REUSE QUALITY EFFLUENT FROM RESTAURANT WASTEWATER James Bell 1, Chris Duhamel 2 and Sheryl Ervin 3

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1 REUSE QUALITY EFFLUENT FROM RESTAURANT WASTEWATER James Bell 1, Chris Duhamel 2 and Sheryl Ervin 3 ABSTRACT Producing water reuse quality effluent from graywater sources has gained in popularity in recent years with numerous full scale examples. To the authors knowledge, no one has attempted to produce water reuse quality effluent from a high strength wastewater source. This paper will discuss how this was accomplished from a high strength restaurant wastewater source. The Matunuck Oyster Bar, an award-winning seafood restaurant in South Kingstown, RI, combines fresh, locally grown produce with farm-raised and wild-caught seafood. An extensive investigation of the wastewater characteristics was undertaken by DiPrete Engineering after the original treatment system failed. The flow for sizing the system was based on water use records and was determined to be less than 6,000 gallons per day (GPD). Influent characteristics based on sampling results were Biological Oxygen Demand-5 day (BOD5) 1,800 milligrams per liter, Total Suspended Solids (TSS) 1,000 mg/l, Total Kjeldahl Nitrogen (TKN) 115 mg/l and Fats, Oils and Grease (FOG) 400 mg/l. Effluent limits established by Rhode Island Department of Environmental Management (RIDEM) were BOD5 < 30 mg/l, TSS < 30 mg/l, Total Nitrogen (TN) < 19 mg/l. The design consists of grease tanks, total capacity 12,000 gallons, followed by septic tanks, total capacity 12,000 gallons, with fine screens on the discharge. The flow is then divided equally to two Bio-Microbics HSMBR 6.0-N trains, each containing a working volume of 6,000 gallons anoxic and 6,000 gallons aerobic zone. Finally, effluent is pumped from the submerged membranes to a pump tank for dosing to the dispersal field. The treatment system was installed in March 2016 and startup completed in May Sampling began June 2016 with monthly sampling thereafter. This paper will provide a review of the results. Although the effluent from the treatment system is currently being discharged to a dispersal field, the quality of the effluent meets water reuse standards as adopted by National Sanitation Foundation/American National Standards Institute (NSF/ANSI) 350 (2017). The results of this project show that in the future, effluent generated from high strength wastewater sources, such as restaurants, can be utilized similar to what is currently being done with graywater sources. 1 Executive Vice President, Bio-Microbics, Inc. 2 Vice President, DiPrete Engineering 3 Director of Regulatory Affairs, Bio-Microbics, Inc.

2 INTRODUCTION The Matunuck Oyster Bar is an existing 80 seat high quality seafood restaurant located on Succotash Road, South Kingstown, RI. The site is approximately 0.8 acres, on historically filled land up to the sea wall adjacent to a salt marsh and coastal pond. The watershed is defined as a critical resource area, with highest concern of total nitrogen loading, regulated by the RI Department of Environmental Management (RIDEM) and the RI Coastal Resource Management Council (RI CRMC). The restaurant onsite wastewater treatment system (OWTS) had previously received RIDEM approval for construction in May 2012 for an extended aeration treatment train with a single pass bottomless sand filter (BSF) leach field constructed to accommodate parking. The RIDEM had established permit limits for effluent water quality discharge of BOD5, TSS and TKN, as well as effluent volume discharge. Sampling and monitoring of the waste water effluent reported exceedance of the permit limits, as well as high content of FOG. As such, the RIDEM expressed concerns over the performance and operation of the permitted design. DiPrete Engineering was contracted to investigate the RIDEM concerns in November The initial investigation included compilation of water quality influent and effluent testing of BOD5, TSS, TKN and FOG. Water meter billing was obtained to evaluate the peak flow for a given season. A review of restaurant cleaning detergents, floor cleaners, mop sinks, and dishwasher soaps was completed. The investigation identified a high strength commercial wastewater influent, with concentrations exceeding that of the initial system design assumptions. In addition, the flow measurements indicated that the peak flow was measured as 4,571 GPD. The treatment system was designed for less than 6,000 GPD which provided a 30% safety factor. CONCEPT DESIGN DiPrete Engineering conferred with Bio-Microbics and the restaurant owner to evaluate concept design options available to address the existing conditions. Initial design consideration included the following: All components or new technology were required to be in the parking lot, requiring all tanks to have an H-20 load rating, as well as limited space for expansion. The design flow was established from the peak seasonal meter readings, which far exceeded the standard regulatory flow requirements. The waste water flow from floor drains and mop sink were isolated to a holding tank to eliminate the potential for inhibitory chemicals that could affect the normal biology of the wastewater treatment systems. The pretreatment of FOG removal was achieved by increasing from a half day to a minimum of 2 days retention time. Given the requirement to remove up to 80% nitrogen in the waste stream, the use of a membrane biological reactor (MBR) was considered as the most effective means to reduce high nitrogen loading. A chemical feed would be incorporated in the event the operator would need to adjust ph or add a carbon source to optimize the denitrification processes. Finally, the single pass sand filter soil absorption system field would be reconstructed and enlarged to the extent available, to accommodate the design flow and to remove the upper sand layer sealed by FOG. DiPrete Engineering, Bio-Microbics, and the property owner presented the concept design to the RIDEM and the RI CRMC for regulatory concurrence and to move towards the final design.

3 TREATMENT SYSTEM LAYOUT Wastewater from the kitchen of the Matunuck Oyster Bar gravity is initially directed through a series of three grease traps; two 2,000 gallon settling tanks and a single 8,000 gallon tank for a combined volume of 12,000 gallons. These settling tanks are provided to reduce the fats, oils and greases (FOG) from the kitchen and also provide a slight reduction in BOD and TSS. The flow is then pumped to a 7,000 gallon settling tank and comingled with wastewater from the restaurant restrooms before flowing by gravity to a 5,000 gallon settling tank equipped with two SaniTEE effluent filters installed on the outlet. The SantiTEE effluent filters screen all solids greater than 1/8 inch before the wastewater enters the pump chamber. The wastewater is then pumped to the two treatment trains; a total of 3,000 GPD to each BioBarrier MBR system. This pump is set up to pump approximately 65 gallons every 15 minutes dividing it equally between the two trains. Two 9,000 gallon tanks are used in series for each treatment train; the first tank is the anoxic zone and the second tank is the aeration zone. The water level is maintained at around 5 ft. in water depth which allows for up to 4 ft. of extra depth for surge flows as the MBR systems operate on a batch basis. Therefore, the effective treatment volume in these two 9,000 gallon tanks is approximately 12,000 gallons. The aeration zone for each treatment train contains a Lixor 6.0 for additional aeration to meet the extra oxygen demand for the higher BOD and eight HSMBR membrane cartridges equipped with their own aeration system to keep the membranes scoured. An additional pump in the aeration zone recycles water from this tank back to the anoxic tank for denitrification. This recycle pump is on a timer that allows for an adjustment of the recycle flow if needed. The effluent from each train is drawn through the membranes with a variable speed pump that discharges into a 9,000 gallon pump chamber. A dosing pump in the pump chamber feeds the effluent to a pressure dosed soil treatment system. INSTALLATION AND START UP The Rhode Island Department of Environmental Management (RIDEM) approved the application for this replacement treatment system on November 12, Construction started on March 17, 2016 and was completed in May of The treatment system startup process was completed the week of May 23 with the new treatment system receiving full loading over the Memorial Day weekend. The first effluent sample was collected in June of 2016 with monthly sampling since that time. RIDEM requires weekly service visits and monthly influent and effluent testing. Service visits are scheduled on weekday mornings to be completed prior to the restaurant opening for business so as not to interfere with customer traffic. The effluent samples are collected from the effluent pump tank. From the startup to the current time there have been no issues with any of the equipment or the performance of the treatment system meeting RI DEM effluent limits for the site. REVIEW OF PERFORMANCE DATA Analytical methods Samples were collected by Wastewater Treatment Services and analyzed by Analytical Balance Corporation. The methods used are shown in Table 1.

4 Table 1. Analytical Methods for Sample Analysis (Analytical Balance Corp) Constituent Method BOD5 SM 5210B TSS SM 2540 D Alkalinity EPA ph SM 4500 H+B FOG EPA 1664 NH3 EPA TKN EPA NO3 SM 4110 B NO2 SM 4110 B Flow Measurements The effluent flow was measured using flow totalizers on the output of the MBR systems. During each monthly sampling event, the operator recorded the value from the totalizers. This was subtracted from the previous month s value which provided the total flow for the month. The total flow was divided by the total days for that month to obtain an average daily flow for that month. Table 2 provides the average daily flow obtained from this measurement method. Table 2. Average Daily Flow for the Month Average Daily Flow Flow (GPD) July Aug Sept Oct Nov Dec Jan Feb Mar Apr May June Influent Sampling The results of the monthly grab influent samples as reported to RIDEM are shown in Table 3. These grab influent samples were collected from the settling tank inlet.

5 Table 3. Influent Grab Sample Results Date BOD5 TSS Alkalinity ph FOG NH3 TKN NO3 NO2 TN 6/24/ NT ND ND /29/ ND ND /14/ ND /19/ ND ND /18/ ND /15/ ND ND /19/ ND ND /14/ ND /15/ ND /13/ ND ND /17/ ND ND /24/ ND ND /14/ ND ND 104 NT No Test ND Non-Detect The influent BOD5 ranged from a 720 to 4,010 mg/l with an average of 1,191 mg/l. TSS ranged from 60 to 2,850 mg/l with an average of 372 mg/l. FOG ranged from 45 to 2016 mg/l with an average of 507 mg/l. TN ranged from 70 to 126 mg/l with an average of 90 mg/l. The BOD5, TSS and FOG are typical of a high-end restaurant. The TN is about double of what we typically see from restaurant wastewater (Lesikar, et.al., 2006). Effluent Sampling The monthly grab effluent sampling data as reported to RIDEM are shown in Table 4. Samples were collected from the effluent pump tank so they would be similar to a composite sample. Table 4. Effluent Grab Samples from the Effluent Pump Tank Date BOD5 TSS Alkalinity ph FOG NH3 TKN NO3 NO2 TN 6/24/2016 < /29/2016 <4 < ND ND /14/2016 < NT ND ND /19/2016 <4 < ND /18/2016 <4 < ND /15/2016 <4 < ND ND /19/2017 < ND ND /14/2017 < < ND 2.4 3/15/2017 < ND ND 2.6 4/13/2017 < ND /17/2017 < < ND /14/2017 <4 < ND 4.21 NT No Test ND Non-Detect

6 The effluent BOD5 was below the detection limit of 4 mg/l on all samples. TSS ranged from 24.5 to below the detection limit of 4 mg/l. FOG ranged from 3.6 to below the detection limit of 1.2 mg/l. TN ranged from 12 to 2.4 mg/l with an average of 5 mg/l representing around a 95% reduction in TN. The resultant total load of TN to the watershed from the wastewater treatment train is below that allowed by the permit limit of 19 mg/l at 3290 GPD. The effluent quality measured was much better than the RIDEM limits with only operator attention only the days as required as a minimum by RIDEM. Thus being in full compliance with the effluent limits of: BOD5 < 30 mg/l TSS < 30 mg/l TKN < 19 mg/l SUMMARY In 2011, NSF International adopted a new standard for onsite residential and commercial water reuse treatment systems; NSF/ANSI 350. This standard defines the water quality requirements for treated effluent that will be utilized for both indoor restricted water use, such as toilet and urinal flushing, and outdoor unrestricted water use, such as surface irrigation. The parameters of this effluent quality are shown in Table 3. Table 3. NSF/ANSI 350 Effluent Quality Limits (NSF/ANSI, 2016) The Class R limits are intended for sources of residential wastewater and Class C is intended for use for sources of commercial wastewater. Based on the BOD5 and TSS levels obtained from the effluent testing at the Mantunuck Oyster Bar, the effluent quality meets the definitions of NSF 350 for water reuse. Additional testing for turbidity, chlorine and E.coli would have to be collected to verify that these limits are also being met by the system, although, based on the NSF test data on the treatment system from the NSF 350 testing protocol, these limits are obtainable. One interesting observation was that the effluent TSS had a spike of 24.5 mg/l in March of This was investigated and the determination was made that the high TSS was not a problem with

7 the membranes, but was the result of water runoff from the gravel parking lot into the effluent pump tank. If water reuse is considered, steps would need to be taken to seal the covers better to prevent this from occurring. In the future, water reuse quality effluent from commercial restaurant wastewater can be achieved. However, the regulatory approval of such a process has never been considered to the authors knowledge. REFERENCES Analytical Balance Corporation. (2017) Retrieved from Lesikar, B.J., Garza, O. A., Persyn, R. A., Kenimer, A. L., & Anderson, M. T. (2006). Food- Service Establishment Wastewater Characterization. Water Environment Research, 78(8), National Sanitation Foundation/American National Standard. (2016). NSF/ANSI Standard Onsite Residential and Commercial Water Reuse Treatment Systems. Rhode Island Coastal Resource Management Council. (2017). RI CRMC Onsite Wastewater Treatment Systems. Retrieved from: RIDEM. State of Rhode Island Department of Environmental Management, Office of Water Resources Rules Establishing Minimum Standards Relating to Location, Design, Construction and Maintenance of Onsite Wastewater Treatment Systems. Retrieved from