Ozone is well known as an effective disinfectant and oxidant and has been operated for drinking water treatment in combination with biofiltration or biologically active carbon filtration for more than 50 years. Its versatility makes ozone/BAC a powerful tool for non-potable and potable water reuse applications. It is frequently applied as major barrier for pathogens and chemicals in carbon-based indirect potable reuse projects, especially for inland applications with limited options for sustainable management of reverse osmosis concentrates. In addition, most recent regulation for California includes ozone/BAC as an important barrier for control of chemicals in direct potable reuse (DPR) projects. In Europe, pilot- and full scale ozonation systems are currently installed in several countries with the aim to mitigate the discharge of chemicals of emerging concern (CECs) into receiving surface waters. Recent regulatory changes are expected to accelerate the implementation within the European Union: In October 2022, the European Commission published a draft of the amended Urban Wastewater Treatment Directive, which for the first time includes requirements for mitigation of organic micropollutants. In addition, EU has defined minimum requirements for agricultural water reuse that came into force on 26th June 2023 and provoked pilot studies testing ozone/BAC also for water reuse applications. This presentation will discuss experiences with ozone/BAF design and operation in Europe and the US, identify key parameters for design and process control, and outline potential concepts for future design. Ozone/BAC for water reuse in the US is designed for simultaneous removal of chemicals and pathogens, often applying ozone to TOC ratios >1 g O3/g TOC. Efficient disinfection (> 6 log inactivation) was confirmed in various spiking tests with bacteriophages at pilot scale. In contrast, ozonation of secondary effluents is designed for CEC removal and recent applications often apply ozone/TOC ratios as low as 0.3 g O3/g TOC. However, even at higher doses around 1 g O3/g TOC only limited inactivation of abundant indicator bacteria was observed in different studies, which often results in the conclusion that disinfection of wastewater by ozone is not effective. While ozone alone is effective for the removal of many contaminants, its combination with post-treatment in BAC filters is typically recommended to remove easy biodegradable oxidation by-products generated during ozonation and thereby lower effluent TOC and adverse effects in downstream processes. Besides, adsorption in BAC filters may serve as additional barrier for CECs if the carbon is regenerated on a regular basis. In our presentation, we will highlight similarities and differences in process design, control and operation in the US and in Europe, discuss potential reasons for deviating results, and outline solutions for an optimized design of ozone-BAC including effective removal of CECs and pathogens as well as the control of by-product formation. The presented results are based on own research (pilot and full-scale studies in Europe and the US) and literature studies including previous work for the WRF project 4832.

Managing utilities operations effectively in the era of big data involves application of emerging technologies, tools, and modern practices. Houston's in-house Wastewater Infrastructure Planning team incorporates technological advancement in its daily operations. The City of Houston (COH) is the largest city in the state of Texas and the fourth largest city in the United States of America. Houston Water owns and operates 38 Wastewater Treatment Plants (WWTPs) with a combined permitted capacity of 564 MGD. The wastewater collection system includes approximately 6,000 miles of sewer pipes, 133,000 manholes, and approximately 380 lift stations spread out over 665 square miles area to serve about 2.3 million customers. Wastewater treatment plants (WWTPs) have long played a crucial role in safeguarding both the environment and public health. The conventional practices of operation and maintenance (O&M) within WWTPs have been predominantly reactive in nature. This reactive approach has created challenges for site staff operating in the field, as they grapple with noisy Supervisory Control and Data Acquisition (SCADA) systems and information overload. This often results in decisions being based on gut instinct rather than data-driven insights. In this context, plant operators typically become aware of issues only when equipment fails or performance reviews uncover underperformance, leading to a reliance on lagging performance indicators and a heavy focus on troubleshooting rather than proactive modeling and operations. To ensure the long-term sustainability and effectiveness of wastewater treatment plants, decision-makers require real-time visibility into plant operations with leading performance indicators that can enable them to optimize performance in a proactive manner. The harnessing of near real-time data from sensors, SCADA systems, IoT devices, and Work Order Management Systems presents an opportunity for WWTP operators to comprehensively understand their systems' performance using innovative digital tools that simplify rather than complicate their daily tasks. Over the past decade, COH has undergone a digital transformation of its wastewater management system. COH has developed an Advanced Infrastructure Analytics Platform (AIAP) which includes all data and analytics needed for wastewater infrastructure planning. This presentation discusses an early initiative by the planning team of COH aimed at developing a Data-Centric 'Smart' Operations and Maintenance platform. This approach begins with the essential step of integrating multiple databases or systems to gain a holistic understanding of the entire WWTP operation and maintenance landscape. In line with the City's Strategic Asset Management framework, this integration brings together the WWTP SCADA, HachWims, Work Order Management System, and Asset's Physical Attributes and Conditions into a unified system. This fundamental integration enables analysts to empower stakeholders to comprehend the status of WWTP operations and maintenance from multiple perspectives. The next critical step involves the development of comprehensive O&M Key Performance Indicators (KPIs) that serve as vital metrics for monitoring system performance. These KPIs, derived from the integrated databases, enable operators and decision-makers to assess the overall health of the WWTP system accurately. To transition towards a proactive mode of operation, advanced analytics and predictive machine learning algorithms are deployed to forecast influent characteristics. These forecasts, combined with real-time data from sensors and the SCADA system, allow for dynamic adjustments to energy consumption, chemical usage, and other operational KPIs. This dynamic approach ensures compliance with environmental regulations while enhancing operational efficiency. Moreover, a machine learning model developed based on the Work Order Management System enables predictive maintenance. It anticipates equipment failures, enabling maintenance teams to address issues before they escalate into costly breakdowns. By embracing proactive operation and maintenance, the integrated approach optimizes resource allocation across the board. This would eventually include personnel scheduling, chemical dosing, and various other aspects of WWTP operations, resulting in substantial cost savings. In conclusion, this presentation underscores the transformative potential of data-centric O&M for WWTPs. By adopting proactive strategies grounded in real-time data and predictive analytics, WWTPs can significantly enhance their efficiency, reduce operational costs, and bolster environmental stewardship. The transition towards data-centric O&M is a crucial step towards ensuring the long-term sustainability and effectiveness of wastewater treatment plants, positioning them as integral components of smart, forward-thinking cities. The tasks identified below are some examples of lesson learned:

*Collaborate with the WWTPs operation team to grasp the challenges and requirements for proactive optimization and maintenance.

*Understand, structure, and establish data systems to facilitate data modeling and integration.

*Utilize Business Intelligence tools such as Power BI and Python for exploratory data analysis and visualization.

*Develop data pipelines for seamless automatic data updates and document procedures to enhance digital transformation effectiveness.

Three compounds in wastewater collection systems stand above the rest regarding the degradation of the environment. Hydrogen sulfide (H2S) is commonly known and has had multiple technologies developed for its treatment, methane (CH4) emissions have been overlooked and hard to quantify until recent years and BOD which requires significate investment at WWTP to remove. Excess BOD in Long untreated force mains consume all of the available Dissolved Oxygen (D.O.) and when gone, the bacteria under anerobic conditions generate H2S, causing severe odor and corrosion problems, and emit the potent greenhouse gas methane. These two components form only under conditions with zero D.O.concentration. Inversely, if there is a positive D.O. the Oxidation Reduction Potential (ORP) will remain positive and prevent these environmentally adverse components from forming due to their very low ORP generation requirement of -300 millivolts. Municipal wastewater collection and treatment systems are critical infrastructures, and the reduction of anthropogenic methane emissions that contribute to climate change as well as obnoxious H2S. Fugitive emissions of methane across the sewer systems remains a major challenge. Research suggests that over half of the US centralized wastewater industries Scope 1 greenhouse gas emissions are from sewer methane, as depicted in Table 1. To mathematically quantify the amount of methane generation within a foreman, we can implement Equation 1 to all existing force mains for an understanding of their methane emission potential. A case study will be provided on a three-mile, 24-inch force main, which left untreated would result in approximately 35 lbs per day of methane generated. This translates to nearly 400,000 lbs per year of CO2 equivalent-- comparable to thirty-two cars worth of CO2 pollutant year-round. Differentiating between the treatment of the two compounds, Hydrogen sulfide once formed under anaerobic conditions is readily biodegradable within ~30 minutes of maintained aerobic conditions. As shown in Figure 1, the vapor phase hydrogen sulfide (H2S) concentration is completely reduced due to the biodegradation of dissolved sulfides in oxic wastewater. However, methane once formed under anaerobic conditions is for all practical purposes not biodegradable in the presence of D.O. or nitrate as demonstrated by the fact that methane cannot serve as the carbon source for denitrification. Focusing on biofilms and bacterial floc, if the bulk D.O. is not sufficiently high to make the entire biofilm depth oxic, H2S formed deep in the biofilm can be re-oxidized completely as it diffuses back out of the aerobic surface biofilm into the bulk liquid and thus does not re-enter the environment. This is not true with dissolved CH4 due to its exceptionally low rate of aerobic biodegradability; essentially, all the CH4 generated will diffuse through the aerobic surface biofilm into the bulk liquid and will eventually escape to the environmental atmosphere at manholes, odor control exhaust, and wastewater treatment process at the facility. Methanotrophs are a class of bacteria that can oxidize methane under oxic conditions. Although this class of bacteria is significant globally over a long-time span, they metabolize so slowly that their contribution over a matter of hours in the collection and treatment system is negligible. Therefore, any methane formed in collection and treatment is not significantly metabolized in the time span of a few hours. Maintaining oxic conditions throughout a collection system has traditionally posed a challenge due to the extended hydraulic retention times experienced during nighttime pumping cycles. These elongated retention times coupled with the biofilms oxygen uptake rate (OUR) requires more dissolved oxygen than physically possible when only utilizing atmospheric air. Superoxygenation is a process designed to use pure oxygen and force main pressure to achieve almost 100% oxygen absorption efficiency with essentially no stripping of volatile components from the wastewater. Conventional aeration absorbs ~5% of the oxygen from air and acts as an efficient stripper for present volatile components, e.g. H2S and CH4. Wastewater treatment plants are being stressed today to treat higher BOD loading than ever before. Large investments are being made at the wastewater treatment plants to increase the plant's capacity to treat the higher BOD loads. An underutilized tool to help municipalities increase WWTP capacity is to do pretreatment in the collection system to reduce BOD. Modern wastewater treatment is based upon converting organic matter (measured as BOD) into biomass under aerobic conditions (in aeration tanks). The same principle can be applied to wastewater collection system where D.O. can be utilized to reduce BOD in the wastewater as it travels through the collection system to the WWTP. In the case study referenced, 180 mg/L of D.O. is added to a force main reducing the BOD by nearly 160 mg/L in the wastewater. That is a reduction of over 80% in typical municipal wastewater of 200 mg/L. SuperOxygenation technology allows for the efficient absorption of pure oxygen by providing an intense captive bubble swarm and utilizing existing line pressure within a Speece Cone. This provides D.O. saturation concentrations of over 100 mg/L, while staying below the saturation threshold and preventing effervescence.

APPLICABILITY Recent years have brought historic levels of grant and low-interest loan funding to the water sector to address issues of aging infrastructure, water availability, environmental impact and climate change. Legislation such as the Bipartisan Infrastructure Act and Inflation Reduction Act have created dozens of specific funding mechanisms with ever changing deadlines and, unfortunately, many water system professionals do not have the experience with grant seeking to efficiently evaluate grant funding opportunities. While successfully applying for federal and state grants can require a lot of advance planning and is highly competitive, finding applicable grant opportunities should not be the stumbling block that prevents a project from moving forward. The EPA's CWSRF and DWSRF are the largest source of federal funding for water, but grants are available from several other agencies as well. By identifying a few key elements of the project — such as community demographics, location, project impact and purpose — grant seekers can find alternative funding programs. This presentation will give water professionals a clear pathway to use for searching for grants and low-interest loans for any type of water project. DEMONSTRATED RESULTS AND OUTCOMES Methodology SRF represents the largest source of federal funding for water infrastructure, but the program falls short of the need for funding for the nation's water infrastructure. While there are many grant opportunities to investigate with new ones opening every day, water professionals can ask themselves a few simple questions about their project and their community to help guide them in the direction of possible funding agencies or programs. Is the community small and rural? USDA's Water & Waste Disposal Loan & Grant Program would be a good program to explore. For larger communities, HUD's Community Block Grant Program would be an option. If your state has had a Presidentially Declared Disaster in the past year, your resiliency project is eligible to apply for FEMA's Hazard Mitigation Grant Program. If your community has not experienced a disaster but you can show the need to make your community more resilient against a future one, FEMA's Building Resilient Infrastructure and Communities or Flood Mitigation Assistance grants are possibilities. Does the project assist in driving economic growth and boosting employment? If so, the U.S. Economic Development Administration's Public Works grants may be available. Recycled water projects in Western states can find funding under the U.S. Bureau of Reclamation's Title XVI program while other regions should consider the USACE's Environmental Infrastructure planning. By following a series of questions, community water system professionals can identify grant opportunities for almost any type of project. The funding process of Industrial Wastewater Treatment Facility Improvements Project for the City of Salinas, California is an example of this methodology. Salinas is known as the 'Salad Bowl of the World' for its production of lettuce, broccoli and other crops. The City needed to make improvements to its industrial wastewater treatment system to address capacity and efficiency issues. The project was not eligible for SRF funding under the state's guidelines for recycled water, so Carollo's grants team used its funding strategy of identifying key elements of the project to find other opportunities. The project was more than just a wastewater plant upgrade; it provided economic advantages to the community's industrial sector and created jobs. Because of the economic and infrastructure benefits that the project creates, it was eligible for an IBank Infrastructure State Revolving Fund Program low-interest loan. Carollo is in the final stages of helping the City complete its application. The City is also in talks with the EDA for funding through its Public Works grant program, which focuses on helping communities improve their economic futures. Outcomes Thinking about a necessary water project in concrete, two-dimensional terms — replacing old canal lining or installing a new sewer main due to capacity issues — can limit an organization's ability to identify grant funding. Most projects have multiple drivers and impacts. By identifying the forces driving the project and addressing what water funding agencies are looking for when selecting grantees, community water system staff can unlock additional grant funding to support infrastructure projects and lessen impacts on ratepayers. RELEVANCE TO AUDIENCE There are more opportunities than ever for water systems to secure grants to assist with projects, but programs are scattered across different agencies with varying priorities and deadlines. It is easy to feel overwhelmed when beginning to search for opportunities. It is possible, however, to take an engineering and analytical approach to finding grants that most water professionals will appreciate. By understanding what types of projects funding agencies are currently looking to support and recognizing the benefits of their projects to communities and the environment, water system professionals can zero in on opportunities that may assist with financing their work. This session will help water professionals find the federal and state funding available to assist in completing their vital projects to improve water quality and protect public health while lessening the impact on the ratepayers.

Objectives Hydrocyclones can intensify activated sludge processes by retaining larger, faster settling flocs and eliminating smaller, slower settling flocs. This can result in lower sludge volume indices (SVIs), higher mixed liquor solids concentrations, higher solids retention time (SRT), and modified mixed-liquor microbial community structures (Roche et al., 2021; Regmi et al., 2022; Li et al., 2020). While it is clear that hydrocyclones improve SVIs, what factors impact separation, and how separation impacts microbial communities, is less obvious. For example, does the relative abundance of heterotrophs, AOB/NOB, and PAOs determine whether a floc is retained in the hydrocyclone underflow? What is more important for floc retention: floc density, size, or shape? Do hydrocyclones affect protozoa? Such information could help program hydrocyclones to promote a desired treatment objective. In order to answer the above questions, we are using dynamic floc imaging, molecular tools, activity test, and floc density analyses to explore the effect of hydrocyclones at a full-scale wastewater treatment plant. We have completed four sampling events and expect to have four more by the time of the conference. This abstract includes our ongoing results. We expect to have full results in time for WEFTEC. Methodology Samples were collected from a full-scale municipal wastewater treatment plant in the Midwest region of the US. The plant was configured for EBPR and implemented a densified activated sludge (DAS) process using hydrocyclones in November of 2022. Starting in May 2023, sampling campaigns for floc analysis were carried out approximately every two months. Four samples have been collected and analyzed at the time of this abstract submission. Sampling included hydrocyclone influent, overflow, and underflow, and MLSS. Floc characterizations were carried out with an integrated laser diffraction analyzer with synchronous dynamic image analysis, i.e., diffraction and imaging were carried out on a single sample at the same time (Microtrac, Germany). By analyzing thousands of individual flocs in each sample, this provides classical particle size histograms, but also a large range of morphological particle parameters, such as circularity, sphericity, roughness, aspect ratio, roundness, and fractal dimension. Microbial community characterization was carried out by 16S rRNA gene sequencing of VSS from the MLSS, hydrocyclone influent, overflow, and underflow. qPCR and FISH were used to quantify AOB, NOB and PAOs. Findings A plot of SVI30, SVI5, and densification index over time is shown in Figure 1. SVIs decreased, and the densification index increased, over time after implementing the hydrocyclones. Floc size characterizations showed that the 50th percentile area-based diameter (D50) increased progressively from 108 µm (May 2023) to 163 µm (December 2023) (data not shown). Based on floc size histograms (Figure 2):

*Hydrocyclones appeared have little separation effect on the smaller flocs (0 — 50 µm). These were present in similar amounts in both overflow and underflow.

*The impact of hydrocyclones on larger flocs increased with time, i.e., there needed to be more large-sized flocs in the MLSS in order for the hydrocyclones to separate them into the underflow. Based on an analysis of floc circularity (Figure 3).

*Smaller flocs tended to be more circular than larger flocs, both in underflow and overflow

*Larger flocs in the underflow tended to be more circular than similarly sized flocs in the overflow, suggesting that floc morphology can play an important role in retention by hydrocyclones.

*Differences in circularity between underflow and overflow increased progressively over time (data not shown) Sampling sequencing data is available for one sampling date (July 2023). Based on these results, the hydrocyclone underflow had higher abundances of AOB, NOB, and PAOs than the overflow (data not shown). Interestingly, NOB (Nitrospira sp.) were more abundant than AOB. Preliminary qPCR and FISH (Figure 4) results are consistent with the sequencing. FISH is currently being used to differentiate the microbial communities for different floc sizes and shapes. Percoll density separation is also being used to quantify and sequence flocs by density. These results will be included in the final paper and presentation. Significance The results suggest that hydrocyclones separate not only based on floc density, but also size and shape. The role of microbial community is currently being analyzed and will be presented at the conference.

This year, cybersecurity attacks against our nation's critical infrastructure sectors have continued to challenge the operational integrity of our manufacturing environments and threaten our way of life. Cybercrime is an economic and national security sustainability threat. As we know, threat actor motives are often rooted in financial gain, as well as ideological differences. In short cybercrime is here to stay. Minutes matter, seconds count and the only control we have as people are over the decisions we choose to make to better protect our communities. As a result of consistently high cyber-attack attempts and incidents, recent changes to Federal and State administrative and civil laws have evolved to drive cyber risk management accountability. The time to act as a collective in the Water and Wastewater community is now because the quantifiable risk and liability associated with cyber-attack incidents has grown to an unsustainable level. To further contextualize, several states have waived sovereign immunity privileges relative to risk management, which directly places municipalities at risk from a Civil-tort liability perspective. Our goal as an organization is to help our customers on three fronts: fiduciary risk quantification, OT risk identification, and the development of a feasible OT system hardening roadmap that is tailored to your organizational needs. In this session, we will review the tactics, techniques, and procedures that every utility should know to protect themselves and build a comprehensive, unified IT/OT cyber resilience plan accounting for all potential security risk before, during, or after a cyber event. Additionally, a detailed explanation of next-generation OT networks and describe why traditional network isolation cyber defenses are no longer adequate for these mission-critical environments. We will offer a detailed cyber strategy and architecture to protect these networks' enhanced capabilities, along with common pitfalls and lessons learned. It is no surprise — Industrial Control Systems (ICS) are in the crosshairs of opposing nations and criminal organizations. Water and Wastewater facilities specifically need a heightened awareness due to their key role in the global supply chain. In addition to known bad actors, the modern facility is connecting to the outside world at an exponential pace and with greater connectivity comes greater security risk. Even well-intentioned actions can mistakenly impact network availability, interrupt operations, and halt productivity. Water and Wastewater organizations need a— including (but not limited to):

*Asset Inventory / Installed Base Identification

*Vulnerability & Risk Analysis

*Qualified Patch Management

*Cybersecurity Policy Development

*Endpoint Protection

*Perimeter Hardening (IDMZ) & Microsegmentation Deployment

*Zero-trust & Secure Remote Access

*Real-time Threat Detection

*Disaster Recovery Planning & Incident Response The best approach is risk-based in alignment with industry best practices with complete organizational adoption. Unfortunately, even the most sophisticated organizations can't manage all aspects of IT/OT cybersecurity alone — you need an ecosystem of trusted experts and partners by your side to extend your protection against next-gen security threats. To secure modern operational equipment — Computer OS Security, Network Security, Endpoint Protection, and continuous Security Monitoring. We will also review the emerging Managed Security Services leading the industry in data-driven cyber protection and response so that you can have confidence running a world-class ICS cybersecurity program.

Introduction. In 2020, Tohopekaliga Water Authority ('TOHO') initiated a significant effort to rehabilitate its aging sanitary gravity collection system. Through a series of acquisitions of surrounding utilities in the growing Central Florida area, TOHO inherited infrastructure nearing, and in many cases exceeding, its functional life resulting in increased frequency of emergency repair situations. TOHO initiated a comprehensive gravity sewer collection system rehabilitation program (Program) to address the issues it was facing. This presentation describes how TOHO worked with the Water Infrastructure Finance and Innovation Act (WIFIA) to help fund improvements to these acquired systems. Objective. Information related to TOHO's WIFIA application and adhering to loan conditions for the improvements of approximately 110,000 linear feet of gravity sewer mains, replacement and rehabilitation of approximately 1,200 manholes, and 200+ point repairs will be explained during this session. Status. As of January 2024, TOHO has completed approximately 95% of the improvements. This includes the gravity sewer mains ranging in size from 6- to 24-inch diameter, replacement and rehabilitation of manholes, and point repairs with much of the work at depths of up to 25-40 feet. The schedule looking ahead includes construction completion of the projects underway and closeout items necessary document the work performed and confirm owner and regulatory compliance. Methodology. To get ahead of increasing costs, regulatory considerations, and customer dissatisfaction associated with the challenges of maintaining an aging collection system, TOHO embarked on a comprehensive program to review the existing gravity collection system and prioritize projects for meaningful impact. This effort included assessment of existing records and collection of new data through. The new data was collected utilizing industry standards to prioritize assets based on criticality which included high consequence gravity interceptors, gravity mains within primary roadways, and mains within known high infiltration areas of the system. Once the critical nature of the effort was understood, TOHO developed an action plan and budget to begin addressing the major issues and pursued funding through WIFIA. TOHO engaged in the application process and in 2020 was awarded a loan for an approximately $82M program with a 49/51 percentage split. This provided TOHO with the ability to accelerate the rehabilitation program with a goal of completion within 5 years from initiation of the loan. Additionally, WIFIA documentation was collected and submitted to meet loan conditions. WIFIA loans are federally funded and, at the time required adherence to regulations such as the American Iron and Steel Act (AIS) and the Davis-Bacon Act. Compliance with all regulations was strongly monitored throughout the loan duration. The Program also included the need to address unforeseen emergencies within the gravity collection system. For these emergencies, a stage-gate process was utilized to facilitate proper decision-making and logical completion of the work utilizing available resources undertaking the critical work within the Program. Communication between TOHO, the engineer-of-record, nearly ten contractors, stakeholders and residents throughout the Program was paramount for its successful completion, which set the stage for continuation of the rehabilitation beyond the performance period of the initial WIFIA program. TOHO's efforts and rapid implementation of this program throughout this 5-year performance period included the establishment of a Program Management Office (PMO) to facilitate and track the design, bidding, and construction. Findings and Significance. To date, TOHO has completed nearly 40 projects, resulting in successful rehabilitation and replacement of over 110,000 linear feet of gravity sewer mains ranging in size from 6- to 24-inch diameter, replacement and rehabilitation of approximately 1,200 manholes, and 200+ point repairs with much of the work at depths of up to 25-40 feet. The ability to leverage and comply with WIFIA funding were significant pieces to TOHO's program.

Clay County Utility Authority (CCUA), serving the greater Clay County area in Northeast Florida, is a substantial water and wastewater service provider catering to 55,000 customers. The County is growing rapidly and is expected to double in population in the next 20-25 years. CCUA operates 7 Water Reclamation Facilities, five of which produce public access reclaimed water, and 22 water treatment plants. CCUA is situated in a region with limited groundwater resources. In response to the growing need to allocate water resources efficiently and limit groundwater withdrawals from the Floridan aquifer, the primary source of water supply, CCUA has embarked on a PAR optimization program while concurrently investigating alternative water supply (AWS) solutions such as potable reuse. Currently operating at 70% water reuse (non-potable reuse, known as public access reuse or PAR), CCUA is committed to achieving 100% PAR by 2030, and is evaluating potable reuse as an alternative water supply to expand the water portfolio. CCUA's potable reuse project is called 'Project Quench,' which uses reclaimed water (tertiary treated filtered and disinfected wastewater effluent) as source water for treating to drinking water standards. While there are other water sources in the area, such as surface water from the ocean, the St. Johns River and Black Creek, and stormwater, reclaimed water remains the most reliable from a quality and quantity perspective. Potable reuse takes careful early planning and piloting to demonstrate the feasibility of treatment techniques and multi-barrier treatment. With this goal, CCUA has completed several steps in the long-range planning efforts for potable reuse:

*Source Water Characterization: A comprehensive water quality sampling program was conducted at several of CCUA's interconnected treatment plants producing reclaimed water, which allowed an understanding of the quality and composition of available sources to ascertain their suitability as an AWS. Sampling was conducted for several regulated and unregulated contaminants, such as perfluoroalkyl substances and chemicals of emerging concern and pathogens. Data suggested that the Mid-Clay Water Reclamation Facility's reclaimed water was best suited for potable reuse from two perspectives: (i) proximity to areas of growth/development and the anticipated increase in water demand in the near future, and (ii) quality of reclaimed water due to lack of industrial wastewater contribution in the collection system and superior wastewater treatment. Reclaimed water quality at this facility averaged (n=4) at 2.5 mg/L total organic carbon (TOC), 350 mg/L total dissolved solids (TDS), 6.6 ng/L perfluorooctanoic acid (PFOA), 2.2 ng/L perfluorooctanesulfonic acid (PFOS), and 1.8 mg/L total nitrogen. Figure 1

*Selection of Treatment Train: Several factors were considered in the process of selecting the optimal treatment barriers for potable reuse at CCUA. These factors included the efficiency of treatment in removing pathogens and chemicals, associated treatment residuals handling, operational complexity, ability to permit a potential future facility, and cost considerations. Two primary treatment types were compared: reverse osmosis-based advanced treatment (RBAT) and carbon-based advanced treatment (CBAT). The selected processes to treat reclaimed water to drinking water standards include ozonation, biologically activated carbon (BAC) filtration, ultrafiltration (UF), granular activated carbon GAC) adsorption, UV disinfection, and chlorine disinfection. The table below shows the results of the different factors considered during process selection. Figure 2 Figure 3

*Design/ Construction, Test Plan, and Commissioning: Potable reuse project planning involves the development of a comprehensive roadmap encompassing design, construction, meticulous testing protocols, and commissioning stages for the potable reuse system. A 20 gallons per minute (gpm) demonstration pilot is currently under construction at the Mid-Clay Water Reclamation Facility site. Construction completion, facility startup, and commissioning will occur in the first quarter of 2024. Figure 4 Public Outreach A key component of potable reuse projects is the early engagement of internal and external stakeholders with clear and consistent messaging. During the facility's construction phase, CCUA developed several public engagement products, including a project website, handouts and brochures, a PowerPoint presentation slide deck, infographics for the pilot facility building, school and classroom resources, and a project video. Having a uniform theme for Project Quench and using clear, consistent, and correct messaging set CCUA up for success in communicating project details, its current investigative stage, and its future. Figure 5 The demonstration facility/evaluation of potable reuse is one element of CCUA's One-Water water supply planning approach. This abstract and presentation will encapsulate Project Quench's stages of comprehensive evaluation, outlining CCUA's vision to leverage reclaimed water as a superior AWS while navigating the complexities of water source integration and quality assurance.

INTRODUCTION VCS is Denmark's third largest and oldest water utility with more than 150 years of operational experience and a strong tradition of innovation, with a focus on implementing triple-bottom-line sustainability practices and emerging technologies to manage the water-energy nexus. The utility 8 water resource recovery facilities (WRRFs). In 2009 IT initiated the Beyond Energy Neutrality program, aimed at improving resiliency and sustainability through turning their largest facility, the Ejby Mølle WRRF with a 410,000 population equivalent (PE) capacity from a large electrical power consumer to a net producer of electricity and heat energy.This biological nutrient removal facility meets very stringent nutrient limits (6 mg/L total nitrogen and 0.5 mg/L total phosphorus) prior to its discharge into a small, local river. By 2014, the Ejby Mølle was net energy positive as the result of implementing several innovative technologies, including ammonia-based aeration control, sidestream deammonification, optimized combined heat power capacity from sludge digestion, and induced biomass granulation through hydrocyclones, which also improved process resiliency during wet weather events (Nielsen and Sandino, 2020). DEMONSTRATION TESTING - UNDERSTANDING MABR'S POTENTIAL The Beyond Energy Neutrality program continued to investigate ways to further provide sustainable water resource recovery at the Ejby Mølle WRRF. Between 2017 and 2020, VCS conducted an industry-first demonstration program focused on how membrane aerated biofilm reactors (MABR) might deliver further energy savings, while reducing greenhouse gas emissions and requiring a much smaller facility footprint, which would be of great importance to other large facilities in need to increase capacity or achieve higher levels of treatment within constraint sites. This emerging technology relies on membranes capable of gas transfer to deliver oxygen to a AOB-rich biofilm that is attached to the membrane. The direct supply of oxygen to the biomass growing in the biofilm makes the theoretical oxygen transfer efficiency, a key parameter for efficient and low energy aeration, close to 100%. The testing program aimed at answering several questions that need to be addressed regarding the applicability of this emerging technology in full-scale and of the installation of MABR modules purchased from two different manufacturers in the last anaerobic zone ahead of the aeration ditches at Ejby and in remote containers next to the tanks, and their operation during a three-year period (Figure 1). FULL-SCALE IMPLEMENTATION — BETTING ON DISRUPTION Based on the encouraging results and further understanding of the anticipated operational and maintenance requirements of the technology gathered from the demonstration testing stage, VCS decided to implement MABRs at their Søndersø¸ WRRF. This 20,000 PE nutrient removal facility was built in 1990 and is configured with two treatment trains running in parallel, each consisting in two oxidation ditches operated under alternate aerobic/anoxic conditions (BioDenitro process). During heavy precipitation events, the maximum incoming flow is more than four times the yearly average incoming flow, when the facility is under stress and its performance worsens, resulting in ammonia peaks discharged in the effluent. Given this challenge, VCS decided to couple the MABR with induced granulation capabilities via heavy biomass selection using hydrocyclones, based on their earlier positive experience at their Ejby Mølle facility. A key component in the road to the full-scale implementation of this emerging and potentially disruptive technology was VCS's ability to secure funding from the LIFE programme, the European Union's funding instrument for the environment and climate action. Essentially, the programme financed 50% of the implementation costs at Søndersø. Improvements at Sonderso included the retrofit completed in 2023 of one of the two oxidation ditches with seven MABR modules, becoming one of the largest facilities with this technology currently operating in the world (Figure 2). Results to date show an average aeration energy saving of 25% compared to the control train. The MABR units are showing an average oxygen transfer rate of 11 g O2/m2/d (Figure 3). Nitrification rates from the MABRs are averaging 2.4 g N/m2/d, corresponding to approximately one fourth of the total nitrogen load to the treatment plant. Normalizing these nitrification rates per volume of reactor used, the MABRs are successfully removing 0.5 kg N/m3/d, which is 25 times more intensive than the existing activated sludge train. These results indicate that the incorporation of this emerging technology does in fact provide significant additional capacity, while reducing energy consumption and maintaining low N2O emissions (Uri-Carreño et al, 2023). RELEVANCE This paper will show how a water utility has successfully embarked in transforming by adopting emerging technologies that have a very high disruptive potential. MABR is one of these them, promising significant process intensification and energy reduction while also resulting in a very low carbon footprint for biological nutrient removal applications. This paper is intended to illustrate the role water utilities can play on moving a promising emerging technology in the water resource recovery industry, a much-needed step in meeting the umprecendented challenges we are facing.

Introduction: Metro Water Recovery's (Metro) Robert W. Hite Treatment Facility (Hite) in Denver, CO is permitted for a maximum month (MM) flow of 220 mgd and has two parallel liquids treatment trains including the North Secondary (NSEC). The NSEC utilizes a modified Ludzack Ettinger (MLE) process with a sidestream anaerobic reactor (SAR) to achieve nutrient removal. In 2018, Metro's facility plan identified a need for increased aerobic solids retention time (aSRT) to meet future potential total nitrogen (TN) and total phosphorus (TP) regulations (Colorado Regulation 31). To avoid costly expansion, Metro commissioned a full-scale demonstration train (NAB2) to trial densified activated sludge (DAS). This work documents findings from the full-scale demonstration facility and discusses how Metro is translating DAS into a full-scale solution at the RWHTF. Specifically, this paper will discuss factors that have led to the development and long-term operation of DAS with biological and physical selection, as well as provide insights into how particle size distribution (PSD) may be impacted by operational parameters and influence nutrient removal. Materials and Methods: DAS facility: The DAS demonstration facility (denoted as NAB2) consisted of an isolated, paired aeration basin and secondary clarifier from NSEC. Description of the facility is provided elsewhere (Avila et al., 2021). Metro operated NAB2 to test multiple distinct metabolic and kinetic selector configurations, with two primary configurations, Fig 1. A 'control' train was also operated without physical and biological selection. Routine influent/eff concentrations of organics, solids and nutrient content were determined using Standard Methods for the Examination of Water and Wastewater. PSD of the MLSS, hydrocyclone UF, and hydrocyclone OF were routinely characterized. Settling Column Testing: Settling column testing of bulk DAS ML was conducted on multiple occasions to determine the Vesilind equation settling coefficients (V0 & k) as well as the PSD. Additionally, settling properties for particle size fractions: <200µm, 200-600µm, and >600µm were characterized across a concentration range of approximately 1,500 mg/L to 6,000 mg/L. Activity Testing: Batch scale activity testing of bulk mixed liquor and three particle size fractions was used to evaluate nutrient removal rates of activated sludge in 5-gallon reactors. Analytes (NH4, NO3, NO2, and PO4) were measured with HACH TNT kits. Hydrocyclone Nozzle Testing: Hydrocyclone UF nozzle sizes ranging from 15 to 25 mm were individually tested at a target pressure of 30 psi. Flow measurements from the hydrocyclone feed and OF were recorded via flow meter. Total suspended solids (TSS) and PSD samples were collected from the RAS, OF, and UF. Process and Capacity Modeling - Data from NAB2 testing were used to develop, calibrate, and validate AB2 specific and a whole plant process model in BioWinTM and computational fluid dynamics (CFD) models of the NSEC secondary clarifiers. These models establish system capacity of existing infrastructure and design criteria for full-scale implementation. Results and Discussion: Impact of biological selection on densification: PSD of NAB2 biomass during configuration 1 (SAR-MLE) mode) stabilized into a uni-modal distribution, with median size increasing from 100 to 200 um respectively (Fig 2A). The average SVI30 for the NAB2 versus control basins were 102 mL/g and 153 mL/g respectively. PSD of NAB2 biomass during configuration 2 (SAR-A2O) mode reflected a bi-model distribution (Fig 2B). The average SVI30 for the test versus control basins were 81 mL/g and 173 mL/g respectively. Cumulatively, results suggest that improved settleability is observed when the mass fraction of granules (particles >212 um) in the sludge exceeds 15%. This was observed on multiple occasions when NAB2 operated in SAR-A2O mode with anaerobic food to microorganism ratio (F/M) being sustained between 1.0 and 3.0 lb sCOD/lb MLVSS-day. Impacts on PSD on Settling Performance and Biomass Activity: Settling velocity and compressibility were observed to increase as the particle size fraction increased (Table 1). Biomass activity results indicated that larger particle size fractions had lower denitrification and nitrification rates versus smaller particle size fractions while Bio-P activity was highest in particles greater than 200 um. These results indicate that minimizing particles sizes greater than 600 um may allow Metro to exploit high nitrification/denitrification/Bio-P rates and with superior settling and compressibility (Quoc et al., 2021). Influence of Physical Selective Pressures on PSD in NAB2 (Fig 3): Results indicated that mass flow through the UF could be reduced when the nozzle size decreases (Fig 2). This phenomenon can potentially be exploited to craft a wasting strategy focused on developing and keeping a target PSD. DAS impacts on Capacity: Stress testing indicated that NAB2 could be loaded at surface overflow rates (SORs) >700 gpd/sf and solids loading rates (SLRs) >60 pounds per day per square foot (ppd/sf) while still maintaining reliable blanket control and stable effluent TSS (Fig 4). Whole plant process and CFD modeling indicated that the densified scenario could allow Metro to successfully treat 2040 flows without needing to invest in additional aeration basins or secondary clarifiers, allowing for savings of $50 million dollars.

As the industry shifts its focus to removal of fine grit particles at wastewater treatment facilities, Village Creek Water Reclamation Facility (VCWRF), one of the largest wastewater treatment plants in the Dallas/Fort Worth area, has completed field performance testing on their 369 million gallons per day (MGD) fine grit removal facility. VCWRF is Fort Worth's only wastewater treatment plant which serves Fort Worth residents and some surrounding small cities. It is a conventional plant with fine screening, primary clarifiers, activated sludge secondary treatment, tertiary filters, and chlorine disinfection. VCWRF does not currently possess an influent grit removal process. Screened influent is sent directly to the primary clarifiers, where grit is settled and removed with the primary sludge and de-gritted before thickening and anaerobic digestion. The primary sludge de-gritting equipment is capacity-limited, outdated, and inefficient, resulting in a substantial amount of grit accumulation in the anaerobic digesters. VCWRF conducted multiple grit characterization studies which are summarized in Table 1 to determine the size and amount of grit entering the plant. This data shows that VCWRF has a significant amount of fine grit entering the plant where roughly 46% is finer than 297-micron and 20% is finer than 150-micron. These findings are consistent with other Texas wastewater treatment facilities. A grit particle's specific gravity and, consequently, its settling velocity is affected by attached surface active agents (SAA) that include fats, oils, greases, and other organic materials. The shape and composition of grit and inert solids also considerably affect settling velocities. Material with similar effective specific gravities may have very different settling velocities due to the shape of the particle. The sand equivalent size (SES) is the sand particle size having the same settling velocity as the actual grit particle and should be considered when designing a grit removal system. Table 2 summarizes the average grit particle distribution and the estimated removal efficiency of a system designed to remove the grit of a specific SES. On average, roughly 80% of the grit in raw wastewater influent has a physical particle size of 150-micron or greater. However, a grit removal system designed to remove 150-micron and larger particles will only have an efficiency of 78% because some grit particles that are 150-micron and greater do not settle as expected. As observed from the data, finer grit particles settle as expected and therefore their physical particle size and SES are very similar. This is why we see higher removal efficiencies for a grit removal system designed to remove 105-micron and larger. Average grit concentrations in the raw wastewater influent varied throughout the grit characterization studies. The difference in concentrations between the sampling days is likely a result of rain events that preceded some of the sampling dates. Average grit concentrations in the raw wastewater influent samples are summarized in Table 3. At the permitted annual average daily flow (AADF) of 166 mgd and average grit concentration of 186 lb/mg the plant is expected to receive 30,900 lbs of grit a day in the influent raw wastewater. Grit handling mass balance flow charts (Figure 1) were developed to illustrate how much grit will be handled daily at the permitted AADF for a system designed for 105-micron. The mass balance shows solids loading, retention, and disposal requirements if 95% efficiency is maintained across the entire grit removal system. If efficiency is compromised, more grit will pass through the grit removal system and be retained in the downstream processes. Given the grit characteristics and quantities, we evaluated various removal technologies and established design recommendations for the grit removal system. Specifically, to address fine grit accumulation throughout the plant, a grit removal system must be capable of meeting the following performance criteria: 95% removal of all grit 105-microns (150 mesh) and greater at the AADF of 166 mgd. 95% removal of all grit 150-micron (100 mesh) and greater at SPTC of 255 mgd. 95% removal of all grit 212-micron (70 mesh) and greater at 2HPF of 384 mgd. Various grit removal system components (separation, pumping, processing) and technologies were evaluated separately to allow a selection of the most appropriate type of equipment for every stage of the grit removal system. Free vortex grit separation units (Hydro International HeadCell(R)) with dry pit recessed impeller grit pumps and cone washer/screw conveyor grit processing system (Huber Technology Coanda) were selected to provide the desired grit removal performance of 105 microns with cleaner, dryer grit for disposal. Table 4 summarizes the performance of eight HeadCell units at the various plant design flows. We established performance testing criteria and required the contractor to complete field performance testing upon start-up of the HeadCell and Coanda Units. Field performance testing was completed in September 2023. Table 5 summarizes the results. This paper will go into detail about the design and performance criteria selection, field-testing details, how the performance results compare to other facilities', and how this effort sets the stage for the future of fine grit removal systems and performance testing.

Introduction The Gold Bar wastewater treatment plant, operated by EPCOR in Edmonton, is an advanced secondary treatment facility with a capacity to process an average of 310 MLD (82 MGD) and a peak capacity of 420 MLD (111 MGD). As one of the largest cold climate treatment plants, it faces operational challenges during temperature drops, particularly in maintaining nitrification processes, which has led to periodic issues with the sludge volume index (SVI) averaging 270 ml/g, prompting the testing of inDENSETM hydrocyclone technology to enhance treatment capacity and maintain low SVIs during colder weather. Continuous flow wastewater treatment processes using biological and physical selectors, including density selectors like hydrocyclones, optimize treatment by accumulating dense biomass while removing lighter forms, leading to improved process efficiency and the retention of crucial organisms for effective nutrient removal (Regmi, et al., 2022) (Gemza, Janiak, Zieba, Przyszlak, & Kusnierz, 2022) (Roche, Donnaz, Murthy, & Wett, 2021) (Daigger, et al., 2023) (Regmi, et al., 2022). This full-scale application will confirm the effectiveness of the plant's design that utilizes InDENSE technology. Additionally, the full-scale pilot seeks to investigate the impact of selective wasting on two process parameters: 1) Increasing the treatment capacity (flows and loads) of a continuous flow activated sludge system through improved settleability and improving the quality and kinetics of the biomass inventory. 2) Understanding the structure of the densified sludge and slow growers at a biological level through DNA sequencing and microbial ecology. Methodology The inDENSETM hydrocyclone technology has been added to Train #2 as depicted in Figure 1. The implementation of inDENSE technology in this full-scale pilot encompasses: 1) commissioning of the inDENSE system and gathering data, 2) Making operational changes to the return activated sludge (RAS) flow and adjusting the feast and famine ratio, and 3) Separating the anaerobic SRT by intermittently mixing for 30 minutes per day. This is aimed at enhancing the anaerobic mass fraction, sustaining nitrification, and improving treatment efficiency. One objective of the technology validation is to quantify the sludge settling speed and compactability improvement using tall settling column tests and developing the Vesilind relationship. At increased settling speeds and higher compaction, the secondary clarifier can operate safely at higher solids loading rates (SLR) without risk of thickening failure. At higher SLRs, the bioreactor MLSS concentration and biological treatment capacity can be increased. Results and Discussion The data from Train #2 (Figure 2) between June and December 2023 shows that using an external selector, such as a hydrocyclone, led to significant improvements in the quality and densification of the sludge. Initially, the sludge had bulking issues with SVI values ranging from 100 to 250 ml/g. However, in addition to inDENSE implementation, applying intermittent mixing and reducing RAS rates, the SVI improved dramatically, stabilizing in the range of 100-150 ml/g, even as the temperature dropped from 19ºC to 14º over the five-month period. Moreover, the hydrocyclone allowed for the separation of the SRT, resulting in the denser granular fraction having a higher SRT compared to the flocculent fraction. This separation, made possible by the hydrocyclone, improved the settling characteristics of the overall biomass as the flocculent particles were more effectively removed. The data clearly demonstrates that the use of an external selector, particularly a hydrocyclone, had a positive impact on the quality and densification of the sludge in Train #2, as seen in the improved SVI values and the enhanced settling behavior of the biomass. The data presented in Figures 3 and 4 demonstrates that the system effectively meets effluent nitrogen requirements despite variability, and the use of a hydrocyclone in enhanced biological phosphorus removal (EBPR) results in consistent effluent phosphorus concentrations below 1 mg P/L with a higher capacity and abundance of phosphorus accumulating organisms (PAOs). The hydrocyclone's operation allows for the retention of denser, more-desirable PAO fractions in the system, creating favorable selection pressure for enhanced biological phosphorus removal. To gain further insights into the EBPR stability and reliability and nitrification performance, this study will extend to perform various stages of tests which further intends to provide sufficient information to allow an assessment of the performance improvement. The information will allow a rational determination of the additional flows and loads that could be accommodated by a bioreactor/secondary clarifier system equipped with selective sludge wasting versus the baseline provided by a conventional treatment train. Conclusion The introduction of hydrocyclones led to an improvement and stabilization in settling, to reduce seasonal variations, allowing for increased process capacity, and supporting higher mixed liquor suspended solids (MLSS), while uncoupled SRT enhanced process resiliency and improved carbon and energy efficiency, although further research is required for validation.