
80.
89.
1.65
1.49
100.
62.
9.
765.
475.
71.
38.
91.
3.0
.4
1.3
7.5
7.4
2208.
83.
4.8
163.
117.
31.
1255.
906.
243.
28.
81.
.31
13.6
3.8
4.4
8.3
5.3
39.
11
Apr '6
19-24
5
.84
.78
1.37
8.1
8.4
1.7
1.3
52.7
54.7
11.1
-4.
79.
84.
1.73
1.65
70.
73.
10.
455.
475.
65.
-4.
86.
z.6
.3
.9
7.5
7.4
2065.
73.
5.
194.
160.
33.
1262.
1042.
215.
18.
83.
.34
19.0
5.2
5.4
10.6
8.4
44.
93
-------
TABLE VII. - FERRIC AND FERROUS TO RAW INFLUENT
Average Daily ValuM of Demonstration Periods
Single level dosing rate throughout each day, except where otherwise Indicated
Col mm nunfcer
Period, 1969
Nuaber of days
Flow, HGD
Total
Thru plant
Dose, mol ratio, Fe/P
AHK
Phosphorus, P, fflg/1
Total, raw influent
Total, primary effluent
Total, Final effluent
Soluble, Final Effluent
Phosphorus, P, Ibs/day
Total raw influent
Total priia effluent
Total final effluent
P, Removal, effectiveness
and efficiency
Across primary, Z
Across plant, Z
Across plant, Z insolubilized
Effective mol ratios
For removal (EMRr)
For insolubilizatlon (EHR1)
TSS
Raw, influent, ag/1
Prim effluent, mg/1
Final effluent, mg/1
Raw influent, Ifas/day
Prim effluent, Ibs/day
Final effluent, Ibs/day
***Removal across primary, Z
Removal across plant, Z
DO, Aeration effluent
Av of daily peaks
Av of daily lows
Av of blhourly rdgs
pH ranges
Primary influent
Aeration influent
Aeration effluent
Aeration solids
MLS, mg/1
Sludge volune index (SVI)
Phosphorus in solids, ZP
COD
Raw influent, mg/1
Prim effluent, mg/1
Final affluent, ng/1
Raw influent, Ibs/day
Prim effluent, Ibs/day
Final effluent, Ibs/day
Removal across primary, Z
Removal across plane, Z
'J.*- CJD/day/lbs aeration solids
Nitrogen
Total S, raw influent, ng/1
**-.;jldl. final effluent, ng/1
S03-Nr final effluent, Eg/1
Total N, final effluent, mg/1
Removal, tocal S, mg/1
Removal, total N, %
* Two level dosing rate each day
1
Dec 28-
Jan 1
5
.63
.63
.80
10.9
9.3
3.5
3.2
57.4
49.0
18.4
15.
68.
71.
1.18
1.13
71.
104.
8.
368.
546.
42.
-46.
41.
i 4
.4
.7
7.3
7.5-7 h
7. 6-7.7
2631.
138.
4.4
268.
261.
33.
1405.
1369.
173.
3.
88.
.30
29.5
18.2
.4
18.6
10.9
37.
2
Feb
18-20
3
1.15
1.00
1.02
5.3
4.9
1.7
1.1
44.2
40.8
14.2
7.
68.
79.
1.50
1.29
73.
80.
16.
608.
667.
133.
-10.
78.
4 1
.7
2.0
7.1-7 1
7.3-7.4
7.5-7.6
2552.
145.
3.3
147.
139.
44.
1226.
1159.
366.
5.
70.
.30
13.1
2.7
1.8
4.2
8.9
68.
3
Feb 26-
Mar 2
5
1.27
.96
1.04
5.0
4.7
1.8
1.5
40.0
37.6
14.4
6.
62.
70.
1.67
1.48
128.
96.
a.
1025.
768.
64.
25.
94.
J c
.5
1.6
7.2-7.3
7.3
7.4
2317.
144.
2.9
183.
141.
27.
1459.
1124.
216.
24.
85.
.35
13.2
2.0
1.1
3.1
10.0
76.
4
March
3-7
5
1.95
.97
1.40
3.9
3.6
.9
.7
32.3
29.1
7.3
10.
76.
83.
1.87
1.69
112.
94.
11.
907.
760.
89.
16.
90.
5.8
.5
3.0
7.1-7.2
7.2-7.3
7.4-7.5
2130.
123.
3.0
133.
115.
34.
1079.
930.
277.
13.
74.
.28
10.5
1.7
5.4
7.2
3.3
31.
5
Dec
5-12
8
1.80
.89
1.43
5.2
5.2
2.1
1.3
38.6
38.6
15.6
0
59.
75.
2.40
1.95
116.
103.
31.
860.
764.
245.
10.
72.
3 .6
.2
1.5
7.0-7.3
7 2
7.3-7.5
2078.
106.
4.5
200.
139.
47.
1490.
1035.
350.
30.
76.
.40
15.2
3.1
7.5
10.6
4.6
30.
6
Dec
13-15
3
.88
.88
1.56
8.4
6.3
1.8
1.2
61.1
46.0
12.8
25.
79.
85.
1.98
1.83
82.
110.
9.
599.
804.
64.
-34.
89.
2. 2
.2
.8
7.1-7.J
7.1-7.4
2503.
79.
3.8
171.
143.
22.
1250.
1045.
161.
16.
87.
.28
22.4
3.4
9.0
12.4
10.0
45.
7"
Dec
24-27
4
.64
.64
1.75
9.9
7.3
1.6
1.3
52.8
39.0
8.5
26.
84.
87.
2.08
2.01
112.
102.
7.
598.
550.
37.
9.
94.
1.0
.4
.7
7.1-7.4
7.5-7.7
2654.
91.
4.9
275.
218.
33.
1475.
1169.
113.
21.
92.
.31
29.7
15.7
1.6
17.3
12.4
42.
8-
Mar 29-
Apr 4
7
.82
.79
1.09
8.7
8.5
2.3
1.0
57.3
56.0
15.2
2.
74.
88.
1.48
1.23
65.
135.
30.
428.
890.
197.
-108.
54.
1.2
.4
7.2-7.5
7 3-7 4
7.3-7.5
2583.
94.
5.0
212.
186.
41.
1397.
1226.
270.
12.
81.
.30
19.7
2.7
6.9
9.6
10.1
51.
9
June
8-13
6
.78
.78
1.31
8.6
1.4
1.2
54.7
56.0
9.1
-2.
83.
86.
1.57
1.53
146.
157.
4.
950.
1022.
26.
-8.
99.
.5
.9
7.3-7.4
7 3-7 4
7.3-7.6
1946.
65.
4.8
246.
264.
33.
1600.
1720.
2X5.
-7.
86.
.39
26.6
8.1
3.9
12.0
14.6
55.
10
May
19-29
11
1.09
.87
1.50
6.1
1.0
.6
46.5
44.3
7.2
5.
85.
89.
1.76
1.68
118.
94.
7.
856.
683.
51.
20.
94.
.3
1.0
7.0-7.3
7.5-7.5
3771.
113.
4.4
165.
141.
25.
1190.
1019.
180.
14.
65.
.18
17.4
2.7
6.5
9.2
8.2
47.
11
June
1-7
7
1.11
.94
1.58
5.8
.7
.5
45.8
45.5
5.7
0
88.
91.
1.81
1.74
130.
116.
7.
1020.
912.
53.
11.
95.
.4
1.0
7.1-7.4
7.4-7.5
27O2.
74.
4.4
179.
154.
24.
1405.
1214.
190.
13.
87.
.29
14.3
3.6
6.5
10.1
4.2
29.
12
Dec
16-23
8
.73
.73
1.62
7.4
1.5
1.1
56.0
45.0
9.1
20.
84.
88.
.193
.177
71.
115.
9.
433.
700.
55.
-62.
87.
.5
1.0
7.1-7.5
7.3-7.6
2468.
73.
4.5
213.
145.
24.
1279.
885.
145.
32.
89.
.29
25.4
7.8
6.9
14.7
10.7
42.
13
May
4-13
•10
i.15
.87
•1.60
5.8
.7
.5
42.8
42.1
5.1
2.
88.
92.
1.84
1.72
137.
92.
6.
994.
668.
44.
33.
96.
2.2
.3
.8
7.1-7,5
7.4
7.4-7.5
2122.
137.
5.1
183.
126.
37.
1333.
919.
267.
31.
80.
.35
18.0
4.5
6.6
11.1
8.9
50.
'**S*apLe»
tliming p
removal* of TSS.
** Including ammonia
!r.rtrlT?T
-------
TABLE VIII — FERRIC AND FERROUS IRON TO PRIMARY EFFLUENT
AND TO RAW INFLUENT
Effectiveness at Increasing Mol Doses, Fe/P
Average Daily Values for Respective Periods
Period, Days
1969 except
where noted
otherwise
Jan 29-Feb 1 4
Jan 2-7 1970 6
Wov 23-30 8
Nov 15-22 8
Mar 8-15 8
Dec 1-4 4
Jan 21-28 8
Apr 5-9 5
Apr 25-30* 6
Apr 10-18 9
Apr 19-24 6
Dec 23 1969-
Jan 1 1970 5
Feb 18-20 3
Feb 26-Mar 2 5
Mar 3-7 5
Dec 5-12 8
Dec 13-15 3
Dec 24-27 4
Mar 29-Apr 4 7
June 8-13 6
May 19-29 11
June 1-7 7
Dec 16-23 8
May 4-13** 10
*April 25-30 dosage was at a diurnal two-level rate. All other dosing of
ferric and ferrous iron to primar^ effluent was at a single-level rate.
**May 4-13 dosage was at a diurnal two-level rate. All other dosing of fer-
ric and ferrous iron to raw influent was at a single-level rate.
Phosphorus
Total
Raw
mR/1 P
Dose Rmvd
Total Sol Fe/P P
Final Final AMR %
Effl Effl
Insolu-
bilized
EMRr
EMRi
Ferric to Primary Effluent
9
9
14
12
5
14
.2
.2
.1
.8
.0
.0
8
3
3
5
1
2
.3
.8
.7
.4
.1
.9
5.
3.
3.
3.
0.
2.
7
0
1
9
7
5
Ferrous
6
9
7
5
8
.7
.2
.9
.5
.1
4
2
1
1
1
.4
.3
.0
.1
.7
3.
1.
o.
0.
1.
9
3
7 *
6
3
Ferric
10
5
5
3
5
8
9
.9
.3
.0
.9
.2
.4
.9
3
1
1
2
1
1
.5
.7
.8
.9
.1
.8
.6
3.
1.
1.
•
1.
1.
1.
2
1
5
7
3
2
3
.28
.80
1.16
1.35
1.41
1.60
9
59
74
58
77
79
to Primary
.28
1.17
1.32
1.34
1.38
to
.80
1.02
1.04
1.40
1.43
1.56
1.80
38
75
*87
80
79
49
68
80
70
82
Effluent
44
85
91
89
84
3.
1.
1.
2.
1.
2.
.
1.
1.
1.
1.
1
36
56
32
83
02
74
56
52
52
75
.57
1.18
1.45
1.93
1.76
1.95
.64
1.38
1.45
1.50
1.64
Raw Influent
68
68
62
77
58
79
84
71
79
70
82
75
85
87
1.
1.
1.
1.
2.
1.
2.
18
50
68
82
47
98
14
1.13
1.29
1.49
1.71
1.91
1.83
2.07
Ferrous to Raw Influent
8
8
6
5
9
5
.7
.4
.4
.8
.2
.9
2
1
1
0
1
.3
.4
.0
.7
.5
.7
1.
1.
0.
0.
1.
*
0
2
6
5
1
5 **
1.10
1.31
1.50
1.59
1.60
1.60
74
84
85
88
84
**88
89
86
91
91
88
92
1.
1.
1.
1.
1.
1.
49
56
76
80
90
82
1.24
1.52
1.65
1.75
1.82
1.74
95
-------
TABLE IX. - REMOVAL OF PHOSPHORUS WITH LIME TO RAW INFLUENT AND TO RETURN SLUDGE SUMP
Daily Averages of Operation and Index Parameters
July 15-19 and July 29-Aug. 5, 1969
Date
July-
Aug.
1969
10
11
12
13
14
Av.
15
16
17
18
19
Av.
20
21
22
23
24
25
26
27
28
Av.
29
30
31
Aug. 1
2
3
4
5
Av.
Flow
MGD
.488
.439
.490
.485
.465
.473
.595
.553
.475
.469
.454
.509
.489
.510
.500
.530
.502
.539
.558
.545
.535
.523
.536
.529
.503
.496
.519
.493
.497
.486
.507
Mol
Dose
Lime/P
0
0
0
0
0
0
1.7
4.2
3.8
3.4
2.1
3.0
0
0
0
0
0
0
0
0
0
0
2.2
3.7
3.5
3.6
4.0
5.1
4.6
8.4
4.4
*PE-Primary effluent;
COD mg/1
Raw FE*
347 36
327 24
338 29
229 27
307 21
310 27
L I
350 22
323 34
307 23
275 40
306 30
312 30
290 30
322 34
239 26
331 29
417 40
357 36
-
324 41
221 15
294 30
223 17
347 25
280 20
273 25
250 18
315 25
236 11
298 29
270 21
Total P. i
Raw
12.0
10.8
11.4
9.5
11.7
11.1
M E
11.4
9.0
11.7
13.1
13.8
11.8
11.4
14.4
12.2
12.2
12.9
12.0
12.9
10.8
12.2
11.2
11.4
12.0
13.1
13.1
13.4
10.9
15.6
12.7
12.7
FE-Final effluent
PE*
11.4
10.8
11.0
9.5
11.9
10.9
ADD
11.0
9.3
12.0
12.7
13.8
11.8
11.2
13.8
12.7
12.5
12.4
13.1
12.9
11.0
12.4
12.4
12.0
11.0
10.4
10.1
12.0
7.9
10.8
7.2
10.4
ng/1
FE*
9.4
9.8
9.0
9.0
9.3
9.3
E D
10.1
7.7
8.4
10.8
10.8
9.6
10.8
10.4
11.2
10.6
10.8
11.5
11.4
10.6
9.8
10.8
L
11.4
10.1
10.8
9.5
10.1
9.8
9.0
8.7
10.0
; MLS-Mlxed
Sol. P TSS
mg/1
FE*
9.4
9.3
8.7
9.0
9.2
9.1
mg/1
FE*
N 0
6
1
9
4
3
5
TO R E T U R
9.8
7.2
8.2
10.3
10.6
9.2
10.8
10.1
11.0
10.1
10.4
11.2
11.4
10.6
9.5
10.8
I M E
11.0
10.1
9.3
9.8
9.5
9.8
9.0
8.4
9.7
liquor
10
6
5
9
1
6
N 0
5
7
8
6
7
6
4
3
4
6
A D D E
6
6
5
6
5
13
7
5
7
Aeration Solids
mg/1 SVI* % P ZCa
MLS* Dry Dry
LIME ADDED
1448 460 1.6 -
1450 480 1.6 1.5
1405 460 1.6 2.7
1440 430 1.3 1.4
1430 320 1.4 2.0
1435 430 1.5 1.9
N SLUDGE IN
1495 290 1.4
1845 210 1.4 3.9
1680 190 1.6 5.6
1798 150 1.7 3.4
1830 140 1.5 5.4
1528 226 1.5 4.6
LIME ADDED
1795 120 1.4
1715 110 1.4 3.0
1675 110 1.4 3.0
1693 120 1.5 2.4
1960 140 1.4 2.4
1748 270 1.3 2.5
1730 290 1.3 1.8
1610 340 1.6 2.4
1733 310 1.5 2.4
1743 205 1.4 2.2
D TO RAW IN
1673 380 1.4 2.6
1865 360 1.5 3.5
1758 443 1.2 2.3
1730 446 1.2 3.0
1615 473 1.4 3.2
1585 512 1.5 2.9
1653 496 1.7
1563 518 1.5 -
1564 489 1.4 2.9
solids; SVI-Sludge volume index
lyidl N**
ZMg
Dry
-
.3
.6
.3
.6
.4
S L
.2
.2
.2
.3
.2
.2
-
.3
.2
.2
.2
.2
.2
.4
.2
.2
FLU
.4
.3
.2
.3
.2
.3
.4
.3
.3
mg/1
Raw
24.0
28.0
25.0
26.0
25.0
25.6
I P -
25.0
23.0
30.0
27.0
30.6
27.1
30.5
32.0
27.0
28.0
31.5
27.5
35.0
27.5
27.0
29.5
E N T
28.0
28.5
29.5
31.0
30.0
33.0
28.0
32.5
30.0
mg/1
FE*
3.5
2.3
2.3
2.3
2.3
2.5
V A L V
4.0
2.0
6.0
3.0
4.0
3.8
2.3
2.8
2.3
2.3
3.0
5.8
4.8
3.8
4.0
3.4
3.5
2.3
2.3
2.8
6.8
6.5
4.0
4.5
4.0
NO,-N
mg/l
FE*
8.2
9.0
14.9
6.0
14.9
10.6
E S U
5.9
6.9
12.5
9.0
10.0
8.8
15.6
13.4
9.5
9.0
5.0
2.8
4.8
6.2
6.2
8.1
1.3
5.0
8.0
7.1
8.2
6.6
13.5
9.3
6.9
%P
Rmvd*
22
9
21
5
20
15
M P
11
14
28
18
22
19
5
28
8
13
16
4
12
2
20
12
0
16
18
27
25
10
42
31
20
pH Values
Raw
-
7.55
-
-
_
-
7.70
7.40
7.55
7.60
7.45
-
-
7.35
7.45
-
-
7.40
_
_
7.35
-
7.40
7.40
7.40
7.90
_
7.40
7.40
7.40
_
PE*
_
7.45
-
-
_
-
7.55
7.45
7.50
7.55
7.50
_
7.40
7.45
_
-
7.55
_
_
7.30
-
7.40
8.60
8.65
8.30
-
8.80
8.65
9.15
_
; Rmvd-Removed **IncludJ
Aerat .
Inf.
_
7.50
-
-
_
-
8.15
8.10
8.15
8.25
8.35
-
_
7.55
7.50
_
-
7.60
_
_
7.50
-
7.55
8.30
8.10
8.10
-
8.35
8.40
8.25
_
Aerat .
Eff.
_
7.50
-
-
_
-
7.60
7.65
7.60
7.90
7.80
-
-
7.50
7.45
_
-
7.65
_
_
7.50
-
7.50
8.05
7.60
7.65
-
7.60
7.60
7.80
_
Lng ammonia
-------
TABLE X. - REMOVAL OF PHOSPHORUS WITH ALUMINUM CHLORIDE,
INJECTED TO RAW INFLUENT AND TO PRIMARY EFFLUENT
Daily Averages of Operation and Index Parameters, plus Averages of Sequential Periods
Aug. 21 - Oct. 15, 1969
Period averages are not weighted according to flow except where indicated as "wt. av."
Date
1969
Aug. 21
22
23
24
25
26
27
Period Av.
Aug. 24-27
28
29
30
31
Sept. 1
2
Period Av.
Wt. Av.
Sept. 3
4
5
g
7
8
Period Av.
Flow
MGD
.696
.882
.867
.690
.555
.485
.575
.576
1.025
.831
.587
.464
.486
.546
.657
-
.545
.565
.517
cno
. JUO
.547
.532
.536***
Mol
Dose
Al/P
.462
.99
1.23
1.11
1.20
1.39
1.31
1.25
.98
2.24
1.84
2.52
1.60
1.75
1.82
2.04
1.75
1.81
1.88
i 77
1.72
1.82
1.79
COD
Raw
369
223
146
229
281
235
278
255
352
155
295
221
233
340
266
270
380
345
400
299
283
341
341
mg/1
~FE*"
53
40
42
34
33
28
52
37
33
19
29
37
11
30
26
27
32
32
34
41
34
34
34
Total P. ma/1
Raw PE* FE
TO RAW
7.9 7.7 8.7
8.9 8.4 3.4
7.2 7.7 3.7
10.1 10.3 3.6
11.5 12.7 3.4
12.4 12.5 3.6
11.0 12.7 3.7
11.2 12.1 3.6
5.3 5.6 2.9
6.8 4.3 2.1
11.4 6.2 2.5
8.3 3.8 3.4
13.1 6.7 2.8
13.4 5.9 3.2
9.7 5.4 2.8
9.0 5.4 2.8
12.9 8.4 3.7
11.0 9.5 2.1
12.7 10.4 2.9
11.0 7.3 4.0
13.8 9.5 3.4
12.5 8.7 3.3
TO PRIMAR
Sept. 9
10
11
12
13
Period Av.
Sept. 14
IS
16
17
18
Period Av.
Sept. 19
20
21
22
23
Period Av.
Sept. 24
25
26
27
28
29
30
Oct. 1
Period Av.
Oct. 2
3
4
5
6
Period Av.
Oct. 7
a
9
10
Period Av.
Wt. Av.
Oct. 11
12
13
14
15
Period Av.
.527
.498
.442
.442
.521
.486***
.467
.495
.491
.523
.541
.503***
.480
.487
.487
.473
.465
.478***
.432
.477
.461
.516
.433
.564
.450
.443
.478
.450
.516
.500
.470
.439
.475
.461
.474
.562
.684
.545
-
.735
.479
1.156
.453
.457
.656
1.68
1.58
1.44
1.65
1.88
1.65
2.02
2.06
2.22
2.17
1.63
2.02
2.30
2.60
2.10
2.60
2.46
2.41
2.52
2.33
2.54
2.01
2.52
2.52
2.81
2.39
2.41
2.05
1.85
2.05
2.30
2.75
2.20
2.52
2.27
2.86
2.53
2.55
2.56
2.02
2.00
1.49
2.54
3.00
2.21
384
396
396
363
365
381
412
363
353
323
433
377
439
505
422
422
414
440
443
445
353
409
398
365
500
396
414
394
408
394
379
377
309
396
438
283
313
357
350
299
634
354
343
338
394
39
39
38
38
33
37
38
29
32
48
48
39
40
57
60
40
52
48
48
38
44
37
41
36
43
47
42
45
25
53
65
23
42
29
33
36
35
33
34
47
49
36
70
84
57
12.0 13.1 2.3
12.0 13.8 2.5
14.2 14.2 2.8
14.7 15.4 2.9
14.5 16.3 2.5
13.5 14.6 2.6
13.4 13.8 2.5
14.4 15.6 2.2
12.2 14.5 2.6
10.6 13.1 2.2
13.7 14.6 2.0
12.9 14.3 2.3
14.9 14.9 2.1
14.6 17.6 3.0
13.8 15.2 3.3
13.8 16.3 2.8
12.9 14.9 2.6
14.0 15.8 2.8
13.8 16.3 2.3
13.8 15.4 2.8
14.2 16.3 3.4
17.2 19.2 3.5
13.9 16.7 2.8
14.9 19.7 3.4
13.1 19.2 3.6
14.1 19.1 3.2
14.4 17.7 2.8
15.8 17.2 2.9
17.9 17.2 2.7
17.2 17.2 2.5
13.8 15.8 3.8
14.9 17.6 2.7
15.9 17.0 2.9
Polyelectrolyte
14.2 16.7 1.3
14.5 14.4 1.4
9.3 10.1 1.1
9.5 10.4 0.8
11.9 12.9 1.1
11.5 12.5 1.2
13.8 13.8 3.2
16.3 14.2 3.4
10.8 11.7 3.0
14.2 15.4 5.0
13.4 16.3 6.9
13.7 14.3 4.3
Sol. P
mg/1
FE
I N
8.5
3.1
2.8
3.4
3.4
3.2
3.6
3.4
2.4
1.8
2.4
2.8
2.3
2.9
2.4
2.4
3.2
2.1
2.5
3.4
2.9
2.9
Y E
2.1
2.3
2.2
2.3
2.1
2.2
1.9
1.4
1.8
1.9
1.5
1.7
1.3
1.1
1.2
.9
1.2
1.1
0.7
1.0
1.2
1.2
1.1
1.1
1.2
1.2
1.1
1.1
1.1
1.2
1.7
1.3
1.3
TSS
mg/1
FE
FLU
16
13
11
8
7
8
7
8
15
3
5
15
3
13
9
9
6
7
11
f.
5
4
6
F F L
4
7
9
5
9
7
10
13
9
16
9
11
6
37
39
32
27
28
26
28
29
50
30
42
40
46
34
32
18
30
42
30
30
to Aeration
1.4
1.1
0.8
0.5
1.0
.9
1.6
1.2
0.8
0.9
1.2
1.1
8
12
0
5
6
6
41
36
44
70
96
63
Aeration
mg/1 SVI*
MLS*
E N T
1375 429
1495 294
1665 234
2050 215
2015 233
2253 204
2630 220
2170 218
2285 153
2160 130
2190 119
2160 110
1910 120
1877 107
2097 123
2127 128
1710 117
2107 100
2100 114
?nnn i i i
£UUU J.-O
1980 120
1945 123
1974 115
U E N T
2140 216
2282 136
2317 142
2270 146
2430 136
2288 155
2510 155
2500 140
2490 156
2490 137
2435 128
2485 143
2522 147
2670 161
2790 136
2687 134
2640 118
2662 139
2707 126
2830 120
2785 108
3065 101
2995 102
2987 102
2730 103
2608 92
2838 107
2150 93
1612 90
1720 88
2010 64
2200 91
1938 85
Effluent
2322 82
2150 85
1920 87
1945 91
2084 86
2063 87
1700 92
2005 94
2035 78
2060 67
1957 70
1951 80
Solids
%P
Dry
1.6
2.0
2.3
2.7
3.4
3.6
3.8
3.4
3.8
3.8
3.7
3.6
3.6
3.4
3.6
3.7
3.9
3.7
4.0
A 3
4.0
4.2
4.0
4.4
4.5
4.6
5.2
5.1
4.8
5.2
5.3
5.5
5.3
5.5
5.4
5.7
5.6
5.3
5.4
5.5
5.5
5.6
5.7
5.9
5.5
5.3
5.6
5.9
5.8
5.7
6.0
6.0
5.7
5.8
5.8
5.9
5.9
5.9
5.8
5.7
5.8
5.8
5.6
5.0
5.0
5.2
5.0
5.2
% Al
Dry
.38
_
-
_
1.4
-
-
1.9
-
_
2.8
_
3.3
_
4.9
_
4.3
-
6.1
5.9
-
5.4
-
8.1
-
7.8
6.7
KJldl
rni/TI
Raw
25.0
22.5
18.0
25.0
29.5
28.0
28.0
27.0
16.0
29.0
21.5
25.0
42.0
45.0
29.7
27.8
34.0
28.0
28.8
9ft n
£.Om U
22.2
33.5
29.1
29.5
29.5
32.0
34.5
32.3
31.6
35.0
34.0
31.0
26.5
23.0
29.9
33.0
24.5
33.0
37.5
32.0
32.0
29.0
32.0
32.0
35.0
37.5
33.5
34.0
33.5
33.3
31.0
38.5
34.0
45.0
35.0
36.7
33.0
35.0
25.0
23.0
29.0
32.4
29.0
39.5
21.3
30.0
33.5
30.7
N**
SgTT
FE
2.5
6.3
3.0
2.5
2.0
1.5
2.5
2.1
1.5
3.1
2.5
7.1
3.5
2.3
3.3
3.0
1.5
1.5
1.9
2.3
2.0
1.5
1.8
2.8
1.9
1.3
2.5
1.5
2.0
2.5
2.3
2.0
1.6
2.3
2.1
3.5
1.8
2.5
3.8
2.5
2.8
2.3
2.5
3.8
2.8
3.8
2.4
1.5
3.0
2.8
2.0
2.8
3.8
3.8
2.0
2.9
1.9
2.5
1.5
2.5
2.1
2.1
3.3
7.3
5.3
4.8
3.8
4.9
N03-N
mg/1
FE
13.9
4.6
5.4
6.2
13.4
11.5
12.2
10.8
1.5
5.6
10.8
6.8
4.0
15.0
4.6
5.8
5.7
13.6
11.8
13.7
16.0
12.2
12.2
10.0
12.0
14.7
10.6
13.4
12.1
9.4
13.6
11.5
10.8
7.8
10.6
9.8
10.6
10.2
12.5
11.0
10.8
13.9
16.4
8.7
7.3
8.2
15.3
8.7
13.2
11.5
14.5
16.8
11.5
13.4
17.5
14.7
16.0
12.5
15.3
9.4
15.8
13.0
9.8
6.2
6.2
11.8
20.6
10.9
%P
Rmvd
-9
62
49
64
71
71
66
68
45
69
78
59
79
77
71
69
71
81
77
75
64
75
74
81
79
80
80
83
81
81
85
79
79
86
82
86
80
76
80
80
80
83
80
76
80
80
77
73
77
80
82
85
86
73
82
82
91
91
88
92
91
91
77
79
72
65
49
68
%P
to
Slds
-8
65
61
66
71
74
67
70
55
74
79
66
83
78
75
71
75
81
80
78
69
79
77
83
81
85
85
86
84
86
90
85
82
89
87
91
93
91
93
91
92
95
93
92
93
92
92
91
92
92
93
94
93
88
91
92
90
93
91
95
92
92
89
93
93
94
91
92
* FE - Final effluent; PE - Primary effluent; MLS - Mixed liquor solids; SVI
** Including ammonia
*** Two level dosing rate, Sept. 3-23
Sludge volume index; RMVD - Removed
97
-------
TABLE XI. - ALUMINUM CKLOk'DE TO UU IMPUIEKI AH) TO PIDUKT EFFLUEXT
Average Dally Valuea of Deaanatratlon Periode
Colun Ho.
Period 1469
Huaber of daye
Flow. MCD
Thru plant
Doae. aol recto. Al/P (AMR)
Fhoaphorua. P. «/l
Total, raw Influent
Total, primary effluent
Total, final effluent
Soluble, final affluent
Fheanhorua. P. Iba/der
Total, raw Influent
Total, primary effluent
Total, final effluent
Acroae privary, *
Acroaa plant, Z
Acroai plant, X Ineolubllliad
Effective Hoi Ratloa
For removal (OOr)
For luolublllutlon (EMU)
TSS
Taw ]
' Influent, •«/!
Primary effluent, eg/1
Final effluent, »g/l
Raw Influent, Ibe/day
Prl. affluent, Ibe/day
Final effluent, Iba/day
Renewal acroaa prlnmry,
ReHoval eeroaa plant, Z
DO. Aeration Effluent
Averege of dally peelta
Average of dally Iowa
Average of blhourly readlaga
PH Kanaea
rriawry Influent
Aeretlon Influent
Aeretlon affluent
Sludge volu*e Index (SVI)
Pboaphorua in aollda, ZP
COD
Raw Influent, ag/1
Pel. effluent, .g/1
Final effluent, •*/!
Raw Influent, Ibe/day
Prle effluent, Iba/day
Final effluent, Ibe/day
Reeoval acroaa primary, Z
Reaoval acrosa plant, Z
Lba COD/day/lba aerat. aollda
HltroRen
Total nitrogen, rau Influent, ag/1
rjldl, final effluent. ei/1****
UOj-H, final effluent, e(/l
lot.I II, final effluent, eg/1
Rawvel, Total ", ag/1
el. Total », Z
Two-level doling rete, Sept. 3-23
Averagea weighted eccordlng to flow
Polyeletrolyte doeLng to eeretlon effluent
Including
1
Aug
24-27
.576
.576
1.25
3.6
53. 8
58.1
17.3
-7.
68.
70.
1.84
1.79
114.
82.
8.
548.
395.
39.
28.
93.
3.0
^3
l!2
7.4-7.5
2170.
218.
3.4
255.
209.
37.
1225.
1004.
178.
18.
86.
.31
27.0
2.1
io!s
12.9
14.1
52.
Raw Ii
2*
Sept
3-8
g
.536
.536
1.79*
3.3
2 9
55.9
39.0
14.8
30.
74.
77.
2.42
2.32
120.
135.
6.
537.
604.
27,
-12.
95.
3,5
13
1.5
7.0-7.4
1974.
115.
4.0
341.
245.
34.
1529.
1098.
152.
28.
90.
.43
29.1
1.8
iz'.i
14.0
15.1
52.
[fluent
3
Aug 28-
Sept 2
.853
.657
1.82
2.8
53.2
29.6
15.3
44.
71.
75.
2.57
2.43
149.
73.
9.
816.
400.
49.
51.
94.
4.7
f2
1.5
7.3-7.4
2097.
123.
3.6
266.
154.
26.
1459.
845.
143.
42.
90.
.39
29.7
3 3
*!s
7.9
21.8
73.
4"
Aug 28-
Sept 2
.853
.657
2.04
2.8
49.3
29.6
15.3
40.
69.
71.
3.14
2.87
165.
78.
9.
904.
427.
49.
53.
95.
4.3
12
1.5
-
2127.
128.
3.7
270.
164.
27.
1480.
900.
148.
39.
90.
.39
27.8
i'.S
8.8
19.0
68.
5*
Sept.
9-13
e
.486
.486
1.65*
13.5
14.6
2.6
54.8
59.2
10.6
-7.
81.
84.
2.03
1.97
140.
104.
7.
567.
422.
28.
26.
95.
2,6
• 2
1.0
7.2-7.5
7.0-7.3
2288.
155.
4.8
381.
292.
37.
1545.
1185.
150.
23.
90.
.38
31.6
2 0
12'.!
14.1
17.5
56.
6*
Sept
14-18
.503
.503
2; 02*
12.9
14.3
2.1
54.1
60.0
9.7
-11.
82.
87.
2.46
2.32
151.
91.
11.
634.
382.
46.
40.
93.
2.2
1.0
7.4-7.8
7.0-7.3
2485.
143.
5.4
377.
280.
39.
1582.
1175.
1(4.
26.
90.
.35
29.9
io!e
12.7
17.2
58.
Frli
7
Oct
2-6
.475
.475
2.20
15.9
17.0
2.9
63.1
67.4
11.5
-7.
82.
92.
2.68
2.39
151.
130.
30.
598.
514.
119.
14.
80.
2.8
1.2
7.4-7.6
7.0
1938.
85.
5.9
390.
290.
42.
1546.
1151.
167.
26.
89.
.44
36.7
2«9
14.7
17.6
19.1
52.
lary HI]
8
Oct
11-15
.656
.656
2.21
13.7
14.3
4.3
75.0
78.2
23.5
-4.
68.
92.
3.25
2.40
230.
152.
63.
1260.
830.
345.
34.
73.
3.1
1.2
8.0
6.9
1951.
80.
5.2
394.
270.
57.
2155.
1476.
312.
31.
86.
.61
30.7
10.9
15.8
14. »
49.
Luent
9
Sept 24
Oct 1
.478
.478
2.41
14.4
17.7
2.8
57.5
70.7
11.2
-24.
80.
92.
3.01
2.62
151.
158.
34.
602.
630.
136.
-5.
77.
2.4
1.1
7.4-7.5
7.0-7.2
2838.
107.
5.7
414.
301.
42.
1654.
1202.
168.
27.
90.
.32
33.3
11.5
14.3
19.0
57.
10*
Sept
19-23
.478
.478
2.41*
14.0
15.8
2.8
55.9
63.0
11.2
-13.
80.
92.
3.01
2.62
191.
132.
28.
763.
527.
112.
31.
85.
2.7
1.4
7.4-7.8
7.0-7.2
2662.
139.
5.5
440.
323.
48.
1755.
1290.
192.
27.
89.
.37
32.0
10.8
13.6
18.4
57.
11***
Oct
7-10
.545
.545
2.55
11.9
12.9
1.1
54.2
58.6
5.0
-8.
91.
92.
2.80
2.77
142.
102.
6.
645.
463.
27.
28.
96.
3.2
1.4
7.5-7.7
7.0
2084.
86.
5.8
357.
249.
33.
1625.
1134.
150.
30.
91.
.43
29.0
15.8
17.9
11.1
38.
12**
Oct
7-10
.545
.545
2.56
11.5
12.5
1.!
.9
52.3
56.9
5.5
-9.
91.
92.
2.81
2.76
143.
100.
6.
650.
454.
27.
30.
96.
3.2
1.4
-
2063.
87.
5.8
350.
244.
34.
1594.
1110.
155.
30.
90.
.43
32.4
2.1
13.0
15.1
17.3
53.
98
-------
TABLE XII— ALUMINUM CHLORIDE TO RAW INFLUENT AND TO PRIMARY EFFLUENT
Effectiveness at Various Mol Doses Al/P
Period 1969
Average of Daily Values for Respective Periods
Aug. 24-27
Aug. 28-Sept. 2
Aug. 28-Sept. 2 wt. av.**
Sept. 9-13*
Sept. 14-18*
Sept. 19-23*
Sept. 24-Oct. 1
Oct. 2-6
Oct. 11-15
Oct. 7-10
Oct. 7-10 wt. av.**
*Periods of Sept. 2-23, diurnal dose rate at two-level.
**Averages weighted according to flow.
Days
Phosphorus me /I P
Total
Raw
Total
F. Effl
Sol
F. Effl
Dose
Al/P
Aluminum CHloride
5
6
6
6
5
5
5
8
5
5
11
12
9
9
13
12
14
14
15
13
.2
.5
.7
.0
.5
.9
.0
.0
.9
.7
3.6
3.3
2.8
2.8
Aluminum
2.6
2.3
2.8
2.8
2.9
4.3
3.4
2.9
2.4
2.4
Chloride
2.2
1.7
1.1
1.1
1.3
1.1
Polyelectrolyte to
4
4
11
11
.9
.5
1.1
1.2
1.0
.9
1
1
1
2
to
1
2
2
2
2
2
Rmvd
P
%
Insolu-
bilized
%
EMRr
EMRi
to Raw Influent
.25
.79
.82
.04
68.
74.
71.
69.
70.
77.
75.
71.
1
2
2
3
.84
.42
.56
.13
1.78
2.32
2.43
2.87
Primary Effluent
.65
.02
.41
.41
.20
.21
81.
82.
80.
80.
82.
68.
84.
87.
92.
92.
92.
92.
2
2
3
3
2
3
.04
.46
.01
.01
.68
.25
1.97
2.32
2.62
2.62
2.39
2.40
Aeration Effluent
2
2
.55
.56
91.
91.
92.
92.
1
2
.80
.81
2.77
2.78
All other periods, one-level rate.
TABLE XIII. - SLUDGE PRODUCTION
Without, and with Iron and Aluminum
Column No.
Period
Flow, MGD
COD load, Ibs/day
Phosphorus load, Ibs/day as P
Phosphorus load, Ibs/day as PO^
Cationic treatment
Point of injection
Dose, mol ratio, Fe/P or Al/P
Dose, Ibs/day as Fe or Al
Phosphorus removed, %
Phosphorus removed, Ibs/day as PO^
Sludge to digester, primary + waste, gal/day
Solids in sludge, dry wt., %
Solids to digester, Ibs/day
% ash in solids
Phosphorus entering sludge, Ibs/day as PO^
Biological uptake, assumed
From Fe or Al precipitation
Total
Fe or Al entering sludge from dose, Ibs/day
Doso minus Fe or Al in plant effluent
Fe or Al plus PO^ entering sludge, Ibs/day
Calculated quantity of precipitants from Fe or Al dose, Ibs/day*
P04 to equiv. FeP04 or AlPO^
Remaining Fe and Al to Fe(OH)3 and A1(OH)3
Total
Calculated solids non-attributed to Fe or Al precipitants, Ibs/day
Sludge solids minus calculated precipitants
1
7/20-28/69
.52
1214.
53.4
164.
none
-
0
0
12.
20.
5350.
1.44
644.
26.
20.
20.
0
-
2
6/8-13/69
.78
1600.
54.7
168.
Fe (II)
Raw infl.
1.31
129.
83.
140.
4679.
2.24
872.
50.
(20)
120.
140.
126.
246.
191.
105.
296.
3
9/9-13/69
.49
1555.
55.2
169.
Al (III)
Prim effl.
1.65
79.
81.
137.
6292.
1.72
900.
38.
(20)
117.
137.
77.
194.
150.
127.
277.
576.
623.
Probable solids content of digested sludge, % **
Probable % ash in solids**
5.5
60.
5.5
65.
2.5
55.
Arbitrary, to estimate at least the minimum of dry weight solids from the iron and aluminum
doses through hydrolysis and phosphate uptake. Aquo ligands are not accounted for.
**Based respectively on analyses of samples of digested sludge drawings before the use of iron
or aluminum, prior to January 20, 1968; 2 to 5 months after initiation of iron treatment;
and 1 to 3 months after initiating aluminum treatment.
99
-------
Digester I—
< y-
S6
Continuous overflow of slurry
from reactor 20-25 GPM
I ntermittent sludge withdrawal
from digester
K
A Lime Slurrier and "Quick Mix"
B 1000 Gal Ion Reactor
C Chemical Storage and Feed
D Chlorine Contact
E Secondary Clarifiers
F Aeration
G Primary Clarifiers
H Degritter
I Wet-Dry Wei I
J Primary and Waste Sludge
K Sludge Drain Beds
RAW Raw Influent
FE Final Effluent
PE Primary Effluent
RS Return Sludge
WS Waste Sludge
SP Sludge Pit
DB Divider Box
Existing flow lines
Auxiliary flow lines
Figure l._ Plant layout and flow schematic for
phosphorus removal processes, Texas City, Plant No. 2
101
-------
Figure la.-Lime-phosphate sludge on the drain bed, from treatment
of digester liquor after drying to 20-30X moisture content.
102
-------
a-
o
12
11
10
9
8
7
6
5
4
3
2
1
A -Flow thru plant, MGD
B - Ibs. COD/day/lbs. MLS
C -COD in raw influent
D -COD in final effluent
Date, June 1968
Flow thru plant, MGD
Flow to plant, MGD
Ibs. COD/day/lbs. MLS
%Phos. in aeration solids
% Phosphorus removed
3 4 5
.829 .724 .677
.920 .810 .677
.45
4.4
59
.33
4.3
51
.31
4.0
37
E - Phosphorus in raw influent
F - Phosphorus in final effluent
G - Do in aeration effluent
-2.5
-2.0
•1.5
-1.0
• .5
'OOOO
June 3, 1968
June 4, 1968
Junes, 1968
E
O
Figure 2._ Bi-hourly variations of plant influent and effluent
phosphorus and COD, aeration effluent DO, plant flow
rate, and COD/MLS ratio, daily variations of other
parameter. No cations added to primary or aeration processes.
103
-------
.3-
0 1
o •1
A-lbsCOD/Day/lbsMLS
o
Q_
§60
40
20
B-%P in Aeration Solids
C-% Removal of P
g
t/i
O
11-
9
7
5-
3-
1-
D-Total Phosphorus in Raw, mg/l
E-Total Phosphorus in Final Effl. mg/l
F-DO in Aeration Effl., mg/l
-4.0
00
P
'•§
CO
h2.0.E
a.
-3.0
1.0
24 26 28 30 1
August
3 5 7 9 11 13 15 17 19 21 23 25 27 29
September 1968
Figure 3._ Daily variations of phosphorus removal,
COD/MLS loading, %phosphorus in aeration solids and
DO in aeration effluent} dry and wet weather flow;
Aug. 24- Oct. I, I968j no added cations to primary or
aeration processes.
104
-------
Date Aug. 1968
Flow to Plant, MGD
Flow thru Plant, MGD
Ibs. COD/day/lbs. MLS
% P in Aeration Solids
% Phosphorus Removed
13 14 15 16 17 18
.479 .475 .475 .490 .456 .474
.419 .385 .355 .390 .376 .394
.52 .26 .26 .39 .35 .37
3.2 3.1 3.8 4.1 3.4 4.0
34. 53. 51. 53. 48. 35.
o
o
500
480
460
440
420
400
380
360
340
320
300
280
260
240
220
200
20
0
Q_
en
E
A-Plant Flow Rate, MGD
B-COD/MLS Ratio
C-COD Load, mg/l
-.7
— .6
— .5
— .4
— .3
.2
—.1
o o
O •*=
^ ro
•= a:
D-Phosphorusin Raw Infl., mg/l
E-Phosphorus in Final Effl., mg/l
F-DO in Aeration EffI., mg/l
Aug. 13, 1968
Aug. 15, 1968
Figure 3a._ Diurnal variations of flow rates, COD/MLS ratio,
influent COD, influent and effluent phosphorus, aeration effluent
DO, % P in aeration solids, and % phosphorus removed Aug. 13-15,
1968; No cations added to primary or aeration processes.
105
-------
A-Flow Rate thru Plant
B- Total Phosphorus in Raw
C- Total Phosphorus in Final Effl.
D-DO in Aeration Effluent
12
Oct. 1, 1968
Ibs COD/Day/lbs MS .34
% Phosphorus in Aeration Solids 4,3
% Phosphorus Removed 67.
.6
Figure 4._ Around-the-clocK variations of plant flow,
influent and effluent phosphorus, and aeration effluent
dissolved oxygen, Oct. I, 1968
106
-------
Date Oct. 1968
Flow thru plant, MGD
Flow to plant, MGD
Lbs. COD/ day/ Ibs MLS
% phosphorus in aeration solids
% phosphorus removed
5
.622
.622
.39
3.9
30
6
.961
1.511
.31
3.1
9
7
1.015
1.022
.30
3.1
78
8
.943
.943
.30
3.5
67
A Phosphorus in Raw, mg/l
B - Phosphorus in final effl. mg/l
C- DO in aeration effl. mg/l
a_a.<<
-------
Date November 1968
Flow thru plant, MGD
Flow to plant, MGD
Lbs. COD/day/lbs. MLS
% phosphorus in aeration solids
% phosphorus removed
18
.689
.790
.41
1.9
24
19
.622
.673
.34
1.7
10
20
.646
.740
.38
1.7
12
13
12-
11
10
~ 9
E 8
*.
5 7
_
O
6-
5
4
3
2
1
A- Plant flow, MGD
B - Phosphorus in raw influent, mg/l
C- Phosphorus in final effluent, mg/l
D- DO in aeration effluent, mg/l
i i
I I
Nov. 18, 1968
04CM'«t>OOOO
I I I
CN CM •«*•
i i i i i
en o CM CN TT
«O 00 O
Nov. 20, 1968
•9 a
Si
.6 I
.5 !C
.3
<
-------
Date November 1968
Flow thru plant, MGD
Flow to plant, MGD
Lbs. COD/day/lbs. MLS
% phosphorus in aeration solids
% phosphorus removed
24
.666
.666
25
.656
.656
26
.646
.655
A- Plant flow, MGD
B - Phosphorus in raw influent, mg/l
C- Phosphorus in final effluent, mg/l
D- DO in aeration effluent, mg/l
Nov. 25, 1968
Nov. 24, 1968
Nov. 26, 1968
Figure 7._ Bi-hourly variations of plant influent and
effluent phosphorus and aeration effluent DO, and daily
variations of other parameters; Nov. 24, Nov. 25, ft Nov. 26,
1968, no added cations to primary or aeration processes.
109
-------
Date August 1969
Flow thru plant, MGD
Flow to plant, MGD
17 19
.470 .614
.470 .614
Lbs. COD/day/lbs. MLS .47 .58
% phosphorus in aeration solids 1.5 1.3
% phosphorus removed ~.8 20.1
20
.564
.564
.54
1.6
'5.7
16-
15-
14-
§ 13-
00
- 12-
^ 10-
O
f 9-
o
£ 8-
7-
6-
5-
-70
D\
A- Plant flow, MGD
B- Phosphorus in raw influent, mg/l
C- Phosphorus in final effluent mg/l
D- DO in aeration effluent, mg/l
i i i
i i i
August 17, 1969
n
r i\ r
August 19, 1969
F I I I 1 I I
CMCMTJ--OCOO CM
I I I I
hl.5
-1.
0 I
'
-.5 .E
20, 1969
Figure 8._ Bi-hourly variations of plant influent and
effluent phosphorus and aeration effluent DO, and daily
variations of other parameters} Aug. 17, Aug. 19, 8 Aug.20,
1969} no added cations to primary or aeration processes.
no
-------
QQ
O
"03
OH
•o
OJ
"5.
o.
o
^1
E
Q
O
O
o3
oo
CT>
3 E
u_ o
^ j=
y s-
o
£L
Q_
H- .8§
.2-4
A -Flow rate thru Plant
B -Applied Mol Ratio Fe/P
80 -
70 -
60-
50-
40 -
30-
20-
10-
C -COD in Plant Effluent
D -TSS in Plant Effluent
E -Total Phos. in Raw
F - Total Phos. in Plant Effluent
l\ G -Soluble Phos. in Plant Effluent
8 -
7 -
6-
5-
4-
3-
2-
1 -
T^PT
o.— CNCO -^-inoixoooor-
CNCNCNCN CSCMCNCNCNCNCOOO
May 1969
Figure 9. _ Ferrous iron injection to row influent, Texas City Plant No. 2
May 1969 *(on May 3 inadvertent acceptance of 1.5-1.6 MGD rate
for 2-3 hours, raised effluent COD, suspended solids and phosphorus
for the day to 108, !4S, and 8.3 rng/l respectively.)
in
-------
14
13
12
u
a, 10-
=T
S 9-
t
o
"S. 7
6-
'? 5
jr **"
c_
3-
2-
1-
oo
o
o
c
i
-1.10
-1.00
-.90
-.80
-.70
-.60'"
-.50
Two level iron dosing rate:
Low dose - 3.01/hr. for 6 hrs.
High dose-7.9 l/hr. for 18 hrs.
Mol. ratio-Fe/P 1.58 (AMR)
%P removal 94.3
Av. flow thru plant .764 MGD
Bypassed .015 MG
!20
110
100
90 i
>,
n>
5
80 £
c
70 S
A- Phosphorus loading rate, Ib/hr
B- Flow rate thru plant, MGD
C- Total phosphorus in raw influent
D- Total phosphorus in final effluent
E- Soluble phosphorous in final effluent
o
a.
30
20
12
10 12
May 12, 1969
8
10
Rgure 10._ Ferrous iron injection to row influent, with two diurnal
levels of iron dosing, Texas City Plant No. 2
112
-------
14
13
12
~ 11
UJ
08
: 10-
o
o.
E
I
VI
o
9-
8
7
6
5
3 -
2-
1-
Q
O
- 1.10
- 1.00
- .90
. .80
- .70
- .60
- .50
\ A
\
SJNGLE LEVEL DOS ING RATE
Av. Dose Mol Ratio 1.62 Fe/P (AMR)
% P Removal 88.5
Av. Flow Thru Plant - .875 MGD
Bypassed .-..01? MG
A -Flow thru plant, MGD
B - Phosphorus loading rate, Ibs./day of P
C -Total phosphorus in raw
D -Total phosphorus in final effluent
E - Soluble phosphorus in final effluent
-90
' 80 5
-70 ?
o>
o.
I/I
-60 £
-50 *
-40 |
—I
i/)
-30 |
Q.
(/)
-20 °
Q-
-10
12 2 4 6 8 10 12 2 4 6 8
May 28, 1969
Figure ll._ Ferrous iron injection to row influent at single level
dosing rate, Texas City Plant No. 2
10
113
-------
1
16
15-
14-
13-
12-
03 io-
O
o" 9-
S 8-
o
00
o
7H
6
5
4
3
2
1
-1.201
1.001
u_
.90
.80
.70
Single level dosing rate
Av. mol. ratio 1.36 Fe/P (AMR)
% P removal =88.3
Av. flow thru plant =1.49MGD
Bypassed = .125MGD
A- Flow rate thru plant, MGD
B- Phosphorus loading rate, Ibs/day
C-Total phosphorus in raw influent
D-Total phosphorus in final effluent
E- Soluble phosphorus in final effluent
100
90
•80
h7o|
"co
60 f
•g
50.1
T3
Jl
h40 ^
o
30 I
JT
D_
1-20
-10
12 2 4 6 8 10 12
June 3, 1969
Figure I2._ Ferrous iron injection to raw influent at a single
level of dosing rate, Texas City Plant No. 2
-------
t_n
95 n
90 H
tr
o
£L
gso
I
Q_
75
65
A - Linear Equation Y=50.55 + 22.32X
B - Power Equation Y=72.09 X-3821
C - 95% Confidence Limits for A
Correlation coefficient +.6975 significant
at 1% level.
.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7
AMR (Applied Mol Ratio Fe/p)(X)
Figure 13a. - Correlation of Applied Mol Ratio (Y) with % Removal of Phosphorus (X). Points
are 3-day Moving Averages.
1.9
-------
_
o
tn
o>
1.3
1
i.H
i.o-
.9-
.8'
.7"
.6"
.5"
.4'
.3
.2
.1
A = Linear equation Y=.2692X - .1181
B - 95% Confidence limits
Correlation coefficient + .7674 significant
at 1% level
0 .'2 .4" .63l!o l'.2 l'.4 l'.6 l'.8 2'.0 2'.2 2.'4 ?.6 2'.8 3'.0 3'.2 3'.4 3'.6
% PHOSPHORUS IN SOLIDS (X)
Figure I3b. - Correlation of % Magnesium (Y) with % Phosphorus (X) in mixed liquor solids.
3.8 4'.0
6.0H
4.0H
3.0H
o
o
i.H
Linear Equation of best fit
Y-3.1583-.5487X
Correlation Coefficient - .3853
significant at 1% level
•2 .4 .6 .8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0
% PHOSPHORUS IN SOLIDS (X)
Figure 13c. - Scatter Diagram of % Calcium (Y) vs. % Phosphorus (XI in Mixed Liquor Solids.
116
-------
o
en
E
a.
tt
o
17-
16-
15-
14-
13-
12-
11-
10-
9-
8-
7-
6-
5-
4-
3-
2-
1-
12
TWO LEVEL DOS ING
Av. Applied Mol Ratio • 1.44 AI/P
Indicated Removal =80.2%
Insolubilized =84.5%
A -Total P in raw influent
B - Plant flow rate, MGD
C -Total P in final effluent
D - Soluble P in final effluent
Analysis of Final Eff. Composite
Total P, mg/l - 2.8
Soluble?, mg/l -2.2
TSS, mg/l - 9.
% Pin Solids -4.7
AM PM
8
8
10 12 2 4 6
September 11, 1969
Figure I4._ Aluminum chloride injection to primary effluent
September II, 1969 Texas City Plant No. 2
10
117
-------
a
00
CT>
o
0.
O
.c
Q_
15-
14-
13-
12-
11-
10-
9-
8-
7-
6-
5-
4-
3-
2-
1-
12
A -Total P in raw influent
B - Plant flow rate, MGD
C -Total P, in final effluent
D - Soluble P, in final effluent
SINGLE LEVEL DOS ING
At ?.33 Mol Ratio AI/P
Indicated Removal =80.%
I nsol utilization =93.%
Analysis of Final Eff. Composite
Total P, mg/l - 2.8
Soluble P, mg/l - 1.0
TSS. mg/l - 28.
% Pin Solids - 5.6
.5
o
.4 «
M §
-.2
4 6 8 10 1? 2 4 6
September 25, 1969
Figure I5._ Aluminum chloride injection to primary effluent
September 25, 1969 Texas City Rant No. 2
10
118
-------
•s& -
§
O
x:
d.
-------
CD
Q_
•23.0-
to
_-2.0H
o
EUH
•a
O)
Q
O
A- Flow rate thru plant
B-Applied mol. ratio AI/P
-.6
-.4
-.1*
= 50H
en
~o~ 4°^
§8 30H
to
to
20-
10-
C-COD in final effluent
D-TSS in final effluent
U_ O
o
sz
Q_
8-
6-
4-
E-Total P in raw influent
F-Total Pin final effluent
G-Soluble Pin final effluent
September
October
Figure I7._ Aluminum chloride injection into primary
effluent Sept. 9-Oct. 11,1969 Texas City Plant No. 2
120
-------
160 -
150 -
140 -
130-
120 -
110 -
100 -
90 -
80 -
70-
60 -
50 -
40 -
30 -
20 -
10 -
§-
p:
O
0.
CM
^^—
TSS PROFILE OF
DIGESTER ON
JAN.
3, 1969
NO CHEMICAL
TREATMENT
0.0.0.
O O 0
«>r \o oe
-
.C JT JT .C JC
O- O- O. Q. C
Q CS C* Q Q
o CM sr
•—
oc
_
E
o
in
o
CD
a
o
CM
—
•o
to
^
•^
c
CT
1C
_o
an
Oi
CD
Q
CM
C\t
TSS PROFILE OF
DIGESTER ON
JUNE 6, 1969
AFTER FOUR MONTHS
OF I RON DOSAGE TO
PRIMARY AND AERATION
PROCESSES
L.CL O.
, QJ Q}
Q Q
Q. Q_
Q> QJ
Q O
CM
TSS PROFILE OF
DIGESTER ON
OCT. 1, 1969
AFTER SIX WEEKS OF
ALUM DOSAGE TO
PRIMARY AND AERATION
PROCESSES
•O
ra
o3
*-*
c
x:
en
.0.0.0. o. o. o.
Q Q Q Q Q Q
OO *~~* OJ *^J *«O OO
o
CO
Q*
O
CM
CM
Figure 18._ Solids profiles of digester, showing effect of iron
and ohiminum dosage to primary and aeration processes.
121
-------
1
5
Accession Number
2
Subject Field & Group
05D
SELECTED WATER RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
Organization
University of Texas, Medical Branch, Galveston, Texas
Title
PHOSPHORUS REMOVAL AND DISPOSAL FROM MUNICIPAL WASTEWATER
1 Q Author(s)
Connell, Cecil H0
16
21
Project Designation
EPA Project 17010
DYB 02/71
Note
22
Citation
23
Descriptors (Starred First)
#Phosphorus Removal, Biological Up-take3 Metallic Salts, Digester Supernatant
25
Identifiers (Starred First)
^Phosphorus variation, lime addition, hydraulic overload, sludge production
27
Abstract Phosphorus removal was implemented at the full-scale, 1 mgd, Texas City, Texas
Activated Sludge Plant. Over a two-year period, several techniques were investigated.
Control of the plant operations to enhance biological removal of phosphorus was not a
reproducible process. The most efficient means of controlling phosphorus was by the
use of iron salts added to the raw wastewater or primary effluent. Aluminum salts were
slightly less effective. All aspects of plant operation were investigated, such as excess
sludge production and drainability of digested sludge. Estimates of the operating costs
associated with phosphorus removal are presented.
Abstractor
Eo
F.
Barth
Institution
EPA,
WQO,
AWTRL
WR:102 IREV, JULY 1969}
WR5I C
SEND TO: WATER RESOURCES SCIENTIFIC INFORMATION CENTER
U.S. DEPARTMENT OF THE INTERIOR
WASHINGTON, D. C- 20240
* GPO: 1969-35 9-33?
------- |