c/EFft United States Environmental Protection Agency Municipal Environmental Research Laboratory Cincinnati OH 45268 " Research and Development EPA-600/S2-84-061 Apr. 1984 Project Summary Priority Pollutants in the Cedar Creek Reclamation-Recharge Facilities Thomas D. Brisbin, Shin H. Ahn, Robert I. Foster, Stanley A. Labunski, and James A. Oliva The Cedar Creek Wastewater Recla- mation Plant in Nassau County, NY, is a 0.24 mVs (5.5 mgd) advanced waste- water treatment (AWT) plant designed to produce a high quality effluent suitable for groundwater recharge. The Reclamation Plant was constructed as a demonstration project under a U.S. Environmental Protection Agency (EPA) grant by additions and modifications to the main 1.96 mVs (45 mgd) Cedar Creek Water Pollution Control Plant. Operation of the Reclamation Plant began in April 1980, and groundwater recharge operations began in October 1982. This research project was initiated with the overall objective of providing preliminary data on the presence of priority pollutants in the Cedar Creek Wastewater Reclamation - Recharge Facilities. The results indicate that 72 priority pollutants were identified in the influent and that significant removals, up to 99% of some individual compounds, were achieved by the plant processes. The data also indicate that the concen- tration of trihalomethanes increases during both the treatment and recharge operations. This Project Summary was developed by EPA's Municipal Environmental Research Laboratory, Cincinnati, Ohio, to announce key findings of the research project that is fully documented in a separate report of the same title (see Project Report ordering information at back). Introduction To retard the contamination of the Upper Glacial Aquifer and to protect the remaining aquifers that provide Nassau and Suffolk Counties with their sole source of potable water supply, Nassau County embarked upon a sewer program in 1950 that, when completed in 1985, will result in 85% of the county being sewered. As part of this program, an Environmental Impact Statement (EIS) on Wastewater Treatment Facilities Con- struction Grants for Nassau and Suffolk Counties, New York, was completed in 1972. Adverse environmental effects associated with the sewer program and subsequent discharge of the treated sewage effluent into Long Island Sound, the South Shore Bays, and the Atlantic Ocean could cause groundwater levels to decline unless the decline is counterbal- anced by groundwater recharge. The declining groundwater levels could result in: (1) decreased groundwater inflow to streams, (2) declining levels of "water table" lakes, (3) decreased subsurface groundwater outflow to the bays and Long Island Sound, and (4) salt-water intrusion into the groundwater aquifers. These declining groundwater levels could cause increased salinity in some of Long Island's estuaries and bays and, thus, alter the ecosystems of these saline water bodies. As part of the EIS conclusions, it was determined that: (1) the construction of collection systems and effective waste- water treatment facilities are essential to protect the public water supply of Long Island, and (2) as soon as the technology is available, it would be advantageous for Long Island to implement groundwater recharge for the ultimate protection of its water supply. A feasibility study on advanced wastewater treatment and groundwater recharge was completed under an EPA grant in August 1973. The ------- results of the feasibility study formed the basis for the design and construction of the 0.24 mVs (5.5 mgd) Cedar Creek Wastewater Reclamation - Recharge Facilities, which were placed in operation in April 1980. The specific objectives of the research project reported herein were to: (1) deter- mine individual treatment processes' and overall reclamation plant performance for the removal of priority pollutants, (2) determine the transformation or genera- tion of priority pollutants by the treatment processes, and (3) determine the priority pollutants present in the groundwater be- fore and after recharge. It was acknow- ledged during the planning period that the number of samples would be minimal and the results would be indicative rather than deterministic. This approach was acceptable because the facility was in its initial stages of operation and the analyti- cal results would indicate potential prob- lems rather than provide statistical eval- uations of performance and reliability. Description of Reclamation Plant and Recharge Facilities The Reclamation Plant is an AWT plant consisting of grit removal, chemically aided primary clarification, suspended growth nitrification/dentification, chemi- cally aided sedimentation, dual-media filtration, carbon adsorption and chlorine disinfection (see Figure 1). The basic approach taken for design of the Reclamation Plant was to combine incorporation of the best available techno- logy in 1973 with the maximum use of existing Cedar Creek Water Pollution Control Plant facilities. Modifications to existing facilities included the following: (1) flocculation chambers were constructed by installing a bulkhead, and horizontal shaft, slow speed, turbine mixers in the influent channel to two of the six existing primary tanks; (2) 2 of the 12 existing aeration tanks and 1 of the 8 final clarifiers were used for combined carbon oxidation-nitrification; (3) 2 aeration tanks and a final clarifier were used for denitrificaiton; (4) 2 aeration tanks and the existing chlorine handling equipment were used for disinfection; and (5) existing solids handling facilities were utilized. New processes and equipment included: (1) rapid-mix basin and chemical handling systems for lime slaking, ferric chloride, polymer, and alum; (2) gravity flow, mixed-media filters; (3) gravity flow, granular activated carbon adsorbers; (4) carbon regeneration furnace; and (5) methanol feed system. The effluent from the Reclamation Plant is transported 10.1 km northwest of the plant, via a 61.0-cm diameter (24 in.) concrete-lined steel pipe, to the Cedar Raw Wastewater r Backwash Waste To Cedar Creek Water Pollution Control Plant Grit Removal Waste CCWF #7 to ^ \ Lime Mixing % Si *~ Sludge CP* imple Point Primary Sedimentation k. Alum and Polymer Methanol Sedimentation (Final Tank No. 7) Post Aeration Denitrification Sedimentation (Final Tank No. 5) Carbon Oxidation- Nitrification Sludge Waste to CCWPCP Chlorine i I Chlorination #5 Effluent Storage fc Ove WCCWP( I Backwashes \Transmission Line (10.1 km) To Cedar Creek Recharge Facilities Figure 1. Cedar Creek wastewater reclamation plant. 2 ------- Creek Recharge Facilities in East Meadow, New York. The Recharge Facilities consist of recharge basins, injection wells, a storage reservoir, and associated equip- ment required to recharge water from the Reclamation Plant. Water to be recharged is received into a 144 m3 central reservoir from where it is distributed to the wells and basins. The reservoir provides 0.17- hr detention at the design flow rate of 0.24 m3/s. Pumping facilities are provided in the Operations Building, along with a sodium hypochloritefeed system that can be used, if required, to control biological activity in the recharge basins. Flow rates, line pressures, and recharge water quality are monitored and controlled at this building. A schematic diagram of the Recharge Facilities is presented in Figure 2. Approach The sampling and analysis program for priority pollutants was divided into three Well "E" Well "D phases. The first phase, conducted during April, May, and June, 1981, was to determine the overall performance of the Reclamation Plant. The second phase, conducted'during August, September, and October, 1982, was designed to investigate the performances of individual Reclamation Plant processes. The third phase involved analyzing samples taken from monitoring wells at the recharge facility site. These samples were collected in May and October, 1982, to determine the effect of recharge on groundwater below the site. Over the project period, 37 samples were collected. The sample locations are indicated schematically in Figures 1 and 2. Plant samples were 24-hour composites started at intervals that compensated for the detention times in the various treatment units. This was done to approximate the same water mass at each location. Composite samples were collected with the use of special, custom- made, glass/Teflon composite samplers designed to minimize loss or contamina- tion of trace organic substances. The samplers were operated at constant flow rates, paral lei ing the constant flow rate of the plant. Observation wells sampled during the third phase of this program were selected on the basis of proximity to individual recharge facilities and the direction and depth of the recharged water flow. Four observation wells were not sampled after recharge because the recharged waste- water had not yet reached these wells, according to conductivity tests performed by the U.S. Geological Survey. Observa- tion wells were grab sampled. Samples were analyzed for a total of 128 priority pollutants (asbestos was excluded): 31 volatile organics, 47 base/neutral-extractable and 11 acid- extractable organics, 25 pesticides/PCB's, 13 metals, and total cyanide. Analyses were also performed to determine con- From Cedar Creek Wastewater Reclamation Plant i Sample Point(sj Figure 2. Cedar Creek wastewater recharge facilities. ------- centrations of nonpriority organic pollu- tants. Results Overall Plant Performance The Phase I investigation identified the constituents present in the effluent to be used for groundwater recharge and evaluated the overall removal of priority pollutants from the wastewater facility. Seventy-two priority pollutants were identified in the raw wastewater: 18 volatile, 23 base/neutral-extractable, and 6 acid-extractable organics; 15 chlorinated hydrocarbons; and 10 heavy metals. Thirty-five nonpriority pollutants were also identified: 2 volatile organics, 28 extractable organics, 1 pesticide, and 4 heavy metals. The analysis of overall plant perform- ance indicated that the Reclamation Plant provides the following removals of pri- ority pollutants, based on total mass of identified compounds: Volatile organics Extractable organics Pesticides/PCB's Metals 85% 80% 47% 64% Some of the volatile compounds iden- tified in the effluent, such as tri- bromomethane, dibromochloromethane, bromodichloromethane, and dichloro- fluoromethane, appear to be formed as a result of chlorination. Unit Process Performance The data collected in Phase II of the project indicates that biological treatment and post aeration are the major processes responsible for removal of volatile organics. Chemically aided primary clarification and biological treatment with alum and polymer addition are almost equally important for the removal of metals. Findings based on the total pollutant mass at each sampling location over the three sampling events indicate that 41 % of the volatile organics were removed through primary clarification and that concentrations of these materials were below detection limits after biological treatment. Fifty percent of the heavy metals were removed through primary clarification, and biological treatment increased the removal to 93%. Further metals removal by filtration/carbon adsorption appears to be negligible. Six volatile organics were detected in the carbon adsorber effluent during the three Phase II sampling events. After chlorination, however, 10 volatile organics were detected in the chlorinated effluent. Apparently several volatile organics most notably, trihalomethanes(THM's) were formed during chlorination. These compounds were, in order of decreasing concentration: bromoform, dibromochloro- methane, chloroform, and bromodichloro- methane. The concentrations of bromoform and dibromochloromethane were, in some cases, higher than their maximum discharge concentrations of 50 /ug/L, as stipulated in the facility's State Pollutant Discharge Elimination System (SPDES) permit. Furthermore, during two of the sampling events, total trihalomethane (TTHM) concentrations were higher than the maximum contaminant level of 100 /ug/L specified in the U.S. EPA's Interim Drinking Water Standards. The relationships between the forma- tion of THM's, COD, chlorine dose, residual chlorine, and pH were investigated using the priority pollutant and plant operating data. The data suggest a combined effect of chlorine and organic precursor presence, as measured by COD, on the formation of THM's. Effect of Recharge During the Phase III testing program, samples were collected from the six monitoring wells before beginning the recharge operations to determine the baseline concentrations of priority pollu- tants in the groundwater. Bis (2-ethyl- hexyl) phthalate and seven volatile organics were detected in monitoring wells before recharge. These data are shown in Table 1. Although THM's were not detected in any of the monitoring wells before recharge, they were detected at significant levels after recharge. TTHM concentra- tions for the two well samples taken after recharge were 256 and 258 /ug/L. These Table 1. Effect of Recharge on Priority Pollutant Concentrations in Monitoring Wells at the Cedar Creek Recharge Facilities (fig/LJ Well4B WellD6 Well 11B Well 11C Well12A Well 12B Compound Before After % Before After % Before After % Before After % Before After % Before After % Rech. Rech. Chg. ftech. Rech. Chg, Rech. Rech. Chg. Rech, Rech. Chg. Rech. Rech. Chg. Rech. Rech. Chg. Volatile Organics Bromodichloromethane Bromoform Chloroform Cis/Trans-1,2- dichloroethene Dibromochloromethane 1,1 Dichloroethane 1,1 Dichloroethene Methylene Chloride Tetrachloroethene 1,1,1- Trichloroethane Trichloroethene Jrichlorofluoromethane Base/Neutral Extractables Bis (2-ethylhexy/j phthalate Metals Copper Lead Zinc BDL BDL BDL BDL 6 BDL BDL 20 9 63 20 3 20 BDL BDL BDL 230 BDL BDL BDL 600 * 55 33 BDL BDL BDL BDL BDL BDL BDL BDL 43 10 BDL 8 49 # BDL BDL 80 BDL BDL BDL BDL BDL BDL BDL 19 * BDL * 50 BDL * 34 124 * BDL 98 BDL BDL BDL BDL BDL BDL BDL (-1 I-) (-1 >47 >eo BDL BDL BDL 6 BDL 34 8 BDL * 46 55 * BDL BDL BDL 33 () 110 (-) BDL BDL BDL 30 BDL >33 BDL BDL BDL BDL 70 BDL >71 20 BDL BDL BDL IIS " BDL BDL BDL BDL BDL 5 BDL * BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL: Below detection limit *: Detected, but /ess than a quantification limit of 10/jg/L (-)' Pollutant concentration in the wells is higher after recharge than before recharge. ------- vels are higher than the maximum jntaminant level of 100 ug/L specified in EPA's Interim Drinking Water Standards. They are also at or above levels measured in the Reclamation Plant Effluent. An analysis of data at various points along the recharge path (effluent storage, transmission, percolation in the soil) indicates that as detention time increases, the concentrations of THM'salso increase. Conclusions The concentrations of the THM's bromoform, chloroform, and dibro- mochloromethane appear to increase in the plant effluent after chlorina- tion. It is difficult to drawfirm conclusions regarding unit process performance for the removals of priority pollutants because the number of samples analyzed was small and many compounds were below detection levels. In a few cases, pollutant concentrations in the effluent were found to be higher than their corresponding concentrations in the influent, which resulted in large variations in removal efficiencies. The combined effect of high COD concentration and high chlorine dose appears to be significant with respect to THM formation. Observation well samples taken after recharge demonstrate an increase in TTHM concentrations in the aquifer. Residual chlorine, combined with organic carbon in the recharge water and long detention times, appear to be determining factors. Recommendations Evaluate the formation of THM's in the plant and recharge operations. As part of this evaluation: (a) optimize chlorine dose to reduce residual chlorine levels; (b) investigate the use of alternative disinfectants, such as chlorine dioxide or ozone; (c) identify and reduce THM precur- sors; and (d) increase the organics removal efficiency of the carbon adsorbers by increased carbon regeneration frequency or increased contact time. Use more sensitive analytical proto- cols than standard EPA methods for future investigations of unit process removals of priority pollutants. The full report was submitted in fulfillment of Grant No. CR804654 by the County of Nassau, NY, under the sponsor- ship of U.S. Environmental Protection Agency. Thomas D. Brisbin. Shin H. Ahn. Robert I. Foster, and Stanley A. Labunskiare with PRO Consoer Townsend Inc., Chicago, IL 60601; James A. Oliva is with Nassau County, NY 11793. John N. English is the EPA Project Officer (see below). The complete report, entitled "Priority Pollutants in the Cedar Creek Wastewater Reclamation-Recharge Facilities," (Order No. PB 84-159 904; Cost: $11.50, subject to change) will be available only from: National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 Telephone: 703-487-4650 The EPA Project Officer can be contacted at: Municipal Environmental Research Laboratory U.S. Environmental Protection Agency Cincinnati, OH 45268 ------- United States Environmental Protection Agency Center for Environmental Research Information Cincinnati OH 45268 Official Business Penalty for Private Use $300 4 U.S. GOVERNMENT PRINTING OFFICE: 1984-759-102/ ------- |