Results

Green infrastructure and source control technologies are increasingly accepted as a best practice for reducing stormwater impacts on water quality and aquatic habitat in urban areas. However, impacts continue to grow in many watersheds within the United States even as progress is being made on other sources of water pollution (NRC, 2009). Stormwater management practices have been improved at the site level, but they are not being implemented on a large enough scale to offset water quality degradation caused by urban and suburban land use trends (WEF Stormwater Institute, 2015). Philadelphia is one city implementing green infrastructure on a large scale as a key component of its approach to manage urban stormwater and combined sewer overflows. The Philadelphia Water Department will complete its tenth year of program implementation in 2021. This paper will cover the status of the program, provide statistics on the types and locations of green infrastructure that have been implemented, and summarize performance monitoring data collected from systems operating in the field. PWD submitted its Combined Sewer Overflow Long Term Control Plan Update in 2009, as required by its National Pollutant Discharge Elimination System permits. In 2011, a modified version of that plan was approved for implementation through a Consent Order and Agreement (COA) with the Pennsylvania Department of Environmental Protection. The COA specifies combined sewer overflow reductions, pollutant load reductions, and implementation of green stormwater infrastructure targets intended to improve water quality in local watersheds and the Delaware tidal estuary. As the program approaches the ten-year milestone, it has implemented stormwater management features managing surface runoff generated by approximately 1,100 acres of impervious urban surfaces (Figure 1). Stormwater management features have been implemented through a variety of programs and on a variety of land uses (Figure 2). These include projects on private property initiated by code requirements governing redevelopment. Projects have been implemented on public property, including streets, sidewalks, and public facilities. Finally, projects have been implemented through incentives for private property. Post-construction monitoring data from selected sites indicate that systems are generally meeting or exceeding design performance expectations (Figure 3).

We invite water utility managers and professionals to join us at the upcoming Utility Management Conference for a presentation that promises to impact the future of the water industry. In 2022-23, a monumental job analysis survey was conducted, involving over 15,000 dedicated industry personnel across water, wastewater, wastewater collection, and water distribution domains. This unprecedented participation underscores the collective commitment to advancing our industry and is the foundation for certification standards in North America and globally. The outcomes of these extensive job analysis surveys, coupled with rigorous psychometric analysis, will serve as the cornerstone for developing the water industry's only standardized certification exams. This pivotal development will transform operator training, industry resource materials, and the content of certification exams. Behind this groundbreaking initiative are more than five dozen dedicated volunteers, who have invested hundreds, if not thousands, of hours in meticulously analyzing survey findings and identifying emerging trends. Our presentation will unveil the draft Need-to-Know Criteria documents derived from these findings, providing an exclusive preview of the future certification landscape. But that's not all. We encourage active audience participation and critique during the presentation. Your invaluable insights will assist the Certification Commission for Environmental Professionals in shaping relevant, robust, and legally defensible certification exams. Remember, water environment operators are the bedrock of our public health systems, and these surveys form the foundation for determining the criteria for operator competence. The Utility Management Conference offers a unique opportunity for participants to contribute to the Commission's final reports before they are released to the public and adopted by state and provincial jurisdictions. Be part of this transformative journey, and help us secure a safer, more efficient, and sustainable future for the water industry. Together, we can ensure that our operators are equipped with the knowledge and skills needed to protect public health and preserve our precious water resources. Join us in shaping the future of water operator certification.

The California Association of Sewerage Agencies Regulatory Workgroup prepared a guidance document in 2022-23 for wastewater agencies who produce biosolids and contract out land application services. The document is aimed at producers of Class B biosolids and it aims to help agencies oversee their contractors in a manner compliant with 40 C.F.R. § 503, i.e. EPA 503 regulations. The purpose of the document is not to address all the elements of an Environmental Management System, nor is it to substitute the best practice guidance from the National Biosolids Partnership. Rather, this document provides a simple distillation of duties retained by a generator of biosolids when the land application of the biosolids is handled by an outside contractor. EPA 503 regulations promote a spirit of cradle-to-grave involvement in biosolids handling on the part of the generator, yet the regulations leave room for interpretation. This is especially complicated for tasks that have been contractually transferred to the biosolids handler and are beyond the operational control of the generator, yet the generator remains responsible in principle. Further complicating interpretation is that EPA 503 does not clearly list generator duties for land application beyond sampling and analysis, leaving the reader to find duties throughout the full legal code. The document describes how the utilities should provide oversight via desktop review and in the field, before, during, and after land application. Aspects of the contractor's operation that can be reviewed via desktop include field permits, trucking routes, crops to be grown, and timing of application. Also, outreach to landowners and local regulators can be conducted in office. It is important to note that EPA 503 promotes communication between the generator and the landowner to ensure that the landowner is aware of the land application practice occurring on their fields. The document describes how a utility can conduct effective site visits to verify that land application practices are consistent with federal, state, and local (county) regulations. Site visits are also encouraged after application to verify the crop being grown at the site. Perhaps most importantly, the guidance describes agronomic loading rates. It provides definitions, calculations, and guidance related to biosolids analysis, soil analysis, field loading, and crop uptake. The guidance addresses how climate and soil type will affect assumptions. The guidance helps agency staff demystify and interpret field reports from a land applier. Finally, while the guidance document describes the limitations of contracts in abdicating a generator's duties, it nevertheless includes example contractual language to help agencies develop strong agreements. In general, the guidance is meant to help both new and experienced agencies monitor their biosolids land application practices. This talk will step through the guidance document and discuss input and nuances for the various recommendations. This talk will be useful to agency staff persons and biosolids contractors alike, as well as consultants and regulators. While the guidance was developed in California, it is applicable to all states.

In 2014 Winston-Salem/Forsyth County (WSFC) Utilities faced a defining moment for their organization. The utility was experiencing historically low levels of service and facing potential regulatory action from the United States Environmental Protection Agency (USEPA) relating to high rates of sanitary sewer overflows (SSOs). These events negatively impact public health, cause property damage, and harm local environments. Primarily caused by pipe blockages, the most efficient path to reducing WSFC Utilities SSOs was identified as more effective asset maintenance programs. By improving WSFC Utilities' approach to clearing and removing grease, roots, and debris from the collection system -- the primary cause of blockages leading to SSOs -- the utility had the opportunity to improve collection system performance and avoid regulatory action. As a part of this mission, WSFC Utilities established the Collection System Improvement Program (CSIP), a multi-year effort to relaunch the organization's Capacity, Management, Operation, and Maintenance (CMOM) program. HDR collaborated with WSFC Utilities to establish its vision and develop a strategic plan to achieve it. Program components included target initiatives to optimize utility operations -- including cleaning -- as well as condition assessment, capacity assessment, repair, rehabilitation, and replacement (3R) design and delivery, and staff augmentation to assist in implementation efforts. A key initiative established early in the program was to develop a methodology to optimize cleaning operations within the utility's 1,800-mile collection system and an associated tool to implement this methodology within the organization. The result of this effort is FreeFlowH20 (FFH20). FFH2O is a web-based application that simplifies systemwide collection system maintenance through the optimization of cleaning operations. Leveraging utility data such as GIS-based asset information, work order histories, maintenance observations, and condition assessment findings, FFH2O creates and manages a pipe cleaning schedule to promote right-time cleaning. By actively managing cleaning schedule within the collection system, FFH20 allows WSFC Utilities to focus cleaning resources on highest risk pipes and limit unnecessary maintenance on lower risk pipes. This results in cleaning activities taking place in pipes that have grease, roots, and debris that need to be removed and avoids unnecessary cleaning on pipes that are already clean. FFH2O implements this approach through a web-based interface that allows users to:

1.Visualize the pipe cleaning schedule
2.Select non-contiguous geographic groupings of pipe for maintenance
3.Manage individual pipe status
4.Directly interact with suggested schedule modifications
5.Review Asset History
6.Create manual recommendations in response to real-time field events
7.Manage active work

FFH2O has allowed WSFCU to transition from a reactive O&M approach to a proactive one. Since the implementation of the pipe cleaning schedule, WSFCU's SSO count has dropped from 124 in FY15 to 55 in FY22 -- a 55% reduction in 7 years. This has resulted in a more predictable operating environment that enables the utility to better plan for resource needs and maintenance operations within its system. In addition, SSO reductions resulted in the USEPA dropping the regulatory case against the utility and avoiding a consent order. By cleaning smarter, not harder, utilities have the opportunity to implement more effective maintenance strategies within their collection system. This enables organizations to positively impact collection system performance in the face of a range of challenges. Regulatory threats, staffing challenges, and budgetary constraints in collection system operations can all be mitigated by becoming more effective in day-to-day cleaning. FFH20 is one way to achieve this goal.

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.

In today's dynamic job market, organizations face challenges in retaining top talent and maintaining a strong workforce. Stay interviews offer a valuable tool for addressing these challenges by engaging and understanding the needs of existing employees. Stay interviews are an emerging mechanism adopted by organizations to improve employee retention. Unlike exit interviews that focus on gathering feedback from departing employees, stay interviews aim to engage and retain existing employees by addressing their concerns, needs, and professional development. This presentation provides an overview of stay interviews as a proactive retention strategy, outlining their purpose, benefits, and best practices. SPR will share their methodology for executing a stay interview project, providing insights into their data collection and analysis processes. They will also showcase their PowerBI dashboard, demonstrating how it visualizes differences between employee populations, including DEI subsets. This in-depth analysis enables leadership to address specific concerns within different groups, make necessary enhancements, and generate ideas for future offerings. Gallup research reports that only about 25% of organizations are currently conducting stay interviews, which can reduce organizational turnover by up to 20%. Overall, stay interviews serve as a valuable tool for enhancing employee engagement, satisfaction, and long-term commitment, contributing to overall organizational success.

Background: This study was performed to evaluate feasibility of implementing co-digestion at San Francisco airport facility (SFO) in California. The overall objective was to obtain preliminary feasibility information regarding diverting organic wastes from the terminal restaurants to its wastewater treatment plant anaerobic digester to enhance biogas production for beneficial use. The study included preliminary regulatory, technical, economic as well as triple bottom-line evaluation. The key objectives of the study included evaluating i) how much organic waste can be added to the airport's anaerobic digester without impacting the digester stability, ii) can all of this capacity be met with the organic wastes generated at the airport, iii) how much biogas will be generated during co-digestion, iv) what are the potential beneficial uses for the quantity and quality of biogas produced that are in alignment with the airport's sustainability goals as well as current and impending regulations, v) what are the potential impacts (e.g. increase in wet cake, polymer demand, metals in biosolids) of this process, and vi) what is the preliminary cost estimate for this program. Regulatory Review: Regulatory evaluation included review of SFO's existing wastewater treatment plant permit requirements (e.g. effluent discharge, emissions) as well as recent changes to co-digestion related regulations. A review of the permits indicated i) discharge limits for ammonia, organics and select metals, and emissions limit for ammonia, select organics and hydrogen sulfide (H2S). The bench scale studies were designed to partially address impacts of co-digestion on these limits. Among the new/emerging regulations, the 'Advanced Clean Fleets' (ACF; Release #23-13) regulation put forward by California Air Resources Control Board (CARB) and approved by the State in 2023 requires all the heavy and medium duty vehicles to be phased out and replaced with zero emission vehicles (ZEV) within the next 20 years. This will have a significant impact on the use of biogas for vehicle fuel. Further, a proposed CARB amendment to suspend Low Carbon Fuel Standard (LCFS) incentives, if implemented, will further discourage pipeline injection of treated biogas (Renewable Natural Gas (RNG)). The impact of these and other regulations were taken into consideration during evaluation of beneficial use alternatives for biogas. Bench Scale Testing: A bench scale test was performed using the TWAS from the airport full scale sequential batch reactors and the organic waste from the airport restaurants to address various objectives of this study. The organic wastes were collected as mixed waste which was then extracted using a Thor process for addition to bench scale reactors. The wastes and TWAS were characterized for organic and inorganic constituents, including metals concentration. The data indicated that the organic content (COD) and degradable solids (VS) were much higher in the food waste than those for TWAS. The COD of the TWAS and organic wastes were approximately 48,000 and 245,000 mg/L respectively. The total and volatile solids of the TWAS were 4.6 and 82%, respectively and the total and volatile solids of the organic waste were 21 and 88%, respectively. Four 10 Liter bench scale digesters filled with 8 L of TWAS and appropriate amount of food waste was used in the bench scale studies (Figure 1). One of the digesters (Control) received only the TWAS. The other three digesters (R1, R2 and R3) received food waste at 20, 40 and 60% of volatile solids as the TWAS volatile solids content. On a volume basis the food waste added was 4.3, 8.3 and 12.25% of the TWAS volume in the three digesters, respectively. The digesters were operated in the anaerobic digestion lab (ADL) at Bucknell University (Lewisburg, PA) at 37 oF. Various operating parameters and biogas quality and quantity were measured during the four-month study. The bench scale data indicated that the control digester (i.e. TWAS-only) produced approximately 6,000 mls/day of biogas whereas the digester with the highest amount of food waste produced approximately 14,000 mls/day of biogas Figure 2). In addition to total biogas production, the biogas yield, i.e. the cubic feet of biogas produced per pound of volatile solids reduced also were higher for the food waste added digester. The biogas yield of the control and the highest food waste added digesters were 35.5 and 47 cu.ft./lb VS reduced, respectively. These data indicated that, the food waste was digested more readily than the TWAS and produced significantly higher amount of biogas at a much smaller volume added. Addition of food waste increases the solids added to the digester. This, in turn, may increase the amount of dewatered cake generated after digestion. Hence, dewatering studies were conducted using the digested sludge from the bench scale study. The data indicated that the net wet cake mass may decrease by about 7% at the loading used in R1 digester and increase by approximately 8 and 12% at the loading used in the R2 and R3 digester, respectively (Figure 3). Projections for Full Scale Operation: The bench scale study data was then used to project various parameters for the airport's full scale co-digestion operation. The evaluations indicated that nearly 1,900 tons of organic waste is required annually for the co-digestion process at the desired (food waste at 60% VS of TWAS VS) loading rates. The airport generates approximately 4,500 tons of organic waste each year. Hence, enough organic waste is available for co-digestion. Further, sufficient volume is available in the digester to receive the food waste is diluted up to 7% solids content for ease of pumping. This operation is estimated to produce approximately 38 to 45 standard cubic feet per minute (scfm) biogas. Based on bench scale data, addition of this amount of food waste may increase the dewatered cake produced by 1.3 wet tons per day and the polymer demand for dewatering by approximately 19.5 lb/day. A preliminary evaluation of regulatory compliance, limited to the data from the bench scale study, indicated compliance requirements for the tested parameters may be met after food waste addition to the digester. However, more detailed evaluation through a larger scale study and detailed discussions with regulatory agencies may be required during the next phases of the study to ensure compliance with regulatory requirements. Evaluation of End Use Alternatives: The above information/data were used to evaluate beneficial use alternatives for the biogas produced through co-digestion. The alternatives evaluated include i) combustion-based combined heat and power (CHP) generation technologies such as internal combustion engines (IC Engine) and microturbines, ii) non-combustion CHP technologies such as fuel cell systems and linear generation technology, iii) use of biogas for vehicle fuel, and iv) pipeline injection of treated biogas. The airport does not prefer combustion-based technologies due to environmental concerns. Further, the current and impending CARB regulations do not favor the use of biogas for vehicle fuel or pipeline injection in the long term. The non-combustion CHP technologies, while relatively new to the market, have made significant advancements in the recent years. Further, they produce much lower greenhouse gas emissions. Hence, these non-combustion technologies (fuel cell and Linear Generation) are recommended for further evaluation in the next phase for potential installation at the airport. Preliminary Cost Evaluation: A preliminary cost evaluation was performed for the implementation of the proposed program. The airport is currently evaluating its options for food waste collection, sorting and processing. Hence, the evaluation did not include food waste collection, extraction, storage and pumping to the digester. The preliminary cost estimate for the rest of the constituents (CHP, biogas treatment and installation, etc.) is approximately $2.95 M. The increased annual O&M cost is approximately $180,000/year. The estimated revenue from the savings in electricity is approximately $ 270,000/year. Triple Bottom-Line Evaluation: Further, a triple bottom-line cost-benefit analysis (financial, social and environmental) was performed for the proposed technology. The evaluation indicated that in the next twenty years the proposed technology will avoid a total of approximately 19,500 tons of CO2e emissions, mainly from diverted waste and fertilizers offset. It is also estimated that the proposed technology will mitigate emissions of approximately 5,200 pounds of contaminants through avoided natural gas purchases. No avoided emissions due to electricity generation is anticipated since SFO already purchases clean energy from San Francisco Public Utility Commission.

An overview of recommended technical design considerations, installation good practices and inspection strategies to help promote successful trenchless structural manhole rehabilitation in wastewater collection systems is presented. This presentation will discuss the various fully structural trenchless rehabilitation systems that are available, what makes these methodologies structural, and when it is recommended to use these different product types. Differences between semi-structural, interactive lining methods such as bonded resin‐based polymer coating/ lining systems including epoxies, polyurethanes, poly-ureas, as well as cementitious materials and geopolymers will be explained and compared with fully structural, independent manhole rehabilitation technologies in a neutral, non-commercial manner. Common problems that can be avoided through proper planning, design, product specification, installation and appropriate quality control procedures will be covered. The importance of performing QA/QC inspections throughout the rehabilitation process and what to look for when performing manhole condition assessment evaluations, with emphasis on implementation of proper surface preparation techniques will be discussed. Design methodologies, product selection, specification development, applicable inspection strategies, and technical standards will be referenced. Structural manhole rehabilitation case studies in Colorado and New Mexico will be introduced and discussed throughout the presentation, with focus on lessons learned for each project.

Introduction At many water resource recovery facilities (WRRFs), when potential environmental impacts are viewed in their totality, thermally processing the sewage sludge remains an environmentally friendly and economically feasible option. Many of these plants have existing, older, multiple hearth furnaces (MHF). Often viewed as having greater emissions than the fluid bed reactors (FBR) which in recent years have gained a greater presence, that is only partially true. Both excess air and afterburner fuel demand can be significantly reduced by conversion of the MHF to a pyrolyzer/gasifier. The paper and presentation will explain how this is possible. History Operation of a MHF in pyrolysis or gasification mode is not a new concept. MHF systems have been used in carbon regeneration and activated carbon manufacturing for decades. Historical applications using MHF systems to process WRRF residuals in these process modes is, however, very rare. On the other hand, FBRs have been more frequently operated in a gasification mode to process WRRF residuals. The first full-scale FBRs operating in a gasification mode were installed at the Hyperion WRRF in Los Angeles. The design capacity of each of the three (3) FBRs was 132.5 dry tons/day of a heat dried biosolids, called sludge derived fuel (SDF). Through heat recovery, superheated steam was produced, then converted to electricity in a condensing steam turbine. The SDF was gasified in the FBR with sub-stoichiometric air addition to produce a syngas. The hot syngas was then combusted in a multi-stage combustion afterburner. The gasification/staged-combustion approach provided significant reduction in nitrous oxide (NOx) emissions compared to conventional incineration. Operation began in 1986 and continued for about 10 years at part load. Problems with the upstream drying process limited throughput to about 100 dry tons/day of SDF. Unfortunately, the continuing problems with the sludge dryers, and a significant decrease in the cost of land disposal, made continued operation no longer economically viable. While Hyperion was a FBR, adaptation of these concepts to a MHF is also feasible. Aside from a MHF being able to produce a synthesis gas with lower particulate than a FBR, a MHF offers another advantage. A safe and stable combustion mode in a MHF can be achieved at a significantly lower exhaust temperature than a FBR, which is because of the reactions that occur in the freeboard that typically create a 200°F(+) increase in exit temperature. The counter-current flow of syngas and sludge feed make an excellent thermodynamic reactor. When operated in a true pyrolysis mode, a biochar would be produced. While production of an agricultural biochar can sometimes generate political currency, it must be balanced against the loss of BTU's that may have to be made up with auxiliary fuel. The use of biochar in a local market will depend on the soil, agricultural needs, and pyrolysis conditions used for producing the biochar. Using the pyrolysis gas from a pyrolysis process is possible but the removal of the tars, oils, and other condensables produced during pyrolysis before sending the pyrolysis gas to a commercial burner have heretofore defied a simple, straightforward, and reliable solution. Any project contemplating on recycling pyrolysis gas directly back to a burner will venture into somewhat uncharted territory. In the early 1980's, the Allegheny County Sanitary Authority (ALCOSAN) installed a dual-mode MHF system at its WRRF in Pittsburgh, PA. This system was designed to process 76.5 dry tons/day of raw sludge, and incorporated both starved-air combustion and conventional excess air combustion modes. When operating in the starved air mode, the furnace was divided into four zones: drying, starved air/gasification, carbon burnout and ash cooling. Burners were fired in the carbon burnout zone, but were rarely needed to any significant degree in the drying zone, as combustion air was introduced to the drying hearths to release a portion of the syngas heat to support the drying process. The carbon burnout zone was operated with excess air to keep temperatures within acceptable limits and yield an ash with less than 2% carbon. The ALCOSAN system sacrificed the production of biochar to provide the heat needed for the gasification process and the drying of the incoming feed. Syngas was combusted in the external afterburner and a waste heat recovery boiler was provided downstream of the afterburner to produce steam for plant and process heating. In the design concept of this paper, bioenergy recovery from the syngas produced in a MHF pyrolysis/gasification system would incorporate an external 'syngas oxidization chamber' equipped with a flame safety pilot burner. This refractory lined vessel is very similar to a separate vessel conventional afterburner commonly installed on MHFs (Figure 1). From the oxidizer, a portion of the heat would be used to heat the Multiple Hearth pyrolysis / gasification reactor and/or to pre-dry the incoming feed. Potential slag formation in the syngas oxidization chamber remains a challenge. This challenge has been meet using indirect heated, rotary kiln pyrolysis reactors. The challenge of slag control and combustion chamber design will be discussed in the paper /presentation. Heat and Material Balances The Heat and Material Balance remains at the heart of any thermodynamic process and the Laws of Thermodynamics: You Can't Beat the Game You Can't Even Break Even This principal remains inviolate and it is essential that any complex design of this nature begin with a thorough heat and material balance at each stage of the process. This enables the engineer to evaluate the interdependencies between each stage; to identify potential problem areas or design challenges; and to fully understand the overall system performance. When a thermal dryer is used ahead of the gasification/pyrolysis, the treatment of the water vapor, thermal or other, must be included in any analysis within the overall Thermodynamic System Boundary. Thermodynamics does not allow a 'free lunch' and the energy requirements for thermal drying are significant. In this basic concept, energy recovery is provided downstream of the external afterburner chamber in the form of hot thermal oil that can be used in an indirect thermal dryer system. This paper will discuss the process in greater detail and through a series of pictorial Heat and Material Balances for both pyrolysis and gasification systems. This will give the reader a better understanding of the process and hopefully prevent repeats of the failures of many previous gasification and pyrolysis ventures. Often these failed to recognize the true thermodynamic balance and the myriad of yet unsolved problems of removing the tars and oils from the pyrolysis gas. Figure 2 illustrates the output from a detailed heat and material balance around a MHF gasifier. Figure 3 shows the distribution of the syngas components from this system. Figures 4 and 5 illustrate the output from detailed heat and material balances around the external afterburner chamber and a subsequent thermal oil heat recovery unit, respectively. Figure 6 provides a summary of the heat and material balances around the entire thermodynamic system boundary. Additional diagrams will be included in the final paper for other optional design concepts. Conclusions The advantages of MHF gasification are readily apparent. The WRRF sludge can just be scalped (thermally dewatered) to 40% and the syngas will have a flame temperature of 1,844°F. Similarly, a 35% solids feed will yield a syngas with a flame temperature of 1,637°F in the secondary combustion chamber. If these flue gases are taken through a thermal oil heater and exhausted at 400°F, the thermal oil will have sufficient heat to dry a raw feed solids of 20% to the feed solids required for the system. Further modeling and evaluation will be included in the final paper to assess the feasibility of MHF pyrolysis. An existing MHF represents a major capital investment and developing means to exploit existing infrastructure and improve performance can have a significant positive impact on both asset management and operational economics at any plant. Converting an existing MHF into a pyrolyzer/gasifier with the addition of a secondary combustion chamber (afterburner) and thermal drying/dewatering system may prove to be a viable option that is worthy of evaluation. With interest growing in the use of gasification and pyrolysis as alternatives to conventional incineration, the options presented in this paper could be attractive in appropriate circumstances and the design approaches described in this paper can be invaluable in assessing the viability of implementing the conversion of an existing MHF to a new pyrolyzer/gasifier system.

A Profile of Wastewater Odors Assessor training and evaluation of odors from facility to the community. Wastewater treatment source odors move downwind into the community with changing intensity and odor character. Odor profiling with intensity measurements is a sensory evaluation tool used to quantify this phenomenon. Odor Profiling requires assessors to assign intensity to odor characters observed at multiple concentration dilution levels through an olfactometer, simulating the changing odor character and intensity of the source odor transported (carried by wind) to the community. Weber-Fechner-Stevens (WFS) studies explained how wastewater odor types smell differently and also change differently as they travel from the source into the community. The Weber-Fechner-Stevens studies and the resulting graphs illustrate odor intensity decreasing at different rates (slope) for each odor type. Trained odor assessors (odor judges) report odor intensity in accordance with ASTM E544-18, Standard Practice for Referencing Suprathreshold Odor Intensity, and other accepted industry standard practices, e.g. sugar water scales. Training assessors is the essential part of odor profiling studies. St.Croix Sensory odor evaluation laboratory uses a 'metric' 10-point odor intensity referencing scale, listed with words to describe the ascending concentration levels. 0 Level No Odor 1 Level Threshold 2 Level Very Slight 3 Level Slight 4 Level Slightly Moderate 5 Level Moderate 6 Level Slightly Strong 7 Level Moderately Strong 8 Level Strong 9 Level Very Strong 10 Level Extremely Strong Assessors (odor judges) can be trained using an ASTM E544-18 10-point Butanol Scale, incorporating the training technique of 'Feedback Calibration Method' (FCM). FCM provides immediate feedback to the test individual during the training. Odor Profiling embraces 'odor wheels', general and specific to odor site studies. With confident assessor intensity performance and a known uncertainty budget applied, predicting the effects of wastewater treatment source odors will become routine for practitioners, engineers, operators, and decision makers. Two cases are present to illustrate the different outcomes of odor profiling: (1) terpene odor profiles for the hemp industry and (2) sanitary wastewater collection system odor profiles.

The 60-mgd F. Wayne Hill Water Resources Center (FWHWRC) is Gwinnett County's largest and most advanced wastewater treatment plant. The FWHWRC utilizes enhanced biological phosphorus removal (EBPR) and chemical polishing to meet a stringent effluent total phosphorus limit of 0.08 mg/L. The liquid treatment train is comprised of influent screenings, grit removal, primary clarification, activated sludge (biological reactor basins (BRBs)), secondary clarification, tertiary filtration, pre-ozonation, biological activated carbon (BAC), and post-ozonation. Solids handling includes co-thickening of primary sludge and WAS, anaerobic digestion, and sludge dewatering. The facility also utilizes the OSTARA Pearl process with WASSTRIP (i.e. Nutrient Recovery) for controlled harvesting of struvite and the reduction of phosphorus recycle loadings on the liquid treatment train. The FWHWRC is a high-profile, complex facility with numerous process components and five operating odor control systems, the largest of which is a 256,000-cfm chemical scrubber system. Despite GCDWR's attempts to work with its on-call contractors and engineers to identify and remedy several known odor sources, odor complaints persisted. An odor study was therefore recommended to fully characterize odors from various parts of the plant. This paper discusses the recommendations from the odor study conducted at the treatment plant, as well as the outcome from implementing the recommended changes in full-scale. Optimization Effort The odor study included an odor source survey, odor sampling and sample analysis, and development of an Immediate Action Plan; odor source prioritization, and development of a Long-Term Action Plan. The Immediate Action Plan was intended to identify issues that could be addressed in the short term to help alleviate any odor complaints originating within the boundary of the treatment plant. This task began with a site visit by a team of odor and process experts, who conducted an operational review of the facilities in the plant. The site visit included visual inspection of all existing odor control systems to identify improvements that can be made to the operation of the systems, in addition to a review of operational practices that may be contributing to off-site odors. As part of the site visit, all potential odor sources were identified, and a detailed sampling plan was developed with more than 40 sample locations. Grab samples were collected and analyzed for sensory samples (odor threshold, intensity, and dose-response), sulfur speciation, and ammonia/amines (at select locations). In addition, several OdaLog units were installed to determine diurnal trends for hydrogen sulfide gas. Results D/T Highest D/T values were observed near the influent distribution box, followed by the solids odor control system. Odors observed near the solids disposal truck bay were determined to be stationary. D/T values measured near the FOG receiving station were also observed to be low. D/T values measured at the exhaust of all other odor control systems were lower than 250 o.u. Sulfur compounds- The highest concentrations of reduced sulfur compounds were detected at the Solids Odor Control System inlet (350 ppb H2S) and exhaust (210 ppb Dimethyl Sulfide); and the Influent Distribution Box (180 ppb Dimethyl Disulfide). The remaining sample locations had concentrations of reduced sulfur compounds that were either non-detectable (ND) or at low ppb levels. H2S concentrations across the range of sample locations were considerably low or not detected, except for occasional spikes at the Influent Distribution Box due to diurnal flow variations at noon and midnight. Amines and Ammonia- With the exception of one sample at the solids disposal truck (17.5 ppm), all ammonia concentrations detected were below the detection threshold (17 ppm). The highest concentration of trimethyl amine (TMA) compounds was detected in the Truck Loading Bay, which had a high concentration of 11 ppb. All other locations sampled and tested, including the Nutrient Recovery Facility and its associated odor control system and solids disposal trucks had relatively low levels of TMA. Odor Emissions The primary odor source on site was determined to be the large chemical scrubber system. Although the measured H2S values were low (0.09 0.9 ppm), D/T values in the scrubber exhausts were higher than expected, ranging from 250 to 1,900. Combined with the high exhaust rate of 256,000 cfm, these scrubbers were determined to be a clear source for off-site odors. In addition, the removal efficiencies for D/T through the chemical scrubbers averaged only about 90%, which is below the expected removal efficiency of 99%. Based on the sampling and emissions rate data, this source was deemed a high-priority source. The Immediate Action Plan helped identify and prioritize odor improvements into three categories: high, medium, and low priority. The highest priority items included refurbishment of the existing 256,000 cfm chemical scrubber system, including: rebalancing of the ductwork system-a 2-month long process that included over 250 individual take-off points, adjustment of chemical feed setpoints, adjustment of chemical feed/sampling locations, operational procedure improvements (including packing cleaning procedures, fan operation, etc.), fine-tuning of automatic controls for fans and chemical feed pumps, and replacement of scrubber packing and spray nozzles for increased efficiency. In addition, other operational improvements were identified, including: adjustment of operation of splitter boxes to minimize fugitive emissions, addition of a new carbon adsorption system to serve the equalization splitter box, recommendations for improvements to the operation of the solids process, and reducing sludge blanket levels in the secondary clarifiers. Conclusion Based on the results of the odor study, many of the Immediate Action Plan recommendations were successfully implemented by GCDWR which in turn has led to mitigating any odor complaints since. Modifications to sampling location and operating parameters such as pH and ORP set points on the chemical scrubbers has also led to significant cost savings from reduced chemical usage (>50% reduction in chemical usage). The other modifications implemented for the chemical scrubbers have increased scrubber removal efficiencies, reduced fugitive emissions from the plant, and reduced scaling in the chemical scrubbing process. In addition, the recommended improvements have increased the reliability of the existing odor control systems and reduced odor emissions from the facility. Completion of the odor study allowed GCDWR to prioritize odor improvements and zero in on the most problematic areas of the plant prior to making any major capital investments.

Microplastics (MPs) are a kind of pollutants that have attracted widespread attention in recent years. Previous research shows that the vast majority of MPs will be intercepted by sludge after the wastewater enters the wastewater treatment plant (WWTP) 1), and will enter the soil with the subsequent utilization of sludge. Before the sludge enters the soil, it is usually subjected to a series of treatments such as high-temperature composting and methane fermentation. Methane fermentation is an energy conversion of sewage sludge, and its use will expand in the future. Recent study found that the shape, quantity and size of MPs in methane fermentation or high temperature composting of sewage sludge changed 2) but the reason and the MPs' characteristics was not deeply studied. This research study and summarized the characteristics of MPs in the sewage sludge before and after methane fermentation in Japan. We sampled sludge before and after methane fermentation at WWTP A and B in Japan several times in 2022 from June to December. Both WWTP A and B use methane fermentation for sludge treatment. WWTP A uses mesophilic fermentation while WWTP B uses thermophilic fermentation. After organic matter removal using H2O2, ultrasonic treatment, and density separation steps, the sludge sample will be screened for particles suspected to be MP using microscopy and their chemical composition will be determined using μ-FTIR (AIM-9000; Shimadzu.Corp.). This study is focus on non-fibrous MPs with particle size greater than 100 μm. The size (long axis and short axis) and the plastic type of every MPs were recorded, concentration by dry weight and monthly discharge of MPs were calculated. With the above information, the characteristics of MPs before and after methane fermentation of sludge were summarized. In the sludge samples in this research, the concentration of MPs ranged from 0.72×104 to 1.8×104 pcs per kg dry weight. (Figure 1.) Overall, WWTP A had a higher concentration of MPs than WWTP B. The sludge from both WWTPs showed 2.9%-37.1% of decrease in MPs' concentration after methane fermentation. The concentration of MPs in samples from the same WWTP did not show great fluctuations from month to month. If the change in the amount of MPs in the methane fermentation system is calculated from the input and production of sludge, the amount of MPs was reduced by 50.1%-71.1% after the methane fermentation. For the plastic type, PE was found in all of the samples, accounting for 9.1%-21.7%. The detection rates of PP, PP-PE, acrylic and ABS were higher than 75%, PVC, PMMA and EVA were higher than 50%. Some particles with the spectral characteristics of MPs but with an ambiguous spectral information, or with the spectral characteristics of several MPs at the same time were founded. These particles may have been subjected to degradation or may be a mixture of plastics. Although it was not possible to determine the exact type of plastic, these particles were determined to be MPs in this study. The maximum size of MPs observed in this study was 1637.5 µm. 86.5% of the MPs in the sludge were smaller than 500 µm, 8.8% of the MPs were between 500 and 1000 µm, and only 4.7% of the MPs were larger than 1000 µm. (Figure 2.) The particle size of MPs became smaller after methane fermentation in WWTP A. Before digestion, the range of 200-300 µm had the most MPs. After digestion, the range of 100-200 µm had the most MPs. In WWTP B, the range of 200-300 µm had the most MPs but after methane fermentation, the percentage of MPs in this range has decreased significantly. After methane fermentation, there was a decrease in MPs' quantity. The degradation of MPs may have occurred during methane fermentation. Since there is a lower limit of detection of MP size in the analytical and detection methods, the accuracy of analysis decreases near this lower limit, and effective analysis is not possible for MPs smaller than the lower limit of size, 3) the possibility that the decrease in the number and size of MPs was caused by physical effects still cannot be excluded in this study.