WATER POLLUTION CONTROL RESEARCH SERIES
17010---01/70
TREATMENT TECHNIQUES
FOR
REMOVING PHOSPHORUS
FROM MUNICIPAL WASTEWATERS
ENVIRONMENTAL PROTECTION AGENCY • WATER QUALITY OFFICE
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WATER POLLUTION CONTROL RESEARCH SERIES
The Water Pollution Control Research Reports describe
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 Water Quality
Offic'e, in the Environmental Protection Agency, through
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Inquiries pertaining to Water Pollution Control Research
Reports should be directed to the Head, Project Reports
System, Planning and Resources Office, Office of Research
and Development, Environmental Protection Agency, Water
Quality Office, Room 1108, Washington, D. C. 202^2.
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TREATMENT TECHNIQUES FOR REMOVING
PHOSPHORUS PROM MUNICIPAL WASTEWATERS
John J. Convery
Sanitary Engineer
Presented
at
New York Water Pollution Control Association
New York, New York
Program #17010
Environmental Protection Agency
Water Quality Office
Advanced Waste Treatment Research Laboratory
Cincinnati, Ohio
January 29, 1970
For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C., 20402 - Price 50 cents
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INTRODUCTION
A great deal of work has been and is being done to develop improved
methods for removing the nutrient phosphorus from municipal waste-
waters,, The literature is replete with articles on the sources of
phosphorus, its eutrophying effects on the water environment, the
necessity for control, and the methodology of control.
The purpose of this paper is to summarize the alternative methods
of removing phosphorus from municipal wastewaterso The intent is
to provide perspective to those municipal officials, engineers and
operators contemplating incorporation of nutrient control measures
into their treatment facilities and to indicate that the necessary
technology is available„ Process selection will depend on specific
wastewater characteristics, existing facilities, desired effluent
quality, and economic considerations.
Processes considered include: conventional treatment, digester
supernatant treatment, modified biological treatment, chemical addi-
tion in primary, secondary and tertiary stages of treatment, and
moving bed filtration.
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TABLE OF CONTENTS
I. PHOSPHORUS REMOVAL BY CONVENTIONAL TREATMENT
A. TREATMENT OF DIGESTER SUPERNATANT
B. BIOLOGICAL PHOSPHORUS REMOVAL
II. PHOSPHORUS REMOVAL BY CHEMICAL PRECIPITATION
A. IRON AND ALUMINUM SYSTEMS
I. Treatment of Raw Sewage
a. Iron Systems
2. Chemical Addition to Secondary Biological Processes
a« Activated Sludge
b. Trickling Filters
3. Tertiary Treatment with Alum
Bo LIME TREATMENT
10 Raw Sewage
2o Tertiary Treatment
III. MOVING BED FILTRATION OF ALUM TREATED WASTEWATER
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I. PHOSPHORUS REMOVAL BY CONVENTIONAL TREATMENT
The conventional treatment techniques of settling and biological
oxidation are capable of removing some phosphorus as indicated in
Table 1.
TABLE 1. Phosphate Removal by Conventional Waste
Treatment Plants
Type of 7o
Treatment Plant Phosphorus Removal
Primary Sedimentation
Primary and Trickling Filter
Primary and Activated Sludge
5-15
20-30
30-50
Regardless of the complex internal mechanism of phosphate removal
(precipitation, absorption, etc0), the actual phosphorus removal that.
a conventional plant can achieve will ultimately depend upon the amount
of sludge permanently removed from the process stream. Since some
807o of the phosphates present in sludge are solubilized during anaerobic
digestion, the higher removal efficiencies cannot be achieved unless
the recycle of untreated digester supernatant is eliminated.
A. TREATMENT OF DIGESTER SUPERNATANT
Treatment of the digester supernatant stream separately can achieve
effective phosphorus removal. Lime clarification and ammonia stripping
have been evaluated*•* for the treatment of digester supernatant. The'
supernatant is first air blown to strip out C02 which raises the pH of
806 thereby reducing the lime requirements. A lime addition- of 3 to 4
gm/1 is then added to achieve the required operating pH of 11 to 12„
At this elevated pH, the phosphorus is precipitated and the ammonia
nitrogen in the clarifier effluent (375 mg/1) can be efficiently •,
stripped in a countercurrent tower. At 20°C, approximately 275 ft
of air/galoois required to achieve 907» ammonia removal. At 60 C,
about 50 ft /gal. would be required to achieve 90% removal. However,
heating the digester supernatant to reduce the air and equipment
requirements is not economically justified. Removal efficiencies
of the lime clarifier are shown in Table 2.
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TABLE 2. Results Achieved by Lime Clarification of
Digester Supernatant*•*
Constituent
Suspended Solids
COD
Total Carbon
Ortho - PO, as P
Total - PO^ as P
Digester
Supernatant
mg/1
1415
2840
1284
44
96
Treated
Effluent
mg/1
140
640
260
1
3.6
% :
Removal
90
77.5
79.8
97.8
96,3
Total operating costs for digester supernatant treatment including
carbon dioxide stripping, lime clarification and ammonia stripping
are estimated to be about $0.30/1,000 gal. of supernatant which is
equivalent to $0001 to $0.015/1,000 gal, of total plant flow.
A comprehensive study to determine the least cost solution for treating
digester liquor (primary digester overflow), digester supernatant liquor,
thickener overflow and a 50% mixture of primary and waste activated
sludge has recently been completed. A report of the findings should
be available for distribution in the near future.
B. "BIOLOGICAL" PHOSPHORUS REMOVAL
Several activated sludge plants have historically experienced high
phosphate removal efficiencies. The most notable is the Rilling Road
Plant at San Antonio, Texas where an average of 80% phosphate removal
was experienced during 1965» There is conflicting evidence in the
literature as to the mechanism of phosphorus uptake. A chemical pre-
cipitation and a biological mechanism can both be postulated to explain
the observed phenomena. A summary of the two schools of thought is
presented by Jenkins and Menar-^. The first hypothesis, advocated by
Sawyer, Sekikawa,'et al., Hall and Engelbrecht, and Jenkins and Menar,
states that biological removal of phosphate can only account for 207» -
307o of the influent phosphate with an activated sludge phosphorus con-
tent of 270 - 370 and standard substrate removal rates in the range of
0.4-1.0 Ib COD removed/lb MLVSS-day. Phosphate removal in excess of
that predicted by biological growth requirements is caused by chemical
precipitation of calcium phosphate. Simply stated, the postulated
mechanism involves:
I. Hydrolysis of condensed phosphate to orthophosphate;
2o Decreased production of C0_ through the aerator as the
organic matter is oxidized;
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3. An increase in pH occurs due to the reduced CO generation
and removal of CCL by aeration;
4. Localized pH conditions exist which are favorable for the
precipitation of calcium phosphate.
The second point of view, advocated by Levin and Shapiro, Borchardt
and Azard, and Connell and Vacker indicates that under certain con-
ditions, activated sludge is capable of removing more phosphate than
it requires for growth. This biological uptake of excess phosphate
has been termed "luxury uptake." It is thought by these authors that
the percentage of phosphate incorporated into the biological sludge
is affected by the growth rate of the organisms and certain process
operating parameters such as the organic loading, mixed liquor sus-.
pended solids concentration (MLSS), aeration rate, and mixed liquor
dissolved oxygen (D.0») concentration. The design and operating
criteria reported in the literature to achieve luxury uptake of
phosphorus are shown in Table 3.^
TABLE 3. Conditions for "Luxury Uptake" as Reported
in the Literature^
DO - mg'/l „ > 2oO
Air Supply - ft /gal. 3-7
Hydraulic Detention
Time - Hours 3-6
Organic Loading
Ib BOD/lb MLSS day 0.4-0.5
MLSS - mg/1 ' 2500-4000
Sludge Detention Time for
Solids Separation - Hours < 1=0
Investigations are currently being conducted to further elucidate the
mechanisms of phosphate removal by activated sludge treatment, A 1-mgd
plant, specifically designed and operated for maximum biological up-
take of phosphorus, has been constructed and operated through a cooper-
ative effort between the Greater Manassas Sanitary District, Prince
William County, Virginia and the Federal Water Quality Administration.
The plant treatment facilities consist of a first-stage aerator, flo-
tation unit, second-stage aerator, final clarifier, chlorine contact
tank, digesters, supernatant treatment facilities and sand drying beds,
A recent report-*-^ on the operation of this plant concluded:
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lo Specialized design of the activated sludge plant to achieve
removal of phosphorus by either luxury uptake and/or physical-
chemical phenomena should be avoided0 Such removals should be
considered a bonus when and if they occur in existing or newly
constructed plants0
2. While maximum phosphorus removals (0.022 to 0.026 Ibs of P/lb
of COD removed) were possible at a cell residence time of 306
days, overall phosphorus removal was limited by plant design
considerations, effluent suspended solids concentrations and
phosphorus release during solids separation.
3o Total plant operating costs were estimated to be $0048/1,000
gal., or 2 to 3 times the cost of conventional activated sludge.
4« Significant operating problems were experienced in handling
the waste activated sludge which was difficult to dewater0
II. PHOSPHORUS REMOVAL BY CHEMICAL PRECIPITATION
The current state-of-the-art of phosphorus removal technology indicates
that chemical precipitation is the most economical method of removing
phosphorus from municipal wastewater. Alternatives which the design
engineer must consider include the choice of chemicals (iron, aluminum
or lime) and the point of chemical addition (primary, secondary or
tertiary). The point at which to add the chemicals is dependent to
a great extent on the other unit processes being utilized in the treat-
ment train. Phosphorus removal is not an isolated design problem
capable of solution through independent considerations; it requires
an integrated solution consistent with all other treatment requirements.
The choice of chemical and point of addition depends on several factors
shown in Table 4. The significance of each will become apparent in the
detailed discussions of each chemical system.
TABLE 40 Factors Affecting Choice of Chemical and Poifft-
of Addition for Phosphorus Removal
10 Influent Phosphorus Level
2o Effluent Discharge Standard
3. Wastewater Characteristics
(Alkalinity, Etc0)
4. Plant Size
5. Chemical Costs Including Transportation
60 Sludge Handling Facilities
7o Ultimate Disposal Alternatives
8, Other Processes Utilized
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A. IRON AND ALUMINUM SYSTEMS
lo Treatment of Raw Sewage
The alternative chemical, systems for phosphorus removal in the primary
are shown in Table 50 The iron and aluminum systems are discussed
together because of the similarity in chemistry, dosing requirements,
design considerations and performance. A discussion of lime precipi-
tation in primary and tertiary treatment applications is deferred for
separate consideration.
Phosphorus removal should be thought of as a two-step operation: preci-
pitation of the soluble phosphorus and removal of the insoluble phos-
phorus.
With the iron and aluminum systems, the primary coagulant is added first
at a dose of 1025 to 1.75 mole of metal ion per mole of soluble phos-
phorus to precipitate the soluble phosphorus. The dosing is therefore
proportional to both the influent soluble phosphorus concentration and
flowo
With the ferrous system, a base, either Ca(OH),, or NaOH must be added
to achieve optimum flocculation in the primary. Next the insoluble
phosphorus is removed by flocculation with anionic polymers and settled
or filtered with a device such as the Moving Bed Filter (discussed in,
detail later).
Sufficient time (0-5 min) should be provided between dosing of the
primary coagulant and base if necessary, and dosing of the organic
polyelectrolyte to insure completion of the precipitation reactions.
This can best be determined by preliminary jar testing. If there is
insufficient detention time or inadequate mixing conditions in the
influent sewer, separate mixing and flocculation facilities will have
to be provided.
TABLE 5. Alternative Chemical Systems for Phosphorus
Removal in the Primary
A. Iron:
Ferrous Chloride - Base Without Polymer
or Sulfate
Commercial or Lime or
Waste Pickle Sodium
Liquor Hydroxide
Ferric Chloride Without Polymer
or Sulfate
B0 Aluminum:
Alum or Aluminate Without Polymer
Co Lime: Without Additives
1 or 2 Stage
. 5 _
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Iron Systems
Performance results from several full-scale plants with chemical
addition in the primary are shown in Table 6. The chemical systems
and dosing levels used are shown in Table 7. Overall removal of sus-
pended solids, biochemical oxygen demand and phosphorus was signifi-
cantly improved. Since these removals were attained.in existing
facilities, higher removal efficiencies can be expected with plants
especially designed for chemical treatment of raw sewage„
It is interesting to note that both forms of waste pickle liquor,
ferrous chloride (9% Fe at Mentor) and ferrous sulfate (67o-970 Fe at
Texas City), were successfully used for phosphorus removal. When
available within reasonable hauling distances, these materials are an
inexpensive source of iron ($0.015/lb of Fe at Texas City and $0.02/lb
of Fe at Mentor, Ohio).
Several features of the Texas City, Texas operation and performance are
significantly different from the other plants mentioned. Ferrous
sulfate was added to the raw sewage without a base or polyelectrolyte.
Very little phosphorus (0.03 mg/1 as P) was removed by primary treat-
ment. The bulk of the phosphorus (4.7 mg/1,as P) was removed in the
aerator and final settler to yield an overall phosphorus removal effi-
ciency of 817o with an effluent concentration of 1.1 mg/1. The ferrous
iron was oxidized to the; ferric iron in the aerator, thereby elimina-
ting the required addition of a base such as Ca(OH),? or NaOH. The
aerator served as an excellent collector of the iron phosphate preci-
pitate, which can be attributed to the large floe mass available in
the aerator to absorb the precipitate,- and the presence of naturally
occurring polymeric material to aid fIocculation0 A ferrous system
can be used to attain phosphorus removal in an activated sludge plant
without the use of a base or polyelectrolyte,, However, if a base and-
polyelectrolyte were used with the ferrous system one could expect to
remove increasing amounts of phosphorus, suspended solids and BOD in
the primary thereby reducing the load on the secondary facilities.
Also, a greater portion of the phosphorus removed in the primary
would be chemically bound, thereby reducing the phosphorus concentration
in the digester supernatant return.
Experience at Mentor, Ohio indicates that addition of a base and
polyelectrolyte are necessary to efficiently remove phosphorus from
a primary plant with a ferrous system as shown in Table 8.
These data indicate that the base is more important than the polymer.
(Compare treatment conditions 4 and 5). The function of the base is
not well understood; it could be an olation reaction in which the
hydroxyl ions bridge between the iron molecules effecting a certain
degree of polymerization.
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TABLE 60 Phosphorus Removal at Full-Scale Plants Adding
Chemicals in the Primary
Type of Plant
Primary:
Grayling
Mentor
Average
Influent
Phosphorus
mg/1
15.5
15.7
Fe/P
mole
ratio
1.1-1.8
1.4
% Removal - Total Plant
Suspended Total
Solids BOD Range
78(61)* 58(40) 60-80
74 59
Phosphorus
, Average
72
83.5
Trickling Filter:
Lake Odessa
Activated Sludge:
Benton Harbor
Texas City
*
7.5
6,2
1.55
1.7
89(78) 82(62) 75-95
92.5[72.5]
*" •&**&••£•
84o7 72-94
) Without Chemical Addition
] Removal Efficiency Across the Primary
COD
82
90.9[65.3]
87.2
TABLE 7. Chemical Systems and Dosing Levels Used at Full-Scale Plants
for Phosphorus Removal
Location
25
Grayling, Mich.
& Lake Odessa, Mich<
Benton Harbor, Mich.
3
Mentor, Ohio
11
Texas City, Texas
23
Chemical
Fed as Fe
NaOH^ as CaCO~
A-23
FeCl, as Fe
A-23
Waste Pickle Liquor,
FeCl- as Fe
A-23
Waste Pickle Liquor,
FeSO. as Fe
4
Dose
15-25 mg/1
30-50 mg/1
Oo3-0«5 mg/1
21.0 mg/1
Oo3 mg/1
43 mg/1
66 mg/1
.4 mg/1
19 mg/1
A-23 Anionic Polyelectrolyte - Product of the Dow Chemical Company
&*
Mention of a proprietary product does not constitute an endorsement
or recommendation by the Federal Government.
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TABLE 8. Results of Selected-Chemical Treatment in Primary Utilizing
Waste Pickle Liquor - Mentor, Ohio
Treatment
Conditions
1.
2.
3.
4.
5o
6,
Polymer
Lime -
Iron -
Iron -
Polymer
Iron -
Lime -
Iron -
-
67
50
50
-
43
55
43
0.5 PPM
PPM
PPM
PPM
0.5 PPM
PPM
PPM
PPM
Flow
MGD
2
2
3
4
4
4
.4
o4
.8
.6
06
.0
7o Removal
Suspended
Solids
37
48
13
5.3
58
74
BOD
24
15
30
29
62
59
COD
44
33
29
34
63
Total
Phosphorus
9.5
46
40
42
76
83 o5
Lime - 66 PPM
Polymer - .4 PPM
The liquid handling aspects of phosphorus removal in the primary clari-
fier are relatively straight forward and well quantified. Sludge
handling considerations and other plant operations are also signifi-
cant, but the current data is less definitive. Probably the..most
quantitative data available are the results at Benton Harbor which
are shown in Table 9,
TABLE 9. Plant Data at Benton Harbor Using Ferric Chloride
11
No Chemical
Addition
Chemical Addition
* *
Recycle to Primary No Recycle
Primary Clarification
Volume Pumped, Gal/Day 53,200
Percent Solids 3080
Percent Volatile 64
51,600
4.29
63
46,100
4.82
60
Mixed Liquor Data
Suspended Solids, mg/1 2500
Sludge Volume Index 85
Dissolved Oxygen, mg/1 4«8
Air Applied, cfm 4480
Digester Operation
3
Gas Production - ft., 37,800
Gas Production - ft /lb 3.48
of solids
* Recycle refers to Waste Activated Sludge
2700
78
5.9
4940
44,400
3.82
2400
64
6.6
4710
40,800
3.67
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The study at Benton Harbor was conducted in three stages, a baseline
period with no chemical addition, a second period with the addition
of ferric chloride and polymer with wasting of the activated sludge
to the primary and a third period in which there was no wasting to the
primary. Benton Harbor utilizes the "Kraus Process" which consists
of returning a reaerated portion of the digested solids and waste acti-
vated solids to the primary. Chemical addition increased the solids
concentration of the primary sludge from 3.8% to 4,37o,' When wasting
activated sludge to the primary was discontinued, the solids concen-
tration increased to A.87»« The chemical addition and removals accom-
plished in the primary benefited the operation of the "Kraus Type"
activated sludge treatment. Dissolved oxygen in the aeration tanks
increased and the settleability of the activated sludge improved with
the sludge volume index decreasing from 85 to 78 and 64 respectively.
No quantitative data are available on the effect of various degrees of
chemical treatment in the primary on the performance of the conventional
activated sludge process, A full-scale study to evaluate these effects
at Grand Rapids, Michigan has been supported by an FWQA grant0 A
short-term study has been carried out at Pontiac, Michigan18. Prelim-
inary results indicate that satisfactory performance of the biological
system was maintained utilizing 757o of the design capacity.
Digester operations proceeded normally at Texas City, Mentor and at
Benton Harbor where gas production increased from 3.48 to 3.82 ft-Vlb
total volatile solids. The soluble phosphate concentration in the
digester supernatant return was very low.
Chemical requirements for sludge conditioning at plants utilizing
ferric chloride and lime such as Pontiac, Michigan (activated sludge)
and Wyoming, Michigan (trickling filter) were unaffected by the iron
treatment. Plants utilizing polymers for sludge conditioning such
as Cleveland Westerly required additional anionic polymer to neutralize
the positive charges of the iron floe18. Vacuum filter yields were
also comparable with and without the iron treatment. There is of
course an increase of about 207» in the total pounds of solids that
must be handled in a primary plant. In an activated sludge plant
this would be offset in part by a reduction in the pounds of waste
activated sludge produced,
Cost Estimates
Operating costs of chemical treatment in the primary depend on the
choice of chemical system, chemical costs, transportation costs, and
handling costs for the additional inorganic sludge.
Capital costs will include chemical storage facilities, slurry and
feeding systems and, where necessary, additional mixing and floccu-
lation facilities. Total operating costs have been estimated for
facilities like Lake Odessa and Grayling, Michigan to range from a
possible low of $0,01/1,000 gal. to $0.05/1,000 gal25,
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The chemical costs at Mentor, Ohio, utilizing waste pickle liquor,
are estimated to be $0,,023/1,000 gal3., An.additional cost of
$0.01/1,000 gal. is required to handle the excess sludge through
digestion and vacuum filtration.
2. Chemical Addition to Secondary Biological Processes
a0 Activated Sludge. The pioneering work in this area was
conducted by E. A. Thomas and more recently by Earth and Ettinger „
For their studies various chemicals were added to the aerator of a
100-gpd activated sludge planto Results are shown in Table 10.
TABLE 10. Phosphorus Removals Obtained by Mineral Addtion
to the Aerator
Chemical
Dose
mg/1
Phosphorus Removal
/o
None
Calcium
150
40
64
Calcium
+
Fluoride
150
6
75
Magnesium 20 50
Ferric Iron 15 75*
Aluminum^ (as Alum) 20 70*
Aluminum (as Alum) 30
90
Calcium 20
Aluminum 5 74-94
(as Sodium Aluminate)
Aluminum 10 90-98
(as Sodium Aluminate)
_
Turbid effluent
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Sodium aluminate was found to be superior to the other additives tested
in terms of phosphorus removal efficiency and the fact that it elimi-
nated the-need for adding sulfate, chloride or calcium if pH control
is necessary„ In general the addition of 1,4 moles of aluminum for
each mole of phosphorus entering the aeration chamber produced a final
effluent containing approximately 0.5 to 100 mg/1 phosphorus. Optimum
dosages ranged from 1.2 to 106 moles of A.l+++ per mole of P, Over-
dosing was detrimental to plant performance causing an increase in
effluent turbidity and phosphorus concentration.
A full-scale evaluation (2 mgd) of mineral addition conducted at
Pomona, California produced the results shown in Table 11.
TABLE 11, Results-of Mineral Addition to 2-mgd Plant
at Pomona, California
Aluminum
Form
NaAl (OH)4
NaAl (OH) ,
NaAl (OH).
A12(S04)3
Ratio
A1:P
1:1
1.5:1
2:1
1:1
Io4:l
Overall Phosphorus
7
to
Unfiltered
78
85
90
80
90
Removal
Filtered
85
94
96
83
95
The results at Pomona indicate that alum was slightly superior to
aluminate in terms of phosphorus removal. One problem resulting from
the mineral addition was a deterioration of effluent quality in terms
of turbidity,, The changes in effluent pH and turbidity as a function
"of aluminum dose are shown in Figure 1. The addition of either alum
or sodium aluminate raised the effluent turbidity from about 4 Jackson
Turbidity Units (J.T.U.) to about 20 J.T.Uo This turbidity can be
attributed to the change in pH beyond the optimum pH for aluminum
flocculation. The effluent turbidity returned to normal within two
days after the mineral addition was stopped. The turbidity problem
was solved by the addition of 2 mg/1 of polyelectrolyte to the mixed
liquor prior to final clarification. The improvement in effluent
turbidity effected by the polyelectrolyte addition is shown in Figure 2,
Before mineral addition was initiated at Pomona the mixed liquor sus-
pended solids averaged 1,800 mg/1 and the return sludge averaged
4,000 mg/1,, The solids were 75% volatile. After aluminum addition
the MLSS increased to 3,000 mg/1 and the RSSS increased to 8,200 mg/1.
- 11 -
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8.0
FIGURE 1
EFFECT OF ALUMINUM ADDITION ON PH AND TURBIDITY
OF SECONDARY EFFLUENT
POMONA STUDY
MINERAL ADDITION
DISCONTINUED
7.5
7.0
30
20
10
0
2
6
8 10
TIME,DAYS
12
14
16
18
-------
18
FIGURE 2
EFFECT OF POLYELECTROLYTE ADDITION ON TURBIDITY OF EFFLUENT
DURING PHOSPHORUS REMOVAL STUDY
POMONA
3
4 5
TIME.HRS.
6
7
8
-------
The solids were 617, volatile0 Because of this significant change in
the percent of volatile solids in the return sludge and mixed liquor
solids, it is imperative that the amount of sludge wasting be accurately
controlled. If this is not done there is a distinct possibility that
not enough active bacterial solids will be retained to maintain the
treatment efficiency of the biological process„ This is particularly
significant in the extended aeration type of operation where the rates
of cell growth are Iow0
4
The pilot plant results of Earth, et al., indicated that the mixed
sludge produced with mineral addition had superior settling character-
istics (SDI=1.3) compared to the biological sludge (SDI=0.5). Digester
operation and gas production were reported to be normal„ The phosphorus
content of digester supernatant was reduced from 50 - 100 mg/1 to 10 mg/1
as P indicating that the phosphorus remained insoluble through anaerobic
digestion.
b,, Trickling Filters. Direct dosing of aluminate to a trickling
filter was evaluated at Fairborn Ohio-*. The results are shown in Table
12o This approach cannot be recommended where high phosphorus removal
efficiency is required„
TABLE 12„ Results of Direct Dosing of Aluminate to a Trickling Filter
Unit efficiency - Primary effluent to final effluent
% Removal
Dosed
Filter
Control
Filter
Total
Phosphorus
63
13
COD
74
75
S. S.
51
51
pH
7,9
7.8
A1:P
1:1
Overall efficiency - Raw wastewater to final effluent
% Removal
Dosed
Filter
Control
Filter
Total
Phosphorus
64
17
COD
83
83
S.S.
84
85
PH
7.9
7.8
A1:P
1:1
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Cost Estimates
Principal operating costs for chemical addition to the aerator will be
the cost of chemicals. Alum at $0.24/lb* or aluminate at $0.35/lb*
are quite comparable in performance and can be used together for precise
pH control if necessary,, To achieve 90% phosphorus removal with a
wastewater containing 10 mg/1 of phosphorus in the primary effluent,
the alum costs would be $0.024/1,000 gal. at a mole ratio of 1.4:1 Al/P.
The only additional costs are the amortized cost of the chemical feed
system and the operating costs associated with handling the increased
quantity of sludge„ Total operating and maintenance costs are esti-
mated to be $0,036/1,000 gal.
3. Tertiary Treatment with Alum
Excellent phosphorus removal can be obtained by tertiary alum clarifi-
cation. Results of studies at the FWQA-Lebanon Pilot Plant are shown
in Table 13.
TABLE 13. Results of Tertiary Alum Treatment at Lebanon, Ohio
Process Stream
Secondary Effluent
Settled Alum-Treated
Effluent
Filtered Product
Suspended
Solids, mg/1
45.6
11.0(76%)"*
1.3(97%)
Phosphate
mg/1 P0=
22.4
2.2(90%)
0.9(96%)
Turbidity
J.T.U.
12.2
1.5(88%)
0.5(96%)
Operating Conditions :
Overflow rate: 700 gpd/ft
Alum dose: 82 mg/1 .
Aluminate dose: 68 mg/1
Silica dose: 3 mg/1
Filtration rate: 3 gpm/ft
Effective size of coal: 1.325 mm
Effective size of sand: .45 mm
Length of run:
Alum sludge
concentration:
25 hrs.
1.2% by wgt<
Solids concentration
in backwash water : 475 mg/1
**
Percent Removal
cost per pound of aluminum
- 15 -
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Tertiary alum clarification, filtration and granular carbon adsorption
is being used to renovate 400-gpm of secondary effluent from the Nassau
County, New York Bay Park Plant. Alum was chosen to minimize post
precipitation problems in the injection well and maintain chemical
equilibrium between the renovated water and the water in the aquifer.
Unlike lime sludges, alum sludges cannot be recovered and reused-
Although several recovery schemes are being investigated for alum
recovery, none has yet proven to be practical.
Alternative methods of alum sludge dewatering might include natural
freezing where appropriate, and rotary precoat vacuum filtration.
B. LIME TREATMENT
The chemistry of lime treatment is entirely different from the chemis-
try of the iron and alum systems. When slaked lime, Ca(OH)2> is added
to the wastewater, it reacts with the bicarbonate alkalinity precipi-
tating CaC03. Calcium ions also react with the orthophosphate to
precipitate hydroxylapatite Ca,. (OH) (PO, )„, the only stable calcium
phosphate phase in the alkaline pH range. The precipitation of Mg(OH)_
begins around pH 10 and is essentially complete at pH 12. A simpli-
fied representation of the reactions that occur are as follows:
Precipitation
5 Ca44" + 7 OH" + 3 H2PO^ = Ca5OH(P04)3 (S) +6 H20
Ca"1"1" + HCO~ = CaC03(S) + H20
Mg44" + 2 OH" = Mg(OH)2(S)
Recarbonation
Ca4"1" + 2 OH" + C02 + H20 = CaC03(S) + 2 H20
Mg (OH) 2 + 2 C02 = Mg44" + 2 HC03
Recalcination
CaC03 + HEAT = CaO + C02
Mg(OH) + HEAT = MgO + H0
- 16 -
-------
1, Raw Sewage
Lime requirements for phosphorus removal are independent of the influent
phosphorus concentration and dependent on the wastewater alakalinity
and operating pH, as shown in Figure 3„
Phosphorus removal by lime treatment is a two-step process involving
the insolubilization of the various forms of phosphorus and the physical
separation of the particulate phosphorus from the wastewater. Jar
test results on phosphorus removal from the raw wastewater, secondary
effluent and a nitrified effluent at the FWQA-DC Pilot Plant are shown
in Figures 4, 6 and 8^1. The total soluble phosphorus (filtered) was
reduced to 0.3 mg/1 as P or less for all three wastewaters at pH 10„
However, the total phosphorus concentration was not reduced to 0.3 mg/1
by sedimentation until pH 11.5 was attained. Two effects are accom-
plished by operation at higher pH: (1) Mg(OH)2> a gelatinous precipi-
tate forms, aiding, clarification and (2) additional CaCC>3 forms enhancing
floe stability and settling characteristics. Examination of Figures
5, 7 and 9^1 provides additional insight into the chemical changes that
occur as lime is added to the wastewaters. Below pH 10, the total and
soluble calcium concentrations increase only gradually as a function
of the lime dose because part of the added calcium settles as precipi-
tates of phosphate and carbonate. Above pH 10, the residual calcium
(total and soluble) decreased in spite of the fact that additional
lime was being added and the precipitation of phosphorus was essentially
completed. The precipitation of most of the bicarbonate alkalinity
as calcium carbonate accounts for this decrease in the residual calcium
concentration. Above pH 11.5, the residual calcium concentration
increases with lime dose as the precipitation of the bicarbonate alka-
linity is nearly completed.
Comparison of the soluble calcium and total residual calcium concen-
trations indicates, especially in the D.C. secondary (Figure 7), the
existence of an unsettleable precipitate as evidenced by a visual
haze. This haze contains phosphorus and reduces overall phosphorus
removal efficiency. The amount of haze was variable and was usually
eliminated at pH greater than 11.5 which corresponds to the pH for
completion of the Mg(OH)_ precipitation. The haze was much less in
the raw wastewater (Figure 5) and nonexistent in the nitrified
effluent (Figure 9).
The behavior of a wastewater of moderate alakalinity (100-150 mg/1 as
CaCCO differs from highly alkaline wastewaters (350 mg/1) such as
found at Lebanon, Ohio. Sufficient calcium carbonate is precipitated
in the pH range between 9.5 to 10 with a highly alkaline wastewater
to produce a settleable sludge, clear effluent and filterable residual
turbidity . In the high pH lime process (pH = 11.5), the excess
calcium ions from the lime may be precipitated with C0? in a recar-
bonation basin and settled in a second sedimentation basin, or may be
precipitated in the first stage with Na.CO.,.
- 17 -
-------
800
TOTAL ALKALINITY (INITIAL)
A 22(mg/l)
Al20(mg/l]
a 240(mg/l)
o600(mg/l)
600
CO
400
200
0
7
9 10 11
PH
FIGURE 3
LIME REQIREMENTS AS A FUNCTION OF pH
AND WASTEWATER ALKALINITY
12
-------
A TOTAL PHOSPHORUS,UNFILTERED
TOTAL PHOSPHORUSJILTERED
0 ORTHOPHOSPHATE, UNFILTERED
• ORTHOPHOSPHATE,FILTERED
0
7 8 9 10 11
PH
FIGURE 4
RESIDUAL PHOSPHORUS IN LIME TREATED D.C
RAW WASTEWATER AS A FUNCTION OF pH
-------
150
100
OJ9
50
0
OTOTAL DECANT Ca
• SOLUBLE Ca
- ASOLUBLE Mg
8
11
8
6
4 d
2
0
12
9 10
PH
FIGURE 5
CALCIUM AND MAGNESIUM CONCENTRATIONS IN LIME
TREATED D.C. RAW WASTEWATER AS A FUNCTION OF pH
-------
CMO
A TOTAL PHOSPHORUS. UNFILTERED
A TOTAL PHOSPHORUS,FILTERED
0 ORTHOPHOSPHATE, UNFILTERED
• ORTHOPHOSPHATE/FILTERED
0
7
pH
FIGURES
RESIDUAL PHOSPHORUS IN LIME TREATED D.C
SECONDARY EFFLUENT AS A FUNCTION OF pH
-------
150
100
50
oTOTAL DECANT Ca
• SOLUBLE Ca
„ A SOLUBLE Mg
7
8
9
10
11
8
6
4 -
2
0
12
PH
FIGURE 7
CALCIUM AND MAGNESIUM CONCENTRATIONS IN LIME TREATED
D.C. SECONDARY EFFLUENT AS A FUNCTION OF pH
-------
10
8
tSJO
C/5
A TOTAL PHOSPHORUS.UNFILTERED
A TOTAL PHOSPHORUS, FILTERED
o ORTHOPHOSPHATE, UNFILTERED
• ORTHOPHOSPHATE, FILTERED
0
7
FIGURE 8
RESIDUAL PHOSPHORUS IN
LIME TREATED NITRIFIED EFFLUENT AS A FUNCTION OF pH
-------
150
100
to*
30
0
TOTAL DECANT Ca
SOLUBLE Ca (SIMILAR TO TOTAL DECANT Ca]
SOLUBLE Mg
7
8
9
10
11
8
6
4 ^
2
12
PH
FIGURE 9
CALCIUM AND MAGNESIUM CONCENTRATIONS IN LIME
TREATED NITRIFIED EFFLUENT AS A FUNCTION OF pH
-------
The reactions for these alternatives are as follows:
Ca++ + 2 OH" + C02 —> CaC03 + H2 CaCCL + 2 Na+
A flow scheme for the two-stage lime treatment process utilizing inter-
mediate recarbonation is shown in Figure 10. The waste lime is thickened,
dewatered on a vacuum filter, recalcined in a multiple-hearth furnace at
1850°F and reused. The COo from the recalcination furnace is used for
the recarbonation step. Phosphorus removal by lime precipitation is a
very flexible process. It can be designed for single-stage or two-stage
treatment of either raw wastewater or secondary effluent. The choice of
design configuration is governed by: (1) residual phosphorus requirements,
(2) influent wastewater characteristics and (3) other unit processes in
the treatment train.
The excellent results obtained at the FWQA-D.C. Pilot Plant.at Washington,
B.C. and the FWQA Pilot Plant at Lebanon, Ohio on physical-chemical
treatment of primary effluent are shown in Table 14. These studies demon-
strate the excellent removals attainable on either soft or hard waters by
two-stage and single-stage lime clarification respectively. The studies
were conducted on primary effluents. Similar studies on raw sewage are
planned. The operating criteria in effect when the data in Table 14 was
obtained were as follows:
FWQA-DC PILOT PLANT LEBANON PILOT PLANT
Overflow rate 1100 gpd/ft2 1400 gpd/ft2
1st stage pH 11.8 - 12.0 9.5
Lime dose 350-400 mg/1 as CaO 250
2nd stage pH 10-10.5
Ferric addition to 5 mg/1 as Fe+++
2nd stage
A 10-mgd plant employing chemical clarification of raw sewage and granular
carbon adsorption is being designed at Rocky River, Ohio. Construction
and operation of this plant is being partially financed by an FWQA
Research and Development Grant.
- 25 -
-------
INFLUENT'
FIRST
STAGE
CLARIFIER
C02
HEARTH
FURNACE
QQ
SOLIDS WASTE
MAKE-UP
LIME
RtCAPBOrt
ATION
TANK
THICKENER
VACUUM
FILTER
FILTRATE
CtASfFIER
PRODUCT
LIME SLUDGE
FLOW SCHEME FOR
TWO-STAGE
HSGH LIME PROCESS
-------
TABLE 14. Results of Treatment by Lime Clarification, Filtration and
Carbon Adsorption of Primary Effluent at Washington, E.G.-
(I) and Lebanon, Ohio24 (II)
Two-Stage Lime
Clarification - Low
Alkaline Wastewater(I)
Single-stage Lime
Clarification - High
Alkaline Wastewater(II)
mg/1
7o Removal
7o Removal
Primary Effluent
Phosphorus , P
TOC
BOD
COD
S.S.
Turbidity (J.T.U.)
Lime Clarified Effluent
Phosphorus , P
TOC
BOD
COD
s.s.
Filtered Effluent
Phosphorus
TOC
BOD
COD
S.S.
Turbidity (J.T.U.)
Carbon Effluent
Phosphorus
TOC
BOD
COD
S.S.
Turbidity (J.T.U.)
10.4
78.4
139
265
-
Oo5
27.1
42.0
86
14.8
0.39
22.6
28
66
-
6.5
4
11
-
94.8
65.2
69.7
67.6
96.2
69.9
80oO
75.0
90.6
97
95.8
8.8
76
76
192
85
55
< 1
26
25
67
10
2
< 1
10
10
27
1
1
> 89
52.3
67.2
65,0
> 89
87
87
86
* All analyses run by Standard Methods 12th Edition
Single-stage low pH lime clarification followed by activated sludge treat-
ment has been suggested as a viable treatment technique to achieve 85%
phosphorus removal. This combination of unit processes has been called
the PEP Process and is being marketed by Dorr-Oliver, Inc.
Rochester, New York is presently planning a 100 mgd plant incorporating
lime clarification followed by activated sludge treatment.
Trademark of Dorr-Oliver, Inc., Stamford, Connecticut (Use of trade name
does not constitute an endorsement or recommendation by the Federal
Government of the item or product mentioned.)
- 27 -
-------
2. Tertiary Treatment
Single-stage and two-stage lime clarification can be applied as tertiary
treatment processes. A notable example of two-stage tertiary lime treat-
ment is the 7.5 mgd facility at Lake Tahoe. Phosphorus removal achieved
by tertiary lime clarification is comparable to the results previously
reported for primary effluent.
Lime requirements: for the treatment of raw wastewater or secondary
effluent at the same raw water source will differ depending on the type
of secondary treatment. Conventional activated sludge can be expected
to increase the lime requirements because of the C02 generated. Nitrifi-
cation can be expected to consume alkalinity and lower the lime require-
ment .
Cost Estimates
The cost of single-stage lime clarification, without recarbonation or
post filtration, for various sized plants are shown in Table 15. A lime
requirement of 300 mg/1 as Ca(OH)2 was assumed. Debt service charges
were based on 4 1/2% for 25 years. Two other assumptions made for these
cost estimates are that the cost of recalcining lime is equivalent to
the cost of buying fresh lime and the cost saving associated with recal-
cining lime sludge is the cost of sludge disposal. The biggest cost
associated with lime clarification for the larger plants is the cost of
the lime. The cost of two-stage lime clarification exclusive of chemicals
is shown in Figure 11. ° The cost of recalcination and make-up lime is
shown in Figure 12.^0 plants smaller than about 10 mgd will use all new
lime; larger plants will use recalcined plus make-up lime.
TABLE 15. Total Cost of Phosphate Removal for Single-Stage
Lime Clarification20
SIZE OF PLANT „ 1 mgd
Capital amortization 1.25
Land amortization .12
Operating and maintenance 2.30
Cost of chemicals
Lime 1.75
Cost of sludge disposal by
hauling to land fill
(25-mile one-way trip) .67
CENTS PER 1,000 GALLONS
10 mgd 100 mgd
1.12
.12
.79
1.75
.67
.84
.12
.50
1.75
.67
250 mgd
.77
.12
.47
1.75
.67
TOTAL
Savings if lime can be
reclaimed
6.09
-.67
4.45
-.67
3,88
-.67
3.78
-.67
TOTAL (with recalcining)
5.42
3.78
3.21
3.11
- 28 -
-------
20.0
10.0
C0
0.10
1IIIITTiIIIII
COST ADJUSTED TO MARCH, 1969
20.0
10.0
.•••
1.0
rs.
oo
1.0
jjJO.10
10.0
100
FIGURE 11
COST OF TWO STAGE LIME CLARIFICATION TREATMENT
EXCLUSIVE OF CHEMICALS
-------
10.0
C9
€/>
1.0
0.10
i i
COST ADJUSTED TO MARCH, 1969
1.0
j i i i i i i i
i i i i i i i i
20.0
10.0
1.0
0.10
COST OF SOPPLYING imt FOR LIME CLARIFICATION PROCESS
•HANTS LESS THAN ABOUT 10 MGD USE ALL NEW LIME;
LARGER PLANTS USE RECALCINED PLUS MAKE UP LIME
-------
III. MOVING BED FILTRATION OF ALUM TREATED WASTEWATER
As mentioned earlier, phosphorus removal is a two-step process involving
insolubilization and solids separation. An alternative to chemical
treatment and settling is chemical precipitation and filtration. Either
a coarse media upflow filter or a multi-media downflow filter may be used,
but both have serious operational limitations. These include: (1) a
limited ability to handle the wide fluctuations in solids load, and
(2) potential plugging from biological growths which may occur in a fixed
bed in the presence of high organic concentrations.
A new filter technology for wastewater involves the concept of a moving
bed. A Moving Bed Filter (MBF) developed by Johns-Manville Products
Corporation* has been operated .under test conditions for over a year,
including limited testing on the treatment of raw sewage. A schematic
diagram of the MBF is shown in Figure 13. This unit is basically a
sand filter with optional chemical treatment. Particulate matter is
removed as the water passes through the sand bed. As the filter surface
becomes clogged, the filter media is moved forward by means of a mechani-
cal diaphragm. The clogged filter surface is hydraulically or mechani-
cally removed thereby exposing a clean filter surface. The sand and
accumulated sludge is washed and separated. The sand is returned to the
base of the filter. The sand moves countercurrent to the water being
filtered. The unit does not have to be taken off stream for backwashing.
In theory, 1% of the filter is being backwashed 100% of the time com-
pared to the conventional practice of backwashing 100% of the filter 1%
of the time. External and more thorough cleaning of the filter media
may prove to be an important factor in minimizing problems associated
with slime growths.
Results from an 8-gpm MBF unit treating raw wastewater at Bernard's
Township, New Jersey are shown in Table 16
The Moving Bed Filter is being designed for plant capacities up to
5 mgdo Moving bed filtration of raw wastewater followed by granular
carbon adsorption would appear to be an efficient alternative physical-
chemical treatment combination; particularly, where land is scarce or
expensive.
Mention of a commercial product does not imply endorsement by
the FWQA or the U. S. Government.
- 31 -
-------
INFLUENT
I
CHEMICALS
FEED HOPPER
DIAPHRAGM
HYDRAULIC
SYSTEM
.SAND
RECYCLE
PRODUCT
"l WATER
SLUDGE
WASH WATER
EDUCTOR-
SAND WASHING
WASTE
SLUDGE
FIGURM3
SCHEMATIC ARRANGEMENT OF MOVING BED FILTER
-------
TABLE 16. Results of Alum Coagulation and Moving Bed Filtration Treat-
ment of Raw Wastewater at the Bernard's Township Plant
Constituent Raw Wastewater MBF Effluent %
Concentration Concentration Removal
mg/1 mg/1
BOD
Phosphorus as P:
Total
Ortho
Filterable
Suspended Solids
Turbidity, JTU
Test Conditions:
115
21.5
13.2
18.6
156
119
19
2,2
0.6
Oo8
27
16
83.5
90.0
95.5
95.5
83.0
86.5
o
Flow Rate 2.5 gpm/ft
Alum Dose 200 gpm/1
Polymer .5-.65 mg/1
The primary application for which the Movirig Bed Filter was designed is
the filtration of unsettled trickling filter effluent. Results of the
MBF unit in this application are shown in Table 17.
Test conditions for the filtration of unsettled trickling filter effluent
were identical to the test conditions for the filtration of raw wastewater.
A 2-mgd Moving Bed Filter facility at the Borough of Manville Plant for
the treatment of unsettled trickling filter effluent is currently under
construction. This project is being partially funded through an FWQA
Research and Development Grant.
- 33 -
-------
TABLE 17. Results of Alum Coagulation and Moving Bed Filtration of
Unsettled Trickling Filter Effluent12
Constitutent Unsettled Trickling
Filter Effluent. MBF Effluent %
mg/1 mg/1 Removal
BOD
Phosphorus as P:
Total
Ortho
Filterable
Suspended Solids
Turbidity
40
19.1
12.9
15.5
96
41
5
0.84
0.43
0.50
7
2.9
87.3
96.1
97.0
97.1
92.8
93.0
Cost Estimates
The capital costs of a 1-mgd Moving Bed Filter are estimated to be $190,000.
Erection costs including influent pumps, electrical and plumbing are an
additional $90,000. The total operating costs including amortization of
capital is estimated to be $0.13/1,000 gal.
Sludge disposal costs with a rotary precoat vacuum filter are estimated
at an additional $0.02 to $0.03/1,000 gal.' based on experience with water
treatment plant sludges. '
- 34 -
-------
SUMMARY AND CONCLUSIONS
There are several alternative methods available for the removal of
phosphorus including biological uptake, chemical precipitation of the
soluble phosphorus and either settling or filtration of the particulate
phosphorus.
Based on today's technology, chemical precipitation is the most practical
method of phosphorus removal. There are numerous chemical systems available
which can be applied to raw sewage, primary effluent or secondary effluent.
The choice of chemical and point of chemical addition depend to a great
extent upon the size of plant, phosphorus discharge standard, influent
wastewater characteristics and other processes utilized in the treatment
train.
Phosphorus removal costs range from $0.13/1,000 gal. for two-stage lime
treatment of raw sewage to attain 977o removal at 1-mgd to a potential
low of $0.015/1,000 gal. for the use of waste pickle liquor in the primary
to achieve 80% phosphorus removal.
In the process of removing phosphorus, several other benefits including
better solids and BOD removal occur. As with all pollution control, the
benefits must be weighed against the costs.
- 35 -
-------
REFERENCES
1. "A Study on Removal of Carbonaceous, Nitrogenous, and Phosphorus
Materials from Concentrated Process Waste Streams," Final Report,
FWPCA Contract No. 14-12-431,. Engineering-Science, Inc., November,
1969.
2. Albertson, 0. E. and Sherwood, R. J., "Phosphate Extraction Process,"
Technical Preprint No. 701-P, Dorr-Oliver, Inc., Stamford, Connecticut.
3. Annual Report on the Water Pollution Abatement Program for Mentor,
Lake County, Ohio, FWPCA Grant WPRD 172-01-68, May 15, 1968 -
August 31, 1969.
4. Earth, E. F. and Ettinger, M. B., "Mineral Controlled Phosphorus
Removal in the Activated Sludge Process," Journal Water Pollution
Control Federation. Vol. 39, No. 8, August, 1967, p. 1362.
5. Earth, E. F., et al., "Phosphorus Removal from Wastewater by Direct
Dosing of Aluminate to a Trickling Filter," Journal Water Pollution
Control Federation, Vol. 41, No. 11, Part 1, November, 1969, p. 1932.
6. Earth, E. F., "Treatment and Control of Phosphorus in Wastewater,"
Internal Report, Robert A. Taft Water Research Center, Cincinnati,
Ohio, 1968.
7. Berg, E. L. and Williams, R. T., "Single-Stage Lime Clarification
of -Secondary Effluent," (In Press).
8. Buzzell, J. C. and Sawyer, C. N., "Removal of Algal Nutrients from
Raw Wastewater with Lime," Journal Water Pollution Control Federation,
39, R16, October, 1967 .
9. Farrell, J. B., et al., "Natural Freezing for Dewatering of Aluminum
Hydroxide Sludge," U. S. Department of the Interior, FWPCA, AWTRL,
Cincinnati, Ohio, November, 1969.
10. Jenkins, D. and Menar, A., "The Fate of Phosphorus in Sewage
Treatment Processes; Part II, Mechanisms of Enhanced Phosphate
Removal by Activated Sludge," SERL Report 68-6, Berkeley, Sanitary
Engineering Research Laboratory, University of California, August,
1968,
-------
REFERENCES
(Continued)
11. Johnson, E. L., Beeghly, J. H., and Wukasch, R. F., "Phosphorus
Removal at Benton Harbor-St. Joseph, Michigan," Dow Chemical
Company, Midland, Michigan.
12. Monthly Progress Report, FWPCA Contract No. 14-12-154, "Experiments
to Determine the Effectiveness of Phosphate Removal by Means of
the Moving Bed Filter", September, 1969.
13. Monthly Report for November, 1969, Joint FWPCA-DC Activities.
14. Mulbarger, M. C., Shifflett, D. G., Murphy, M. C. and Huffman, D. D.,
"A Full-Scale Evaluation of 'Luxury Uptake1 for Phosphorus Removal",
(In Press).
15. "Nutrient Removal from Digester Supernatants and Related Process
Streams," Monthly Report No. 7, FWPCA Contract No. 14-12-414^ FMC
Corporation, February 17, 1969.
16. O'Farrell, T. P., Bishop, D. F., and Bennett, S. M. , "Advanced Waste
Treatment at Washington, D. C.", presented at the 65th Annual AlChe
Meeting, Cleveland, Ohio, May, 1969.
17. Personal Correspondence - D. Bell, Johns-Manville Products Corporation.
18. Personal Correspondence - R. Schuessler, Dow Chemical Company.
19. Slechta, A. F. and Gulp, G. L., "Water Reclamation Studies at the
South Tahoe Public Utility District," Journal Water Pollution Control
Federation, Vol. 39, No. 5, May, 1967, p. 787.
20. Smith, R., "Cost and Performance Estimates for Tertiary Wastewater
Treating Processes", Internal Publication, Robert A. Taft Water Research
Center, Cincinnati, Ohio, June, 1969.
21. Stamberg, J., Bishop, D., Warner, H. and Griggs, S., "Lime Precipitation
in Wastewater," (In Press).
22. Stenburg, R. L., Convery, J. J., and Swanson, C. L., "New Approaches
to Wastewater Treatment," Journal of the Sanitary Engineering
Division, Proceedings of the American Society of Civil Engineers,
SA 6, December, 1968, p. 1121.
23. Summary Progress Report for May, 1969, "Phosphorus Removal and
Disposal from Municipal Wastewater", FWPCA Grant WPD 223-01-68,
The University of Texas Medical Branch, Galveston, Texas.
-------
REFERENCES
(Continued)
24. Villiers, R. V., Berg, E. L., Brunner, C. A., and Masse, A. N. ,
"Treatment of Primary Wastewater by Lime Clarification and Granular
Carbon", November, 1969 (In Press).
25. Wukasch, R. F., "New Phosphate Removal Process, Water.and Wastes
Engineering, September, 1968, p. 58.
-------
1
Accession Number
w
5
2
Subject Field &, Group
05D
SELECTED WATER RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
Organization
Environmental Protection Agency, Water Quality Office, Washington, D. C,
Title
TREATMENT TECHNIQUES FOR REMOVING PHOSPHORUS FROM MUNICIPAL WASTEWATERS
10
Author(s)
Convery, John J.
16
Project Designation
17010---01/70
21
Note
22
Citation
Water Pollution Control Research Series, EPA
23
Descriptors (Starred First)
*Waste Water Treatment, *Tertiary Treatment, Biological Treatment, Chemical
Precipitation
25
Identifiers (Starred First)
*Nutrient Removal
*Phosphorus Removal
27
Abstract
Technology is available to remove the nutrient phosphorus from municipal
wastewaters. This paper summarizes the alternative methods for both biological
and physical-chemical treatment. The information should be helpful in
providing perspective to municipal officials, engineers and treatment plant
operators contemplating incorporation of nutrient control measures into
their treatment facilities. Process selection will depend on specific
wastewater characteristics, existing facilities, required effluent quality,
and economic considerations.
Processes discussed include conventional biological treatment, digester
supernatant treatment, modified biological treatment, chemical addition
in primary, secondary and tertiary stages of treatment, and moving bed
filtration.
Abstractor
R. L. Sffinburg
Institution
EPA, Water Qualify Office, Cincinnati, Ohio
WR:102 (REV. JULY 1969)
WRSI C
SEND, WITH COPY OF DOCUMENT. TO: WATER RESOURCES SCIENTIFIC INFORMATION CENTER
U.S. DEPARTMENT OF THE INTERIOR
WASHINGTON. D. C. 20240
* GPO: 1 970-389-930
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