Introduction The largest reclaimed to water wetlands system in the world was placed into operation over a decade ago in Panama City Beach, Florida. The 3,000-acre Conservation Park (Park) site has been a success story for the City of Panama City Beach (City) in multiple ways including surface water nutrient reductions, ecological restoration, new parks and recreation facilities, eco-tourism, and public education. At the same time, with over 10-years of operation, the City has a better understanding of the Park's nutrient uptake performance as well as made improvements to the Park and collected different lessons learned. Objectives This presentation explains the system operations over the last 10-years with performance data associated with nutrient uptake by the receiving wetland system and quantified reporting of ecological habitat improvements. Information related to system facilities and improvements implemented over the last 10-years along with lessons learned since implementation will be presented. Status The City achieved 100% reclaimed water use in the fall of 2012 with their public access irrigation and reclaimed water to wetlands systems. The flows from the City's Water Reclamation Facility (WRF) to the wetland system have ranged between 3 - 12 MGD over the past 10-years and have typically been 1.5 times the flow to the City's public reclaimed system. Nutrient concentrations leaving the Park have been tracked in effluent leaving the WRF and at the discharge point from the Park and show the nutrient levels 25% to 50% below those observed in the WRF effluent. Based on quarterly sampling, the total nitrogen (TN) and total phosphorus (TP) have remained below the permitted discharge limits. The Park has also become established as a destination for locals and tourists with top rankings on trip websites such as TripAdviser and AllTrails as well as the location for guided bird walks. In addition, the City has implemented a program to restore nearly 30% of the site from silviculture to it's natural habitat through physically removing evasive plant species, natural plants and tree plantings, and incorporating control burns. Methodology The hydraulic loading of the eight (8) natural wetland cells on site is based on their natural composition, function, hydroperiods, and habitat value and sized for up to a maximum flow of 32 MGD. All the cells are interconnected through various surface water interactions ultimately draining to a single location in the northern most basin. Each wetland cell was designed and constructed with the unique ability to control the hydraulic loading to maximize storage capacity based on WRF flows with lessons learned in topographic mapping of the drainage basins. The City has taken extensive steps to restore site habitat from when the lands were primarily used for silviculture (i.e., to grow trees) and fast-growing slash pines were densely planted in replacement of upland and wetland habitat. The City determined several prudent ecological activities should be incorporated, including tree harvesting, invasive plant thinning, native tree and wiregrass seedling planting, and prescribed burning. These efforts have made a marked difference on site where large areas of historic wire grass and long-leaf pine communities are now thriving with 269 acres documented as being restored or in process of restoration. In addition, along with the tree thinning and harvesting, a prescribed burning regimen was introduced to remove excessive buildup of organic detritus leading to devastating fires. Restoring periodic fires to the plant community has promoted growth of native species depending on fire to stimulate germination, provided additional sunlight through the canopy, and opened serotinous pinecones for seed dispersal. Lessons learned include routine maintenance for over 24 miles of hiking trails including over a mile of boardwalk through cypress domes is a necessity. At the same time, guided Audubon bird walks, volunteer, and recreational programs for Park guests are offered seasonally and in high demand since the site opened which brings an added need for routine Park maintenance. Findings and Significance The City's project is an excellent example of beneficial use of reclaimed water to replenish and restore native habitats. In addition, the performance of nutrient uptake in the receiving wetland system and the successful restoration of native habitat provide examples for other communities to consider in their efforts to remove surface water nutrient loads. Finally, the project has set an example for how a nature-based solution can be leveraged as a parks and recreation amenity and promote eco-tourism.

Background Water resource recovery facilities (WRRFs) around the world are constantly faced with significant challenges 1, 2. It is estimated that WRRFs are operating at an average of 81% of their design capacity, while 15% of systems are at or have exceeded that threshold3. As the most prevalent biological nutrient removal (BNR) process, any improvements to conventional activated sludge (CAS) processes are highly desirable in our industry4. However, upgrading CAS trains is costly and alternative technologies often tend to be more energy-intensive, expensive1, and time consuming to install, commission, and operate. Thus, the use of physical selectors (e.g., hydrocyclones) for biomass densification has emerged as a front-runner for increasing secondary clarifier capacity and improving nutrient removal. Objective and Approach Despite the many studies exploring the advantages of densified activated sludge (DAS) systems compared to CAS systems, DAS impacts on microbial communities and fecal indicator bacteria (FIB) are unknown2, 5. In 2023, the Water Research Foundation funded a tailored collaboration with the Metro Water Recovery (MWR) in Denver. The collaboration aimed to investigate FIB removal and disinfection kinetics. This study focused on CAS and DAS treatment trains at three North American full-scale operating WRRFs (Figure 1). The WRF project aims to: A) Compare E. coli concentrations over a 15-month period and investigate factors influencing differences (e.g., granulation size distribution, floc/granule mass fraction, floc/granule aSRT, microscopy, COD, Turbidity, TSS, NH3, pH, Temperature, Color, UV-254, TKN, TP, TOC). B) Determine how changes in Secondary Effluent (SE) properties between DAS and CAS affect disinfection efficacy using chlorine, peracetic acid (PAA), performic acid (PFA) and ultraviolet disinfection (UV) seasonally (n=12), with the same water quality parameters listed in Objective A. C) Assess impacts of operational variables on DAS and provide utilities with recommendations. These can include how to utilize modeling and statistics to improve performance using demand and decay values and mechanistic disinfection efficacy models D) Determine if additional analyses (e.g., protozoa counts, granule sieving analyses) provide operational value to utilities adopting DAS. Results Data collected for one year at the MWR Hite Treatment Facility highlights the statistically significant difference in E. coli concentrations between the CAS and the DAS trains (Figure 2). This could be explained by a variety of variables that have not yet been evaluated. FIB counts may be impacted by the predator protozoan community5, but this has yet to be supported by data (Figure 3). While percent mass fraction (Figure 4) and seasonality (Figure 5) have been hypothesized to impact DAS E. coli counts6, this has not been shown by the preliminary data collected, which highlights the importance of a more detailed study to explain the differences observed . Summary DAS is able to be implemented with low capital cost while increasing the capacity of CAS systems. However, there is little data on how SE from DAS systems impact downstream disinfection processes. This WRF project will evaluate the impact DAS systems have on disinfection processes compared to CAS systems. Data collection and testing for this project will begin in April 2024.

Purpose: Struvite (MgNH4PO4*6H2O) and other precipitates have long posed persistent maintenance and operational challenges at wastewater treatment plants. These precipitates can be enhanced at plants that utilize biological phosphorus removal and can precipitate within anaerobic digesters and on final dewatering equipment which causes damage and decreases efficiency. Struvite can be sequestered as nutrient rich biosolids if properly controlled to remain in the cake. In a digested solids storage tank (DSST) that is in between anaerobic digestion and final dewatering, precipitation can be controlled by manipulating variables such as mixing, aeration of digestate to achieve a shorter solids retention time (SRT) version of post aerobic digestion (PAD) and by chemical addition. Optimizing this via batch and pilot testing can control nuisance struvite formation, increase phosphorus in the cake and achieve additional volatile solids reduction (VSR). This research will review findings from batch and pilot scale tests and discuss the nature of these precipitates. Objectives include determining the mechanism that provides optimal phosphorus removal, ammonia removal, and analyzing the precipitated solids of interest. The presentation will discuss results across batch, pilot, and full-scales and the lessons learned of each. Motivation and Background: The Atlantic Treatment Plant (ATP) in Virginia Beach, VA, operated by the Hampton Roads Sanitation District's (HRSD) is a high-rate facility with an A/O process configuration. In solids handling, a Cambi Thermal Hydrolysis Process (THP) is utilized prior to anaerobic digestion. ATP is actively engaged in efforts to control formation of scaling precipitates and nuisance struvite for optimal operational efficiency. Precipitate formation is determined predominantly by the solids solubility product (Ksp) and the saturation in solution and can be controlled by pH [1]. Manipulation of pH via CO2 stripping from aeration has successfully been shown to control solubility reactions [2, 3]. Increasing the saturation index via chemical addition can also control precipitation reactions and improve cake dryness with an SRT of a few hours [4]. Likewise, PAD has been shown to achieve ammonia removal and additional VSR at a 5-6 day SRT [5]. Based on these findings, a pilot scale set up (Figure 1) will run at an SRT of 3 days to provide benefits from PAD, but with a longer reaction time that may be more beneficial for phosphorus sequestration. Various mixing, aeration rates, and chemical addition will be manipulated to determine the optimal operation conditions on phosphorus sequestration in the class A biosolids. Pilot Design and Operation: The pilot set up at ATP consists of four tanks. Each tank has a volume of about 63 gallons. Simulating the DSST, the tanks are operated as daily batch fed continuously stirred tank reactors maintained by pump recirculation with a 3-day SRT. The tanks are aerated with fine bubble diffuser membranes which can be operated at constant or intermittent air flow rates, or via Dissolved Oxygen (DO) or pH set points. Preliminary operation has included mixing and aerating the four tanks at a constant airflow rate of 5 LPM, while recording online measurements of DO, pH (Figure 2), and temperature, which has been maintained between 22 and 38 degrees C. At this operation, about 50% OP removal and 10% COD degradation across the pilot has been measured with minimal NH3 removal. Future plans include operating at higher aeration rates, DO control setpoints, the potential establishment of partial nitrification/nitritation, and the addition of Ca(OH)2 or Mg(OH)2 at various dosages. Preliminary mixing operations conducted under suboxic conditions without the use of chemical addition results in a sustained OP removal by about half across the pilot. This suggests value in this continued effort. Batch Testing: The following test was conducted on a Phipps and Bird Jar Tester at a continuous mixing speed of 300 rpm. Five jars of digestate consisting of a control with no chemical addition, two jars dosed with a carbide lime slurry at Ca2+ + Mg2+/P ratios of 0.5:1 and 1:1, and two jars dosed with thioguard, at the same Ca2+ + Mg2+/P ratios. Chemical dose was injected as a spike at time zero of the test. Analytical measurement of OP-P and pH were determined daily via spectrophotometry (HACH TNTplus UHR mg-PO4-P/L and pH meter) (Figure 3). The pH of the digestate sample was about 7.4 and increased up to a maximum of 8.7 within 24 hours likely due to CO2 stripping from the mixing intensity. OP removal in the control condition was measured as 68%. The addition of chemical helped to increase OP removal as high as 95%. The digestate pH increasing towards alkaline within the first test day showed the greatest impact on OP removal rate. The higher Ca2+ + Mg2+/P molar ratio tested of 1:1 for both the chemicals had higher OP removal rates than those dosed at lower ratios of 0.5:1. Thioguard compared to the carbide lime slurry overall had a slightly more significant effect on OP removal. The pH decrease measured after 24 hours may be due to struvite's production of hydrogen ions in the formation reaction, however, future plans of repeat experiments and X-Ray Diffraction for precipitate analysis will further determine this.

INTENDED OBJECTIVE: Biosolids from water resource recovery facilities (WRRFs ) are increasingly used for agricultural and recreational land purposes due to their sustainable means to replenish macronutrients. However, the relatively high phosphorous content of biosolids limits certain applications. This study aims to identify optimal locations for recovering vivianite and subsequently phosphorus, to allow class A biosolids reach ideal phosphorus levels. INTRODUCTION: Global consumption rates of synthetic fertilizers per unit of cropland have increased 3 to 8 times over the past half century (Lu et al. 2017). Class A biosolids are increasingly explored as an alternative to commercial fertilizers due to their effective means to replenish carbon and macronutrients (Gilmour et al. 2013). However, the N:P ratio of biosolids is typically lower than commercial fertilizers which can cause an accumulation of phosphorus when applied to soil, increasing risk for eutrophication (Penn et al. 2002). Therefore, it is critical to implement efficient phosphorus-removal technologies/techniques within the biosolids treatment train to improve the N:P ratio and limit the amount of phosphorus that result in the cake. Therefore, this study aims to analyze the P mass balance of the Blue Plains advanced wastewater treatment plant in Washington, DC as well as its vivianite characterization in full-scale. The process sampling, modelling and analysis led to identification of potential locations for vivianite recovery, and initial estimations on how much the P content in our class A biosolids might be reduced by recovering vivianite upfront. MATERIALS AND METHODS: Sampling campaign: Samples were collected in DC Water Blue Plains over a 3-month period (Mid-February to Mid-May 2022). Quantitative analysis: Phosphorus is measured by the EPA 365.1 method. Scanning Electron Microscopy with Energy Dispersive and Mossbauer Spectroscopy: Prepared by method in Prot et al. 2021. Modelling method: Visual Minteq version 3.3 with DOC SHM model RESULTS & DISCUSSION P mass balance at Blue Plains and P content in biosolids product Blue Plains advanced WWRF achieved a 98% incoming TP removal over its primary (enhanced-chemical phosphorus removal) and secondary systems through iron dosing. The removed P is diverted to the solids fraction and results in a Class A biosolids product (BLOOM) with 2.88% P (dry weight basis) and 28-32%TS (Fig.1A). The P:N ratio of our product is 1:1 and thus higher in P content than the target of 1:2 P:N for typical fertilizers. Decreasing P content in BLOOM by 50% or thus recovery 60% of vivianite would increase the value and applicability of BLOOM. Vivianite formation and formation potential along the Solids Treatment Train A total Fe/P molar ratio of 1.5 or greater allows for optimal vivianite precipitation (Cong et al. 2017) which is reflected in DC Water treatment flow diagram (Figu 1). Vivianite was detected in primary thickened sludge, blend of thickened primary (PS) and waste activated sludge (WAS), and digested sludge b ased on sequential extraction method in Wang et al. 2021. This was also further supported by the clear co-location of Fe and P in SEM images (Figure 2A and 2B). These locations are consistent with the vivianite scaling seen in primary sludge gravity thickening lines and centrifuge lines in the facility. Through quantitative analysis, the vivianite mass flow in thickened primary sludge, blended PS/WAS and digested solids accounted for 8%, 52%, and 49% of the incoming P to the plant (Fig. 1). These vivianite ranges are like those reported by iron-dosing plants in Prot et al. 2021 and Wilfert et al. 2016. Estimation of P recovery potential needed to impact Class A biosolids P content Based on the current vivianite-P levels in the three identified locations (Fig. 1), sludge after anaerobic digestion contained the highest level of vivianite-P. This is likely due to higher orthophosphorus levels after thermal hydrolysis treatment which allows for additional vivianite formation with Fe(II). This notion is supported by the low levels of Fe(II) concentrations after anaerobic digestion indicating that most of it is bound (Fig. 1). We estimated how much vivianite recovery efficiency we might need to decrease the P content in the BLOOM with an ideal target of ~0.014 kg P/kg TS and acceptable target of 0.022 kg P/kg TS. Given the highest vivianite levels in digested sludge, a recovery efficiency of at least 40% with ideally 70% is sufficient to meet our targets (Fig. 3). Utilizing vivianite recovery technologies such as magnetic separation (80% of vivianite recovery in digestates according to Wijdeveld et al. 2022), and other alternative options could provide the potential recovery target needed to improve BLOOM. CONCLUSIONS Based on current vivianite-removal technology efficiencies, removing vivianite will significantly impact the phosphorus levels in BLOOM. Results suggest that after anaerobic digestion is a preferred and feasible option to implement recovery technology due to its high vivianite content as well as the opportunity to recover vivianite in a fraction of the digestate to produce low P BLOOM rather than the whole biosolids treatment train. Future testing will explore recovery efficiencies of P and vivianite to confirm feasibility and setup a path towards pilot testing approaches.

Despite early evidence indicating that co-treating leachate with municipal wastewaters is beneficial, over the last decade more plants refusing to accept leachate for co-treatment. Leachate exhibits great temporal and spatial variations in physical and chemical properties and strength making predictions of process upsets difficult for operators. It can adversely affect water resource recovery facilities (WRRFs) biological nutrient removal (BNR) processes due to the presence of inert, nonbiodegradable chemical oxygen demand (COD) and recalcitrant dissolved organic nitrogen (rDON), which are not treated but mainly diluted increasing the difficulty of compliance with increasingly stringent discharge standards, particularly for total nitrogen (TN) limits. There is currently no framework that informs WRRF operators how much leachate they can accept without causing process upsets. Our objective was to evaluate the impacts of leachate co-treatment on a full-scale municipal wastewater treatment plan (WWTP) by comparing plant performance at varying levels of leachate contributions and hydraulic loadings. We used the K-Nearest Neighbors (KNN) machine learning algorithm to determine at which leachate volumes BNR was impacted. Leachate BOD:COD ratio was 0.08 +/- 0.07. The ratio indicated a stabilized, old matrix. Zinc, iron, aluminum, chloride, and sulfate concentrations were 0.174, 38, 1.47, 1803 and 119.1 mg/L, respectively. The average volumetric leachate ratio (VLR%) was approximately 0.01% corresponding to a daily volume of 30 meters cubed (m3) but reaching a maximum of 270 m3 (VLR% = 0.1%) and fluctuating on a daily basis. The cluster analysis revealed 5 VLR% groupings that were used for subsequent analyses: no leachate, 0 < Low ≤ 0.001, 0.001<Medium ≤ 0.02, 0.02<High ≤ 0.05, and 0.05< Very high ≤ 0.2. The completed study results showed that treated effluent concentrations of TKN, ammonia, fecal coliforms (FC), E. coli (EC), TSS and TP experienced a trend where effluent quality was improved at low and medium VLR% compared to no leachate addition, but deteriorated in high and very high VLR%. Treated effluent UVT% and EC were not statistically significantly different at varying VLR%, but FC was. Plant hydraulic had a significant impact on removal rates. Ammonia removals and nitrite concentrations improved in high flow conditions, while TP, BOD and cBOD removals deteriorated. Finally, VLR%, leachate COD, TKN ammonia, chloride and arsenic had significant relationships with plant performance. The study's findings mean that for leachate with comparable age and strength, VLR% should not exceed low to medium contributions (0 and 0.02%) during co-treatment at this WWTP.

Antimicrobial resistance (AMR) makes diseases more difficult to treat and has been spreading worldwide. It is considered a major public health concern. Over the last two decades, numerous projects investigated the occurrence of AMR, especially antibiotic resistance, in wastewater. In 2023, several papers (e.g., Berglund et al., 2023; Wang & Smith, 2023; Zhao et al., 2023) reported the detection of antibiotic-resistant genes (ARGs) and mobile genetic elements (MGEs) in wastewater, resulting in negative news stories and media inquiries at water resource recovery facilities (WRRFs) about AMR and potential risks from wastewater or biosolids (Wigglesworth, 2023). In addition, the Centers for Disease Control and Prevention (CDC) has expressed interest in including wastewater-based surveillance (WBS) of AMR targets in its National Wastewater Surveillance System, which will lead to continued focus on AMR. This presentation is intended to help inform the water sector as attention to this complex topic grows. It provides a summary of concepts related to antimicrobial and antibiotic resistance and the current state of the science related to antibiotic resistance at WRRFs. It highlights the following take home messages:

*Antibiotic-resistant bacteria (ARB) and ARGs are widely detected, including in natural environments and food, but their associated human health risks remain poorly understood and inadequately characterized.

*The risk of getting infected by ARB is not greater than the risk of getting infected by the same antibiotic-susceptible bacterium. Humans are exposed to millions of microbes with antibiotic-resistant traits every day via natural and necessary activities, such as the ingestion of water and food (Pepper et al., 2018). Most of these exposures do not cause infections.

*Antibiotic-resistant bacteria and ARGs are detected at WRRFs, but treatment processes, including coagulation, clarification, filtration, disinfection, and anaerobic digestion, generally reduce their levels.

*The Global Water Pathogen Project (2019) estimates that conventional WRRFs reduce the types of ARGs observed and their numbers in raw wastewater by approximately 33% to 98%. Though some ARGs and mobile genetic elements (such as integrons) are not reduced.

*Current practices for wastewater and municipal drinking water treatment are adequate to prevent enteric bacterial infections from ARB via drinking water.

*Workers at WRRFs could be exposed to ARB and ARGs through contact with wastewater, solids, and bioaerosols. The associated risks are uncertain but can be mitigated by following the worker safety recommendations of the CDC (n.d.-a) and WEF (2020).

*Wastewater-based surveillance is an emerging approach to complement public health data, but is not intended to inform risk assessment from wastewater exposure.

*Water resource recovery facilities are important critical control points and are one of the most effective means of removing or reducing the occurrence of ARB and ARGs in wastewater and the environment.

Ozone is well known as an effective disinfectant and oxidant and has been operated for drinking water treatment for more than 100 years, often in combination with biofiltration or biologically active carbon filtration. More recently, it is also applied on wastewater treatment plants (WWTPs) to mitigate the discharge of chemicals of emerging concern (CECs) into receiving surface waters. As a first European country Switzerland implemented a regulation to reduce the discharge of CECs from WWTPs in 2016. With the overarching goal to substantially reduce the load of CECs discharged into surface waters, requirements for advanced wastewater treatment were defined for the largest WWTPs and those plants which are discharging into sensitive water bodies in the country. In total more than 100 WWTPs of different sizes are affected. The discussion about the specification of the regulation was supported by pilot- and full-scale trials like at the WWTP in Regensdorf/Switzerland (Abegglen et al., 2009). Currently, there are ten WWTPs operating ozonation systems or combined ozonation + biologically activated carbon filters in Switzerland. The biggest installation is located at WWTP Werdholzli, which treats the wastewater of Zurich with a design flow of 6,000 l/s. No regulation for CEC mitigation on WWTPs is currently in place in the EU, but a draft of the Urban Wastewater Treatment Directive was proposed in October 2022, which for the first time includes requirements for advanced wastewater treatment. The approach is similar to regulations in Switzerland and defines an average removal of 80% for a list of indicator CECs, which will become mandatory for all large WWTPs (>100,000 PE) within the EU. In addition, requirements for CEC mitigation at medium sized WWTP will be assessed following a risk-based approach. Despite the lack of regulatory pressure, CEC mitigation has been applied at numerous WWTPs in different EU member states. In Germany, the installation of advanced treatment is funded by some federal state governments. Main treatment goal is the improvement of the chemical conditions of the receiving water bodies. Currently, sixteen ozonation systems are in operation on German WWTPs with the biggest at WWTP Aachen-Soers treating up to 3,000 l/s. In the Netherlands, Belgium, Sweden, and France first full-scale installations are close to start or in operation. Other EU member states such as Austria or Italy tested the process in pilot installation (e.g., KOMOZAK (Kreuzinger et al., 2015) and KOMOZAK II (Krampe et al., 2020)). It can be expected that the number of installations in the EU will increase rapidly once the revised UWWTD will become into place. Beside regulatory changes the design and control strategies have changed during the last years. The first installations were designed for ozone dosages up to 0.2 2 mgO3/mg DOC (Lyko et al., 2013), but recommended ozone doses decreased over time, these big ozone generators are nowadays operated a lower production level. Today, the recommended ozone dosages are ranging from 0.5 0.7mg O3/mg DOC (DWA, 2022) and can be even lower for combined processes of ozone and activated carbon. Ongoing research on related topics, e.g., testing of surrogate parameters for performance monitoring or dose control, leads to further optimization of the installed process. These optimizations significantly reduce the size of ozonation systems and the specific operational costs. In addition, different mixing concepts such as diffusors or injectors were installed and compared at pilot- and demonstration-scale. New tools such as computational fluid dynamics modelling (CFD) and kinetic model approaches support the optimization of ozone contact basins and support the layout of ozone mixing and effects on the water quality during the engineering of ozone installations. Additionally, the feedback from operators provides valuable input for improvement since some effects can only be seen during long-term operation. Based on experiences and optimization, new guidelines, for example in Germany (DWA, 2022) and Switzerland (VSA, 2021), support the design, installation, and operation of new systems. The current draft regulation in the EU includes medium to large WWTPs, which raises the question if comprehensive implementation of CEC removal is also expedient for small WWTPs. Although there is no active regulation in place, first projects were launched at smaller WWTPs that are discharging into small and sensitive waterbodies, which might even be used as drinking water sources. The adaptation of advanced treatment technology for small WWTPs bears new challenges because staff for operation and maintenance is often not available, influent flow and quality can have stronger variation, and specific operational and investment costs of smaller WWTPs are often higher. This presentation will provide an overview on current and planned installations of ozonation for CEC removal on WWTPs, highlight lessons learned from 15 years of full-scale operation, and outline expected trends for the future. Besides the discussion on small-scale WWTPs, we will emphasize potential synergies of CEC removal with the recently launched EU minimum requirements for water reuse in agriculture (EU Regulation 2020/741). Since reuse becomes more relevant for different EU member states, the considerations for CEC removal at WWTPs should include the option of future upgrades for water reuse purposes.

Introduction As population growth, urbanization, and climate change intensify pressures on water resources, utilities are faced with an increased urgency for advanced water treatment (AWT) solutions and a need to enhance resilience against evolving climatic conditions. Concurrently, wastewater resource recovery facilities (WRRFs) are faced with increasingly stringent nutrient discharge limits that surpass the capabilities of conventional treatment methods. Consequently, utilities are compelled to adopt innovative approaches to address the quality and quantity of water supplies while ensuring regulatory compliance and sustainability. In this work, we highlight case studies of two forward-thinking utilities, distinguished by geographical contexts and unique drivers, yet united by a commitment to advance climate change adaptation strategies, achieve ultra-low nutrient limits, and integrate holistic one water initiatives. Metro Water Recovery (Denver, CO): Upcoming Colorado water quality regulations are set to impose stringent stream standards, notably 2.01 mg/L for total nitrogen (TN) and 0.10 mg/L for total phosphorus (P) on WRRFs, including Metro Water Recovery's Robert W. Hite Treatment Facility (RHWTF) and Northern Treatment Plant (NTP). AWT technologies like carbon-based advanced treatment (CBAT) schemes (e.g., coagulation/flocculation/sedimentation (floc/sed), ozone (O3), biofiltration (BAF), and granular activated carbon (GAC)) may address stringent nutrient limits while also aligning with Direct Potable Reuse (DPR) requirements. A study was initiated to: 1) assess the treatability of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and soluble non-reactive phosphorus (sNRP) using CBAT technologies; and 2) discern the capabilities of CBAT in concurrently achieving nutrient limits and DPR compliance. Evaluation of nutrient removal through tertiary CBAT processes spanned full-scale applications (floc/sed at NTP and BAF/floc/sed at RHWTF's Denver Water Recycling Plant (DWRP)) and pilot-scale (O3 only, BAF only, and O3/BAF at RHWTF), supplemented by bench-scale floc/sed (jar testing) and GAC evaluations (rapid small-scale column tests). Parameters such as O3 dose and empty bed contact times aligned with potable reuse standards. While full-scale floc/sed/filtration at NTP (Figure 1; Figure 2) and DWRP (Figure 3, Figure 4) (~20 mg/L alum) effectively managed particulate P and sNRP removal, it did not meet DOC and DON targets for Direct Potable Reuse (DPR) applications. CBAT testing showed potential for control of DOC and DON, albeit with the need for multiple potentially costly unit processes. The GAC runtime (up to 3,500 Bed Volumes for DOC and DON targets) was notably extended through enhanced upstream treatment. While floc/sed processes achieved comparable DOC and DON removal rates (up to 40% each) at the expense of elevated coagulant doses (80 mg/L Ferric chloride), O3/BAF treatments realized a modest 26% reduction in DON. Future pilot efforts aim to assess the efficacy of a comprehensive CBAT treatment train, inclusive of tertiary denitrifying BAF, to fulfill TN requirements and optimize DPR suitability. AWT Utility (Midwest): A midwest AWT utility has seen significant population growth in recent years and is estimated to double by 2040. Rapid growth and a desire improve the health of the receiving water body have urged the utility to consider alternative water supplies. Subsequently, the utility commissioned a CBAT pilot consisting of O3, two-stage BAF, GAC, and UV advanced oxidation process (UVAOP). The objective of this study was to pilot CBAT technologies to demonstrate the ability of AWT process trains to produce high quality finished water that meets stringent water quality targets. This study utilized a multi-barrier scheme of O3/two-stage BAF (aerobic/anoxic) to meet low TN limits. Filters were operated in several phases (Table 1) until effluent quality targets were met (TOC < 3 mg/L, TN < 2 mg/L, contaminants of emerging concern (CECs)- meet MCLs) and steady-state was achieved. Select operational parameters were varied during each phase and the resulting water quality surrounding the first anoxic BAF (BAF 3) is shown in Figure 8. Table 2 shows the effluent DO, nitrate (NO3-N) concentrations and corresponding % NO3-N removal achieved across each anoxic BAF. Results indicate that when supplemental carbon and upstream feed DO levels were controlled, anoxic BAF 1 established and maintained anoxic conditions and achieved NO3-N removals up to 60% with anoxic BAF 2 acting as a polishing biofilter (%NO3-N removal ~30%). When supplemental carbon and upstream DO quenching chemical doses were reduced, anoxic BAF 1 turned into a sacrificial BAF, consuming excess DO and displaying poor nitrate removals (~15%), while anoxic BAF 2 became the dominant anoxic biofilter (> 60% NO3-N removal). Piloting efforts demonstrate how a modified CBAT train may simultaneously meet low TN targets (< 2 mg/L) and produce high quality product water. Conclusion Case studies at Metro Water Recovery and a midwest AWT utility demonstrate CBAT's potential for improving finished water quality for reuse and meeting ultra-low nutrient discharge requirements. Project findings provide first guidance on how WRRFs can adjust operational setpoints using CBAT process infrastructure to meet DPR or discharge water quality requirements in ecologically sensitive and drought-prone watersheds.

Introduction Partial-Nitritation/Anammox (PN/A) processes are increasingly being selected as energy and carbon positive options in the treatment of ammonium-rich side-streams from digestate. Two-stage, sequential PN/A systems were the first to be developed and subsequently, single-stage PN/A (where PN and Anammox reactions occur simultaneously in a single reactor) processes were developed. Although the later possesses the advantage of footprint reduction, these processes have lower HRT and require a balance in aeration and loading such that DO concentrations remain high enough to drive nitritation, but low enough to avoid inhibiting Anammox metabolism, which proves to be a persistent challenge. In general, the highly sensitive nature of the anammox process requires that all plausible inhibiting factors (such as heavy metals, sulfate, etc.) are curbed within practical thresholds. A Two-stage PN/A (AMX(R)) process recently reported by Jung et al. (2019) reduces the HRT required in dedicated PN reactors and improves the system's resilience to high ammonium, COD and solids loads. This technology was therefore employed for the reject water treatment within B City's N-treatment plant in Korea, making it the first and only full-scale domestic application in Korea. This paper discusses the resilience of this AMX technology and adopted strategies in overcoming unforeseen high levels of Sulfate (SO42-) in the influent streams. High sulfate concentrations inhibit anammox and reduces nitrogen removal efficiency (E. Rikmann et al., 2016). Therefore, the exact effects of high strength sulfate on a full-scale PN/A process and the resulting steps to long-term operation to stabilize nitrogen removal efficiency in a practical, economical, and innovative way is presented in this work. Methods Fig. 1.1 shows the industrial treatment processes at B City's N-WWTP with a capacity of 184,000 m3·d-1. A combined 778 m3·d<sup?-1 of concentrated sludge and food waste sludge are introduced into the anaerobic digester. After approximately 30 days in the digester, the sludge is further dewatered into 123 m3·d-1 of sludge cake. Meanwhile, the 817 m3·d-1 of filtrate from the dewatering process, is channelled to the Two-stage AMX(R) (Fig. 1.2) process, which is tailored for treating digester effluents with elevated nitrogen levels. Highest measured sulfate levels exceeded the reported anammox threshold by 90%. Results and Discussion The operation for the full scale PN/A process was segmented into three distinct phases: seeding and SO42- control, continuous nitrogen load increase, and performance validation phase. In Table 1.1, the summarized key operating factors and performance results for each phase is tabulated. In Phase I, the unforeseen high sulfate concentration wastewater (Fig. 1.3) fed into the Two-stage AMX(R) process prevented a quick start-up and acclimation of the anammox. According to S. Zhou et al, 2022, in the absence of sulfate reducing ammonium oxidizing bacteria (sulfammox), sulfate levels exceeding 100 mg/L can instantly inhibit any species of anammox bacteria. Therefore, to prevent complete microbial activity loss and intuitively introduce additional biomass, the energy currency of all living cells, ATP was quickly monitored alongside the specific anammox activity (SAA). By measuring SAA, intermittent biomass was gradually added in a timely and economically manner to prevent further SO42- shock and activity loss. SO42- control was simultaneously carried out. Consequently, the anammox reactor HRT was extended beyond its design, while the NLR dipped far below its design value of 0.87 kgN·m-3·d-1. By phase II, as the sulfate concentration in the influent was controlled and kept below 300 mg·L-1, the nitrogen load in the Anammox reactor was gradually increased. HRT was shortened to 2.1 days (design HRT: 1.5 days). This led to an average NLR of 0.57 kgN·m-3·d-1, with a nitrogen removal efficiency of 81%. In Phase III, the NLR reached its design value of 0.87 kgN·m-3·d-1, and performance was evaluated over roughly a month. The operating HRT and average NLR during this phase stood at 1.5 days and 0.89 kgN·m-3·d-1, respectively. The nitrogen removal efficiency averaged 84.6%, surpassing the operational goal of 82%.By analyzing the data of the existing S-WWTP and K-WWTP, provided by B-City, the N-WWTP was identified to have reduced operating costs by 83%, capital expenditures by 64- 93%, and process footprint by 70-90% by applying the Two-stage AMX(R) technology, compared with conventional technologies. In monetary terms, energy costs were reduced by 60%, chemical costs by 99%, and sludge treatment costs by 49%, saving more than KRW 1.5 billion ($1.15M) per year in OPEX. Construction costs were reduced by KRW 1 billion to up to KRW 7.5 billion ($5.73M). Conclusion This paper summarized the effects of high strength sulfate on the full-scale anammox process and the resulting long-term stable nitrogen removal efficiency by simultaneously counteracting the sulfate and phasing the nitrogen loads in a pragmatic but intuitive and repeatable manner. By employing innovative techniques like direct ferric addition and microbial specific activity monitoring at specific intervals, anammox reseeding was done to prevent complete activity loss in a unique but economical fashion. The resilient AMX technology achieved the designed NLR of 0.87 kgN·m-3·d-1 and exceeded the nitrogen removal performance target of 82% reducing nitrogen loads.

INTRODUCTION Water is key at every step of the lithium ion battery life cycle. This paper discusses four case studies involving the use of novel reverse osmosis (RO) membrane processes and energy recovery devices (ERDs) for lithium related water reuse, zero liquid discharge (ZLD), and resource recovery applications in China. The cases include several key stages of the li-ion battery life cycle including lithium brine mining, battery manufacturing, and battery recycling and how RO and ERDs are used to add value within these applications. 1. RO Related Trends for Industrial Wastewater Zero Liquid Discharge in China China has made water conservation and environmental protection key priorities and is ramping up regulations around wastewater discharge, limiting both the concentration of contaminants and discharge volumes. Industrial wastewater treatment is a crucial, but oftentimes expensive process. ZLD is becoming a requirement in many highly polluting industries. An example in the lithium industry is battery manufacturing, which includes many facilities that have been required to implement ZLD to prevent the discharge of certain contaminants and nutrients into the environment. The first case study will discuss and present data for a lithium battery manufacturing facility in central China that implemented ultra-high pressure reverse osmosis (UHPRO) operating at 1,500 psi with new UHPRO energy recovery devices (ERDs) to reduce energy use when implementing ZLD and resource recovery. The waste streams contain primarily ammonium sulfate, a valuable fertilizer sold as a byproduct. Recovering ammonium generates sufficient revenue to cover the ZLD system operating costs and eliminates a harmful discharge into the environment. 2. RO Related Trends for Lithium Mining in China Western China has significant amounts of lithium in salt lakes and in brines located in subsurface geological deposits. Some of the salt lakes in Tibet have low concentrations of magnesium and other divalent salts that can make it more challenging and expensive to extract lithium from the brine. In these locations, evaporation ponds are used to concentrate the brines and eventually precipitate out different salts into different ponds to allow the separation of monovalent salts so that when lithium bicarbonate (Li2CO3) precipitates, it is of sufficient quality for some lithium ion battery manufacturing. However, demand is growing for high purity lithium to help make higher quality cathodes. In the Qinghai province, there is more lithium in salt lakes and subsurface geological brines than in Tibet; however, the chemistry of these brines makes lithium extraction more challenging and expensive to implement with evaporation ponds, thus direct lithium extraction (DLE) is required. Novel nanofiltration (NF) and RO membranes are becoming common as tools to improve lithium quality and/or to increase lithium production in both of these mining applications. The second case study will discuss and present data from a lithium brine mining project in Tibet China that uses osmotically assisted RO (OARO) and ERDs to generate high-purity, battery grade lithium. The purity is improved by a OARO process designed to separate key monovalent salts, while also reducing by half the time it takes to concentrate lithium bicarbonate (Li2CO3) using evaporation ponds in an environment not ideal for solar evaporation. The third case will discuss and present data for a combination of low pressure RO, seawater RO, and UHPRO membrane systems with ERDs at a direct lithium extraction (DLE) facility at a salt lake in the Qinghai region of China. The RO systems concentrate lithium chloride (LiCl) downstream of an ion exchange based DLE system and upstream of a thermal evaporator used prior to conversion from LiCl to Li2CO3. UHPRO was added during a plant expansion to reduce the cost per ton of Li2CO3 from one of the first commercial DLE projects in the world. 3. RO Related Trends for Lithium Recycling in China In Europe and North America, various startups are conducting research and development (R&D) to demonstrate and commercialize recycling of lithium ion batteries to recover lithium and other key components for reuse. In China, however, the government has put the responsibility of recycling batteries onto the makers of EV materials such as automakers and/or battery manufacturers. While RO membranes are used to concentrate lithium chloride at battery recycling facilities in the US, it is not yet common and R&D is ongoing. In China, however, the use of RO systems for battery recycling is already common and a unique process has been developed to separate and concentrate lithium, nickel and cobalt with RO membranes prior to further processing to recover battery grade material. The fourth case study will be on a lithium battery recycling facility in China that is using a unique combination of pretreatment and a single RO system with ERDs designed for a unique operating strategy to recover lithium chloride, lithium sulfate, nickel sulfate, and cobalt sulfate from recycled batteries that include manganese and other challenging constituents prior to additional refining to recover lithium, nickel and cobalt for reuse in batteries.

The City of Portage la Prairie lies 50 miles west of Winnipeg, in the heart of Manitoba's farming belt. As the global population increases, food processors increase production to meet the global demand, which subsequently generates more wastewater. To meet pre-treatment requirements associated with existing food processors in the aera increasing production and new food processors developing new plants in the area, the city of Portage la Prairie needed to build a new anaerobic treatment system prior to their existing aerobic treatment system to handle wastewater from different food processors, such as potato and peas. In 2017, the city decided to partner with Evoqua (now Xylem) to build an anaerobic wastewater treatment system to replace an existing BVF reactor previously operating on-site. This treatment system was designed to treat 8,400 m3 of wastewater per day from potato and pea processing plants, totaling 32,800 kg/d of COD. Pairing an anaerobic system with a downstream aerobic system minimizes the energy consumption of the overall wastewater treatment plant, which algins with global sustainability efforts aimed at reducing carbon footprint. Not only does the anaerobic system reduce electricity consumption associated with aeration, mixing, and sludge dewatering in the aerobic system, but it also generates biogas from industrial wastewater, providing renewable energy for the wastewater treatment plant. For this anaerobic wastewater treatment system. Evoqua decided to use a low-rate anaerobic treatment system which consists of a lead ADI-BVF reactor, followed by a lag ADI-BVF reactor to clarify the effluent to meet pretreatment requirements. The entire anaerobic wastewater treatment system (i.e. BVF reactors) significantly digests the soluble COD, BOD, and TSS, and coverts the biodegradable organics into valuable biogas. As part of a future project, biogas will be utilized in a dual fuel boiler to meet heating demands around the plant. Technology Description The anaerobic ADI-BVF(R) reactor is an earthen basin with a concrete perimeter wall lined with a geomembrane liner. Specially designed influent piping evenly distributes incoming wastewater throughout the front-end of the reactor, where the majority of the biologically degradable organics are digested and converted to biogas. A supernatant recycle (SREC) pump is used to mix clarified liquid from near the top of the reactor through the influent distribution system, and a return anaerobic sludge (RANS) pump is used to periodically return settled sludge from the back end (sedimentation zone) of the reactor to the front-end. The lag BVF reactor is also an earthen basin covered with a geomembrane system (same material as lead BVF reactor cover). Further anaerobic pre-treatment and solids clarification is conducted in the lag BVF reactor. The lag BVF reactor has the ability to withdraw RANS and return settled solids to the lead BVF reactor influent and sludge blanket using the RANS pumps. The supernatant from the lag BVF reactor flows by gravity to the existing aerobic system. The BVF reactors are covered with a multi-layered, flexible, insulated geomembrane cover which allows for the reactor to operate under a slight vacuum. Biogas generated in the system migrates to the reactor cover perimeter, and speed-controlled blowers transmit the biogas to a waste gas incinerator. The wastewater treatment plant has been operational for 4 years since its commissioning in January 2020. The BVF reactors have effectively treated the incoming wastewater and produce high quality effluent. The ADI-BVF reactors have consistently removed over 95% of the wastewater COD load, discharging anaerobic effluent with an average COD concentration under 200 mg/l, and an average TSS concentration under 100 mg/l.

Introduction Coastal regions globally are experiencing the growing manifestation of the effects of climate change, where the intensified frequency and severity of storm events, along with the rise of sea levels, pose escalating threats to communities, infrastructure, and ecosystems. It is in this context that nature-based solutions, often referred to as 'green infrastructure,' have emerged as sustainable and adaptive measures to counter the multifarious challenges arising from coastal vulnerability. The challenges and lessons learned from three living shoreline projects from around the country includes: Lister Park Project (LPP) on the south shore of Long Island, NY; Clover Island Shoreline Restoration Project (CISRP) at the Port of Kennewick along the Columbia River in Kennewick, WA; and Miami-Dade County (MDC) Living Shoreline Project in southeast Florida. Objectives This presentation will gain insight on lessons learned from three nature-based solutions projects in three separate geographies and environments. Seamlessly integrating flood protection, habitat restoration, and public access along the Mill River waterfront, the LPP addresses multifaceted impacts of climate change with a focus on community engagement. Simultaneously, the CISRP aims to overcome ecological challenges from historical waste concrete deposition, emphasizing biodiversity and shoreline stabilization through the creation of a strategically designed submerged bank for juvenile salmon. The MDC Living Shoreline Project initiative seeks to navigate regulatory complexities, developing a Living Shorelines Guidance Document for nature-based solutions. Status Construction of the LPP was completed in December 2023, the CISRP was completed in May 2023, Methodology The LPP integrates living shorelines-a nature-based design alternative employing a blend of green and grey solutions to combat erosion while concurrently promoting the restoration of vital ecosystems along a tidal river. This 5,500 LF living shoreline was meticulously designed to encompass a variety of riverbank conditions, serve as a buffer against both routine and extreme flooding events, thereby protecting the community and its assets. The CISRP confronts substantive ecological challenges stemming from the deposition of concrete waste along its shoreline. This has precipitated adverse effects on the habitat for federally listed species including juvenile salmon, which necessitated prompt and comprehensive restoration initiatives. The project's objective is to surmount these challenges through the systematic creation of a strategically designed submerged bank tailored to the precise requirements of juvenile salmon. Concurrently, the project addresses the stabilization of the shoreline, mitigating the effects of concrete deposition, and the establishment of riparian habitats fostering biodiversity. The MDC Living Shoreline Project involves the development of a guidance document poised to assist public and private entities in securing funding opportunities, navigating regulatory complexities, and incentivizing living shoreline creation through time and cost savings. Despite the recognized ecological benefits of living shorelines, challenges arise from perceived regulatory complexities. MDC, having undertaken multiple living shorelines projects on public lands, faces concerns over onerous regulations, prompting calls for changes in relevant acts and codes. Findings and Significance For the Lister Park Project, the design team encountered challenges necessitating adaptive solutions, such as the potential impact on existing utilities, change in conditions, and constraints of budgetary allocations precipitating iterative adaptations throughout the design and construction process. Additionally, existing conditions from when the living shoreline was surveyed to when construction began drastically changed due to the continual shoreline erosion. The CISRP stands as a testament for ecological sustainability, envisioning harmonious coexistence between industrial progress and environmental conservation on Clover Island. The MDC Living Shoreline provides a valuable resource for stakeholders involved in shoreline development and conservation within the county. These three projects emphasize the significance of adaptive strategies, tailored designs, and regulatory considerations in effectively implementing nature-based solutions to combat the multifaceted challenges of coastal vulnerability.