WATER  POLLUTION CONTROL RESEARCH SERIES • 17O1ODYBO2/71
PHOSPHORUS REMOVAL AND DISPOSAL
             FROM
     MUNICIPAL WASTEWATER
           ION AGENCY
RESEARCH AND MONITORING

-------
        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.

-------
  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

-------
              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.

-------
                                    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

-------
                            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	

-------
                              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-

-------
 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

-------
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.

-------
                       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

-------
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

-------
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),

-------
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

-------
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.

-------
                        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.

-------
     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.
                              10

-------
             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.
                              11

-------
                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).





                              12

-------
                 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.


                              13

-------
     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

-------
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.





                              15

-------
     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.




                              16

-------
     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

-------
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

-------
 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

-------
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

-------
       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

-------
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

-------
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

-------
     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

-------
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

-------
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

-------
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

-------
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

-------
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

-------
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

-------
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

-------
     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

-------
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

-------
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

-------
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

-------
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

-------
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

-------
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

-------
 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

-------
     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

-------
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

-------
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

-------
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

-------
     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

-------
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

-------
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

-------
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

-------
                               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

-------
     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

-------
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

-------
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

-------
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
                             52

-------
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
                               53

-------
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
                             54

-------
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).
                               55

-------
     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.





                                56

-------
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







                               57

-------
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.
                                58

-------
      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
                               59

-------
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
                               60

-------
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.
                               61

-------
     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.
                               62

-------
     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
                               63

-------
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
                               64

-------
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
                               65

-------
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-
                                  66

-------
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-
                                67
                                                        C LIBRARY  U.S. EPA

-------
 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
                                68

-------
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


                                69

-------
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.





                              70

-------
     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.





                              71

-------
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.
                               72

-------
 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

                               73

-------
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.
                               74

-------
     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
                               75

-------
          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;







                               76

-------
$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.
                                    77

-------
                    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.
                              78

-------
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-
                               79

-------
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.







                              80

-------
      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


                                   81

-------
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.
                                    82

-------
     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


                                 83

-------
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.







                                   84

-------
                          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.
                                 85

-------
                                REFERENCES
 1.   Sawyer,  C.N.  "Biological Engineering in Sewage Treatment,"  Sewage
     Works Journal, JL6  (5):925,  Sept.,  19440

 2.   Levin, G.V.  and  Shapiro, J.  "Metabolic Uptake of Phosphorus by Waste-
     water Organisms,"  Journ. Water Pollution Cqptrol Federation,
     317(6):800, June, 1965.

 3.   Katchman, B.J. "Phosphates  in Life Processes," Phosphorus  and Its
     Compounds, Vol.  II,  Interscience Publishers,  Inc., New York (1961).

 4.   Reid, G. W.,  etaal.   "Biological Treatment  of Ureal  Wastes,"
     Bureau of Water  Resources Research,  University of Oklahoma,
     Norman,  Oklahoma,  1961.

 5.   Porter,  J.R.  "Bacterial  Chemistry  and Physiology," John Wiley & Sons,
     Inc., New York,  New  York (1946).

 6.   Vacker,  D.,  Connell, C.H.,  Wells,  W.  N. "Phosphate Removal  Through
     Municipal Wastewater Treatment at  San Antonio, Texas," Journ.
     Water Poll.  Control  Fed., _39_(5):750,  May, 1967.

 7.   Harold,  F. M., "Inorganic Polyphosphates  in Biology:  Structure,
     Metabolism,  and  Function,"  Bacterial Reviews  J50_(4) ,  December,  1966.

 8.   Harold,  P.M.  "Accumulation  of Inorganic Polyphosphates in Aerobacter
     Aerogenes  I. Relationship  to Growth and Nucleic Acid Synthesis,"
     J. Bacteriol., 86:216-221,  1963.

 9.   Smith, I. W., Wilkinson, J.F., and Duguid,  J.P.,  "Volutin Production
     in Aerobacter Aerogenes  Due to Nutrient Imbalance,"  J.  Bacteriol.,
     £8:450-463,  1954.

10.   Shapiro, J., Levin,  G.V. and Zea H.  "Anoxially Reduced Release of
     Phosphate in Sewage  Treatment," Journ.  Water  Poll. Control  Fed.
     J39_(ll):1810, November, 1967-

11.   Witherow, J. L.  "Phosphate  Removal by Activated Sludge", U. S.  Dept of
     the Interior, Federal Water Pollution Control Administration,
     Robert S. Kerr Water Research Center, Ada,  Oklahoma.

12.   Tenney,  M.W.  and Stumm,  W.  "Chemical Flocculation of Micro-organisms
     in Biological Waste  Treatment", Journ.  Water  Poll. Control  Fed.,
     37.(10): 1370, October, 1965.

13.   Witherow, J.L.,  Priesing, C.P., et.al.  "Phosphate Removal by  Activated
     Sludge—Amenability  Studies  at Baltimore, Maryland," U.  S.  Dept.  of the
     Interior, Federal  Water  Pollution  Control Administration, Robert S. Kerr
     Water Research Center, Ada,  Oklahoma.
                               86

-------
14.  Menar, A.B. and Jenkins, D. "The Fate of Phosphorus in Sewage Treatment
     Processes," Part II—Mechanism of Enhanced Phosphate Removal by
     Activated Sludge," Sanitary Engineering Research Laboratory, University
     of California, Berkeley, Serial Report No. 68-6.

15.  Rudolfs, W. "Phosphates in Sewage and Sludge Treatment," Part I—
     Quantities of Phosphates, Sewage Works Journal, JL9_(1):43, Jan, 1947.

16.  Clesceri, N.W. "Physical and Chemical Removal  of Nutrients ,"
     Paper presented at the International Conference, "Algae, Man, and
     Environment" Rensselaer Polytechnic Institute, 1967.

17.  Sawyer, C.N. "Some New Aspects of Phosphates in Relation to  Lake
     Fertilization," Sewage and Industrial Wastes, _24(6):768, June, 1952.

18.  Karanik, J.M. and Nemerow, N.L. "Removal of Algal Nutrients," Water  and
     Sewage Works, 112:460.

19.  Rand, M.C. and Nemerow, N.L. "Removal of Algal Nutrients from Domestic
     Wastewater," Report No. 9, Dept. of Civil Engineering,  Syracuse
     University Research Institute, 1965.

20.  Buzzell, J.C. and Sawyer, C.N. "Removal of Algal Nutrients from Raw  Sewage
     with Lime," Presented at the Missouri Water Pollution Control Association
     Meeting, Jefferson City, Missouri,  March 1,  1966.

21.  Albertson, O.E. and Sherwood, R.J.  "Phosphate Extraction Process," Paper
     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?

-------