WATER RESOURCES BULLETIN VOL. 11, NO. 2 AMERICAN WATER RESOURCES ASSOCIATION APRIL 1975

PHOSPHORUS REMOVAL BY LEGISLATION'

N. E. Hopson'

INTRODUCTION

Biological growth is dependent on the nutrient phosphorus. However, biological waste- water treatment facilities traditionally have not removed all the incoming phosphorus because the phosphorus required in the treatment process is much less than the available supply. Since the phosphorus in the effluent of wastewater treatment facilities is gener- ally accepted to significantly contribute to eutrophication of some lakes, the develop- ment of technology for the removal of this phosphorus source has been accelerated to attack the problem.

Recent articles concerning the technology associated with phosphorus removal gener- ally cover biological, chemical, chemical-biological, and chemical-physical methods. In the biological system, (P. H . Jones, 1973; C. V. Levin, et al., 1972) phosphorus is removed from the main flow and is assimilated into the sludge. The phosphorus is then released from the sludge, into a liquid phase, and then chemically removed from this phase. Levin reports 90% removal at a cost of 4-7&/1000 gallons using biological methods and Jones reports greater than 80% removal. These percentages reflect effluent phosphorus concen- tration approaching 1 mg/l and biological phosphorus removals of up to 8 or 9 mg/l.

The various chemical techniques (C. R. Minton and D. A. Carlson, 1972; D. Jenkins, et al., 1971) generally involve precipitation of phosphorus with the following cations: aluminum, ferric, ferrous, and calcium. These cations can be added at various points in the treatment facility. The general schemes include adding the cation into the primary step, in conjunction with the biological system, or as a final step. The pros and cons of these methods have filled the recent literature. These chemical methods produce phos- phorus concentrations of less than 1 mg/l and the costs range from 4-14d/1000 gallons depending on the size of the plant and method of addition.

An alternative method of phosphorus removal which is generally ignored is the re- moval of phosphorus at its source. One of the major controllable sources is the household heavy-duty synthetic detergent which may contain large amounts of polyphosphates.

'Paper No. 74049 of the Water Resources Bulletin. Discussions are open until August 1, 1975.

'Havens & Emerson Ltd., Cleveland, Ohio, formerly Assistant Professor, SUNYAB, Buffalo, New Presented at Ninth Water Resources Conference, Seattle, Washington, October 22, 1973.

York.

356

PHOSPHORUS REMOVAL BY LEGISLATION 357

Many of these detergents contain as much as 20 percent phosphorus. The function of phosphorus in detergents (M. E. Purchase, 1971) include the following:

1. Soften water by sequestering hardness ions. 2. Increase the efficiency of the surface active agents. 3. Furnish necessary alkalinity for cleaning and provide resistance to change in

alkalinity during the washing. 4. Reduce redeposition of dirt by keeping the dirt particles suspended. 5. Emulsify oily and greasy soils.

The use of these phosphorus-containin4 detergents greatly increases the phosphorus con- tent of domestic sewage. Prior t o synthetic detergents municipal sewage contained con- centrations of about 2.0 t o 3.0 nig/l of inorganic phosphorus and 0.5 t o 1.0 mg/l of organic phosphorus, (C. N. Sawyer and P. L. McCarthy, 1967)for a total of 2.5-4.0 mg/l concentration. The EPA technology Transfer Manual (E.P.A., 1971) on phosphorus re- moval indicates that a mean annual contribution from synthetic detergents with phos- phorus builders is about 2.3 Ibs./capita/year and human excretions contribute 1.2 lbs./ capita/year. Thus, exclusive of industrial wastes and other sources, the domestic phos- phorus contribution to wastewater is about 3.5 Ibs./capita/year. This estimate is in agree- ment with recently reviewed figures. (L. J. Hetling and I . G . Carcich, 1973) A simple calculation based 011 these numbers indicates an expected phosphorus concentration of 11.5 mg/l for a flow of 100 gallons per capita per day. This value agrees with measured values found in some municipal wastewaters. Further calculations show that removal of the detergent phosphorus would produce a phosphorus concentration of about 4 mg/l or about a 65%' reduction. Such a reduction indicates that a legal ban on phosphorus- containing detergents should be considered as an alternative t o existing and more expen- sive methods of phosphorus removal. In certain areas the removal of detergent phos- phorus may well approach standards on a short-term basis and would beneficially affect total costs on a long-term basis.

To combat phosphorus discharge the Erie County (New York) Legislature passed a law concerning domestic use of detergents. The legislation involved a partial ban commencing on May I , 1971 and a complete ban on January 1 , 1972. The law is as follows:

RESOLUTION NO. 155 - COUNTY OF ERIE LOCAL LAW INTRODUCTION NO. 8, 1971

A LOCAL LAW prohibiting the sale of certain detergents containing phosphorus. BE IT ENACTED BY THE COUNTY LEGISLATURE AS FOLLOWS:

Section 1. Legislative findings and declaration of policy. It is hereby declared that: (a) The waters of Erie County, particularly those of Lake Erie and its tributaries, are

being seriously polluted by the continuous discharge into such waters of phosphorus- containing detergents which fertilize excessive algae growth. Such growth creates a hazard t o fish and wildlife as well as t o human health and this can destroy the recreational potential of such waters.

(b) The International Joint Commission's Third Interim Report on Pollution of Lake Erie, Lake Ontario, and the International section of the St. Lawrence River with regard to the eutrophication of Lake Erie, etc. recommends the immediate reduction t o a minimum practicable level of the phosphorus-based detergent phosphorus content and the total

358 Hopson

quantities of phosphorus-based detergents discharged into the basin with the aim of complete replacement of all phosphorus in detergents with environmentally less harmful materials to follow, and the Dominion of Canada, following the recommendations con- tained in said report has adopted regulations controlling the use of nutrients in laundry detergents pursuant to the Canada Water Act.

(c) To abate and control the pollution of the waters of Erie County in the public interest, it is necessary to ensure that the ingredients of detergents which are sold or offered for sale in Erie County do not contribute to the pollution of such waters.

Section 2. (a) It shall be unlawful for any person, firm, or corporation to sell, offer or expose for

sale, give or furnish any synthetic detergent or detergent containing more than eight and seven-tenths percent (8.7%) of phosphorus by weight, expressed as elemental phosphorus, within the County of Erie from and after April 30, 1971.

(b) It shall be unlawful for any person, firm or corporation to sell, offer or expose for sale, give or furnish any synthetic detergent or detergent containing any phosphorus expressed as elemental phosphorus, within the County of Erie after January 1 , 1972. Section 3. The concentration by weight of phosphorus in any detergent shall be deter- mined by the method prescribed from time to time by the American Society for Testing and Materials. Section 4. Notwithstanding the foregoing, synthetic detergents or detergents manu- factured for use in machine dishwashers, dairy equipment, beverage equipment, food processing equipment, and industrial cleaning equipment shall not be subject to the limitations of this local law.

Section 5 . Definitions: (a) The term “synthetic detergent or detergents” means cleaning compound which is

available for household use, laundry use, other personal uses or industrial uses, which is composed of organic or inorganic compounds, including soaps, water softeners, surface active agents, dispersing agents, foaming agents, buffering agents, builders, fillers, dyes, enzymes, fabric softeners and/or other additives, whether in the form of crystals, powders, flakes, bars, liquids, sprays, or any other form.

(b) The term “machine dishwasher” means equipment manufactured for the purpose of cleaning dishes, glassware and other utensils involved in food preparation, consumption or use, using a combination of water agitation and high temperatures.

(c) The terms “dairy equipment,” “beverage equipment,” and “food processing equip- ment” mean that equipment used in the production of milk and dairy products, foods, and beverages, including the processing, preparation or packaging thereof for consump- tion.

(d) The term “industrial cleaning equipment” means machinery and other tools used in cleaning processes during the course of industrial manufacturing, production and assembly . Section 6. Penalties for Violation: any person violating any provisions of this local law shall be deemed guilty of a violation, as defined in section 10.00 of the penal law of the State of New York and subject to a fine of not more than two hundred fifty dollars or by imprisonment for a term not t o exceed fifteen days, or by both such fine and imprison- ment. A separate and distinct violation shall be regarded as committed each day on which such person shall continue to permit any such violation.

PHOSPHORUS REMOVAL B Y LEGISLATION 359

Section 7. This local law shall take effect immediately. STATE OF NEW YORK: COUNTY O F ERIE: COUNTY OF BUFFALO:

THE STUDY

After the inception of the law, civil engineering students (H. C. Jain, 1971 ; A. Quadir and D. S. Machod, 1971; and P. Pieczonka, 1973) at the State University of New York at Buffalo made several studies in order to determine the effectiveness of the legislation. Very few treatment plants determined phosphorus concentrations prior to the recent concern and many of the smaller plants still do not perform these tests. Along with the general lack of data, the study was further complicated by differences in techniques in sampling and analysis from plant to plant. In-plant studies showed that the influent wastewater in each treatment plant differed in phosphorus concentrations, forms of phosphorus and dilumal patterns. Because of these variations no consolidation of data is valid and each facility was analyzed separately. Initial results in June 1972 indicated reductions of total phosphorus from 434% in some interior facilities and about 30% for two facilities bordering on Niagara County, New York which had no county ban, although a state ban was in effect at that time which imposed detergent phosphorus levels similar to the partial ban in Erie County.

Three treatment facilities are updated in this paper because of the quantity and reli- ability of their data. The three are the Buffalo Sewer Authority (Bird Island Treatment Plant), Cheektowaga Water Pollution Control Plant No. 5, and the Lackawanna Sewage Treatment Plant.

The Cheektowaga facility has a contributing population of about 65,000 persons with significant numbers of commercial contributors. The collection system consists of separ- ated storm and sewage lines but the problem of extraneous water does exist causing wet weather overflows. The data reported is part of the recent Wastewater Facilities Report for W.P.C.P. No. 5 Service Area. (Brown-Devlin Associates, 1972) Chemical tests were performed by a private independent laboratory. The 1972 values are calculated using I0-hour composites of the influent wastewater and a factor relating this time period to the full day developed by representative hourly measurements.

The Bird Island Treatment Plant of the Buffalo Sewer Authority has a contributing population of over 500,000 persons. The area consists of the City of Buffalo and some border suburbs. The collection system is combined storm and sewage lines resulting in the obvious wet weather problems. The data reported was developed by plant personnel on 24-hour composite samples of influent wastewater.

The Lackawanna Sewage Treatment Plant has a contributing population of about 25,000 persons. The area contains large industries but the industrial waste is treated separately. Therefore the contributed waste comes primarily from the residential area with a minimum of commercial waste. The collection system is primarily separated but extraneous water does cause wet weather overflows. The data reported is part of a student project (P. Pieczonka, 1973) and consists of a calculated 24-hour average load based on five-hour composites from 9 a.m. to 2 p.m.

All chemical tests were performed as prescribed in Standard Methods for the Examin- ation of Water and Wastewater.

360 Hopson

RESULTS

The results of the study are presented in the Figures 1 and 2 and summarized in Table 1. No comparison between facilities should be attempted due to the differences in community, collection system, and sampling techniques. However, observing each facility does indicate a reduction of 50 to 60 percent in total phosphorus received by the treatment facilities in these communities. Because of community composition,

BUFFALO SEWER AUTHORITY BIRD ISLAND PLANT INFLUENT PHOSPHORUS

w

T IME

Figure 1. Phosphorus Loads Entering the Buffalo Sewage Treatment Plant Before and After the Detergent Ban.

CITY OF LACKAWANA SEWAGE TREATMENT PLANT IN F LU E NT PHOSPHORU S

TIME

Figure 2. Phosphorus Loads Entering the Lackawanna Sewage Treatment Plant Before and After the Detergent Ban.

PHOSPHORUS REMOVAL BY LEGISLATION 36 1

Lackawanna should have exhibited the largest reduction and this was the case. Similarly, Buffalo would be expected t o show the least effect and this was also the case. Unfor- tunately, little no-ban data is available for Cheektowaga and the reduction values are open t o question although a significant reduction is indicated.

TABLE 1. Phosphorus Reductions

No Ban Partial Full Ban % Decrease (NB) Ban(PB) (FB) NB-PB NB-FB PB-FB

Buffalo Total P #/day 7082 5760 3572 18.6 49.6 38.1 Total P mg/l 5.5 4.6 2.2 16.3 60.0 52.1 Ortho P#/day 3440 2446 1160 28.9 66.3 52.6 Ortho P mg/l 2.7 2.0 0.7 25.9 74.0 65.0

Lac kaw anna Total P #/day 246 202 100 17.3 59.3 50.5 Total P mg/l 7.6 6.3 2.6 17.1 65.7 58.7

Cheektowaga Total P #/day 879* 521 354 40.8* 59.8* 32.0 Total P mg/l 10.4* 8.1 3.8 22.1* 63.4* 53.0

*These numbers are based on a 48-hour composite in December 1969. The remaining Cheektowaga values are based on about 40 days during the partial and full ban periods.

DISCUSSION

Conventional biological treatment is normally reported t o remove 3030% of the phos- phorus due to biological assimilation. Using influent concentrations of about 8-10 mg/l and the lesser (30%)) removal assumption indicates that conventional biological systems could remove 2-3 nigh of phosphorus. Table 1 shows that this magnitude of removal might be sufficient in some instances t o meet New York State standards which require less than 1 mg/l in the effluent for a facility larger than 1 mgd capacity. However, the values in the table are averages and it should be noted that the phosphorus concentrations d o fluctuate up t o about 4 mg/l for short periods of time during dry weather on the Buffalo system. The example does indicate the tremendous impact that a phosphorus detergent ban could have on some localities.

Short- and long-term effects should be analyzed. The major short-term effect is t o reduce the phosphorus load t o the receiving water by 50-60%. This reduction can be demonstrated t o occur within days of a legal ban. In areas where activated sludge treat- ment facilities exist and an effluent concentration of 2 mg/l(8% removal) is acceptable, a ban should be capable of meeting the standards with no additional facilities for phos- phorus removal. In areas with primary treatment only and/or more strict effluent stand- ards, the ban will at least provide a significant reduction and may approach the standards. A major long-term effect of such bans is the reduction in chemical costs required to reduce phosphorus levels to meet the effluent standard. The Cheektowaga Facilities Report (Brown-Devlin Associates, 1972) reports that lower phosphorus removal costs are obtained because of a combination of nitrification and the phosphorus ban. The chemical removal of phosphorus is accomplished by either metallic salt or lime addition.

362 Hopson

Metallic salt addition for phosphorus removal is dependent on the amount of phos- phorus to be removed. Therefore less phosphorus entering the plant will require lower chemical additions and lower chemical costs. The dependence on influent phosphorus concentration is reportedly (E.P.A., 1971) not the case when using lime to remove phosphorus. Side reactions predominate in this chemical process and the required lime addition is dependent primarily on alkalinity rather than phosphorus concentration. The results of this analysis can be shown via Figure 3. This figure shows the theoretical

BREAKPOINT

METALLIC I I I I

SALTS

I

COSTS - Figure 3. Ideal Curves Showing the Effects

of Incoming Phosphorus on Chemical Costs.

relationship between chemical costs for metallic salts and lime and the raw sewage phos- phorus concentration. For a given wastewater a reduction in phosphorus concentration will reduce the chemical requirement and cost by some constant amount resulting in a straight sloped line. In the same wastewater, however, the lime requirement and cost will remain constant no matter what the phosphorus concentration since no change occurs in alkalinity. The true relationship should be developed for a specific wastewater.

Some recent information shows that the shape of these idealized curves are correct for alum but incorrect for lime. A student paper (P. Pieczonka, 1973) indicates that with Lackawanna, New York sewage the metallic salt additions essentially fit the sloping straight line but lime addition also slopes to the left. He realized a 10-30% savings of lime requirements with a 50 percent reduction in phosphorus concentrations from 5-2.5 mg/l P using jar tests. Studies in Ontario, Canada (B. 1. Boyko and J . W. G . Rupke, 1973) present data which also indicates that lime addition requirements are reduced as influent phosphorus concentrations decrease. They indicate a 20-30% reduction in lime require-

PHOSPHORUS REMOVAL BY LEGISLATION 363

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ments corresponding to a 5% reduction in phosphorus concentration from 8-4 mgll P. In both studies the chemical requirement was based on reducing the effluent to a concen- tration of 1 mgll P. Figure 4 shows the relationship between chemical costs and influent concentration based on the recent studies. The chemical additions have been normalized by using unit cost figures (I. J . Kumar and N. H . Clesceri, 1973) of 2.54/#for alum and l.54/# for lime. The two alum curves are shown to stress that this figure should not be

_ _ ALUM - SINGLE PLANT (BOYKO)----.- 1

/ LIME - GENERAL (BOYKO)

(PI ECZON KA)-

/ LIME -SINGLE PLANT - -.-'I /' .

r

/ 0

, 1

/ T

/ I

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Figure 4. Actual Curves Showing the Effects of Incoming Phosphorus on Chemical Costs.

considered useful for design purposes. The single plant data vanes significantly from the generalized data obtained from many plants. This would also be the case for lime addi- tions. The single plant data by Pieczonka does not vary from the generalized data as much as alum addition except at the very low influent phosphorus concentrations. More data is required to actually quantify the variation of lime addition with phosphorus influent concentration.

Although application to specific wastewaters will require individual studies, these studies indicate that whether lime or alum is considered the best method of phosphorus removal, the reduction of influent phosphorus concentration produced by a legal ban of phosphate-containing detergents should reduce the operational cost associated with the chemicals required.

SUMMARY

Many phosphorus removal techniques have been discussed. The legal ban of phos- phorus-containing detergents will cause a significant reduction of phosphorus entering

364 Hopson

wastewater facilities. In the area studied this reduction appears to be 50-60% with influent phosphorus concentrations reduced to well under 4 mg/l.

The impact of such a reduction is also significant. Depending on existing treatment and prevailing standards, the expected reduction will immediately reduce the load to receiving streams. . . and may satisfy standards. If further phosphorus removal is required legan bans can reduce the cost of additional treatment.

With the magnitude of reduction and the resulting beneficial impacts, it becomes apparent that the legal ban of phosphorus-containing detergents is a viable alternative to be considered in phosphorus removal techniques.

ACKNOWLEDGEMENT

The author wishes to thank the Buffalo Sewer Authority, the Town of Cheektowaga, and their consultants, and the City of Lackawanna for their cooperation in this study.

LITERATURE CITED

B. I. Boyko and J. W. G. Rupke, 1973. “Technical Implementation of Ontario’s Phosphorus Removal

Brown-Devlin Associates, Consulting Engineers, 1972. “Town of Cheektowaga Wastewater Facilities,”

E.P.A., 1971. “Process Design Manual for Phosphorus Removal,” Technology Transfer. L. J. Hetling and 1. G. Carcich, 1973. “Phosphorus in Wastewater,” Water and Sewage Works, Vol.

H. C. Jain, 1971. “Phosphates in Detergents and Erie County Public Law,” unpublished student

D. Jenkins, J. F. Ferguson, and A. B. Menan, 1971. “Chemical Processes for Phosphate Removal,”

P. H. Jones, 1973. “Treatment in Municipal Plants: Innovations for Removal of Phosphorus,” Water

I. 1. Kumar and N. H. Clesceri, 1973. “Phosphorus Removal from Wastewaters: A Cost Analysis,”

G . V. Levin, G. J. Topol, A. G. Tarney, and R. B. Samworth, 1972. “Pilot-Plant Tests of a Phosphate

G. R. Minton and D. A. Carlson, 1972. “Combined Biological-Chemical Phosphorus Removal,”

M. E. Purchase, 1971. “Phosphates and Detergents in Water Pollution,” New York State College of

P. F‘ieczonka, 1973. “The Effect of Phosphorus Detergent Bans - A Case Study,” unpublished student

A. Quadir and D. S . MacLeod, 1971. “Effect of Erie County Phosphate Ban on Wastewater,” unpub-

C. N. Sawyer and P. L. McCarthy, 1967. Chemistry for Sanitaly Engineers, 2nd edition, McGraw Hill

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