Conference Papers

PFAS in biosolids have undoubtedly become a major topic and concern for the public and the industry. Some state regulations are outpacing federal regulations, forcing utilities to consider alternative biosolids management strategies. Therefore, interest in thermal technologies has grown substantially. New incinerators are difficult to install, rendering torrefaction, pyrolysis, and gasification as possible treatment process options. However, information is scarce on the mass balance of PFAS, and specifically fluoride, through these processes and their end products. This project will i) develop methods to quantify PFAS, total organic fluorine, and inorganic fluorine in end products, ii) generate lab-scale data on the fate of PFAS and fluorine through torrefaction, pyrolysis, and gasification, and iii) generate an LCA tool that is user friendly to incorporate critical aspects (e.g. energy, carbon footprint, as well as PFAS fate) for assessing thermal technologies.

Purpose: Attendees of this presentation will gain an understanding of how the latest trends within asset management and risk management can be leveraged with today's technology to drive decision making in wastewater system planning. These solutions can be integrated as a holistic tool to manage system resiliency and provide a return on investment. Benefits of Presentation: When we think about advancements in technology and software innovation, the wastewater industry does not necessarily come to the top of everyone's mind. However, our industry has evolved into a much more data-driven community and is finding new and more valuable ways to take advantage of these innovations. In fact, the wastewater industry is in the middle of a significant digital revolution that is continuing to evolve. We see new software platforms being introduced all the time across a variety of functions within the wastewater industry, including asset management, GIS systems, operations and maintenance, design, and construction. While the wastewater industry has evolved with these new software solutions, utilities have also been evolving. Today, we collect more data in these systems than at any other time in history. Utilities increasingly interact with their systems and view these systems through data and computers. Over the last decades, utility planning, operations, and management have been slowly moving from the physical to the digital world and seeking the ability to do more with less through the use of data. Operators use digital information through Supervisory Control and Data Acquisition (SCADA) platforms to monitor and control utility systems. Planners use computerized hydraulic models to forecast how the systems will react to a change. Asset managers use Geographic Information Systems (GIS) to predict the useful lifespan of the assets. In all these cases, utilities interact with the system digital model instead of the physical system. Now the question becomes how do we use this data and these digital tools to collaboratively manage wastewater system assets and plan for a resilient wastewater utility? How do we manage aging infrastructure while also managing wet weather issues and Operations and Maintenance (O&M) tactics? Recent innovations allow utilities to further advance through the digital transformation lifecycle, which takes us from collecting and warehousing data to making informed decisions. To take full advantage, utilities need to integrate principal foundations of risk management coupled with technological innovations including data visualization and analytics to develop a collaborative decision support platform that integrates risk models, O&M program data and GIS. The City of Shreveport (City) embarked on a mission to better refine how to focus spending on their wastewater utility by building a digital tool, a risk model, to better understand how to utilize years of sanitary sewer evaluation survey (SSES) data to make more informed decisions. It began with adopting risk management principles that considers the Likelihood of Failure (LoF) coupled with the Consequence of Failure (CoF) for their wastewater assets including gravity sewers and sanitary manholes. Together, the LoF and CoF risk mechanisms are calculated to inform Business Risk Exposure (BRE), or in other words, overall risk to the City. The audience will learn about the development of LoF factors which consider NASSCO compliant sewer assessment data, as well material properties, external pipe/manhole characteristics and system hydraulics. Collectively, these groups are weighted and combined to compute an overall LoF risk on a 1-10 rating scale. The presentation will cover CoF, which includes a variety of factors developed around a triple bottom line approach which considers impacts to economic, environmental, and social impacts of a failing asset. Similarly, CoF weights these individual cohort groups and computes a single CoF score on a 1-10 rating scale. Collectively, once these values are computed, BRE is able to be determined on a 100 point scale by considering both LoF and CoF components. Once the LoF, CoF and BRE values are determined for individual asset rankings, the audience will learn how sensitivity within the risk model can be assessed to evaluate the impacts of the weighting of contributing factors in the scoring. Finally, the audience will benefit from understanding how risk modeling can be coupled with advancements in geospatial tools and data visualization tools (dashboards) to better define how risk is distributed throughout the wastewater collection system, considering not only quantitatively, but also spatially to answer where and how individual asset rankings may have more commonalities based on when and where the assets were constructed. Advancements in technology promote the ability to keep the risk modeling up-to-date on a routine basis considering new inspections inventories, updates to assets in the field and changes within other analytical tools used to compute risk. The audience will gain an understanding of how the fundamentals of risk management can utilize new innovations in technology and software to develop more informed decision support systems Status of Completion: The City of Shreveport has finished the modeling, sensitivity testing and development of digital tools to support the understanding of risk. Risk Management is constantly evolving, the audience will be informed of how the digital tools currently are deployed and discussions about the maintenance protocols and continuous improvements that are planned for the future. Conclusion: We need to ask ourselves how to use technology and innovation to collaboratively manage and improve long-term wastewater system resiliency. The answer is through utilizing the foundations of risk management and coupling them with the use of emerging software tools including data visualization, analytics, and data processing tools. By coupling risk management and technological innovation, we can evolve in how we manage our wastewater systems and focus spending money where it is most needed. These tools allow us to prioritize resolution of the issues impacting communities such as aging wastewater systems, operation and maintenance strategies and wet weather management.

Inequity in historical infrastructure investment and racist urban development policies have created conditions where low-income communities and communities of color are disproportionately impacted by the flooding and water pollution. And these challenges are compounded by limited access to green space, higher rates of pollution, and associated physical and mental health disparities. However, these interwoven challenges can be met by a holistic approach to green stormwater infrastructure (GSI) development. Equitable GSI development is a foundational step in every city's march toward reducing the flooding and pollution burdens on low income communities and communities of color, as well as correcting disparities in access to high quality green space. Greenprint Partners, a national leader in equitable GSI, will share a series of case studies that illustrate three pillars of a scalable solution: equitable project selection, benefits-driven design, and community involvement. - Youngstown GSI Master Plan: Greenprint has led an effort to develop a health-first GSI master plan to address CSOs in Youngstown, OH. As a legacy city with a majority-minority population and significant economic challenges, the ability to leverage this investment drive measurable community benefits is paramount. - The Well Farm at Voris Field (US Water Prize award recipient): Dubbed the most inclusive public works process to date in Peoria, this project transformed a vacant parcel in one of America's 100 poorest zip-codes into a tapestry of multi-functional, community-driven stormwater BMPs. This included a hybrid poplar stand, a flowering bioswale, and 100 raised beds, home to an agricultural apprenticeship program. - Green Infrastructure Retrofits: Greenprint's private property GSI retrofit operations in St. Louis, Philadelphia, and San Francisco created a pipeline of projects from disadvantaged communities and provided them the full suite of wrap-around services to ensure successful participation in grant programs with high barriers to entry.

The City of Grapevine, Texas is in North Central Texas and serves a population of nearly 54,000. Its' destination status could cause population to triple on any given week or weekend. In 1983, the City undertook efforts to re-construct the only raw water line for the city's single water treatment plant. City staff decided in 2020 that an inspection of approximately 1 mile of twenty (20) inch bar-wrapped cylinder concrete pipe should be performed so that a condition assessment consisting of remaining useful life and other analyses could be conducted. When it was decided that an inspection was necessary, a comparison of the available technologies for in-line inspection of pressure pipe was initiated. Since the City of Grapevine had experience with near field transmission inspection platforms, this is where the comparison began. Near field transmission and remote field transmission have been the technologies most utilized for over 20 years. While each of these technologies have contributed greatly to the water and wastewater community, the data produced by each technology is very specific in scope, limited to ferrous pipe, and can be inconsistent at times. Moreover, the transport mechanisms utilized to deploy these technologies introduce another complex variable. Ultimately, the City of Grapevine came to the temporary conclusion that they would utilize the most prominent provider in the market since they had experience with the near field transmission platform and its associated deliverables. Sounding in conjunction with visual inspection have been utilized by owners since the 1980's as a means of inspecting pipe. However, this requires confined space entry, is subjective, and is limited in diameter. The advent of Ultrasonic Testing (UT) in an in-line inspection technology for pressure pipe has eliminated these limitations while producing more data that can be utilized for condition assessment of water transmission mains and force mains. The reach of this technology is also expanded by the existence of multiple deployment options. This technology was only available in the Netherlands until recently. When presented with the opportunity to utilize the new in-line inspection platform with ultrasonic testing capabilities to inspect their pressurized pipe, the City of Grapevine re-evaluated their selection of a near-field inspection platform. The primary reason City Staff elected the UT based technology was the availability of more data, absolute anomaly location, joint defect data, and to a lesser extent, cost. This technology has the capabilities of inspecting any material type, both ferrous and non-ferrous providing wall thickness, joint condition (angular displacement/ gap width, sub-meter XYZ mapping, leaks, and gas pockets in a single inspection. The decision-making process that the City of Grapevine undertook to determine the best course of action for inspecting pressure pipe is not dissimilar from the process collections systems personnel and management must make when determining a course of action for inspecting pressure pipe. By understanding the primary technologies and deployment mechanisms that are most utilized for in-line inspection of pressure pipe, a better understanding of what to expect from each technology is gained. Near field, remote field, and ultrasonic testing platforms will be explored in depth to provide an understanding of how each technology works, is deployed, and what to expect from each deliverable. A presentation of the project itself is necessary and will provide familiarity with the ultrasonic tool its operational process and in depth look at the value of the deliverables since it has been used extensively in the Netherlands and most recently in the UK. Pre-planning, civil engineering, launch and retrieval, and the deliverable(s) will be presented to provide a full scope of this new innovative technology. By understanding all aspects of an inspection of a single pressurized raw water line in Grapevine, Texas, collections system personnel and management can prepare themselves for future, larger scale inspections by being equipped with knowledge about the most widely used platforms, advantages, and disadvantages of each, what to expect from a civil engineering standpoint, and from a deliverable. This information empowers collection system operators and owners to make informed decisions about inspecting and assessing the condition of their critical infrastructure and better manage their pressurized assets.

Introduction The San Antonio Water System (SAWS) is a public water and wastewater utility serving over 2 million people in the San Antonio area. SAWS owns and operates a collection system consisting of nearly 6,000 miles of sewer mains and over 150 lift stations. Like many wastewater utilities, SAWS experiences odor and corrosion issues in the collection system. One particularly troublesome area is at Stinson Park and consists of parallel 72-inch trunk mains and a 60-inch sewer that combine at a junction box and pass under Six Mile Creek via a siphon. Sulfide and other odorous compounds generated in the upstream collection system volatilize to hydrogen sulfide (H2S) gas and other odorous gases in the sewer headspace. The odorous air cannot continue downstream past the siphon and would vent from the Apollo Street junction box about 1700 feet north of Six Mile Creek, resulting in numerous odor complaints. SAWS has dosed ferrous sulfate in the collection system for many years to precipitate liquid sulfide and control volatilization of sulfide. In 2012, a vapor phase biotower odor control system was constructed at Apollo Street to capture and treat odorous air from the junction box and the surrounding collection system, but odor complaints persisted from an adjacent school and a nearby youth sports complex. In 2015, several improvements were made to the Apollo Street odor control system by cleaning accumulated grease and adding carbon polishing. Odor complaints from the school ceased, but odor complaints from the sports complex continued. In 2018, SAWS began a thorough, stepwise investigation to determine the source of the odor complaints and how to control them. Objectives The objectives of the investigation were as follows: -Assess the cause and source of odor complaints near Six Mile Creek. -Develop odor control options to mitigate odor complaints near Six Mile Creek. -Evaluate options to improve the performance of the Apollo Street odor control system to better mitigate odor complaints. -Evaluate the option of constructing an air jumper at the Six Mile Creek siphon to convey odorous air past the creek to be treated at the downstream Rilling Road odor control system. Methods/Findings Figure 1 shows prominent features of the evaluation area including the Apollo Street odor control system, sports complex, and Six Mile Creek. The media in the carbon vessel was replaced before the 2018 baseball season, but odor complaints from the sports complex continued. No major sources were identified around the baseball fields at the complex, but siphons were cleaned. In 2019, SAWS staff attended a baseball game upon receiving an odor complaint at the start of the baseball season and there were indications the odors came from the Apollo Street odor control system (see Figure 2). Investigative efforts revealed partially treated air discharged from the Apollo Street odor control system was the source of odors at the sports complex. Flow pacing of ferrous sulfate addition was implemented to control the diurnal H2S concentration allowing the biotower media to effectively remove H2S and not overload the carbon vessel. Spent carbon media was also replaced. In addition, better and more consistent maintenance of the Apollo Street and Rilling Road odor control system began in 2020. Following these improvements, only one odor complaint was received between 2019 and the beginning of 2022. Odor complaints returned in the spring of 2022. Investigation indicated the biotower was not operating properly and repairs were made. An odor process and ventilation model of the area was developed that validated the results of the field investigation. The sewer ventilation assessment determined the airflows needed to better depressurize the collection system and to determine the airflow required to potentially convey odorous air downstream via a siphon air jumper to the Rilling Road odor control system for treatment. The ventilation model provided a properly sized system rather than an oversized system using overly conservative estimates or an expensive fan test saving hundreds of thousands of dollars in construction costs. The model was also used to identify improvements to optimize the odor control system, making the system more resilient and reducing operational costs. The recommended improvements included: -Install high performance structured plastic media in the biotower -Increase airflow to 6,000 cfm -Expand the activated carbon bed -Replace the virgin carbon with both high capacity H2S carbon and virgin carbon -Improve flow pacing of ferrous sulfate Conclusions The following are conclusions as a result of the field investigation and ventilation modelling: Capital and operational improvements made to the Apollo Street odor control system since 2015 and upstream flow paced ferrous sulfate addition have mitigated odor complaints. -Optimizing performance of the odor control system through further relatively low-cost improvements will make the system more resilient and reduce operational costs by reducing the frequency of carbon replacement and decreasing ferrous sulfate addition. -Constructing an air jumper and treating odorous air at the Rilling Road odor control system is extremely expensive and not recommended as the Apollo Street odor control system can adequately treat odorous air at a lower cost. Lessons learned for utilities: -Be aware of the area odor history -Make note of all potential sources of odor -Do not dismiss complaints -Note the time, wind direction/speed, odor type for odor complaints -Assess all aspects of available mitigation options including reliability -Assess performance and condition of equipment -Maximize equipment efficiency -Revisit and continuously improve -Utilize third party experts to validate results This presentation will demonstrate how combining a stepwise approach encompassing field investigations with modeling tools is used to identify and develop solutions to mitigate odor complaints and control corrosion in a collection system.

Introduction: The Truckee Meadows Water Reclamation Facility (TMWRF), serving the cities of Reno and Sparks, Nevada, has had historic difficulty of their dewatering operation with their biosolids averaging just over 16% total solids (TS). This poor performance is largely the result of TMWRF running an enhanced biological phosphorus removal (EBPR) process, which has limited their maximum mechanical dewaterability due to the large amount of dissolved phosphate and volatile solids in their centrifuge feed. Centrifuge replacement in 2015 further exacerbated the dewatering performance with the newer machines requiring high polymer dosages and delivering consistently poor centrate quality. Since June of 2020, TMWRF has carried out an alternative strategy to their dewatering operation by sending the thickened waste activated sludge (TWAS) produced in their EBPR process directly into their centrifuges, bypassing all digestion. The impacts of this change have been major and wide-reaching with effects on biosolids character and volume, chemical usage, plant wide nutrient removal, biogas production and quality, and centrate treatment. This presentation will discuss the background of the facility including their historically low-quality performance as well as the many facets that have been positively impacted by carrying out this change to direct TWAS dewatering, This presentation will also examine the role of this operating strategy in the long-range planning of the facility. Dewatering Background: TMWRF, a 30 million gallon per day (MGD) facility, had operated the same three centrifuges since 1983, producing just over 15% TS biosolids with a centrate quality of slightly over 400 mg/L total suspended solids (TSS). To improve both process parameters and energy demand, a centrifuge replacement took place in 2015. While the centrifuges were specified to produce a 22% TS biosolid from a polymer input of 23 active pounds per dry ton of solids, these machines have averaged 16% TS biosolids with a typical dosage of 44 active pounds per dry ton of polymer. While some marginal improvement occurred in the biosolids, the centrate produced from these machines worsened, averaging approximately 1,100 mg/L TSS which has burdened downstream centrate handling processes. With continued struggles to produce a higher solids content product from the centrifuges, in August of 2019 TMWRF submitted their sludge for further laboratory analysis to determine the maximum mechanical dewaterability. The results indicated that the sludge grab sample had a maximum achievable TS content of 15.8%. Also noted was the high phosphate concentration (292 mg/L) and volatile solids content (73.8%) present in the sludge liquor. Streaming current detector measurements were carried out to quantify polymer demand and indicated an optimal polymer dosage of 40 active pounds per dry ton. Direct TWAS Dewatering Study and Results: Given that many of the factors negatively affecting dewaterability stemmed from the TWAS sludge and were independent of the centrifuge, a study commenced to determine to what extent this sludge could be dewatered directly. With no beneficial reuse customers, the only standard to meet for TWAS biosolids was to pass a Paint Filter Liquids Test in order to be landfill compliant. After several discrete trials demonstrating this was possible, full-scale direct TWAS dewatering was implemented on June 9, 2020. After the passing of several detention times within the digesters, TWMRF experienced marked improvement in sludge dewaterability of their digested sludge with it being solely comprised of primary sludge. This digested primary sludge demonstrated the ability to consistently produce over 20% total solid biosolids with the highest achieved solids content of 28%. The waste activated sludge has shown to have nearly the same level of dewaterability as the historic sludge, averaging near 15% total solids without presenting any disposal concerns. In the time since beginning the experiment, there have been profound impacts throughout the treatment plant. The centrate, which had historically provided nearly 30% of the ammonia loading to the facility, saw a rapid and sustained decrease of 47%. This has significantly improved the nitrification and denitrification operations present at TMWRF as well as enabled more capacity for their nitrifying trickling filters. This reduction in ammonia translates to a lower loading into the denitrification process, resulting in an annual methanol savings over $200,000. Through the direct dewatering of the TWAS, a sharp decline in concentration of orthophosphate within the centrate has also been observed. This concentration has reduced from approximately 250 mg/L to less than 100 mg/L and as a result has removed the need for centrate sidestream phosphorus removal. The decommissioning of this additional treatment and associated chemical consumption has created a benefit of nearly $250,000 per year. The other large impact to chemical usage that TMWRF has experienced is a reduction in polymer usage. Waste activated sludge is thickened in a dissolved air flotation thickener and had previously utilized polymer to maximize TWAS total solids. This dosing has since been discontinued since the centrifuge design parameters require a lower feed solids content. Overall, this has led to a 20% reduction in polymer use, creating an annual savings of approximately $170,000. The continued duration of this project has identified other numerous benefits such as a 26% reduction in the hydrogen sulfide of the digester biogas, consistent phosphorus loading reducing aluminum sulfate demand, ability to achieve higher centrifuge hydraulic loads, and realized capacity of the digestion process. The demonstrated benefits of this full-scale experiment have resulted in its recommended implementation in TMWRF's latest facility plan, prompting an addition to TMWRFs Capital Improvement Program to begin analysis for making it a permanent process. This paper will outline the common challenges that EBPR sludge has on dewatering and the historical poor performance solids processing of TMWRF. Insight will be provided on a variety of operating configurations such as pure TWAS dewatering versus TWAS/digested primary sludge blended centrifuge feeds and the impacts of these on centrifuge outputs and total biosolids volumes produced. Detailed discussion will occur on the utilization of direct TWAS dewatering as an effective nutrient removal process not only for ammonia and phosphorus, but also for organic nitrogen.

This presentation shares the unique journey undertaken by the Manasquan River Regional Sewerage Authority (Authority) to understand the odor and corrosion issues in their system and the systematic steps taken to study, sample, evaluate, and select a holistic solution. The project is divided into three phases: Study, Chemical Trial, and Design Phases. During the Study Phase, air and wastewater hydrogen sulfide (H2S) data was collected and a triple bottom line (TBL) evaluation was performed to recommend potential improvements for odor and corrosion control. Results from the Study Phase indicated that the Authority’s system is generally functioning well, but there are hot spots in the system that need to be addressed locally. These locations were the focus of the TBL evaluation, which evaluated three alternatives using economic, social, and environmental criteria. The recommended alternative was evaluated during a three-month Chemical Trial that showed that the Authority’s systems can be treated effectively using calcium nitrate (i.e. Bioxide) and/or hydrogen peroxide (H2O2) to reduce H2Sand dissolved sulfide concentrations. As of March 2021, the Study Phase and Chemical Trial have been completed and the Design Phase is in progress. Calcium nitrate systems will be implemented at two meter chambers within the Authority’s system. A technology evaluation was completed for implementation of odor control systems to mitigate odors and corrosion at two pump stations. A new carbon column system will be implemented at Upper Manasquan Pump Station (UMPS)while a high plume up-blast exhaust fan will be implemented at the Lower Manasquan Pump Station (LMPS). Civil, process, structural, mechanical, electrical, and instrumentation and controls components were included in the designs.

Introduction The Dry Creek Water Reclamation Facility (DCWRF), owned by the Cheyenne Board of Public Utilities (BOARD), is located in Cheyenne, Wyoming. Thickened waste activated sludge and primary sludge are anaerobically digested and the digested biosolids are pumped to high solids centrifuges for dewatering. The biosolids are transported across the site to air drying-beds for storage and supplemental air drying prior to offsite transport for beneficial use land application. A site map of the existing DCWRF biosolids processing sites are shown in Figure 1. DCWRF generates approximately 1,600 metric tons per year of primarily Class B biosolids. Some Class A biosolids product is produced by complying with the 'two-summer method' as allowed by the United States Environmental Protection Agency (USEPA). The air-dried Class A and Class B biosolids are land applied by the DCWRF staff at private ranches. Much of the soil in the region has low organic content and it is a challenge to successfully grow native grasses and crops without a significant amount of fertilizer. Therefore, the ranches benefit from the application of the organically-rich biosolids material. Challenges with the Existing Solids Processing Facilities The utility is currently facing numerous solids processing challenges including aging equipment as well as a potential loss of nearby ranch sites that had been used for land application. The uncertainty in the continued acceptance of Class B biosolids, due to change in ownership of the ranch sites currently accepting biosolids, will result in lower reliability and flexibility for solids beneficial use for the plant in the future. Faced with this potential future challenge, the BOARD selected Jacobs Engineering Group to evaluate Class A stabilization technologies that are appropriate for the needs of the utility. The production of Class A biosolids material that has multiple end-use markets would give the BOARD more reliability and flexibility to land apply in locations such as the City of Cheyenne's parks, open spaces, golf courses and sporting fields which would reduce hauling cost and the reliance on private farmers and ranchers. Ranchers would also be more receptive to land application of Class A biosolids. Objectives of the Evaluation The objective of this study was to compare the suitability and applicability of three different Class A drying alternatives including belt drying, solar greenhouse drying and hybrid drying (solar greenhouse and air drying) to DCWRF. The three alternatives were evaluated based on capital cost, operations and maintenance (O&M) cost as well as life cycle cost considerations. Additionally, a combined financial and non-monetary ranking and sensitivity analysis was performed. The advantages and disadvantages of each drying alternative, considering the plant's geographical constraints, were outlined. Alternatives Evaluation The thermal drying and solar drying equipment preliminary design criteria is shown in Table 1. The three alternatives evaluated are summarized below and a screw press was assumed to be the selected dewatering technology. The process schematic for Alternatives 1, 2 and 3 are shown in Figures 2, 3 and 4. The advantages and disadvantages of each alternative will be described in detail in the paper and presentation. The proposed solar greenhouse configuration location on the existing air-drying beds is shown in Figure 5. The proposed configuration of the hybrid solar greenhouse structure solar greenhouse located adjacent to the existing air-drying pads is shown in Figure 6. Results of the Evaluation Non-Monetary Evaluation Several non-monetary evaluation criteria were used in the assessment of the three drying alternatives. The results of the weighted benefit scores based on the DCWRF staff input are summarized in Table 2. Based on non-monetary considerations, belt drying and solar drying were shown to be the most beneficial to DCWRF, with essentially the same score, with solar drying being slightly better, while the hybrid alternative represented the least non-monetary benefits. The belt dryer ranked significantly higher in the product end use flexibility criterion. The hybrid and solar drying alternatives had lower scores for the odor generation criterion because operators are exposed to these odors for extended periods of time compared to belt drying odor exposure. Based on non-monetary considerations only, solar drying is the best alternative for the DCWRF, but belt drying is ranked approximately the same. Life Cycle Cost Evaluation In addition to non-monetary considerations, opinions of probable construction cost, annual O&M cost and net present worth costs were estimated for the three drying alternatives. Life cycle costs comparison are summarized in Table 3. The solar drying alternative had the highest life cycle cost followed by the belt drying alternative; while the hybrid drying alternative had the lowest life cycle cost. Based on relative cost ranking, the solar drying option is approximately 40 percent higher than the other two options. Combined Ranking and Sensitivity Analysis The cost rankings and non-monetary rankings for the different alternatives were combined and the total weighting rank was used to determine the best overall drying alterative. The combined ranking included the following three monetary to non-monetary ratios: 1. 30 percent weighting for cost and 70 percent weighting for non-monetary criteria 2. 50 percent weighting for cost and 50 percent weighting for non-monetary criteria 3. 70 percent weighting for cost and 30 percent weighting for non-monetary criteria The belt drying option ranked highest against all three weighing ratios and is therefore the preferred option. Conclusion The belt drying option ranked highest on all three weighting ratios, had the highest non-monetary ranking and the most advantages and was therefore the preferred option for the DCWRF. This presentation will be valuable to owners, operators and consultants that want to consider Class A drying alternatives. In addition to presenting the results of the study, advantages and disadvantages, preliminary and final design criteria, equipment layouts and cost estimates will be presented for the three drying alternatives.

The City of Cuenca is a large metropolitan City located in the high lands of Ecuador at about 2,560 meters above seal level. The wastewater collection and treatment system for the City consists of approximately 1,300 kms of sewage networks and 80 kms of interceptor networks that convey wastewater to various treatment plants, the Ucubamba WWTP being the largest of all treating approximately 95% of wastewater produced by the City. The rated design capacity of the Ucumamba WWTP is 1.8 cubic meter per second (m3/sec). The treatment process at the Ucumamba WWTP consists of preliminary treatment consisting of screens, followed by a 3-step biological process consisting of primary aerated lagoons, secondary facultative lagoons and tertiary maturation lagoons. Exhibit 1 is a process flow diagram of the Ucumamba WWTP liquid treatment process. The Ucumamba WWTP is challenged with accumulation of solids in the lagoons. In 2013 the City installed sludge removal and dewatering system to remove and process approximately 3,000 cubic meter of sludge per year (m3/year). However, the sludge removal and dewatering is capacity limited to remove and process sludge accumulated in the facultative lagoons. As a result, approximately 50% of the lagoon volume is occupied by sludge, thereby reducing the active hydraulic retention time, and leading to compromised treatment efficiency. To address challenges with reduced treatment capacity of the Ucumamba WWTP, reduce dependence on the Ucumamba WWTP to meet the City's treatment needs, and diversify treatment options to meet future growth, the City completed the design of the new Guangarcucho WWTP having a rated design capacity of 1.8 m3/sec. With the new Guangarcucho WWTP being operational, the City will be able to effeciently treat wastewater produced by the City and remove portions of the Ucumamba WWTP out of service for maintenance and sludge removal to restore capacity. Exhibit 2 summarizes the future wastewater treatment strategy for the City of Cuenca after the Guangargucho WWTP becomes operational. Wastewater biosolids are considered a valuable resource in Ecuador due to the high nutrient content and its benefit to the agricultural industry. Evaluation completed by the City indicate that the sludge removed from the Ucumamba WWTP is low in nutrients (nitrogen) due to the prolonged stabilization and meets EPA Part 503 Class B biosolids standards. As a comparison, the wastewater biosolids to be produced by the advanced Guangarcucho WWTP is assumed to have a high nutrient content and potential to meet EPA Part 503 Class A biosolids standards. The liquid treatment process for the Guangargucho WWTP consists of preliminary treatment (screening and grit removal), primary clarification, biological treatment, secondary clarification and disinfection. Primary sludge produced by the primary clarifiers will be thickened in gravity thickeners and waste activated sludge produced by the secondary treatment process will be thickened with gravity belt thickeners (GBTs). Thickened primary and waste activated sludge will be anaerobic digested and dewatered with centrifuges. Exhibit 3 provides the process flow diagram of the solids treatment process at the Guangarcucho WWTP. Limited quantity of biosolids currently produced by the Ucumamba WWTP is currently conveyed to the Pichacay Landfill for disposal. However, the Pichacay Landfill is nearing the end of its service life by 2031, and thus does not have the capacity to accept additional biosolids to be produced by the City's Ucumamba and Guangarcucho WWTP in the future. The City is currently challenged to find disposal or beneficial use options for biosolids produced by the two WWTPs. In addition, there are no regulations to regulate the general conditions and obligations to be fulfilled for beneficial use of biosolids e.g. land application. To address its biosolids management challenges, the City has initiated a Feasibility Study to investigate treatment and beneficial use options to manage biosolids that will be produced by the two WWTPs in the future. The treatment approach will focus on maximizing reduction in mass and volume of biosolids that will require outside the fence management, and produce high quality biosolids that can be beneficially used for agriculture and/or mine reclamation. Treatment solutions that will be investigated include thermal drying, solar drying, incineration and innovative treatment solutions such as pyrolysis and gasification to produce value derived products such as biochar. Beneficial use opportunities for biogas to be produced by anaerobic digestion at the Guangarcucho WWTP will also be investigated e.g. cogeneration, biosolids drying, etc. The paper will provide an overview of the current and future wastewater treatment for the City of Cuenca, and the challenges the City faces to sustainably manage biosolids that will be produced by the Ucumamba and Guangarcucho WWTPs in the near future. An overview of treatment options investigated to achieve a reduction in mass and volume of biosolids requiring end use management, advantages and disadvantages of the various alternatives and a triple bottom line evaluation to identify the most cost-beneficial alternative will be presented. Consideration of other factors such as operational and maintenance know how, energy requirements and costs, availability of manufacturer services and spare parts in Ecuador will also be considered in selecting the preferred treatment approach. The presentation will be useful to Utility Managers, Consultants and Engineers who also face biosolids processing and management challenges similar to the City of Cuenca. The paper will provide the attendees an understanding of a Citywide approach and initiatives to implement a sustainable biosolids management strategy in a resource constrained environment. The paper will also provide an overview of the City's existing and planned wastewater collection and treatment infrastructure.

Steep Slopes, Odors and Corrosion Flow Together Richard J. Pope, P.E., BCEE Vice President - Hazen and Sawyer For over 100+ years sewer designs have maximized gravity in pipes/conduits to convey wastewater to the treatment facility. Unfortunately, land contours and obstructions require that pumps be used to lift and/or convey the wastewater vertically through force mains to reach a point where the wastewater can again run by gravity. This process is repeated as many times as it takes until reaching the treatment facility. The point where the force main ends and the wastewater flow turns back to gravity is commonly at a high point in relationship to the surrounding landscape to again take advantage of gravity. Sometimes the slope of this force main discharge is steep enough to create a negative air pressure in the pipe headspace, as the drag from the downward movement of the wastewater sucks air in. In many cases this force main discharge connects with another downstream sewer/interceptor line that has a flatter slope. The pipe intersection of a steep slope with a flatter slope, is known to create a hydraulic jump as the faster moving wastewater from the steeper slope pipe tries to overrun the slower moving wastewater. This causes a 'jump like' action in the flatter slope pipe. These features associated with force mains have been recognized and understood since the initial designs of collection systems. But it has taken decades for the engineering community to observe and understand the odor release and corrosion potential of these features. For too long our sewers have suffered from being out of sight and out of mind, and generally ignored. The recent heightened focus on wastewater facility and collection system asset condition and management, helped to open our collective industry eyes on the potentially devastating impact that these features can impart. Regarding these physical layout features, it is not clear that engineers have always anticipated the ramifications of their designs and how the physical layout of the sewer pipe network can exacerbate both odor formation and release. Odor release encompasses stripping from the wastewater into the headspace of the sewer where it travels through laterals and house connections, as well as escaping the confines of the sewer headspace into the ambient atmosphere where it can impact communities, properties and homes. This paper focuses on a typical physical sewer layout that has been designed by engineers for years and is common to many collection systems: the fast-moving wastewater flow of a steep slope pipe and the intersection where it meets a flatter slope pipe. These physical layout features occur quite often, particularly at the discharge end of a force main where it breaks to a gravity line. Our discussion is not intended to direct engineers to avoid these situations, that is likely impossible given local topography issues, but to recognize these transition zones for what they are, understand how the wastewater and airspace within the sewer will react and protect against their potential impacts. A few of the key issues with the steep slope and transition zone where steep and flat slopes intersect include: Steep slope sections of pipe create a negative air pressure along that line as the wastewater drags the headspace air with it as it accelerates downward. That vacuum can create a positive impact as it draws outside air into the system to replace the air it is dragging downstream. It can create a negative impact if the vacuum is strong enough to drain the water out of lateral and house traps that are in place to keep sewer gases out of upstream lines/homes. Hydraulic jumps occur at the transition zone, which means an area of high turbulence. Turbulence is directly related to stripping odors from the wastewater. The intersection of fast-moving water meeting slow moving water also creates a positive air pressure shock wave that radiates out and away in both directions from the transition zone. These are real problems facing many communities across the country. Four different case histories will chronicle the impact that these physical layout features, steep slope and intersecting steep and flat slope sewer pipes, had on the surrounding communities and the steps that were taken to address it. The four case histories represent: California creating nuisance odor problems for a downtown community New York intersecting steep and flat slope sewer odor release was followed and aggravated by an inverted siphon Kentucky a simple solution to odors released from intersecting steep and flat sewers saved a lot of money, capital and operating Kentucky house traps connected to a steep slope sewer were emptied, and odors were found in the homes. A background will be presented along with the approach taken and the solutions implemented for each of these case histories. In the bigger picture, practical examples like these should remind engineers that their designs need to consider the potential odor and infrastructure corrosion conditions that they may cause and include ways to address them.

Best Management Practices (BMPs) are continually evolving with new technology being developed to treat stormwater runoff. The maintenance needs for all BMP types needs to be clearly understood for communities so they are able to maintain the water quality benefits they provide to the overall ecosystem. This presentation will walk through how one community recognized this need and developed a comprehensive BMP maintenance program to meet the challenges of a wide range of BMP types. The overall goal of the presentation is to: (1) educate individuals on the need to develop a comprehensive program to ensure budgets are adequately addressing the long-term costs, (2) taking this systematic approach to maintenance will ultimately save the community money in the long term and (3) how a community can go about setting their own program up. The City of Woodbury, is one of the fastest growing cities in Minnesota. As part of the development process, the City requires the creation of stormwater management best practices (BMPs) within the developments which has led to over 1,700 city owned BMPs within Woodbury. As the City's BMP system has expanded so have the stormwater regulations as well as the complexity of BMPs being used to meet the increasing requirements. This increased complexity of the system and maintenance needs created an opportunity for the City to step back from regular pond dredging projects and reconsider the system in its entirety. City staff from various departments worked together over the course of a year to understand the system, identify any challenges, and review best practice recommendations from external and internal sources to create the Woodbury BMP Maintenance Plan which takes a holistic approach at managing every part of the public stormwater system to meet the requirements within the current MS4 permit, manage the resources responsibly, and do so cost efficiently. Developed in collaboration with this plan are three guides for the City to use: 1) an Inspection and Maintenance Framework and Guides for each BMP type to be used to train new staff, to increase consistency between staff and to help inform private owners on operation of their systems, 2) a public engagement plan, which provides guidance to city staff on when and how to engage the general public on projects and 3) cost estimation model was created for staff to utilize and inform decisions on budget, capital improvement plan and utility rate adjustments. The findings from these guides will be shared in order to show how plan concepts can be turned in to usable materials. The Plan was published in October 2021 and the City completed their first annual BMP maintenance project using the plan in Winter 2021/2022. Submitted with this abstract are graphics from the plan and results from the initial use of the plan will be included in the presentation.

Introduction The problem of food waste accumulation, combined with the pollution of petroleum-based plastic, presents a significant environmental challenge (Atiwesh et al., 2021, Paritosh et al., 2017). Converting food waste into bioplastics offers a potential solution to these issues by reducing landfilled food waste and replacing traditional plastics with biodegradable alternatives. Haloferax mediterranei (HM), a halophilic microorganism, is notable for its ability to produce the bioplastic poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) while thriving in high-salinity environments, which inherently reduces contamination risks (Meereboer et al., 2020). Previous studies have demonstrated that HM can produce PHBV from food waste in single-batch reactors, yet these systems are inefficient for large-scale industrialization (Wang and Zhang, 2021). The sequencing batch reactor (SBR) system addresses these limitations by enabling semi-continuous production, thereby enhancing economic feasibility and scalability (Allman, 2024). Despite these advantages, research on the long-term stability and operational optimization of SBRs for PHBV production remains limited. This study aims to fill this knowledge gap by investigating the effects of cycle time and volume exchange ratio (VER) of SBR on PHBV production performance. This work presents an opportunity to address both food waste management and plastic pollution challenges in one approach, contributing to a more sustainable and environmentally friendly future. Materials and Methods The food waste used as a substrate in the experiment was processed into digestate through arrested anaerobic digestion, which breaks down complex molecules into simpler, more digestible forms. The digestate was prepared with controlled composition, including organic acids and other nutrient sources, and was diluted to minimize substrate inhibition. The arrested anaerobic digestion was conducted at 35°C with a hydraulic retention time of 12 days and maintained a consistent organic loading rate of 2.5 g volatile solids (VS)/L-day. The PHBV production process was conducted in a 500 mL SBR, with a working volume of 400 mL (Figure 1). Each cycle included phases of feeding, reaction, and discharging, with the cycle time and VER as key variables. The SBR operated at 37°C with aeration and maintained high salinity (156 g/L NaCl) to support HM's growth while minimizing contamination risks. The cycle time was systematically increased from 1 to 12 days in the initial phase, while the VER remained constant at 0.5 (Figure 2). In the subsequent phase, the VER was adjusted from 0.3 to 0.5, with the cycle time determined by HM growth. The experiment included a 450-day continuous operation, making it one of the longest durations reported for HM fermentation. To assess HM growth, total organic carbon (TOC) reduction, and PHBV production, samples were collected at regular intervals and analyzed using various analytical techniques. Cell density was monitored with OD600nm, and PHBV content was measured using gas chromatography following a series of extraction and purification steps. Results 1.Optimal Dilution and TOC Utilization: HM demonstrated substrate inhibition with undiluted food waste digestate, showing no growth or PHBV production. A dilution factor of 2, with an initial TOC concentration of 7 g/L, achieved optimal PHBV yield, maintaining approximately 70% PHBV content and 6% 3-hydroxyvalerate (HV) fraction in the cellular biomass. This condition was chosen for subsequent SBR operations. 2.Growth and Substrate Utilization: Stable HM growth was observed over the 450 days, with optimal cell concentrations achieved at low VERs due to higher retention of HM cells in the reactor (Figure 3A). Substrate utilization showed a direct correlation with cell growth; however, around 2 g/L TOC remained unutilized, which was hypothesized to be linked to product inhibition (Figure 3B). 3.\PHBV production performance: PHBV cellular content stabilized at around 65% for over 450 days without contamination (Figure 4A). The HV fraction in PHBV remained consistently near 15%, aligning with commercial application standards. PHBV titer followed the same trend as HM growth (Figure 4B). PHBV yield declined as VER decreased, likely due to product inhibition (Figure 4C). PHBV productivity followed organic loading rate (OLR) trends, demonstrating that higher OLR increases PHBV production rate (Figure 4D). Discussion The study demonstrates that SBRs provide a viable solution for long-term PHBV production from food waste, maintaining stable production and minimizing contamination risks due to HM's halophilic nature. However, substrate inhibition from food waste digestate and product inhibition in the SBR pose limitations to production titer and yield. The relationship between PHBV productivity and OLR suggests that increasing OLR can enhance productivity, while controlling VER can mitigate inhibitor accumulation, optimizing yield and titer. These findings underscore the importance of managing cycle time and VER to balance microbial growth, product accumulation, and inhibitory effects. This research offers insights into scaling PHBV production sustainably, aligning with industry goals to reduce reliance on petroleum-based plastics. Conclusion This study successfully demonstrates the feasibility of long-term, stable PHBV production by HM using food waste digestate in SBRs over 450 days. By optimizing operational parameters such as cycle time and VER, the study presents a scalable approach for converting food waste into bioplastics, addressing environmental concerns associated with food waste and plastic pollution. Future research should focus on mitigating substrate and product inhibition to enhance industrial applications of this bioplastic production method, contributing to more sustainable waste management and plastic reduction efforts.