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Washington State Department of Ecology Agreed Order to Conduct Nitrogen Discharge Reduction Pilot ProjectSTATE OF WASHINGTON DEPARTMENT OF ECOLOGY Northwest Regional Office • 3190160th Avenue SE • Bellevue, Washington 98008-5452 • (425) 649-7000 711 for Washington Relay Service • Persons with a speech disability can call (877) 833-6341 October 26, 2020 The Honorable Michael Nelson, Mayor City of Edmonds 121 5th Avenue North Edmonds, WA 98020 Re: Agreed Order Dear Mayor Nelson: Order Docket # 18226 Site Location City of Edmonds Wastewater Treatment Plant 200 2nd Ave. South Edmonds WA 98020-3578 Enclosed is a copy of the signed and effective Agreed Order number 18226. The enclosed Order may not be appealed. The Order is effective as of October 26, 2020. If you have any questions concerning the content of the document, please contact Stephanie Allen at (425) 295-5760 or by email at sa11461 ec .wa. ov. Sincerely, :F0helMc'CLrea' Water Quality Section Manager Northwest Regional Office Enclosure: Agreed Order # 18226 Sent by Certified Mail: 9171 9690 0935 0233 2083 79 ecc: Pamela Randolph, Plant Manager, City of Edmonds Phil Williams, Public Works & Utilities Director, City of Edmonds Stephanie Allen, Facility Manager, Ecology Laura Fricke, Municipal Unit Supervisor, Ecology Greg Lipnickey, Municipal Compliance Specialist, Ecology Central Files: City of Edmonds WWTP; Permit No. WA-0024058; WQ 6.4 STATE OF WASHINGTON DEPARTMENT OF ECOLOGY IN THE MATTER OF AN ADMINISTRATIVE ORDER WITH: City of Edmonds The Honorable Michael Nelson To: The Honorable Michael Nelson, Mayor City of Edmonds 121 5th Ave. N. Edmonds, WA 98020 AGREED ORDER DOCKET # 18226 Order Docket # 18226 Site Location City of Edmonds Wastewater Treatment Plant 200 2nd Avenue South Edmonds, WA 98020-3578 I. INTRODUCTION This is an Agreed Order between the Department of Ecology (Ecology) and the City of Edmonds (City) to conduct a pilot project in compliance with the City's NPDES Permit No. WA-0024058 (Permit), Chapter 90.48 Revised Code of Washington (RCW) and Chapter 173-220 Washington Administrative Code (WAC) by taking certain actions which are described below to reduce nitrogen discharged at the City's Wastewater Treatment Plant (WWTP). II. RECOGNITION OF ECOLOGY'S JURISDICTION This Agreed Order is issued pursuant to the authority vested in Ecology by the Federal Water Pollution Control Act (FWPCA), 33 U.S.C. sec 1311, et seq. and Chapter 90.48 Revised Code of Washington (RCW). RCW 90.48.030 provides that Ecology shall have the jurisdiction to control and prevent the pollution of streams, lakes, rivers, ponds, inland waters, salt waters, water courses, other surface and underground waters of the state of Washington. RCW 90.48.120 authorizes Ecology to issue administrative orders requiring compliance whenever it determines that a person has violated or created a substantial potential to violate any provision of Chapter 90.48 RCW or fails to control the polluting content of waste to be discharged to waters of the state The City agrees to undertake all actions required of it by the terms and conditions of this Agreed Order and not to contest Ecology's jurisdiction and authority to administer this Agreed Order. The City agrees not to appeal this Agreed Order. Agreed Order Docket # 18226 City of Edmonds Wastewater Treatment Plant Page 2 of 7 Nothing in this Agreed Order shall in any way relieve the City of its obligations to comply with the requirements of its Permit. Nor shall anything in this Agreed Order limit Ecology's authority to enforce the provisions of the aforementioned Permit. .III. FINDINGS OF FACT Ecology's determination to issue an Agreed Order is based on the following facts. The City operates a conventional secondary wastewater treatment plant consisting of a headworks with screening, primary clarifiers, aeration basins for biological treatment, secondary clarifiers, and chlorine disinfection. Treated and disinfected effluent flow into the main basin of Puget Sound through an outfall. The City's WWTP treats flow from the City of Edmonds, King County, Olympic View Water and Sewer District, Ronald Sewer District and the City of Mountlake Terrace (collectively called `partners'). The plant has a design capacity of 11.8 MGD average monthly flow. While the City of Edmonds operates the WWTP, the design capacity is owned by the partners. 2. The Salish Sea Model has shown that nutrients discharged from wastewater treatment plants contribute to low dissolved oxygen (D.O.) levels, below state water quality criteria, in the Salish Sea. Nitrogen is the limiting nutrient in the Salish Sea waters. More specifically, total inorganic nitrogen (TIN), the sum of nitrate -nitrite and total ammonia, is the form of nitrogen more available for algal growth that drives eutrophication and the dissolved oxygen impairment. Early model runs ("Bounding Scenarios") confirmed that circulation within the inner basins of Puget Sound distributes a portion of pollutants throughout the waters of the Puget Sound. Discharges in one basin may affect the water quality in other basins. The City's discharge contains inorganic nitrogen. The inorganic nitrogen in the City's discharge has reasonable potential to contribute to far -field water quality impacts. At this time, including a numeric water quality based effluent limit (WQBEL) for nitrogen in the City's NPDES permit is infeasible. This is due to the additional modeling necessary to quantify both the City's far -field water quality effect and the corresponding effluent limit necessary to prevent an exceedance of the D.O. standard. 4. The City's NPDES Permit expired on October 31, 2019 and remains in effect under administrative extension (WAC 173-220-180). Ecology is developing a Nutrients General Permit applicable to nearly 70 domestic WWTPs discharging to marine and estuarine waters of Puget Sound. The Nutrients General Permit will focus on controlling nutrients and will work in conjunction with the WWTPs' existing individual permits. 5. Prior to the issuance of the Nutrients General Permit, the City plans to conduct a pilot project to evaluate potential nitrogen reduction at the WWTP. The City's WWTP faces limitations incorporating nutrient control into its process. The City constructed the existing facility using the entire available footprint, so options for expanding treatment at the existing site are limited. In good faith, the City decided to evaluate retrofitting existing processes with an in -situ nitrogen reduction technology. The City will conduct a pilot project of a mobile organic biofilm (Nuvoda MOB) process with a biofilm media, as Agreed Order Docket # 18226 City of Edmonds Wastewater Treatment Plant Page 3 of 7 a new and developmental technology. The duration of the pilot project will run concurrently with the development of the Nutrients General Permit, with final results reported in 2021. See project schedule below. 6. Ecology intends to administratively extend the conditions of the City's current NDPES permit until the pilot project is complete and Nutrients General Permit issued. If Ecology does not issue a Nutrients General Permit before October 31, 2024, Ecology will incorporate appropriate nutrient controls into a reissued individual Permit. 7. Ecology accepted the City's Technical Memo dated May 1, 2020 for the WWTP Nuvoda MOB Process Evaluation and Trial on June 4, 2020. The document includes the sampling and analysis program, which complies with provisions of G1-5.4 of Ecology's Criteria for Sewage Works Design (Orange Book). 8. The pilot project will be carried out in one of the plant's three treatment trains. The City anticipates that one train will be capable of treating dry weather flows up to 5 MGD. Limiting the project to a single train provides greater flexibility to stress the MOB process but can temporarily limit hydraulic capacity. Stress testing likely won't be possible until the wet weather months when flow reaches above 5 MGD. If, during the trial period, the City anticipates exceeding the hydraulic capacity of the pilot treatment train, the City will route the excess flows through the plant's conventional active sludge process. 9. The pilot project began July 2020 and has an anticipated end date of April 30, 2021. IV. ACTIONS REQUIRED IT IS AGREED that the City of Edmonds shall take the following actions by the dates set forth below and notify Ecology as early as practicable. These actions are necessary to satisfy the requirements of Chapters 173-220 WAC, 173-50 WAC, and 173-240 WAC. The City of Edmonds has participated in defining these actions and the dates by which they shall be completed. The pilot project has an anticipated duration of approximately nine months. The project may need to conclude earlier if unforeseen problems are encountered. Similarly, given the experimental nature of the pilot project, the project schedule may require adjustment in the event of unforeseen developments. The City of Edmonds shall notify Ecology as early as practicable of adjustments that may impact the below deliverable. No later than August 31, 2021, the City shall submit a final report to Ecology presenting the results of the project and verifying the developmental or new technology complies with provisions of G 1-5.4 of Ecology's Criteria for Sewage Works Design (Orange Book). The final report may be submitted as a Technical Memo or Engineering Report, or both. "Engineering Report" refers to a single preliminary engineering document developed for the City that thoroughly examines the technical and administrative aspects of the project while meeting the minimum requirements of WAC 173-240-060. Submit the final report through the Water Quality Permitting Portal -Permit Submittals application by the date specified in this Agreed Order. Agreed Order Docket #18226 City of Edmonds Wastewater Treatment Plant Page 4 of 7 Lab Accreditation and Data Quality: Provisions of G l -5.4 of the Criteria for Sewage Works Design "Orange Book" require that all monitoring data except flow, temperature, settleable solids, conductivity and pH shall be prepared by a laboratory registered or accredited under the provisions of Chapter 173-50 WAC. The City's lab is accredited for several parameters being monitored during the pilot project. Those include Total Suspended Solids (TSS), pH, and Carbonaceous Biological Oxygen Demand (CBOD). The City's lab is not accredited for the following parameters to be monitored during the pilot project: Chemical Oxygen Demand COD, Ammonia, Nitrate (NO3) and Nitrite (NO2). Table 8 of the City's Technical Memo, W WTP Nuvoda MOB Process Evaluation and Trial, presents testing methods for the analysis of COD, Ammonia, NO3 and NO2. The City has decided to use Hach methods and products for the monitoring program. Hach methods for COD, Ammonia, NO3 and NO2 are accepted by the EPA as equivalent to EPA methods (40 CFR 136.6) for use in compliance monitoring: httos://www.hach.com/epa. Until the City's lab is accredited for these parameters, IT IS AGREED the City will split samples weekly, at the influent and effluent, for COD, Ammonia, NO3 and NO2 (effluent only). Consistent with Ecology's Information Manual for Treatment Plant Operators, a week is defined as a seven-day period beginning on Sunday and ending on Saturday. The City will send the split samples to an accredited lab, compare the City's lab results with the accredited lab results and report this to Ecology. AmTest is the lab currently contracted, but an accredited laboratory of the City's choice is acceptable. For each parameter, if three consecutive comparisons are within 10%, Ecology will accept the City -only lab results for the subject parameter, for the remainder of the pilot project. If the difference in results are greater than 10%, the City will submit to Ecology the following for the subject parameter: • Method procedures ■ QC/QA procedures • Bench sheets • Raw data, calculations and computer data entry The City will continue with the split sample comparisons, until the results of 3 consecutive samples -are within- I0%,-or--until-Ecology-provides-written-approval based on a review of the above submittals, whichever comes first. If the City reports split sampling comparisons at a frequency greater than once per week, a comparison of weekly averages will replace a comparison of single sampling events for that week. The City will submit the lab comparison results to the City's NPDES Permit manager, Stephanie Allen, within one week of the City's receipt of the data from the external lab, following the effective date of this Agreed Order. Agreed Order Docket # 18226 City of Edmonds Wastewater Treatment Plant Page 5 of 7 Attachment A is the City's Technical Memo dated May 1, 2020 for the WWTP Nuvoda MOB Process Evaluation and Trial. V. PROGRESS REPORTING The City of Edmonds shall provide progress reports to Ecology on a monthly basis for the below items: • Summary of any changes to project scope. • Summary of any NPDES permit reporting resulting from the pilot project. ■ Monthly monitoring data for parameters sampled at the influent and effluent consistent with S2.A of the NDPES permit. Progress reports shall include applicable dates, attachments and/or references. The first report must be submitted by the 15th day of the month following the effective date of this Agreed Order and monthly for the duration of the project. Submit the progress reports through the Water Quality Permitting Portal -Permit Submittals application. VI. FORCE MAJEURE If a milestone set forth in the Project Schedule is not met or is likely not to be met, the City shall submit to Ecology, in writing, any reasons for failing to meet the specific milestone as soon as they are reasonably aware of the delay. The City shall not be held responsible for a delay if the City has demonstrated a good faith effort to meet the deadline and the delay is attributable to delays outside of the City's control ("force majeure"). For purposes of this Agreed Order, force majeure shall mean only those occurrences or events beyond the control of the City, including acts of God, natural disasters, or action or lack of action by government agencies or third parties on permit, right-of-way, or other requests for required authorizations timely submitted by the City. VII. EFFECTIVE DATE This Order is effective on the date the agreement has been signed by both parties. Vill. TERMINATION OF THE AGREED ORDER Upon completion by the City of Edmonds of the actions identified in Section IV of this Agreed Order and issuance of a Notice of Compliance by Ecology, the requirements of this Agreed Order shall be deemed to be fulfilled and shall have no further effect on the City of Edmonds. IX. DISPUTE RESOLUTION If a dispute arises between Ecology and City of Edmonds regarding any noncompliance with this Agreed Order, the parties shall attempt to resolve the dispute by informal resolution. A dispute shall be considered to have arisen when one party notifies another, in writing, that there is a dispute. If the parties cannot resolve the dispute informally within thirty (30) days, City of Edmonds shall serve on Ecology a written Statement of Position. Within thirty (30) days after Agreed Order Docket # 18226 City of Edmonds Wastewater Treatment Plant Page 6 of 7 receipt of City of Edmonds Statement of Position, Ecology shall provide City of Edmonds with a final administrative decision. X. ENFORCEMENT --►- Failure to comply with this Agreed Order may result in the issuance of civil penalties or other actions, whether administrative or judicial, to enforce the terms of this Agreed Order. Ecology may consider enforcement discretion if the City has demonstrated a good faith effort to meet the terms of the agreement. XI. THIRD PARTY RIGHT TO APPEAL By signing this Agreed Order, City of Edmonds may not appeal this Agreed Order, however, a third party may. A party other than City of Edmonds has a right to appeal this Order to the Pollution Control Hearing Board (PCHB) within 30 days of the date of receipt of this Order. The appeal process is governed by Chapter 43.2113 RCW and Chapter 371-08 WAC. "Date of receipt" is defined in RCW 43.21 B.001(2). To appeal you must do both of the following within 30 days of the date of receipt of this Order: « File your appeal and a copy of this Order with the PCHB (see addresses below). Filing means actual receipt by the PCHB during regular business hours. ■ Serve a copy of your appeal and this Order on Ecology in paper form - by mail or in person. (See addresses below.) E-mail is not accepted. You must also comply with other applicable requirements in Chapter 43.21B RCW and Chapter 371-08 WAC. Your appeal alone will not stay the effectiveness of this Order. Stay requests must be submitted in accordance with RCW 43.21B.320. XII. ADDRESS AND LOCATION INFORMATION Street Addresses I Mailina Addresses I Department of Ecology Attn: Appeals Processing Desk 300 Desmond Drive SE _ Lacey, WA 98503 Pollution Control Hearings Board 1111 Israel Road SW STE 301 Tumwater, WA 98501 Department of Ecology Attn: Appeals Processing Desk PO Box 47608 _ _- Olympia, WA 98504-7608 Pollution Control Hearings Board PO Box 40903 Olympia, WA 98504-0903 Agreed Order Docket # 18226 City of Edmonds Wastewater Treatment Plant Page 7 of 7 XIII. CONTACT INFORMATION Please direct all questions about this Order to: Greg Lipnickey Department of Ecology Northwest Regional Office 3190-160th Ave. SE Bellevue, WA 98008 Phone: 425-449-6560 Email: glin461(wecy.wa.gov X1V. MORE INFORMATION -W � • Pollution Control Hearings Board Website http://www.eluho,wa.gov/Board/PCHB • Chapter 43.21B RCW - Environmental and Land Use Hearings Office — Pollution Control Hearings Board h ttp ://aMs.l eg. wa. go v/RCW /defau It. aspx?cite=43.21 B • Chapter 371-08 WAC — Practice And Procedure http://anos.leg.wa.gov/WAC/default.aspx?cite=371-08 • Chapter 34.05 RCW — Administrative Procedure Act littp://apps.leg.wa.gov/RCW/default.aspx?cite=34.05 • Ecology's Laws, rules, & rulemaking website https://ecology.wa.gov/About-us/How-we-operate/Laws-rules-rts 1 emaking XV. SIGNATURES M' hael Nelson Mayor City of Edmonds Rachel McCrea Water Quality Section Manager Northwest Regional Office Washington State Department of Ecology 10/21 /20 Date 10/26/2020 Date SIAN S TECHNICAL MEMORANDUM Date: May 1, 2020 To: Pamela Randolph, City of Edmonds From: Tom Giese, PE; Greg Mockos, PE; Casey Bryant, EIT, BHC Consultants, LLC Subject: WWTP Nuvoda MOBTM' Process Evaluation and Trial ti ppUL C: �a x■ � Thomas Paul Giese Jr., PE BHC Consultants, LLC This technical memorandum discusses the nitrogen removal potential of the Edmonds Wastewater Treatment Plant (WWTP) with the addition of the Mobile Organic BiofilmTM (MOB1m) process from Nuvoda. This investigation was done as a proof of concept using Envirosim's BioWin process modeling software. As part of the ongoing Puget Sound Nutrient Reduction Project, the Washington State Department of Ecology (Ecology) has begun work on a new general permit that will require WWTPs discharging directly to Puget Sound to achieve nitrogen removal to a level yet to be determined. Because the Edmonds WWTP discharges directly to Puget Sound, it will be included in the forthcoming general permit and required to remove nitrogen in the foreseeable future. The City of Edmonds (City) has decided to proactively start exploring possible alternatives for achieving nitrogen removal, of which the Nuvoda MOBTM' process is one such alternative. This alternative is particularly attractive because of its relatively low cost and overall ease of implementation. This technical memorandum also discusses how the City will conduct a trial of the Nuvoda MOBM technology to further assess its effectiveness and how it could be integrated into the existing WWTP. 1. Base Model Calibration To produce a relatively accurate representation of the Nuvoda MOB'rM process, a baseline BioWin process model representing current conditions and operations was first prepared and calibrated to check influent characterization and model assumptions. The baseline process TECHNICAL MEMORANDUM 1 BHC Consultants, LLC WWTP Nuvoda MOBTm Process Evaluation and Trial influent CC?Nc411 il�i' i `� model (see Figure 1) was created using record drawings and process operating data provided by the City from January 2019 to January 2020. The process data was sorted to only consider time periods in which two aeration basins and two final clarifiers were in use to ensure consistency with the process model representation. RAS Nxing Box1 AB1 Z1a ABt Z1bI A81 Z2+ AB7 Z3 AB 1 Ef11uentChannel Effluent RASNWng Box2 A82Z1a AB2Z1b A92Z2 A02Z3 AB 2 EBNen(Channel Blend Tank Dewafered Sludge �r Figure 1 — Baseline BioWin Process Model Diagram Influent wastewater characterization was based on influent flow and loading data provided by the City from January 2019 to January 2020, as well as ratios defined in the 2007 Process Control Improvements Study by Brown and Caldwell (Brown and Caldwell Report). Typical assumptions were made where these sources did not have applicable or representative information, such as raw influent chemical oxygen demand (COD) fractions. The ratios in the Brown and Caldwell Report were based on primary effluent. A comparison of the solids balance and total solids inventory (inventory in the aeration basins and final clarifiers) from actual data provided by the City and process model predictions was made to confirm the assumptions and influent characterization. A summary of the model calibration results are provided in Table 1. Table 1 Model Calibration Results and Comparison with Actual Values Parameter 1/1/19 - 4/22/19, 6/27/19 - 9/8/19, 10/11/19 - 10/29/19 BioWin Values A Notes Effluent CBOD (mg/L) = 9.2 7.58 -1.6 TSS (mg/L) = 10.7 11.80 1.1 pH = 7.2 6.72 -0.5 Ammonia-N (mg/L) = 20.2 20.42 0.2 Nitrate+Nitrite-N (mg/L) = I1.0 5.30 4.3 TKN (mg/L) = 1 32.1 21.7 1 -10.4 TECHNICAL MEMORANDUM 2 BHC Consultants, LLC WWTP Nuvoda MOBT11 Process Evaluation and Trial '1 -1 * s CONSULTANTS Solids Balance Primary Effluent TSS (mg/L) = 81 122 50% See discussion below Primary Effluent COD (mg/L) = 333 369 10.8% _ Per COD data from _ City 3.4 3.44 1.2% 3.4% per Carbon Primary Sludge TSS (%) Recovery SRT = 3.7 3.65 -1.4% Measured SRT recalculated MLSS = 1,555 1,460 -6.1 % Total Solids Inventory Mass (Ibs) = 19,328 19,607 1.4% Sec. Clarifier RAS TSS (mg/L) = 6,813 5,411 -20.6% 1 Average RAS TSS WAS (Ibs/d) = 4,926 4,924 0.0% As indicated in Table 1 above, there is a significant variation between the model predicted primary effluent TSS and the measured primary effluent TSS. This is based on the assumed removal rate of TSS in the primary clarifiers. However, increasing the removal rate yields large discrepancies in the model predicted solids balance versus measured data. Although primary effluent TSS can vary substantially from day to day and the April 2007 Process Control Improvements Study (Brown and Caldwell) suggested higher primary effluent TSS concentrations, the City collects composite samples four times a week to test for primary effluent TSS. This would suggest the primary effluent TSS data should be representative. It is possible that reported values of mean -cell residence time (MCRT) are calculated differently than in the solids retention time (SRT) in the model. However, the model calculated SRT accounts for both wasted solids and effluent solids, which is typically representative of MCRT. Because the source of the discrepancy is currently not known and a higher primary effluent TSS is conservative with respect to analysis of the secondary process, further changes were not made to the model calibration at this time. This question will be revisited during the trial period when more data is available and there is an opportunity to analyze the solids balance further. Further data on other parameters may impact assumptions that could also affect primary effluent parameters predicted by the model. For instance, assumptions of influent COD fractions may account for discrepancies in the primary effluent COD, which are still considered reasonably close for this level of analysis. Additionally, inclusion of recycled solids from the incinerator ash scrubber in the model could also impact the solids balance. Effluent Total Kjeldahl Nitrogen (TKN) values also differed significantly between measured data and predicted values. Given the small data set, it is difficult to determine if the few higher TECHNICAL MEMORANDUM 3 BHC Consultants, LLC WWTP Nuvoda MOB"' Process Evaluation and Trial measurements of effluent TKN were unusual or assumptions of refractory dissolved organic nitrogen need to be revisited. These considerations can be verified with collection of additional data, but do not significantly impact the conclusions of the analysis herein. Generally, a reasonable calibration with respect to the solids balance is achieved when predicted values are within 10% of measured values. This criterion is met for all parameters except for primary effluent TSS (as discussed above) and return activated sludge (RAS) TSS. Due to uncertainties related to assumptions for COD fractions and TSS removal in the primary clarifiers, the fact that the rest of the predicted values compare well with observed values, and because RAS TSS concentration is not a critical parameter, the differences in BioWin process model predictions and observed data are considered acceptable for this level of analysis, but will be revisited in more detail after more data has been collected from the Nuvoda trial. 2. MOBTM Modeling Modeling of the Nuvoda MOB TM process is meant to examine how a trial might perform under current average flow and loading and how a full-scale installation might perform under design maximum month flow and loading. Information gained from the technology trial will be used to update these models to improve accuracy of predictions and help determine how this process could be integrated into the existing WW'fP. The MOB TM process was modeled in BioWin based on parameters provided by Nuvoda. BioWin predicted a slightly thicker biofilm than Nuvoda indicated as typical. Past observations by Jacobs has indicated recirculation of the kenaf can reduce the biofilm thickness, which suggests the typical thickness indicated by Nuvoda may be more accurate. Biofilm thickness and mass can be examined more closely during the trial. The parameters recommended by Nuvoda and the values used in BioWin are summarized in Table 2. Per Nuvoda, multiple recommended parameters are estimates and will need to be confirmed during the trial. Table 2 MOB TM Modeling Parameters Parameter Fill Percentage Nuvoda Recommendation Input to BioWin 1.26% 1.26% Specific Volume (ft3/ft3) Specific Area (ft2/ft3) 1 1 6,092 6,092 Number of Layers (through film) N/A 3 TECHNICAL MEMORANDUM 4 BHC Consultants, LLC WWTP Nuvoda MOB TM Process Evaluation and Trial Boundary Layer Thickness (um) N/A 1 50 Biofilm Thickness (mm) 0.30 0.36 Min. Biofilm Concentration for streamer formation (gTSS/m2) 10 1 10 The Nuvoda MOB TM process is configured as an integrated fixed film activated sludge (IFAS) system within the BioWin process model, such that the carrier media is contained within each basin. As a result, the effect of the kenaf particles on the clarifier is not modeled, as the IFAS system assumes the biofilm carriers do not leave the basins. However, due to rapid settling of the kenaf particles, this was still considered to be reasonably representative, since the kenaf particles should have no adverse effect on settling of mixed liquor suspended solids (MLSS). Therefore, the settling of suspended growth MLSS will still be the controlling factor with respect to clarifier loading. In fact, Nuvoda indicates that the presence of the kenaf particles should improve settling characteristics of the MLSS. Settling of MLSS in the BioWin process model was based on 30-minute settleometer and sludge volume index (SVI) data provided by the City. The 90th percentile of SVI values for the calibration period is approximately 400 mL/g. This was converted to a diluted sludge volume index (DSVI) to differentiate between poor sludge settleability due to a low settling velocity or hindered settling (i.e., too much sludge). The 90th percentile of DSVI values for the calibration period is approximately 270 mL/g. This DSVI value was used to determine the maximum Vesilind settling velocity and the Vesilind hindered zone settling parameter, which can be input into the BioWin process model to generate a state point analysis for settling of the solids in the final clarifiers. Nuvoda has indicated a positive change in settling characteristics is expected with the implementation of the MOB TM process. This includes the sweeping action of the fast settling kenaf particles and agglomeration of MLSS with the kenaf particles due to production of extracellular polymeric substance (EPS) acting as a cationic polymer. Data for the MoorField Case Study was provided by Nuvoda, which observed an average SVI of about 460 mL/g before implementation of the MOB TM process. Once the process was installed and the treatment process acclimated, average SVI values were typically around 50 mL/g. Therefore, in addition to considering current SVI values, settling parameters associated with an SVI of 100 mL/g were also considered in the BioWin process model. Based on SVI data collected during the trial, any improvement in SVI can be correlated to settling parameters within the BioWin process model to help determine actual final clarifier capacity with the Nuvoda MOBT"" process. TECHNICAL MEMORANDUM 5 BHC Consultants, LLC WWTP Nuvoda MOB TM Process Evaluation and Trial 3. MOBTm Results 3.1 Current Average Flaw and ,Loading (Trial Period) A diagram of the BioWin process model representing the Nuvoda MOB TM process trial utilizing one aeration basin and one final clarifier is shown in Figure 2. 807E NaOH Influent RASMixing Box Zia Zib Z2 Z3 BlandTank Dewatarad Sludge Figure 2 — Nuvoda Trial BioWin Process Model Diagram E4WentChannal EMuwnt The predicted performance of the Nuvoda MOB TM process during the trial at current average flow and loading is summarized in Table 3. This data is preliminary, meaning it is based on several assumptions that need to be confirmed. Data from the trial will aid in confirming or modifying assumptions and validating the BioWin model for the Nuvoda MOB TM process. Table 3 BioWin Results with MOB TM Process at Current Average Flow Parameter Quantity Unit Influent Flow 4.5 MGD Waste Activated Sludge 4,820 Ibs/day SRT 5 days Effluent Ammonia-N 0.2 mg/L Effluent TIN 28.1 mg/L Mixed Liquor Recycle (MLR) N/A %Q Supplemental Alkalinity (50% NaOH) 500 gpd MLSS 3,580 mg/L _ RAS Rate 2.44 MGD TECHNICAL MEMORANDUM 6 BHC Consultants, LLC WWTP Nuvoda MOB TM Process Evaluation and Trial The SRT in Table 3 is representative of the total solids inventory (aeration basin and final clarifier) and loss of solids through both wasting and effluent. Nuvoda typically recommends a suspended growth SRT of around 5 days for the MOB TM process, though has indicated processes have run at an SRT of up to 8 days. This correlates with past observations by Jacobs that indicate a 4 to 5 day SRT (avoiding growth of nitrifying bacteria in the suspended biomass) appears to achieve the best results. Even a 5-day SRT is significantly higher than what the \NWTP typically operates at currently. As a result, it is expected that sludge production will be reduced and MLSS will increase, resulting in increased solids loading to the final clarifier, However, as discussed previously, improvements in sludge settleability and SVI should allow the final clarifier to handle the increased load. Because the current configuration of Aeration Basin No. 1 does not allow the formation of anoxic zones, all zones (except the small RAS mixing box) are aerated. This helps achieve complete nitrification, but does not allow for significant denitrification. During the trial, tapered aeration (stepping dissolved oxygen down sequentially through the zones) will be utilized in an attempt to achieve some level of simultaneous nitrification/denitrification. However, it is expected that a dedicated anoxic zone will be necessary to reach the levels of denitrification that will be necessary to achieve a total inorganic nitrogen (TIN) concentration of less than 8 mg/L in the effluent. The lack of denitrification also prevents recovery of alkalinity, which generates low effluent pH that can inhibit complete nitrification and violate the NPDES permit. Based on model predictions, it is estimated that a dose of about 500 gpd of 50% sodium hydroxide would be needed to maintain effluent pH above 6.5 during the trial to avoid inhibiting nitrification. Aeration Basin No. 1 has a total diffuser area of 1,298 square feet. The diffuser design for Aeration Basin No. 1 was based on an average diffuser flux rate of 1.35 standard cubic feet per minute per square foot (scfm/sf) for average summer conditions and 2.11 scfm/sf for peak summer conditions. Although product literature for the diffusers suggests a maximum flux rate of 4 scfm/sf, this may be just for periodic peak conditions. The operation and maintenance manual suggests a maximum flux rate of 2.15 scfm/sf, which would equate to a total airflow of about 2,800 scfm. The BioWin model predicts an air demand on the order of 3,000 scfm, which equates to a flux rate of 2.3 scfm/sf. This potentially slightly higher flux rate is likely not be an issue for the diffusers, particularly given that the design had diffusers in particular zones TECHNICAL MEMORANDUM 7 BHC Consultants, LLC WWTP Nuvoda MOB TM Process Evaluation and Trial CONSULTANTS operating at higher flux rates. So, it appears there should be enough diffuser capacity in Aeration Basin No. 1 for the trial. As a single blower has a capacity of about 2,600 scfm, there should also be sufficient blower capacity. 3.2 Design Maximum Month Flow and Loading A separate BioWin process model was utilized to predict performance of a full-scale installation at the design maximum month flow and loading. For this scenario, the BioWin process model was simplified to depict all three aerations basins as a single basin and all three final clarifiers as a single clarifier, as shown in Figure 3 below. It is assumed that for all three aeration basins, Aeration Zone 1 (Zones 1A and 1 B) is operated as anoxic volume to allow for denitrification and Aeration Basin No. 3 is configured for plug flow similar to Aeration Basins No. 1 and 2. The Influent L� Y filtered BOD concentration entering Zones 1A and 1 B is low, suggesting that these zones are carbon limited. Supplemental carbon could be added to achieve higher levels of nitrogen removal. Supplemental carbon could be added in the form of chemicals (e.g., Micro-C or methanol), or potentially from within the facility (e.g., diverting some influent directly to the aeration basins), as a significant portion of carbon is removed in the primary clarifiers. Alkalinity RAS Mixing Box Zia Zib Z2 Z3 Figure 3 — Full -Scale BioWin Process Model Diagram Eflluentchannei Effluent 1 A summary of predicted effluent quality and operating parameters for the design maximum month flow and loading scenario is provided in Tabled This data is preliminary, meaning it is based on several assumptions that need to be confirmed. Data from the trial will aid in confirming or modifying assumptions and validating the BioWin model for this scenario. TECHNICAL MEMORANDUM 8 BHC Consultants, LLC WWTP Nuvoda MOBT"' Process Evaluation and Trial Table 4 BioWin Results with MOBT11 Process at Design Maximum Month Flow Parameter 1 Quantity Unit Influent Flow 11.87 MGD Sludge Production 14,330 Ibs/day SRT Effluent TIN 5 days 16.2 mg/L Effluent Ammonia MLR MLSS 2.59 mg/L 300 %Q 3,650 mg/L RAS Rate 7.32 MGD The BioWin model did not quite predict complete nitrification at a 5-day SRT. However, it is quite possible that with current assumptions the model is underpredicting the biofilm mass and associated nitrification. Data collected during the trial will allow refining the model parameters and could very well yield better nitrification performance than currently predicted. A potential limiting factor under the maximum month design conditions is the final clarifiers. Figure 4 illustrates a state point analysis for the final clarifiers based on current SVI values (using a DSVI of 270 mL/g). The final clarifiers clearly do not have capacity to under these conditions without some improvement in SVI. 32-..-_.--- -- 30 26- �+ 26 1� 22 - - ---- - O Y0 -... 'a 18 .�._ ..... .r_- -... N 16 .. E _ 14 _._ Y_ 12 X 10 J 6 4 0 - 0 1 2 3 4 6 6 7 8 9 10 11 12 13 14 SOLIDS CONCENTRATION (kglm3) Secondary Clarifier 1 Overflow Secondary Clarifier 1 Underflow Secondary Clarifier 1 Flux Secondary Clarifier 1 Feed Figure 4 — Design Maximum Month State Point Analysis w/ Current SVI (5-day SRT) TECHNICAL MEMORANDUM 9 BHC Consultants, LLC WWTP Nuvoda MOBT11 Process Evaluation and Trial In comparison, Figure 5 illustrates a state point analysis for the final clarifiers based on an assumed SVI of 100 with the Nuvoda MOB TM process. In this case, the intersection of the overflow and underflow lines fall below the flux curve, indicating that there is some excess capacity within the clarifier. As this scenario is for maximum month conditions, some capacity is necessary to allow for increases over maximum month flows (peak day, diurnal peaks, etc.). 657- 60 55 _._._----- _ .................... ........ _ 660 .. - 40. .......... _. O 35 - N E 30 j 20 J LL 15 .. .. .� _ .. 0 O 1 2 3 4 5 6 7 6 9 10 11 12 13 14 SOLIDS CONCENTRATION ftlm3) Secondary Clarifier 1 Overflow Secondary Clarifier 1 Underflow Secondary Clarifier 1 Flux Secondary Clarifier 1 Feed Figure 5 — Design Maximum Month State Point Analysis w/ Reduced SVI (5-day SRT) For comparison, the BioWin model for design maximum month conditions was also ran using an SRT of 8 days. A summary of predicted effluent quality and operating parameters at this higher SRT is shown in Table 5. Table 5 BioWin Results with MOB TM Process at Maximum Month Flow and Reduced SVI Parameter Quantity Unit -lnfluenfflow- 1-18-7 -MGD- Sludge Production 10,920 Ibs/day SRT 8 days Effluent TIN 17.7 m /L Effluent Ammonia 0.3 mg/L MLR 300 %Q 5,020 mg/L MLSS RAS Rate 7.4 MGD TECHNICAL MEMORANDUM 10 BHC Consultants, LLC WWTP Nuvoda MOB TM Process Evaluation and Trial ��NsU�fiAN S The BioWiin model predicts complete nitrification at this higher SRT, though denitrification is not improved. This again suggests that the anoxic zones are likely carbon limited. The increase in MLSS associated with the higher SRT increases loading on the clarifiers. However, assuming an SVI of 100, the state point analysis show in Figure 6 suggests there might still be sufficient clarifier capacity. Although the intersection of the overflow and underflow lines are just below the flux curve, the underflow line is over the trailing end of the flux curve, indicating a higher RAS flow is likely necessary than assumed in the model. 66so 60 O N Of Y_ K J LL 0 1 2 3 4 6 6 7 6 9 10 11 12 13 14 SOLIDS CONCENTRATION (kglm3) Secondary Clarifier 1 Overflow Secondary Clarifier 1 Underflow Secondary Clarifier 1 Flux Secondary Clarifier 1 Feed 66 46 Figure 6 — Design Maximum Month State Point Analysis w/ Reduced SVI (8-day SRT) If improvement in settling characteristics to the level suggested by Nuvoda are not observed during the trial, such that substantial increases in MLSS are not practical, it is still possible to further increase treatment capacity by increasing the fill percentage of kenaf. Nuvoda typically applies a fill percentage of 1.26% and generally does not recommend increasing this percentage for municipal applications, as it is rarely necessary. However, the fill percentage could be increased if that were deemed appropriate for this application. It should also be noted that the WVVfP is well short of the current design maximum month flow and so it is unlikely to experience flows that high for quite some time, if ever. If it were determined that the Nuvoda MOB TM process alone could not achieve the level of denitrification required under design TECHNICAL MEMORANDUM 11 BHC Consultants, LLC WWTP Nuvoda MOBT11 Process Evaluation and Trial conditions, even with supplemental carbon, there are processes targeted for denitrification that could be added in the future when necessary. 4. Initial Conclusions Although the process modeling indicated that the Nuvoda MOB TM process may not achieve sufficient nitrogen removal under design conditions, the assumptions made in conducting this analysis are generally conservative. The above analysis indicates that this technology is a viable method of gaining capacity for nutrient removal and could be found to perform better than the conservative estimates herein. Even with the conservative assumptions herein, the performance of the Nuvoda MOB TM process could still be a fundamental piece of the City's strategy for achieving nitrogen removal, possibly on its own for some period of time before any subsequent improvements are necessary. Therefore, it is recommended that the City proceed with conducting a trial of the Nuvoda MOB TM process, as this will provide valuable data on the process to more accurately assess the performance of a full-scale operation. For example, improvements in settling may yield lower SVI values than assumed above, which would provide greater final clarifier capacity. Additionally, there may be more biofilm mass than predicted by the model, which could increase overall treatment capacity without increasing the suspended growth MLSS. 5. Nuvoda MOBTm Technology and Trial This section provides an overview of Nuvoda's Mobile Organic BiofilmTM (MOB TM) process, the pilot system that will be utilized for a trial of the technology, identification of the trial objectives and schedule, and a sampling and testing plan for data collection during the trial. An overview of the responsibilities during the trial is provided in Table 6 below. Table 6 Responsibilities for Nuvoda MOB TM Process Trial Activft_or Item Develop this Technical Memorandum I City R _Nuvoda R BHC Jacobs_ Notes P R Submit Technical Memorandum to Ecology P 1 Furnish Pilot System P Furnish Ancillary Items (e.g., piping, etc.) P Electrical and water connections P Temporary Supplemental Alkalinity System P Pilot System Setup P P A TECHNICAL MEMORANDUM 12 BHC Consultants, LLC WWTP Nuvoda MOBTI Process Evaluation and Trial C�A150111LTANTS Table 6 Responsibilities for Nuvoda MOB TM Process Trial Activity or Item j City Nuvoda BHC Jacobs Notes Pilot System Startup, Troubleshooting, and P P Training Pilot System Operation P Sampling and Testing P 2 Operate pilot system P A Process Monitoring and Testing Data P Recordkeeping Execute Trial Objectives P A A Assessment of Initial Trial Period R R P R Decision on Trial Extension P A A A Demobilization of Pilot System P P Prepare Engineering Report R P R Notes: P = Primary Responsible Party; R = Reviewer; A = Assist/Advise 1) Responsibilities and manner in which the trial is conducted may be impacted by input from Ecology. 2) The City will send some samples to an outside laboratory for testing of certain parameters. 5.1 Technology Overview The Nuvoda MOB TM process is designed to oxidize organic matter and remove nitrogen using both fixed film and suspended growth. The fixed film growth utilizes a media with a significantly different size and consistency compared to traditional plastic media. The Nuvoda media consists of processed kenaf, a renewable lignocellulosic material that is harvested from the woody kenaf, a fast-growing fiber plant. In order to serve as a recoverable and sustainable mobile biofilm media, the kenaf is machined to an effective size of approximately 1 millimeter. This allows it to combine with suspended biomass thus form a hybrid matrix of suspended and fixed biomass that acts similar to mixed liquor (i.e., free to circulate between process basins/tanks). The kenaf material typically enhances the settleability of the MLSS and tends to be completely captured in the final clarifier and thus retained within the process. Waste activated sludge (WAS) is passed through a drum screen to separate the kenaf media from the wasted suspended growth. The kenaf media is returned to the process and the wasted suspended growth is handled as wasted sludge would be normally. The Nuvoda MOB TM process is similar in concept to an integrated fixed film activated sludge (IFAS) process, but does not require vigorous aeration/mixing (normal fine bubble aeration is sufficient to keep the kenaf media suspended), utilizes a simpler media retention system that does not impact the TECHNICAL MEMORANDUM 13 BHC Consultants, LLC WWTP Nuvoda MOB TM Process Evaluation and Trial hydraulic profile, and uses an organic media that positively impacts settleability in the final clarifiers. 5.2 P►lot System Layout and Configuration The pilot system provided by Nuvoda will consist of a rotating wedge wire drum screen with 0.5 millimeter perforations and enough kenaf media to achieve a fill of 1.26% one aeration basin. The drum screen will be located in the Blower Building. There is available space between two existing blowers where the drum screen can be temporarily installed (see Figure 7), which will allow it to dump kenaf directly into Aeration Basin No. 1. Therefore, the City will be using Aeration Basin No. 1 for the trial along with Final Clarifier No. 1. Although the City had originally planned to replace the drive in Final Clarifier No. 1 this summer and thought about using Final Clarifier No. 2 instead, the City has some concerns additional stress on the spiral scraper collector mechanism in Final Clarifier No. 2 compared to the traditional plow -type scrapers in Final Clarifier No. 1, since the spiral scrapers are designed to move more material faster. Although there should not any significant additional stress imparted on the collectors due to the low specific gravity of the kenaf, to be safe the City decided to defer the drive replacement for Final Clarifier No. 1 until after the completion of the trial period. However, the City will still drain Final Clarifier No. 1 before the start of the trial to replace the scrapers on the plows to ensure proper tolerance such that a significant amount of kenaf is not stranded at the bottom of the clarifier. If the City extends the trial into the wet weather months, there could be an opportunity to switch operation from Final Clarifier No. 1 to Final Clarifier No. 2. Additionally, if more capacity is required during wet weather, the City may still run their conventional activated sludge process in a parallel train. Typically, the City does not utilize more than two aeration basins and clarifiers at a time, even during the wet weather months. TECHNICAL MEMORANDUM 14 BHC Consultants, LLC WWTP Nuvoda MOB TM Process Evaluation and Trial CONS;L A[ 5 Figure 7 — Photos of the Proposed Drum Screen Location Looking East and West As shown in Figure 8 below, existing WAS Pump No. 1 will be used to convey WAS from the Final Clarifier No. 1 RAS pipeline to the drum screen. A temporary flexible pipe will be routed from the discharge of the WAS pump to the inlet of the drum screen. The flexible pipe will pass through an opening in the floor of the Blower Building connecting it to the WAS pump on the level below. Similarly, a flexible line will be routed from the drain of the drum screen through the same opening to existing sump pumps on the lower level. The WAS drained from the drum screen will flow by gravity to the sump pumps. Valves on the discharge from the sump pumps can be arranged to direct the WAS to the existing WAS storage tank. The City has confirmed that the existing sump pumps have sufficient capacity to convey the drainage flow from the drum screen. TECHNICAL MEMORANDUM 15 BHC Consultants, LLC WWTP Nuvoda MOBT°" Process Evaluation and Trial N-D!7' r C SULTANTS DRUM SCREEN Figure 8 - Nuvoda MOB TM Process Pilot System Configuration The City had given consideration to potentially running two trains with kenaf during the wet weather months, assuming the duration of the trial is extended. There was some concern that returning the kenaf only to Aeration Basin No. 1 would likely yield some imbalance in the distribution of kenaf between two aeration basins. Nuvoda did not think the imbalance would be a concern for the duration of the trial and the imbalance could be partially offset by opening the isolation valve on discharge header between RAS Pumps No. 1 and 2 to allow mixing of RAS flow and modifying RAS pumping and wasting rates to maintain a relatively even balance. However, after further di`scussion,-it-wasdecided that the addedcostto purchase -the additional kenaf would likely not yield significant benefits to the information gained. Furthermore, having a single train with kenaf provides greater flexibility to stress the MOB TM process to determine the limits of nitrification. TECHNICAL MEMORANDUM 16 BHC Consultants, LLC WWTP Nuvoda MOB TM Process Evaluation and Trial 10 JWS;LT;N t'5 Because the existing configuration and equipment within the aeration basins does not allow the creation of anoxic zones, the trial of the Nuvoda MOB process will focus on achieving complete nitrification and the conditions (e.g., volume, MLSS, SRT, etc.) needed to maintain complete nitrification. Knowing this will help determine how much of the existing aeration basin volume could be freed up for use as anoxic zones. 5.3 Pilot System Requirements and Monitoring Equipment Based on the information provided by Nuvoda, the drum screen will require a 480-volt, 3-phase power feed and a 1-inch water connection. The 0.75 horsepower motorized drive for the drum screen will require a 15A breaker to feed the drum screen control panel, which contains the motor starter and overload relays. The City will need to run a temporary conduit and wire from a spare MCC bucket that has or can be fitted with a 15A breaker to the control panel. Optionally, a 20A would probably be work as well, but a breaker larger than 20A is not recommended. The drum screen requires a 1-inch waterline to connect in two locations on the drum screen for external washing of the drum. The waterline connection must be able to supply 14 to 45 gpm at 70 psi. The wash water could utilize either plant effluent or non -potable water. The City plans to install a temporary flow meter along the pipeline feeding the drum screen to monitor and control the WAS flow. The City is also considering installing a temporary density meter to monitor the concentration of solids in the WAS drained from the drum screen. These two measurements will allow calculation of the wasted mass. Alternately, the City could utilize routine grab samples to monitor solids in the drained WAS flow. To gather more complete and accurate information on the primary effluent that is feeding into the Nuvoda MOB TM process, a composite sampler will be added temporarily to sample primary effluent. As discussed in Section 3.1 above, the model predicts that pH will become depressed to the point that it could limit nitrification and violate the NPDES permit limit without the addition of supplemental alkalinity. The City currently uses sodium hydroxide for their odor control scrubber. Sodium hydroxide could be fed from the existing sodium hydroxide storage tank using one of the existing feed pumps. Alternatively, the City could use a separate temporary storage TECHNICAL MEMORANDUM 17 BHC Consultants, LLC WWTP Nuvoda MOB"' Process Evaluation and Trial tank provided by the chemical supplier that is dedicated for supplemental alkalinity, thereby providing greater storage and allowing more time between refills. Although totes would be another option, the estimated quantities required likely make the use of totes impractical. 5.4 Testing Objectives and Schedule Major milestones for the Nuvoda trial are as follows: • May 18, 2020 — Nuvoda is set to deliver the drum screen to the'V VV� ii P. June 1, 2020 — Nuvoda will begin installation of the drum screen. This may be delayed due to restrictions or requirements associated with the COVID-19 pandemic. Kenaf will be delivered no later than 1 week after installation of the drum screen. a June 1, 2020 — Earliest start of the trial period. The start of the trial may be adjusted based the screen installation date. • September 30, 2020 — Earliest end of the initial trial period. The end of the initial trial period may be extended based on the trial start date. • February 28, 2021 — End of the extended trial period. Extension of the trial is optional and will be determined based on the level of success during the initial trial period. The goals of the Nuvoda MOB TM process trial are to demonstrate the following: Consistently achieve the following effluent quality: o BOD5 < 10 mg/L (30-day running average, minimum 1 sample per week) o TSS < 10 mg/L (30-day running average, minimum 1 sample per week) o Ammonia-N < 0.5 mg/L (30-day running average, minimum 3 samples per week) o Ammonia-N not exceeding 1.5 mg/L in any sample • Assess improvements to sludge settleability and its impact on performance of the final clarifier and allowable loading. Assess the minimum hydraulic retention time to sustain complete nitrification. Assess the capability to achieve simultaneous nitrification/denitrification at reduced dissolved oxygen levels, while maintaining essentially complete nitrification. A schedule of the objectives to achieve the goals of the trial is as follows: 1. Step 1 — Startup, training, troubleshooting and acclimation of the process. Generally, about 3 times the SRT is necessary to ensure a stabilized process. Although the SRT of suspended growth will initially be targeted for 5 days, the SRT of the biofilm will be much longer. Therefore, it is expected that the acclimation period to establish the biofilm could TECHNICAL MEMORANDUM 18 BHC Consultants, LLC WWTP Nuvoda MOB TM Process Evaluation and Trial be about 2 months following an initial week for startup, training and troubleshooting. During the acclimation period, all zones within Aeration Basin No. 1 will be operated as fully aerobic (no tapered aeration) to facilitate complete nitrification, which should be confirmed by the end of the acclimation period. 2. Ste 2 — Determine Lowest SRT Necessa for Complete Nitrification. The next step will be to reduce the SRT of the suspended biomass based on maintaining complete nitrification. A reduced SRT will decrease MLSS and solids loading on Final Clarifier No. 1, but increase wasting. To start, the suspended growth SRT will be reduced from 5 days to 4 days. Although the suspended growth may acclimate more quickly, it could over a month for the biofilm to fully acclimate. Depending on how the process operates at an SRT of 4 days, a second adjustment to the SRT may be made. During this period, all zones will continue to be operated as fully aerobic. 3. Step 3 — Examine Simultaneous Nitrification/Denitrifcation. Investigate the impacts of decreasing dissolved oxygen (DO) concentrations with respect to achieving simultaneous nitrification/denitrification. Taper the dissolved oxygen concentrations among the different aeration basin zones, starting at a higher value in the first zone and lowering DO incrementally in each subsequent zone. Assess how lower DO may enhance denitrification within the biofilm. How low the DO may be reduced in each zone may be limited by a minimum level of aeration to keep the biomass and MOB suspended. Although the process may respond relatively quickly to changes in DO, it may take several weeks to for the biofilm to fully acclimate. Therefore, once minimum DO settings are established, the process will continue to operate at these levels for at least a month to determine if changes there are subsequent changes in the biofilm that impact the results. 4. Ste 4 -- Determination for Extended Testing. It is expected that the initial trial period will at most carry through Step 3 (maybe only Step 2) and that the extended trial period will be necessary to complete the rest of the testing outlined herein. However, before proceeding with the extension, results from the initial trial period will be reviewed to confirm that further testing is warranted. If the initial results are disappointing, further testing may not be pursued. 5. Step 5 — Reduce HRT_in the Aeration Basin. The MOB TM process would be stressed at higher flows to help determine how HRT impacts the ability of the process to meet the effluent quality goals (e.g., no significant bleed through of ammonia). Because it is TECHNICAL MEMORANDUM 19 BHC Consultants, LLC WWTP Nuvoda MOB TM Process Evaluation and Trial ■r C �JLTAN S expected that one train will be capable of treating dry weather flows, stress testing likely won't be possible until the wet weather months when influent flows increase. It is anticipated that the City may need to bring a second process train online (operated separately with their current activated sludge process) when flows reach around 5 MGD. 6. Ste 5 — Examine Impact of increased Organic Load. To simulate increased organic load, all flow could be passed through a single primary clarifier. This would help determine the impact of reduced removal in the primary clarifiers on the MOB TM process and whether or not the process could effectively maintain the effluent quality goals. This may be examined most effectively during wet weather months when multiple primary clarifiers are most likely to be needed to meet current typical levels of performance. If the process reacts well initially, the increased load could be continued for a month or more to see if there are changes in the biofilm that impact process performance. 7. Step 6 — Demobilization. The final week of the trial, after all the above steps have been completed to the satisfaction of the City, the pilot system will be decommissioned and demobilized. As stated previously, it does not appear possible to create a temporary anoxic zone that would allow operating the secondary treatment system as an MLE process. Although the air could be turned off to one or more zones in an aeration basin, there would then not be sufficient mixing energy to keep the kenaf and other solids suspended. Furthermore, it would be difficult to implement an internal mixed liquor recycle. For example, installing a submersible pump and piping would require significant time to procure, place and power the equipment. Therefore, rather than directly assessing denitrification in a separate anoxic zone, the focus will be on understanding the requirements needed for nitrification and the potential for simultaneous nitrification/denitrification. These will subsequently help determine how much of the existing aeration basins volume is required for nitrification and how much could be made available for denitrification. 5.5 Sampling and Testing A summary of the sampling and laboratory testing to be implemented for collection of data to evaluate performance and efficiency of the Nuvoda MOB TM process in relation to achieving the goals of the trial is provided in Table 7 below. All laboratory analyses will be performed TECHNICAL MEMORANDUM 20 BHC Consultants, LLC VWVTP Nuvoda MOB TM Process Evaluation and Trial ; m) S; A N S in accordance with the latest version of the Standard Methods for the Examination of Water and Wastewater or established EPA methods, unless noted otherwise. TABLE 7 SAMPLING AND LABORATORY TESTING SCHEDULE Sample Location Sample Type Analysis Frequency Notes Influent Metered Flow Continuous 1 Grab Sodium Hydroxide Dose 5 / week 5 Temperature 5 / week 24-Hour Composite CBOD5 3 / week 1,2 TSS 3 / week 1,2 pH 3 / week 2 VSS 1 / week 2 COD 3 / week 2 Filtered CBOD5 1 / week 2, 3 Filtered COD 1 / week 2,3 Filtered -Flocculated COD 1 / week 2,4 TKN 1 / week 2,6 Ammonia 3 / week 2 Nitrate 1 / week 2 Alkalinity 1 / week 2,6 Primary Effluent 24-Hour Composite Metered TSS 1 / week 2 CBOD5 1 / week 2 COD 1 / week 2 TKN 1 / week 2,6 Aeration Basin No. 1 Airflow Continuous Zone 1A DO Continuous Zone 2 DO Continuous Zone 3 DO Continuous Grab MLSS (w/o kenaf) 5 / week 7 MLVSS (w/o kenaf) 5 / week 7 Biofilm Mass 1 / week 7 Kenaf % Fill 1 / week 7 RAS Metered Flow Continuous Grab TSS 5 / week WAS Metered Flow Continuous Grab TSS 5 / week Final Clarifier No. 1 Grab Sludge Blanket Depth 5 / week SVI (w/ kenaf) 5 / week 8 SVI (w/o kenaf) 5 / week 7 Final Effluent Metered Flow Continuous 1 TECHNICAL MEMORANDUM 21 BHC Consultants, LLC WWTP Nuvoda MOB"' Process Evaluation and Trial --:In-[ CONSULTANTS Grab pH Daily 1 Temperature Daily 24-Hour Composite CBOD5 3 / week 1, 2 TSS 5 / week 1,2 COD 1 / week 2 TKN 1 / week 2,6 Ammonia 3 / week 2 Nitrate 3 / week 2 Nitrite 3 / week 2 Screw Press Filtrate Grab TSS 1 / week 1 / week 2 2 Ash Scrubber Drainaae Grab TSS Notes: 1) Sampling and testing already required per the NPDES permit. 2) Take all of these samples on the same day(s) as one another so that they may be correlated. 3) Filter the sample using a 1.2 micron glass fiber "C" filter. Run the test on the filtrate. 4) Measurement of filtered -flocculated COD is not a Standard method, but is documented in the 1999 WERF publication on Methods of Wastewater Characterization in Activated Sludge Modeling and is as follows: a) 1 mL of 100 g/L zinc sulfate solution is added to 100 mL of wastewater. b) The sample is mixed vigorously for approximately 1 minute. c) The sample pH is adjusted to approximately 10.5 using 2 M sodium hydroxide solution with slow mixing for 5 minutes. d) The sample is then allowed to settle for a few minutes and a volume of clear supernatant is withdrawn for filtration through a 0.45 micron membrane filter. e) The filtrate COD is measured. Filtrate COD can be measured using spectrophotometry. 5) Sodium hydroxide dose as measured in gallons per day or mg/L delivered into the wastewater. 6) Samples for analysis of alkalinity and TKN will be sent to AmTest for testing. 7) Filter sample through a 0.5 mm sieve. See Attachment A for further detail. 8) Note the settled sludge volume at the 10 minute mark. See Attachment A for further detail. A list of test methods to be used and the associated method detection limit (MDL) is provided in Table 8 below. TECHNICAL MEMORANDUM 22 BHC Consultants, LLC WWTP Nuvoda MOB TM Process Evaluation and Trial IGL.IA TABLE 8 SAMPLE TESTING METHODS Parameter Tested EPA/Standard Method MDL Alkalinity SM 2320 B 1 mg/L TSS SM 2540 D 5 mg/L VSS SM 2540 E 2 mg/L Temperature SM 2550 B N/A Settled Sludge Volume SM 2710 C N/A Sludge Volume Index SM 2710 D N/A 2 - 14 pH SM 4500-H+ B Ammonia -Nitrogen EPA 350.1 0.1 mg/L Nitrite -Nitrogen SM 4500-NO2- B 0.02 mg/L Nitrate -Nitrogen EPA 353.2 0.3 m /L Dissolved Oxygen SM 4500-0 G 0.2 mg/L TKN EPA 351.2 0.19 mg/L CBOD5 SM 5210 B 2.0 mg/L COD SM 5220 D As required by the NPDES permit, the City will submit monthly the available test results from the pilot study to Ecology as an attachment to the monthly discharge monitoring report. In addition to the sampling and testing listed in Table 7, the City is looking into engaging with Dr. Mari Winkler at the University of Washington who is a specialist in the study of biofilm/granular sludge. Nuvoda has worked with Dr. Winkler in the past to evaluate samples of kenaf and biofilm growth and provide information on the structure and makeup of the biofilm. Dr. Winkler could also run nitrification and denitrification tests separately on the biofilm and suspended growth. 6. Next Steps Following completion of trial, this technical memorandum will be amended and expanded into an engineering report that summarizes observations and data from the trial, discusses operation of the Nuvoda MOB TM process during the trial to fulfill the objectives, assesses performance of the technology with respect to established goals, and updates predictions for performance at current and design flows and loads. TECHNICAL MEMORANDUM 23 BHC Consultants, LLC WWTP Nuvoda MOB TM Process Evaluation and Trial ATTACHMENT A Nuvoda Testing Methods NUVODA Innovative Wastewater Solutions Nuvoda US Testing Methods SVI & MLSS Using a 1000 mL graduated cylinder, collect a well -mixed sample of mixed liquor in a 1-gallon container. Keep the sample mixed and fill the graduated cylinder to the 1000 mL mark. Allow for the sample to settle for 30 minutes and take note of the top of the sludge blanket. For granular sludge/fixed film systems, the SVI10 — SV13o. Make note of the sludge depth at the 10-minute mark to evaluate if the MOB process has started to grow biofilm. The testing method is the same as with Kenaf, but you will use a 0.5 mm screen to filter the mixed liquor sample to ensure the Kenaf particles are not in the sample. MLSS Testing Method Wth KenaM- Collect a well -mixed sample of mixed liquor in a 500 mL beaker. Remove two filter papers from a desiccator and record the weight of each. Place the filter holder on a vacuum flask and then place a filter on top of the filter holder by using a pair of tweezers. Stir the sample of mixed liquor in order to get a good mixture for the experiment. After sample is mixed, pour 25 mL into a graduated cylinder. Turn on the vacuum pump and pour the sample into the filter holder. After all the mixed liquor has gone through, run three portions of 30 mL distilled water through the filter holder to rinse any particles that may have stuck to the glass. Allow the vacuum pump to run an additional three minutes. This will help remove any extra water from the filter before drying. Switch the vacuum pump off and remove the filter from the filter holder and place in the corresponding weighing dish. Repeat above process for as many trials as needed. Place the filter(s) into a drying oven, which is set to 103°-105° C, for one hour. Upon drying, replace filters into a desiccator for 30 minutes. After 30 minutes in the desiccator, the filters are to be weighed. t. ® 0 733 W. Johnson Street + 1 919 615 1205 www.nuvodaUS.com Suite 200, Raleioh, NC 27603 ` NUVODA Innovative Wastewater Solutions i. U. 7 ,17� The testing is the same as the previous MLSS testing with the Kenaf. Using a sample from the original 500 mL sample pulled, screen the 25 mL through a 0.5 mm screen. The Kenaf can be rinsed lightly with DI water to help remove any particulates that are not a part of the Biofilm. The collected screened sample, although slightly more volume than the 25 mL poured, will be tested for TSS to give the MLSS without the Kenaf. it . + .>'M..ii[►T� Collect a well -mixed sample of mixed liquor in a 500 mL beaker. Use a 0.5 mm screen to filter the sample of the Kenaf particles. Rinse the Kenaf particles with DI water. Resuspend the Kenaf with biofilm particles in DI water that were collected from the 500 mL sample. Remove two filter papers from a desiccator and record the weight of each. Place the filter holder on a vacuum flask and then place a filter on top of the filter holder by using a pair of tweezers. Stir the sample of Kenaf with biofilm and DI water in order to suspend the Kenaf with biofilm in solution. Turn on the vacuum pump and pour the sample into the filter holder. After all the solution has gone through, run three portions of 30 mL distilled water through the filter holder to rinse any particles that may have stuck to the glass. Allow the vacuum pump to run an additional three minutes. This will help remove any extra water from the filter before drying. Switch the vacuum pump off and remove the filter from the filter holder and place in the corresponding weighing dish. Repeat above process for as many trials as needed. Place the filter(s) into a drying oven, which is set to 103°-105° C, for one hour. Upon drying, replace filters into a desiccator for 30 minutes. After 30 minutes in the desiccator, the filters are to be weighed and the mass of the Kenaf with biofilm to be recorded. After the mass is recorded, resuspend the Kenaf particles in DI water and screen Kenaf again through a 0.5 mm screen. Rinse the particles with DI water, to ensure all sluffed biofilm is not attached to Kenaf, and resuspend rinsed Kenaf particles without the biofilm in a DI solution. Remove two filter papers from a desiccator and record the weight of each. Place the filter holder on a vacuum flask and then place a filter on top of the filter holder by using -a -pair oftwuezers.-Stir the sample -of Kenaf and -DI -water -in order -to suspend the Kenaf in solution. Turn on the vacuum pump and pour the sample into the filter holder. After all the solution has gone through, run three portions of 30 mL distilled water through the filter holder to rinse any particles that may have stuck to the glass. Allow the vacuum pump to run an additional three minutes. This will help remove any extra water from the L ® G + 1 919 615 1205 www.nuvodaUS.com 733 W. Johnson Street Suite 200, Raleioh, NC 27603 NUVODA Innovative Wastewater Solutions filter before drying. Switch the vacuum pump off and remove the filter from the filter holder and place in the corresponding weighing dish. Repeat above process for as many trials as needed. Place the filter(s) into a drying oven, which is set to 103°-105° C, for one hour. Upon drying, replace filters into a desiccator for 30 minutes. After 30 minutes in the desiccator, the filters are to be weighed. The mass of the filters with Kenaf without biofilm should be subtracted from the mass of the filters with Kenaf with biofilm to give a close estimate of the mass of biofilm growth on the Kenaf. Since the Kenaf is porous, it will be difficult to have 100% accuracy with this test. Pgrgent Fill of Kenaf.- 1. Using Mass (best method after biofilm forms) From the previous testing determining the Mass of Biofilm on Kenaf, the weight of the Kenaf without the biofilm can be recorded as (Mass of Kenaf g) and using the density of raw dry Kenaf (0.263 g/mL) the total volume of kenaf can be determined in (mL). The percent fill of Kenaf is calculated as: (Volume of Kenaf mL) / (500 mL Sample) 2. Using Volume (easiest method with fresh Kenaf addition) Using a 1000 mL graduated cylinder, collect a well -mixed sample of mixed liquor in a 1-Liter container. Screen the mixed liquor sample through a 0.5 mm screen. Lightly rinse the screened Kenaf particles with DI water to remove any particulates that may have attached to the Kenaf. Resuspend the Kenaf particles in a solution of DI water (The volume of the solution should be no less than 500 mL and no greater than 1 L). Mix the solution of DI water and Kenaf particles and pour into the 1000 mL graduated cylinder. Allow the sample to settle for 30 minutes and take not of the top of the Kenaf blanket in (mL). The percent fill of the Kenaf is calculated as: (Volume of Kenaf mL) / (1000 mL Sample) t. ® 0 + 1 919 615 1205 www.nuvodaUS.com 733 W. Johnson Street Suite 200, Raleiah, NC 27603