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On the heels of a major BNR upgrade completed in 2016, Capital Region Water (CRW) in Harrisburg, PA set out on making significant improvements to its solids and energy streams. CRW operates a 22 MGD Advanced Wastewater Treatment Facility (AWTF) with a pair of mesophilic digesters dating back to last major plant expansion in the 1970s. These digesters are currently undergoing refurbishment including grit removal, new covers, and mixing. With BNR and fresh digesters in place, CRW is now setting its sights on sustainability goals by targeting a project to enhance energy recovery from its solids resources. To help identify the most beneficial energy recovery project, CRW engaged with an engineering team led by Arcadis in 2018 to undertake a comprehensive solids and energy planning effort targeting upgrades. The CRW plant already had an operational history of recovering its biogas for energy using CHP engines. The plant has been operating a set of 600 kW Waukesha 'Enginators' since 1984 to make electricity and recover hot water for heating (see Figure 1). Interestingly, CRW does not utilize the CHP electricity internally, but instead transmits its generated power to the local utility and receives full delivered unit pricing via an interconnection agreement. These engines are reaching the end of their useful lives, however, and the CRW staff initially envisioned an in-kind replacement of the CHP engines with upgrades to heat recovery. The solids and energy planning effort was aimed at looking at a wide range of options both in conjunction with and in lieu of CHP. For example, the plant currently co-thickens primary sludge and WAS in gravity thickeners, leading to significant seasonal deterioration in thickening performance (see Figure 2) especially after the implementation of BNR. One of the improvements examined was the separation of WAS for mechanical thickening to improve sludge feed concentrations to the digesters. This, along with the following list enhancement items were examined: Separated mechanical WAS thickening WAS lysis for enhanced digestion New CHP engines with upgraded heat recovery Biogas to Renewable Natural Gas (RNG) Acceptance of High Strength Waste (HSW) Backup power generation with CHP Upgrades to biogas compression and transmission The key tool used to evaluate all these options and their interacting effects was holistic solids and energy flow model (see Figure 3). With this tool, any potential combination of processes or loading rates was quantitatively analyzed for annualized cost, greenhouse gas (GHG) reductions, net power generation, and capital cost. Along with determining an operationally sound and cost-effective treatment facility, processes were also examined to meet goals of maximizing value of the plant's energy resources and supporting the cost effective Class B biosolids land application program already in place. There were some very significant site specific factors identified early in the planning process. One item was the existence of a natural gas 'peaker' facility directly adjacent to the AWTF fence line in the area of the digesters. This facility is operated by the local natural gas utility. Engagement with this utility revealed a positive and cooperative position regarding connection of RNG to their system. This meant that CRW had not only identified a partner for RNG, but also would have an interconnection pipeline requirement of essentially zero. Another site specific item for this project was the abundance of high quality HSW in the area due to the presence of local food producers such as Hershey Creamery and Utz Potato Chips. These producers have previously shown high interest bringing their material to the AWTF, making the acceptance of HSW a high priority for CRW. With these site specific conditions in mind, Figure/Table 5 give the results of some of the most prominent scenarios from solid and energy flow model tool. One of the major conflicts facing this facility and many others is the illogical incentive structure under the current Renewable Fuel Standard (RFS) where digesters receiving HSW get penalized as RINs are downgraded from D3 to D5. This was confounded by the acute drop in D3 RIN pricing occurring in late 2019 during the time of the study. Significant sensitivity analysis on both D3 and D5 RIN pricing was done using the flow model tool, allowing many potential future RIN pricing scenarios to be considered. Ultimately, the decision to target both RNG and HSW acceptance was made. While accepting HSW reduced RIN value potential, it also brings in tipping fees and avoids the higher sensitivity swings related to D3 RIN prices. Some other conclusions were as follows: The replacement of CHP engines with new equipment and upgraded heat recovery did not provide an annualized savings to the plant. This included maintaining the existing interconnection agreement at $0.075/kWh and taking a capital credit for offsetting backup power generation. The main driver was the high cost of biogas conditioning and the O&M support package which is difficult to overcome for newer engines at this scale. The addition of enhanced sludge thickening by separately mechanically thickening WAS did not provide annualized savings to the plant. However, this was viewed as a fundamental investment in solids infrastructure, providing operators more control over thickening and eliminating the difficulties with seasonal bulking and performance deterioration in the gravity thickeners. Savings from other parts of the project would offset this long term investment in improved operations. The addition of WAS lysis beneficial on an annualized costs basis, paying for its capital by increasing biogas recovered as RNG and reducing biosolids to be managed. Implementation of lysis was selected, with major driver being current dewatering difficulties. Currently the AWTF must produce 20% TS cake as part of their land application which has been a struggle. With lysis, a cake TS increase of 2-3% is expected which would significantly improve dewatering operations for land application. Based on the results of this work, CRW has moved forward with implementation of the recommended project with the design completed and construction slated to begin in early 2021. The project includes a new Thickening and Lysis Building to house new WAS thickeners as well as thermal-alkaline WAS lysis. Heated and lyzed WAS will be blended in-line with received HSW in a new feed line to the digesters. A new biogas to RNG skid will be implemented with the neighboring natural gas peaker facility taking custodial transfer of the product gas for injection into the pipeline. The engineering team has also recently identified a local PA 'green gas' program in the Philadelphia area willing to pay premium prices for RNG. Partnering with this type of offtake can remove headaches related to the RFS by avoiding swings in RIN market prices and value conflicts around accepting HSW. By partnering with local food producers and natural gas utility, this project serves as model for how cooperation and regionalization can significantly uptick the value that can be obtained for energy resources at a WRRF. This also demonstrates the value of effective solids and energy planning as CRW staff were able to quickly and confidently move forward with implementation, and take on long term operational improvements such as thickening in combination with money savings aspects like HSW and RNG.

NEW Water, the brand of the Green Bay Metropolitan Sewerage District, has completed a program, with initial planning starting in 2008, to replace its biosolids management system at the Green Bay Facility (GBF) in Green Bay, Wisconsin. The facility is permitted to treat 49 MGD of wastewater and process biosolids from the GBF and waste activated solids from their other wastewater facility, the DePere Facility (DPF). The GBF was constructed in 1975 and included a thermal conditioning system (TCS), belt filter press dewatering and two multiple hearth furnaces (MHFs) to process wastewater solids. This process train was chosen because agricultural land application in Wisconsin was deemed not to be practical. Subsequently, the TCS was shut down and in 2008, NEW Water took over operations of the DPF. The almost 40-year-old GBF did not have sufficient treatment capacity into the future and the equipment required replacement due to its age and increasing maintenance costs. In addition, the existing MHFs would not meet the pending federal Clean Air Act Maximum Achievable Control Technology (MACT) air pollution regulations for sewage sludge incinerators (SSIs) that became effective in 2016. Between 2008 and 2011, NEW Water and CH2M (now Jacobs) developed a Solids Management Facility Plan that evaluated numerous solids processing technologies and process trains to respond to these issues. Seventy-three solids unit processes were considered, some were eliminated and the remaining 52 unit processes were used to develop 17 process configurations. Of these 17 configurations, six alternative configurations were selected and evaluated in detail. The Digestion with Thermal Processing and Electrical Generation alternative was selected and later named the Resource Recovery and Electrical Energy Project, or R2E2. The R2E2 process flow configuration, shown in Figure 1, is an integrated solids processing system comprising mesophilic anaerobic digestion (MAD), dewatering and fluidized bed incineration with waste heat recovery (WHR). MAD was chosen as a first processing step to generate biogas for combined heat and power (CHP). High strength liquid organic wastes are co-digested in the MAD process to enhance biogas production and maximize power production and waste heat utilization. Dewatering using centrifuges, followed by fluidized bed incineration was selected as the most efficient method of managing the biosolids, given there is not land within economical distance of Green Bay for agricultural utilization. The fluidized bed reactor (FBR) is equipped with a partial scalping dryer, utilizing waste heat recovered from the FBR and using thermal oil to ensure autothermal combustion. Phosphorus is recovered from the dewatering centrate to produce a fertilizer product. In addition, beneficial uses of the residual ash are being pursued. The CHP, dewatering and FBR equipment trains were purchased and the balance of plant design completed in 2014. Construction commenced in August 2015 and commissioning and performance testing were completed by the end of 2018. Figure 2 shows operating data from the startup of the two digesters through August 2019. The system has been operating since November 2018, as an integrated system. Figure 3 shows a summary of the system energy distribution and usage at the design year of 2035 at annual average wastewater flow conditions. The R2E2 project is expected to generate more than 65% of the GBF projected electrical power requirements in 2035 using biogas only and up to 85% using supplemental natural gas to the full CHP loads. With the system thermal efficiency of about 60% based on heat recovered, the R2E2 project will meet NEW Water's goal of producing electricity in the most efficient way while maintaining autothermal combustion. The paper will discuss the energy recovery and production performance of the facility during the two years of full operation, including the Covid-19 period. Since operation of both digesters commenced, NEW Water has initiated its program of importing high strength organic waste (HSW) and has been increasing quantities to achieve design quantities. Biogas production has increased, with increased electricity production of green energy. The monthly biogas and natural gas electricity production, together with the monthly HSW imported quantities and generator run times in the first year are shown in Table 1. As part of the energy management system, SCADA options allow determining when is the optimum time to operate the CHP and the number of units to operate to reduce demand and other electrical charges. NEW Water continues to optimize energy production with waste heat recovery and matching plant heating requirements. The presentation will be of interest to municipal plant operators, wastewater utility managers, planners and design engineers who are considering integrated biosolids processing systems to maximize energy recovery and provide resource recovery opportunities.

A Public-Private Success Story for Biosolids Management in Northern California James Dunbar, PE, General Manager, Lystek International Limited Jordan Damerel, PE, Director of Engineering, Fairfield-Suisun Sewer District The Fairfield-Suisun Sewer District (FSSD) and Lystek International Limited (Lystek) have built a progressive public-private partnership (P3) to provide solutions to the biosolids management challenges faced by Northern California wastewater agencies. FSSD is a special district (located 45 miles northeast of San Francisco) and has a history of looking for progressive approaches to wastewater treatment technologies. Lystek is a Canadian-based private company with a patented biosolids treatment technology, a thermal-chemical hydrolysis process employing high-speed shearing, alkali pH, and low-pressure steam injection (Lystek THP). The Lystek THP process hydrolyzes biosolids and residuals to produce a concentrated liquid that has multiple applications in resource recovery, including as a Class A biosolids fertilizer (LysteGro), and a digester enhancement (LysteMize). This paper will present the background of biosolids issues in Northern California and the steps taken by FSSD and Lystek to be leaders in overall biosolids solutions, resource recovery, and high-value beneficial uses. The San Francisco Bay Area relies on a diverse portfolio of biosolids outlets. More than 1,500,000 wet tons of biosolids are generated each year from almost 40 wastewater treatment plants. The solids treatment processes employed by the various plants include digestion, lime-stabilization, mechanical drying and solar/wind drying. The management outlets include incineration, landfills (both for disposal and alternate cover material), composting, and agricultural land application. For many years, there were economical outlets for the seasonal volume fluctuations and land application requirements of regional governments. About 15 years ago, it became clear that alternative solutions needed to be explored due to increasing volumes and a desire to capture the value inherent in biosolids. Individual agencies and sub-regional groups started to investigate potential solutions and spent considerable time, effort, and money in this area, however, a lack of financial commitments by both the private sector and public entities prevented any real progress in finding a proven solution. In 2016, Lystek and FSSD entered into a +20-year partnership to develop an onsite solution for biosolids management and resource recovery. The partnership agreement allowed the development of the Fairfield Organic Material Recovery Center (OMRC) as a regional biosolids and organics management facility, owned and operated by Lystek, leveraging under-utilized infrastructure and assets at the FSSD plant. The Fairfield OMRC location is ideally situated to provide a regional solution, straddling the edge of urban density which provides biosolids quantities, and an established agricultural community seeking soil amendments. The partnership between FSSD and Lystek has successfully created a complete solution for utilities in the Bay Area through Lystek's efficient process, on-site storage solution, and development of a strong market for the Class A biosolids fertilizer. The OMRC accepts residuals year round, is able to store the fertilizer during inclement weather periods, and land applies fertilizer throughout the year as field conditions allow. The material is classified as a Class A biosolids by USEPA (Part 503 standards), and has received a bulk fertilizer registration by the California Department of Food and Agriculture (CDFA). This dual-designation material has allowed LysteGro to be widely used and accepted by area farmers and ranchers as a fertilizer (Figure 1) to avoid the use of chemical and synthetic fertilizers. The use of Class A LysteGro is now accepted in multiple counties which have historically been restrictive to traditional Class B biosolids and its land application practices. The other major component of the FSSD-Lystek partnership involves enhanced digestion and biogas generation. FSSD operates anaerobic digesters to treat wastewater solids and utilize the biogas for onsite co-generation (electricity plus heat for the digesters). This reduces the overall plant energy dependence on fossil-fuels sources. Through the LysteMize process, a portion of the Lystek THP treated biosolids can be re-fed to anaerobic digesters to increase volatile solids destruction and boost biogas yields. The LysteMize process was initiated at FSSD in 2018, refeeding 10% - 30% of processed biosolids from FSSD and third party generators to the digesters. Due to new California legislation related to organics diversion from landfills, generators of undigested biosolids who send their material to the OMRC are able to obtain diversion and recycling credits for the volumes processed with this enhanced digestion. The LysteMize process has measurably increased biogas quantities generated compared to historically generated volumes. At the greater than 30% refeed rate, gas levels have increased by approximately 17% compared to pre-feeding quantities. There is also a noticeable increase in biogas yield (the cubic feet of methane per lb of influent VS) as a result of the increased digestibility of the hydrolyzed material. Since Lystek became operational, there have been additional regulatory and market changes in options for biosolids management. Private companies, primarily landfills, have banned or limited the amount of biosolids they are willing to accept, stressing winter outlets for biosolids. In addition, regulatory requirements have been established, mandating organic material diversion and increased recycling goals, further limiting landfills' ability to offer beneficial uses on a year-round basis. These changes have resulted in a growing customer list of utilities utilizing the Fairfield OMRC as a secure, sustainable biosolids management option (Figure 2). This successful P3 partnership between FSSD and Lystek has offered regional agencies a reliable, sustainable and cost-controlled biosolids management solution. Generators now have a local management facility which produces and manages a Class A biosolids fertilizer, and reduces GHG emissions through additional biogas recovery in the FSSD digesters. The successful LysteGro management program has sold and applied more than 250,000 tons of CDFA registered fertilizer (Figure 3), and substantially grown the market and demand for the product. Increasing fertilizer value has provided the opportunity for revenue sharing opportunities with generators who send their biosolids to the FSSD OMRC. This paper will present a case study of this regional processing facility and discuss the successes and challenges experienced over this time.

Problem Since the startup of the three fluidized bed incinerators (FBIs) at the Northeast Ohio Regional Sewer District (NEORSD) Southerly Wastewater Treatment Center (Southerly WWTC) in 2014 greater than expected auxiliary fuel, that is natural gas, usage has been observed. The original FBI design assumed no auxiliary fuel would be necessary during typical operations. This abstract updates the paper submitted for the 2020 RBC, which was unfortunately cancelled due to the pandemic, with additional data obtained during the interim. Background The NEORSD owns and operates three FBIs at the Southerly WWTC, each design to process 100 dry tons per day (dtpd) at 28 percent solids and 68 percent volatile solids. The FBIs are fed dewatered sludge cake consisting of primary and waste activated sludges generated at the Southerly WWTC. Sludge from the Easterly WWTC managed by NEORSD, discharges into the headworks at the Southerly WWTC for ultimate processing by the FBIs. Typically, FBIs do not require auxiliary fuel when operated near the design condition. Auxiliary fuel is required during startup and sometimes during shutdown operations. Continued use of auxiliary fuel throughout all operations indicates the system is not operating as designed. Objective This study evaluated the existing conditions the FBIs operate under to determine which parameters might be adjusted for more efficient operation. NEORSD can then adjust, as possible, to reduce auxiliary fuel use. Historical Operation Evaluation NEORSD originally provided one year of hourly (average) data from April 2016 to March 2017, see Table 1 for the operational averages. The data was evaluated to determine which parameters impact autogenous operation. The screened parameter set included the following six which were likely to have the greatest impact on autogenous operation. Sludge feed Sludge percent solids Sludge percent volatiles Windbox temperature (preheated air from heat exchanger) Bed temperature Fluidizing airflow All these parameters statistically correlated with autogenous operations at specific levels per the t-test results in Figure 1. So, BC further evaluated this list using NEORSD's existing operating strategy as a guideline. In the end, BC determined the sludge feed rate was the most readily adjustable parameter to achieve more reliable autogenous operation. The sludge feed provides all the heat, when operated close to design values, to heat the combustion air and evaporate the water from the sludge without natural gas addition. When averaging all three FBIs the average sludge feed rate is 1.2 wet tons per hour (wtph) higher during autogenous conditions. It should be noted that the average sludge feed rate, during these autogenous conditions, was roughly 64 percent of the incinerator capacity (13.9 wet tons per hour at 30 percent total solids [TS]). The data suggests that operating the FBIs at higher feed rates will result in autogenous conditions more often. Operational Alternatives Two distinct operational changes could increase the sludge feed rate per FBI. Each option increases the number of thermal cycles, that is the frequency the system goes from operating temperatures to a significantly cooler level. Revised Operations — Option 1 - The first option utilizes storage capacity to provide consistent incinerator operations. Each storage tank holds approximately 1.5 days' solids processing capacity of one incinerator. There are three storage tanks available for operational storage with a fourth one for emergency storage. This option uses one sludge storage tank with one FBI to handle the solids with excess flowing into a second sludge storage tank. When the second sludge storage tank becomes half full and climbing a second FBI can be brought on line to help deplete the incoming and stored solids until one FBI can again handle the solids production. This option includes some concerns about placing additional thermal cycles on the equipment. Revised Operations - Option 2 - The second option operates two FBIs at a higher capacity. This is accomplished by placing one of the operating FBIs in hot standby mode for 6 to 8 hours every day. Though the FBI internals would likely see a relatively small thermal cycle, downstream equipment will undergo a larger cycle or temperature range. Option 2 would also likely not yield the same natural gas savings due to heating if the standby FBI required intermittent heating during downtime. Revised Operation Implementation An industry survey was conducted to better understand thermal cycling on sewage sludge incineration systems and impacts on equipment. Based on the survey Option 1 would likely result in less thermal cycle impacts due to relative infrequency compared to Option 2. Furthermore, discussions with the key equipment supplier (primary heat exchanger and waste heat boiler) indicated the equipment was designed for far more thermal cycles than practical over the anticipated service life of the equipment. After reviewing the two options NEORSD selected and began planning to implement Option 1. NEORSD operates three sludge storage tanks, two are normally used with a third for peak demands. At an assumed 5 percent solids concentration each tank holds roughly 230 dry tons of solids. Each cycle from 1 FBI to 2 FBIs and then back to 1 FBI should take approximately 30 to 40 days, depending on the sludge generation rate, the sludge incineration rate, and the sludge solids concentration achieved in thickening and storage. Based on this approach the FBI sludge feed rate will exceed 80 percent of the design capacity, greatly increasing the chances for autogenous operation. NEORSD conducted multiple full-scale trails, with a month-long campaign in April of 2019 providing the most representative operations of the selected option. Other trials in May 2019, September/October 2019, and August 2020 resulted in shorter durations and experienced other complications resulting in higher energy consumption. Table 2 presents the comparison between the trials and historical costs spanning 2016 through 2018. Costs in the table represent annual values. The trial values were projected to annual operations for comparison. The results of the trials indicate energy and economic savings will result from the revised operating strategy. The April 2019 trial most represents the anticipated revised operating strategy and would result in an annual savings of $390,000. Conclusions This study initially investigated the alternatives to minimize the use of auxiliary fuel during normal operations. This effort identified that recommended increasing the sludge feed rate reduces auxiliary fuel demand and presented two options to achieve a higher FBI throughput. NEORSD opted to manage the sludge in the SSTs to operate the FBIs at a higher sludge feed rate which requires alternating between one and two FBIs in service. The recent April 2019 full-scale trial showed significant energy reductions from the revised operating strategy. Based on this effort NEORSD will continue to pursue operating in the revised manner full time. NEORSD will also continue to closely monitor equipment condition to prevent unplanned outages and whether the slight increase in thermal cycles have any effect. Status NEORSD continues to test the revised operating strategy to verify the operational savings and gain experience. Ultimately the strategy will be implemented as the standard operating procedure.

Introduction Transition of Class B to Class A biosolids is becoming a way of life for POTW's. With this trend, a communication gap has emerged between the consultancy community and the utilities. Consultants follow a script of sorts (i.e. current physical state of the facilities, projected growth, financial health) in their evaluations of the needs of the Utility and then provide alternative technology recommendations based on their findings. This is their job and how they have been trained. The generators will hopefully do their due diligence by visit facilities to see what the technologies look like, how they operate and talk with those utility folks about issues they had in purchasing, construction, maintenance and the like. This is what is expected as they are who must convince their bosses to invest in these technologies. What has been missing is the vital evaluation of whether there is a market for the products once they are produced and has the regulatory community of the respective state embraced the distribution of these products. This paper will provide case studies and lessons learned by Utilities: in market development for the variety of products available (THP, dried, pelletized, third party composting and lime stabilized); show examples of market analyses completed prior to making technology decisions; explore the importance of consultants providing additional expertise specific to identification of end use markets; and provide a check list that generators can use in their evaluation including the position regulators have on the different products. Case Studies and Lessons Learned Charlotte Water completed a thorough biosolids master planning process as have many Utilities. Along with the normal equipment and process evaluation, a market analysis with field demonstrations was performed. Two different Class A products (THP from DC Water and Pellets from Cary NC) were physically brought to farm fields and spread. Farmers, Agricultural Extension representatives and State Regulators attended the demonstrations. The State Regulator had an unexpected reaction to the THP product that looks much like Class B products. They said if it looks like Class B then it needs to be managed as a Class B. The Cary pelletized product was very much favored over the THP but still not as popular as Class B. If Charlotte goes to a Class A then education of the farmers will become a vital part of the marketing plan. Pyrolysis of biosolids produces a residual solid phase called biochar and gas phase referred to as syngas. Biochar is used as a beneficial soil amendment and has been shown to improve moisture holding capacity in soil and increase crop yields for agricultural purposes. MWRD (Chicago) evaluated this process at a California facility. They have opted not to pursue this technology and their reasons will be provided in the paper. The EPA is also interested in making sure Biochar is included in Class A evaluations. A market analysis was performed by Material Matters for The City of Rock Hill SC. They are opting to send their products to a third party compost/soil blending facility. Material Matters is submitting a full abstract on this project but their market analysis is worth mentioning as part of this paper. The Town of Mooresville NC installed a belt dryer several years ago but have been unable to find a market for this Class A product. It has been going to a landfill to use in daily cover. A market analysis was not performed. A biosolids related company did take the product and distributed it to farmers for a short period of time, the farmers refused to take it soon after because the product did not have enough density (it was too light) for them to be able to use it. DC Water has a very successful program in place but they had a steep learning curve in the beginning. They had confidence that their existing agricultural base would embrace this new product but found that that was not the case. Their farmer base had grown accustomed to a lime stabilized Class B product that provided nitrogen and pH adjustment in one product. All of these examples are technically not 'case studies' however they are all well documented with field demo photos, detailed market studies and excellent examples of lessons learned from which to generate a useful checklist for Utilities to use in their evaluations.

Relevance Organic food waste is an underutilized energy and nutrient source in North America that is mostly disposed of in landfills. This common practice contributes to global warming and wastes precious carbon and nutrient resources. Some private and public entities have started to separate, collect, pretreat, distribute, and recover so-called 'source separate organics' (SSOs) at water resource recovery facilities (WRRFs). Many more WRRFs are interested in evaluating similar practices for their future operation. The substrate quality of SSOs added to anaerobic digesters requires focused evaluation: It varies between locations and might contain contaminants of potential concern to digester stability, operation, equipment, or final quality of biogas and biosolids. To date, we have a few but no standardized industry specifications to monitor and control the quality of SSO feedstock or pre-treated slurries accepted by WRRFs. To address these challenges, this project aims to develop accurate and reproducible analytical methods for food waste characterization. These methods are applied in this project to various engineered bioslurries produced from SSO food waste. This presentation will present the characterization results and implications for co-digestion performance, operation, and design. Results point to practical guidance for the wastewater industry to create cost-effective and meaningful sampling strategies as well as acceptable minimum quality specifications for accepting SSO substrates for co-digestion. Introduction The Water Research Foundation (WRF) Project #4915 called 'Characterization and Contamination Testing of Source Separated Organic Feedstocks and Slurries for Co-Digestion at Resource Recovery Facilities' aims to develop guidance for the characterization and assessment of SSO food waste quality for WRRFs who are planning or practicing co-digestion. The quality of accepted SSO foodwaste may impact the stability of digester operation, biogas production, quality of the final end products (such as biogas and biosolids) and even longevity of infrastructure used for receiving, pre-treating, storing, conveying, and digesting this material. SSO food waste may comprise of heterogeneous material from private households, restaurants, grocery stores, food producers and industry, and displays variability in quality characteristics depending geography, season, collection practices and pretreatment processes. Current laboratory methods applied by commercial producers of engineered bioslurries and by WRRFs have limitations and are not tailored to this type of material. For these reasons this project has the following objectives: 1. Identify, evaluate, and develop techniques for characterizing SSO feedstocks and slurries. Develop an Industry Guidance Document for a systematic, tiered, and comprehensive approach to characterizing feedstocks and slurries. Assess current and emerging concerns for potential SSO feedstock contamination. Define analytical methods for relevant feedstock characteristics needed for process modeling. 2. Standardize sampling protocols for rapid and comprehensive monitoring of feedstocks. Develop simple and robust methods for representative sample collection, preparation, and analysis. Recommend a timely and cost-effective quick-test strategy for WRRFs to assess relevant SSO feedstock characteristics. 3. Develop guidelines for minimum feedstock quality standards for various product goals. Provide guidance on potential contamination of SSO wastes and slurries, depending on their sources and pre-treatment process. Develop guidance on typical quality parameter ranges. Recommend limits for aesthetic, operational, and health-related parameters of concern, as well as final products and objectives. 4. Link characteristics to final product quality. Summarize cause-effect relationships for practitioners on how SSO feedback quality affects final effluent quality, process performance and stability, digester loading capacity, biogas/energy production, biosolids and biogas quality, and downstream treatment processes. The results for goal 1 have been previously presented. This presentation will focus on the results related to goals 2, 3, and 4. Methods Parameter Selection A broad literature review was conducted in the first part of the study from which our team identified relevant SSO food waste parameters for the operation, design and stability of co-digestion food waste systems. These parameters were then grouped into five tiers representing logical analytical parameter groups that can help utilities answer specific operational questions. 1. Tier 1: Immediate inspection. Parameters based on operators' fast inspection upon arrival of SSO to WRRFs. SSO delivery might be rejected or accepted based on this inspection. 2. Tier 2: Frequent routine monitoring screens. Parameters that are relevant for daily anaerobic digester operation and SSO feed control to the digesters. 3. Tier 3: Monitoring for final product quality. Parameters that are relevant for biogas, effluents, emissions or biosolids for land application. These parameters might be tested quarterly or when accepting material from new sources as they are more expensive and time consuming. 4. Tier 4: Comprehensive assessments. Parameters that are of interest for process modelling or research. These might need to be analyzed by commercial labs since they require specialized equipment. Table 1 lists the suggested parameters under each of the four tiers. Analytical Methods Analytical methods for SSO feed stock analysis were compiled from established standard methods currently employed by practitioners for the analysis for SSO feedstock bioslurries. A utility survey was conducted that solicited feedback on which protocols were challenging to conduct or resulted in poor analytical reproducibility or accuracy. The analytical protocols were established at the University of Michigan lab and were tested and refined on an exemplary sample received from a commercial producer of Engineered Bioslurry. Methods that resulted in poor reproducibility were refined until reproducible results were achieved. The written protocols were compiled and documented in a draft deliverable for publication by WRF upon completion of this project. Bioslurry Sample Sites and Monitoring Plan Four U.S. sampling locations were selected for sample collection and SSO feedstock characterization applying the analytical methods selected earlier in this project. The sample locations are in general terms listed in Table 2 and provide a diverse representation of bioslurries in the U.S. that reflect A geographical variety (within the U.S. and Canada); Pre-consumer and post-consumer SSO feedstock; A variety of pre-processing slurry technologies o onsite pretreatment process o commercial small scale pre-treatment o Commercial large-scale pre-treatment using various different technology approaches Good coverage of established slurry manufacturers Names and locations of the sample locations are kept anonymous by request while results can be published and shared. Samples are collected by the participant facilities on a monthly basis until early 2021. The samples are shipped to University of Michigan for analysis. and split samples are shipped to Eurofins for certain specialized tests. QA/QC procedures for sample preservation are followed prior to analysis. Split samples are shipped to Eurofins for certain specialized tests. Guidelines for Minimum Feedstock Quality Standards Monitoring data from the SSO bioslurry characterization is evaluated along with available full-scale data from the co-digestion facilities to assess cause effect relationships between the SSO food waste quality and co-digestion stability, operation, and quality of the final end products biogas, biosolids, and dewatering recycle streams. Table 3 summarizes relevant effects for WRRFs that could result from different SSO food waste characteristics. Conclusions Co-digestion of SSO food waste at WRRFs is quickly becoming industry practice in densely populated areas in the US where landfill space is limited and the sensitivity surrounding negative impacts of GHG emissions through climate change is rising. Co-digestion is an attractive option for WRRFs to increases energy recovery through enhanced biogas production and can generate economic benefits from tipping fees and reduced energy costs. This project fills an important need of the wastewater industry by developing robust analytical methods for the characterization of SSO food waste and helping WRRFs to understand cause-effect relationships between food waste quality and digester stability, operation, and design recommendations.

This paper and presentation will survey and analyze the latest lawsuits and regulatory developments affecting the beneficial use of biosolids to provide wastewater and residuals professionals current information that will help inform their decisions on risk, liability, management, and planning. Slaughter and Silton regularly defend land application in litigation, and they are currently working on behalf of a major land application contractor-and its farm partners-to challenge a Pennsylvania locality's attempt to restrict land application. The speakers will discuss the challenges posed by local ordinances, tort litigation, and the ongoing campaign to regulate per- and polyfluoroalkyl substances (PFAS). This talk will outline potential risks, while also highlighting potential strategies for managing land application and discouraging attacks on beneficial use in the face of a changing legal environment and local communities that may be hostile to land application. Slaughter and Silton will first address the interplay between state and local regulation by exploring several case studies involving local attempts to restrict or ban land application. Their discussion will cover California, where decade-long litigation over a local biosolids ban resulted in a trial and settlement striking down the ban. City of Los Angeles v. Kern County, 2017 WL 1292822 (Tulare Co. Super. Ct. Mar. 14, 2017). Among other things, the Kern trial resulted in findings that land application poses few risks after hearing evidence concerning minimal concentrations of PFAS in soil and groundwater beneath a farm where biosolids had been land applied for decades. The speakers will also address recent developments in other states, including Pennsylvania, where the speakers are currently challenging application of a local waste ordinance to land application. Second, the speakers will survey risks to land application posed by tort law suits. Cases in which plaintiffs' lawyers have alleged nuisance conditions caused by land application will be discussed, including the important decision of the Pennsylvania Supreme Court in Gilbert v. Synagro Central, LLC, 131 A.3d 1, which ruled that farming with biosolids is a normal agricultural operation entitled to protection under Pennsylvania's Right to Farm Act. The speakers will also discuss a case brought in Maine, Stoneridge Farms v. 3M, in which a dairy farmer alleges that land application resulted PFAS contaminating his land, groundwater, and dairy cows. This case was voluntarily dismissed but portends a new generation of tort litigation seeking to challenge land application. Third, the talk will assess the regulatory landscape for land application. Legislators and regulators, at the behest of many advocacy groups, have turned their focus to trace chemicals that may be found in biosolids, including PFAS. Silton and Slaughter will highlight recently regulatory developments and their implications for POTWs, biosolids service providers, and farmers. The presentation will conclude with how stakeholders in land application-POTWs, contractors, and farmers-can collaborate to reduce their risks and navigate a challenging, dynamic legal and regulatory landscape.

INTRODUCTION Recently, the Western Branch (WB) Water Resource Recovery Facility (WRRF), one of the five major WRRFs of Washington Suburban Sanitary Commission (WSSC), has the immediate challenge with the biosolids odor produced during the processes of storage, dewatering, and transport of biosolids. The dewatered biosolid cake in WB-WRRF is disposed in landfills now, but the landfills have expressed concerns over excessive odors and in some instances stopped accepting the dewatered biosolid cake. This problem will be continued for the next 3 years. WSSC is looking for some solutions to reduce the biosolids odor issue. According to the processes operated in WB-WRRF, there are several possible reasons causing the odor emission issue. First of all, the blending of sludges with different characteristics may contribute to biosolids odor development. At WB-WRRF, three separate streams of waste sludge, namely high-rate activated sludge (HRAS), nitrification activated sludge (NAS), and denitrification activated sludge (DNAS) are combined in WAS Wet-Well and thickened using a dissolved air flotation (DAF) system. It is likely that the combination of these sludges has augmented the biosolids odor production. Second, the anaerobic condition created during the sludge holding time in the sludge holding tank may be another possible factor contributing to the biosolids odor emission issue. The dewatering centrifuges were shut down during the weekend, leading to 15 ft deep blended sludge accumulation in the two holding tanks for around 48 hours. The bottom of the holding tank may be considered anaerobic, and many offensive odor compounds could be produced during the holding time. It was reported that the major odor-causing compounds emitting from anaerobically digested sludge are mainly H2S, and volatile organic sulfur compounds (VOSCs) including methanethiol (MT) and dimethyl sulfide (DMS) (Novak et al., 2006). Therefore, it is our hypothesis that process such as aeration may maintain a relatively high oxidization reduction potential (ORP) in the sludge holding tanks and mitigate the odor generation. The objectives of this research include: 1. Measure ORP profiles throughout all treatment trains in WB-WRRF to infer the suspicious spots that have high odor generation potential. 2. Test various combinations of the blending of HRAS, NAS, and DNAS to study their effects on the odor emission following sludge dewatering. 3. Evaluate the effect of aeration in the sludge holding tank on odor emission from dewatered cake. METHODS Fresh HRAS, NAS, DNAS and blended sludge were collected from WB-WRRF and blended based on the actual blending ratios used in the WB-WRRF. A laboratory dewatering protocol was established to mimic the full-scale centrifuge dewatering processes following three key steps: (1) polymer conditioning under controlled mechanical shearing at G t value of 105, where G is the mean velocity gradient and t is the retention time taken for sludge to be exposed to shear force; (2) centrifugal sedimentation using a lab centrifuge; (3) cake compressing using a piston under controlled pressure to obtain a cake around 20% total solids which is similar to that in the full scale. The dewatered cake was stored in a glass jar with a septum stopper. The contents of odor compounds such as H2S, MT, DMS in the headspace of the jar were measured using a gas chromatograph (GC). Headspace gas samples were collected on a timely basis and manually injected into the GC. Meanwhile, the ORP profiles across the entire WB-WRRF were measured using two ORP probes. RESULTS ORP profiles along with the treatment trains of WB-WRRF. The three types of sludge in WB-WRRF, namely HRAS, NAS, and DNAS, were firstly combined in a WAS wet-well and then thickened in DAF prior to being stored in holding tanks in preparation for dewatering. As shown in Figure 1, we measured the ORP profiles along with these treatment tanks and found that the ORP quickly dropped from 113 mV in HRAS reaction tank to -81.55 mV in WAS wet-well. Thereafter, the ORP further dropped to -218.95 mV in the sludge holding tank, creating ideal conditions needed for formation of odorous compounds such as H2S, MT and DMS. High-rate activated sludge is the major source of odor generation The headspace peak concentrations of H2S, MT, and DMS measured during the storage time for seven combinations of the three types of sludge are shown in Figure 2. As can be seen, whenever HRAS was blended in, the peak concentrations of the sulfur-containing odorous gas were always prominently high. In contrast, only negligible peak concentrations of H2S, MT, and DMS were observed in NAS, DNAS, and NAS + DNAS. Since the blending ratios used in this study were based on the actual blending ratio in the WB-WRRF, it can be concluded that HRAS accounts for the odor generation during the dewatered cake storage, and NAS and DNAS appear to have little to do with odor generation. Aeration effect on the odor emission from dewatered cake (bench-scale). Aeration of thickened solids in the sludge holding tank was tested at bench-scale as an odor mitigation strategy. As can be seen in Figure 3, all control groups and the mechanical mixing groups demonstrated the higher peak concentrations of odorous compounds than corresponding aeration groups during the storage time (Figure 3). Particularly, the cake from the control group had the highest MT peak concentration, while the aeration group had the lowest one (Figure 3b). Likewise, the aerated sample gave the lowest DMS level (13.86 mg m-3 g-1) which is approximately 30% lower than those in the other two conditions (Figure 3c). Undoubtedly, the aeration in the simulated holding tanks substantially attenuated the extent of H2S, MT, and DMS emission from dewatered cake. Aeration effect on the odor emission from dewatered cake (full-scale). After obtaining the favorable result in the bench-scale SHTs aeration test, full-scale testing of aeration in SHTs as an odor mitigation strategy was conducted, as well. As shown in figure 4, the dewatered sludge with aeration pretreatment during the sludge holding time in the SHTs generated less H2S than the group without aeration pretreatment during the storage time (Figure 4a). There was not much difference between these two groups in terms of MT concentration (Figure 4b). Moreover, only minor levels of DMS were produced (Figure 4c), indicating that the major odorous compounds emitted from the full-scale dewatered cake were H2S and MT. We can conclude that aeration during the sludge holding time can reduce odorous compounds generated from the dewatered cake.

INTRODUCTION Anaerobic digestion is utilized by water resource recovery facilities (WRRFs) to stabilize wastewater residuals and recover renewable energy in the form of biogas. Recently, anaerobic co-digestion of wastewater residuals with high strength organic waste has gained much popularity in the wastewater industry due to it's potential to improve methane yield. Fats, oils and grease (FOG) is one of the desirable co-substrates due to its higher methane production potential and degradability (compared to wastewater residuals) (Salama et al., 2019). However, some studies (Amha et al., 2017; Wu et al., 2018) have shown that higher FOG loadings can be inhibitory to the digestion process or the complex consortium of microorganisms involved. Therefore, it is critical to explore and understand how FOG impacts the co-digestion process and evaluate methods to avoid inhibition. One of such methods examined in this work was to evaluate if microbial acclimation through stepwise introduction of the co-substrate can avoid inhibition during FOG co-digestion. The goal of this study was 1) to determine the impact of co-digestion of waste activated sludge (WAS) with FOG on methane yield and microbial communities using short term Biomethane Potential (BMP) tests and long-term bench-scale reactors; and 2) to determine if microbial acclimation through stepwise introduction of FOG can be implemented to avert inhibition by comparing step-load and shock-load conditions in bench-scale reactors. METHODOLOGY Substrate and inoculum collection: Anaerobic inoculum was obtained from the Nashville Metro Biosolids WRRF's anaerobic digester which treats primary sludge and secondary scum. The WAS was obtained from City of Cookeville WRRF. The FOG used in this study was pure fats and grease obtained directly from a pork roasting grill at a local restaurant. BMP tests design and operation: Three experimental phases were carried out in 160 mL serum bottles at 35 °C. Phase 1 involved mono-digestion of WAS, as well as the co-digestion of WAS with FOG fractions of 25%, 50% and 75% (volatile solids basis). Phase 2 involved the co-digestion of 50% FOG with the 25% FOG digestate from Phase 1 as inoculum, while Phase 3 involved the co-digestion of 75% FOG with digestate from Phase 2 as inoculum. Phase 1 lasted for 20 days, while the phase 2 and 3 lasted for 13 days each. Bench-scale experimental design and operation: The experiments were conducted using two identical 10 L bench-scale reactors with a working volume of 6 L and operated at 35 °C. During the startup phase, all the reactors were fed with 100% WAS until they reached steady state. The designated control reactor was fed with WAS throughout all experimental phases, while the test reactor received various fractions of FOG. Phases 1 to 3 were conducted at volatile solids loading rate (VSLR) of 2 g-VS/L/d, and involved co-digestion of 25%, 50% and 75% (VS basis) of the co-substrates, respectively. Due to digester failure in Phase 3, Phase 4 was experimented as a recovery phase by feeding the test digester with only WAS. Phase 5 involved the co-digestion of 75% co-substrate at higher VSLR of 4 g-VS/L/d without prior exposure to the co-substrate, and therefore without prior microbial acclimation. Reactors were operated at 20 days SRT and each experimental phase was run for 3 SRTs. The digesters were monitored weekly by measuring parameters such as biogas volume and methane content, pH, and VS removal. The methanogenic community present within the different experimental phases were also examined through 16s rRNA gene sequencing to understand the impact of the FOG fractions on the methanogenic communities. RESULTS & DISCUSSION Results from the study revealed that compared to the mono-digestion of WAS, co-digestion with FOG can improve specific methane yield (i.e the total methane volume per gram VS added) up to 16.5-fold. The specific methane yields of all the tested FOG fractions were higher at the BMP level than the ones observed in the bench-scale as shown in Table 1. In the BMP study, inhibition was not observed even at the 75% FOG fraction; however, 75% FOG was found to be inhibitory in the bench-scale experiment as seen in the decline in weekly average biogas production rate in Figure 2. The BMP tests were loaded only once, which made it less likely to cause inhibition as compared to the continuous loading in the bench-scale experiment which resulted in organic overload and subsequent inhibition. At the microbial scale, the overall methanogenic community was dominated by Methanolinea, a hydrogenotrophic methanogen, and its abundance remained similar across all the tested FOG fractions at the BMP level. However, significant reduction of methanogenic population was observed during the inhibitory conditions at 75% FOG fractions in the bench-scale experiment, as shown in Figure 3. The results suggest that bench-scale experiments provide more realistic methane yields with detectability of inhibitory thresholds of FOG as well as reveal methanogenic community response to different FOG fractions under stable and unstable conditions. The bench-scale experiment also showed that step-wise increment of the FOG could not achieve microbial acclimation to avert inhibition in this study. Further, FOG co-digestion was only viable with up to 50% FOG addition at the 2gVS/L/d loading rate. At the higher loading rates, inhibition occurred due to accumulation of volatile fatty acids above 2,000 mg/L and decline in pH. It should be noted that the 50% FOG threshold observed in this study may have been influenced by the inoculum, the FOG characteristics or lack of continuous pH adjustments within the experimental phases. CONCLUSION The study shows that FOG can be used as a co-substrate to improve methane yield when up to 50% FOG fraction is used at an organic loading of 2gVS/L/d. The study also provides insights about the influence of operational modes and stepwise acclimation strategy on FOG co-digestion and highlights the need for other strategies to avoid inhibition in FOG co-digestion systems.

Improving soil health is based on the premise that soils have the ability to optimally function within natural or managed (agro)ecosystems to sustain plant productivity and to create an environment conducive to system resiliency. Global evidence suggests that biosolids land application can positively alter some function(s) within the context of soil health, yet to date no one has effectively tackled this concept within the context of biosolids land application. We utilized a 22-year biosolids dryland wheat-fallow research location jointly operated between South Platte Renew (Englewood, Colorado) and the Department of Soil and Crop Sciences at Colorado State University (Fort Collins, CO) to answer the question 'Can biosolids really improve soil quality/soil health aspects?' Soil samples (20 cm depth — plow layer) were obtained from plots (four replicates, randomized complete block design) receiving either biosolids (0, 2.2, 4.5, 6.7, 9.0, 11.2 Mg/ha) or N fertilizer (0, 22, 45, 67, 90, 112 kg/ha) every other year over 22 years. We utilized the Soil Management Assessment Framework (SMAF) to identify changes in soil texture, organic C content, clay percentage, wet aggregate stability, microbial biomass C, potentially mineralizable N, pH, EC, extractable P and K, bulk density, and beta-glucosidase activity. Within SMAF, data are scored as unitless values, from 0 to 1, based on pre-determined functions associated with either 1) more is better, 2) less is better, or 3) somewhere in the middle is better. The above indicators were then pooled into categories associated with changes in soil physical, chemical, nutrient, biological, or overall soil health indices. Results showed that soil organic C, potentially mineralizable N, and extractable P were greater in biosolids treated plots as compared to N fertilizer plots. Increasing biosolids application rate increased soil organic C, and other trends existed favoring biosolids over N fertilizer applications. However, when indicators were pooled into respectively soil health indices, increasing biosolids application positively influenced soil chemical, biological, and overall soil health. Biosolids applications improved biological soil health as compared to N fertilizer applications, suggesting that the combination of increasing soil organic matter, microbial biomass C, potentially mineralizable N, and the ability of microorganisms to degrade readily available cellulosic material, was enhanced with biosolids land application. Within this dryland wheat-fallow agroecosystem, biosolids can indeed be utilized to improve soil health, potentially leading to improved resiliency and sustainability.