Conference Agenda

As wastewater treatment facilities are being rebranded as water resource recovery facilities, carbon is being viewed in a new light. Traditionally, the removal of carbon, expressed as biochemical oxygen demand (BOD) or chemical oxygen demand (COD), is the primary objective in wastewater treatment. However, with recent nutrient removal requirements and energy recovery incentives, carbon is now viewed not as a waste, but as food for the biological nutrient removal process and a source of renewable energy by capturing and re-using the digester gas. The increased attention on carbon benefits is now putting a spotlight on how it is managed across the entire treatment facility process. Understanding the nuances of carbon management is a critical issue for many municipalities, as more treatment facilities in the Puget Sound area are required to provide nitrogen removal, while others have both effluent nitrogen and phosphorus limits. To gain insight on how carbon can be used, it is critical to know the factors that affect carbon management. This presentation will provide a discussion of these factors including presence and types of primary treatment, biological nutrient removal requirements, energy recovery potential and methods, fermentation use, and external carbon sources. In the first case study, a treatment plant currently without primary treatment and digestion is being retrofitted to include primary treatment and digestion. While carbon re-use was not originally the main driver for the plant expansion, carbon management has become an important topic during the planning and design process. The implications of adding primary treatment and potential future fermentation are presented. In the second study, the carbon values of different digester gas uses are compared to the offsets of external carbon addition with sludge fermentation. This study allows a comparison of both costs and greenhouse gas emissions based on the different carbon management schemes. The findings from these examples can be applied to many municipalities in the Northwest as they are faced with the need to meet more stringent nutrient limits and to become more energy-neutral.

This presentation provides an overview of Pima County RWRD Biosolids and Biogas Management Program’s two sustainability projects: beneficial biogas utilization and controlled struvite formation. The Pima County RWRD serves the City of Tucson Arizona and the surrounding communities. The PCRWRD serves 900,000+ wastewater customers within a service area of approximately 700 square miles. It owns and operates 3,400 miles of sewer pipes, 66,000 manholes, 29 active lift stations, and two major regional Water Reclamation Facilities and several small sub-regional WRFs.

PCRWRD’s has been proactively planning for biosolids and biogas beneficial utilization. Land application continues to be the preferred option for its Class B biosolids due to lower cost, simpler to operate, satisfies current regulations, and is consistent with current market conditions. For biogas utilization, different options have been considered, such as CHP for onsite plant use, CNG for fleet use, recovery of carbon dioxide, district heating system, use of excess thermal energy to generate ice for local skating rink, among others.

In the past, biogas was captured and used for onsite cogeneration. An Energy Study for the WRF concluded that a higher value of the one million cubic feet per day of biogas was to purify the biogas to natural gas quality and sell the product in the renewable gas market. Sale of renewable natural gas is scheduled for early 2021.

Dilution of dewatered sludge centrate, and/or chemical addition to the digesters had long been practiced to suppress struvite formation. Planning studies evaluated the pathways of struvite formation and recommended struvite sequestration to control unintended struvite formation. A struvite sequestration process has been constructed after digestion and before dewatering of the biosolids. This facility was brought into service in the fall of 2020.

Several WWTPs have been practicing co-digestion with FOG or food wastes to increase biogas production and subsequent energy. A main effect of co-digestion is the impact on biogas quality. Depending on the quality of the organic waste used, co-digestion may alter the concentrations and/or introduce additional impurities to the biogas. Such change in biogas quality can impact (i) compliance with regulatory requirements and (ii) treatment needs for various end uses of biogas such as co-generation, vehicle fuel, and pipeline injection. However, limited to no information is available on complete characterization of biogas produced from co-digestion of different feed stocks with wastewater sludge. The Water Research Foundation (WRF) project focused on investigating the relationship between a wide range of organic wastes and the resulting biogas quality from their co-digestion. This presentation will highlight: field and bench scale co-digestion of wide range of organic wastes and impact on biogas quality and quantity, complete biogas characterization including major components, siloxanes, VOCs, alkanes, ketones etc, guidance to estimate emissions more accurately from co-digestion and evaluation of biogas quality parameters to assist with permit compliance.

Clean Water Services (CWS) is pursuing an opportunity to use available digestion capacity of the Rock Creek Water Resources Recovery Facility (WRRF) by developing a Co-digestion Program. This program serves two purposes: (1) it allows CWS to better serve the district by creating and strengthening relationships with surrounding industries as well as with local contributors that can provide High Strength Wastes (HWS) and, (2) it increases the overall biogas generation to a quantity that allows CWS to consider Renewable Natural Gas (RNG). This is mutually beneficial, as this service can lower the discharge costs of the industries’ byproducts and their environmental impact. Furthermore, our biogas system infrastructure is aging, which makes shifting to RNG and partner with Northwest Natural an attractive prospect.

Multiple groups within CWS are collaborating in this program to systematically identify, characterize and select wastes that can contribute to gas production goals for RNG without compromising digestion capacity and stability. The evaluation process consists of:

1. Defining the capacity of the system and gas production goals. This has allowed us to stablish an initial requirement of 4.4 ft3of gas/gallon of HSW.
2. Identifying sources of HSW within our service district. We engage with contributors to determine the reliability of their practices and consistency of their product.
3. Assessing potential impacts to operations and maintenance of the digesters, and infrastructure requirements. This is achieved through: a) novel bench-scale testing approach, b) pilot testing and, c) evaluation of the physical characteristics of the HSW.
4. Selecting the HSW and negotiating with suppliers.

This presentation will focus on the challenges associated to implementing this program, which include: coordinating efforts from multiple groups within and outside CWS, pushing a recalibration of the organization’s culture to get staff buy-in, and to make data-driven decisions based on results from relevant testing. Additionally, we will talk about our operational experience using fats, oil and grease at the Durham WRRF that has helped define our HSW selection criteria.

The production of biogas, a renewable resource, was increased using the microbial hydrolysis process (MHP) with anaerobic digestion. Anaerobic digestion performance was enhanced with the MHP using Caldicellulosiruptor bescii (C. bescii), a hyper-thermophilic bacterium. The innovative MHP enhances any anaerobic digestion process by adding a bioaugmentation stage. Digestate from an anaerobic digester (AD) is fed to a hydrolysis tank populated with C. bescii for a hydraulic retention time of 2 days at 75 degrees Celsius (C). The C. bescii hydrolyses cellulose and other recalcitrant volatile solids that are otherwise resistant to digestion into volatile acids. These volatile acids are returned to the AD where methanogens convert them into biogas. MHP was tested at lab-scale and pilot-scale with anaerobic digestion of solids from three water resource recovery facilities (WRRF). The three WRRFs were the City of Gresham Wastewater Treatment Plant in Gresham, OR with mesophilic anaerobic digestion (MAD) and fats, oils, and grease (FOG) addition; Encina Water Pollution Control Facility (WPCF) in Carlsbad, CA with MAD; and Oakland County’s Clinton River WRRF in Pontiac, MI with thermal hydrolysis process (THP) and MAD. These WRRFs had high performing full-scale AD systems averaging 58-60 percent volatile solids reduction (VSR). A test AD system with MHP was compared to a control AD system without MHP. The addition of MHP enhanced the AD performance of all three WRRFs from a VSR of 60 percent to over 75 percent. Enhanced performance would result in a 25 percent increase in biogas production and corresponding reduction in biosolids production. A conceptual design was completed for implementation of MHP at VCS (VandCenter) Denmark’s Ejby Mølle Water Resource Recovery Facility (EMWRRF). A calibrated whole-plant model was used to evaluate MAD performance with and without MHP. The model incorporated VSR results from lab-scale and pilot-scale testing of MHP. Results of modelling at EMWWRF predicted an increase in VSR from 55 to 75 percent corresponding to a 36 percent increase in biogas production.

“Empresa de Acueducto y Alcantarillado de Bogotá (EAAB)”, Bogotá, Colombia, is responsible for the implementation of the Bogotá River Sanitation Program. EAAB currently operates the 90-MGD Salitre WRRF, located on the north end of the city, which is undergoing an upgrade to expand its capacity to 160-MGD. This plant will treat 30% of the city’s wastewater. EAAB recently completed the design of the 370-MGD Canoas WRRF, to be located in the southern end of the city. The Canoas WRRF will treat the remaining 70% of the city’s wastewater, with a total service area population of 7.2 million.

The Canoas WRRF secondary treatment facilities designed include activated sludge step-feed aeration, secondary clarification, and chlorine disinfection. The associated solids train include sludge thickening, sludge pre-dewatering, thermal hydrolysis process (THP), anaerobic digestion (AD), biosolids dewatering, beneficial utilization of biosolids and a Biogas Co-generation facility.

The solids line for the Canoas WRRF was designed with two main objectives: 1) minimize Biosolids production, 2) maximize beneficial utilization and energy recovery.

A critical component of the solids train is the THP/AD system. This process allows less sludge to be generated versus conventional anaerobic digestion, given the greater VSS destruction and improved sludge dewaterability, generating biosolids which can be classified according to its pathogen content as Class A biosolids. This baseline design scenario was later compared with other biosolids minimization processes (thermal drying, solar drying, and incineration, among others), together with a preliminary market study of potential uses of the end product, to determine the most cost-effective solution.

The design also considered biogas utilization for onsite co-generation. The use of Combined Heat and Power (CHP) is anticipated to utilize the biogas for electric energy generation as well as production of the steam required for the THP system. An estimate of 12 MW of electrical power will be generated to cover plant uses (close to 2/3 of the plant’s electrical power requirements). Heat from the exhaust gases of the turbines will be recovered and used to produce the vapor needed for the THP, thus maximizing the energy recovery in the plant, and saving critical electrical energy costs.

Communities across the Pacific Northwest face a diverse set of water resource challenges. From developing additional water supplies to managing wastewater under tightening discharge limits, communities are exploring and selecting water reuse to meet their water resource needs. This session will present case studies from around the Pacific Northwest on how water reuse is being assessed, pursued and the partnerships built to advance water reuse. The session will include short case studies and a moderated discussion with pre-developed questions to provide a robust dive into the technical, economic, and social aspects of assessing and advancing water reuse in a variety of community settings.

This session will provide an update of water reuse news and accomplishments from a national and regional perspective. Attendees will learn about federal advocacy to advance water reuse and the communication tools, peer networking and reuse technical learning opportunities provided by the WateReuse Association. The session will then shift gears to highlight accomplishments and work within the Pacific Northwest to advance reuse through advocacy, legislation, and communications in the states of Oregon, Washington and Idaho, including the second successful Oregon Water Reuse Summit held in June 2023. Attendees will learn about advocacy, networking and information sharing opportunities for water professionals in the Pacific Northwest.

Advancing water reuse requires considerable community outreach and engagement. This session will highlight effective water reuse communication engagement efforts with real case examples. Attendees will gain tools and strategies to effectively engage with their communities about projects that span complex science, engineering, and financial topics. This will include examples of building an engagement plan, translating complicated ideas into resident-focused language, and finding ways to make engagement relevant to the audience.

In this presentation, staff from the WateReuse Association will provide updates on important federal legislation and regulatory activities that impact water recycling throughout the Pacific Northwest. We will cover the latest legislative developments related to federal appropriations, PFAS, and other important items. We will also provide an update on Executive Branch actions, including the federal Interagency Working Group on Water Reuse, the National Water Reuse Action Plan, PFAS and Build America, Buy America regulations, and the Administration's implementation of federal water recycling programs.

Embracing water reuse requires people to shift their mindset about clean water. This session will highlight innovative and creative water reuse demonstration projects that have occurred in the Pacific Northwest and nationally. From recycled water beer to a recycled water supplied public wading pool, attendees will learn about how demonstration projects can be leveraged to change public attitudes and grow support for water reuse. From small, low-budget projects to large projects, attendees will gain new ideas about how demonstration projects can grow public support for water recycling and clean water services more broadly.

The body of research, public concern, and general media coverage relating to contaminants of emerging concern (CECs) is growing rapidly throughout the United States. This session will describe general trends in current research related to CEC occurrence and composition that is most relevant to water and wastewater professionals. Commonly detected CECs in regional water will be described including wastewater, reuse water and stormwater. Using published academic studies and regional studies and sampling, attendees will learn about CECs that might be of most concern to common regional uses of reuse water. Attendees will come away with a greater understanding of CECs, their presence in wastewater, stormwater and natural waters, the pathways CECs enter the environment, and risks and concerns associated with CECs in the environment.

The RWP seeks to address multiple drivers impacting Boise’s local water supply and resilience including regional growth and capacity needs, climate change, water scarcity, equity and affordability, regulatory compliance, and city-wide sustainability goals. As the RWP addresses these challenges and opportunities, it will demonstrate long-term stewardship over its water resources and build resilience in the face of uncertain futures. Over the next several decades, the RWP will advance the construction of new recycled water facilities, the development of new partnerships, and the adoption of new policies that will work toward the following common program outcomes:

• Increase the WRS system capacity by managing flows and loads through new recycled water facilities.
• Increase the resilience to climate change and water scarcity by diversifying water supply through the production of recycled water.
• Demonstrate regulatory stewardship by anticipating future regulatory needs.

The City of Boise AWT started operation in the Spring of 2023 and will operate for the next 18 months. The pilot is designed to pilot provide information in six key areas including:

1. Transparency in water quality data.
2. Development of financial data.
3. Increased stakeholder confidence.
4. Develop and train workforce.
5. Support regulatory approvals.
6. Develop data to inform design criteria.

The pilot started operation in April 2023 and will be operating for the next 12 to 18 months. The presentation will include information on the startup process, Operation, and how the pilot will help inform the six key areas.

Many utilities are considering or embarking on monitoring programs for contaminants of emerging concern to respond to community concerns about presence of these chemicals in water supplies, including recycled or reclaimed water. However, proceeding with monitoring is a daunting task. Selecting which chemicals to monitor, finding analytical labs to process samples, interpreting and communicating results are challenging tasks. This session will feature a facilitated panel discussion between professionals that have built and implemented CEC monitoring programs. Panelists will provide a brief overview of their work on CEC monitoring and share lessons learned and best practices relating to all aspects of CEC monitoring.

Regulations for recycled water have historically been driven from a state level which leaves a regulatory framework that is unique for each state. From a regulatory standpoint water reuse will be discussed from the regulating in the Pacific Northwest: Oregon, Washington, and Idaho. Additionally, other states will be participating to discuss their considerations and differences from the Pacific Northwest. The rules and considerations for protection of public health and the environment from each state’s perspective will be discussed along with questions from the moderator and the audience.

New and expanded facilities must respond to a full range of future conditions and operating scenarios to ensure system performance and regulatory compliance over their design life. Operators’ perspectives are an essential part of the design process, especially to provide guidance on system controls. Jacobs engaged with the Bureau of Environmental Services’ (BES) operations staff during early design of two new secondary clarifiers which resulted in more certainty with complex control schemes and the potential to reduce cost and risk during startup and commissioning. Presentation includes viewpoints from Jacobs, BES engineering, and BES operations staff.

The Secondary Treatment Expansion Program (STEP) includes the addition of two new circular 145-ft diameter secondary clarifiers at the Columbia Boulevard Wastewater Treatment Plant (CBWTP) that will be the largest clarifiers in the state of Oregon. CBWTP treats up to 450 million gallons per day with the combination of a wet weather treatment system and a secondary treatment system. STEP is increasing capacity through the secondary treatment system and changing the flow split between the two systems.

Early design workshops highlighted the complexity of the flow split scenarios (multiple flow streams and multiple control points) and effectively communicating how control decisions impacted hydraulic performance was challenging. Jacobs developed a design-level digital twin of the CBWTP secondary treatment system, so operations staff could engage with the flow parameters using the same visual interface and control logic as the constructed facility. The digital twin combined a detailed, dynamic hydraulic and simplified solids model, database structure, and instrumentation and controls narrative to simulate plant performance under a range of flow scenarios. Once the scenarios and control logic were developed, the design was stress-tested, using the tool, in an efficient and low risk environment. The operators’ input during design refined control logic and narratives which will allow for more intuitive operation and smoother startup and commissioning to meet regulatory compliance goals.

The Puget Sound Nutrient General Permit (PSNGP) became effective on January 1, 2022 and requires larger dischargers implement optimization to maintain nitrogen discharge below action levels established by the permit. The Wastewater Treatment Division (WTD) of King County operates three large treatment facilities, South Plant, Brightwater, and West Point. As allowed by the PSNGP, WTD elected a bubbled action level for compliance flexibility, instead of individual action levels for each facility. This presentation discusses actions taken by WTD under its bubbled action level in 2022 to comply with the PSNGP.
This presentation will describe the optimization planning work that HDR Engineering, Inc. (HDR) conducted with WTD staff and discuss lessons learned from optimization strategy implementation. HDR used WRF 4973, Guidelines for Optimizing Nutrient Removal Plant Performance, as a guide for screening optimization strategies. HDR led a collaborative process with WTD staff to assess current influent and effluent nitrogen loadings, identify, model and screen potential optimization strategies, and engage staff in reviewing and selecting strategies.
Previous testing at South Plant indicated that the facility could be operated in Ludzack-Ettinger mode during dry weather conditions to accomplish partial nitrogen removal, and this was selected as the initial optimization strategy as it could be implemented immediately with limited to no capital improvement. At Brightwater, a construction project is underway which will allow the plant to operate at low dissolved oxygen levels and increase nitrogen removal while improving process stability.
The PSNGP requires continual planning and adaptive management to respond to optimization challenges and maintain discharges below action levels. Both South Plant and Brightwater leveraged flexibility in implementation. They used trials and troubleshooting to maximize their success, and identified several potential strategies to improve outcomes, including an interim alkalinity feed system at South Plant.
As a result, WTD complied with the PSNGP in 2022 by staying more than 10 percent under the action level. Lessons learned from the first year optimization planning will be shared, along with a discussion of how WTD is planning to build and operate under an adaptive management framework for optimization planning and implementation.

Bacteria in biological nutrient removal (BNR) activated sludge treatment reactors uptake and metabolize wastewater nutrients to achieve effluent desired by operators and engineers. Induced metabolisms – i.e., the metabolic pathways by which the bacteria “digest” nutrients – are the backbone of biological wastewater treatment. However, little data is available to study and understand these metabolic pathways directly. Moreover, differences in metabolic activity at a molecular level between differing BNR systems and configurations are, at best, poorly understood.

Metabolomics is the scientific study of biochemical processes involving metabolites, which are the small molecule substrates, intermediates, and products of bacterial metabolism. Metabolomics is an emerging scientific field that holds promise to help fill the knowledge gap in BNR processes with an easy sampling and analytical process that can be used to study a broad range of intracellular compounds. Research at the University of Idaho is focused on applying metabolomic methods to better characterize and describe BNR processes, with the ultimate aim to generate new knowledge on process operation and control. This presentation will describe metabolomics and its potential application in research and activated sludge troubleshooting. Original research will be shared on developing a “metabolic fingerprint” for different full-scale, pilot, and bench-scale BNR configurations; employing metabolomics to troubleshoot EBPR failure; and a metabolomic investigation into the upset of a BNR culture associated with addition of elevated concentrations of emerging contaminants.

The City of Pasco has been one of the fastest-growing cities in the State of Washington and the nation for several years and keeping ahead of this growth has taxed the City’s water and wastewater utility infrastructure and associated fund balances. The City is actively planning for future improvements at their wastewater treatment plant (WWTP) which have included, fast-track short-term capacity modifications, a comprehensive 20-year facility plan, the acquisition of State Revolving Fund (SRF) loan project funds, design of the first two phases of high priority improvements, and construction of the Phase 1 liquids-focused WWTP upgrade that will roughly double the capacity of the plant to just under 10 million gallons per day.

This presentation will focus on the planning, design, construction, and start-up of the WWTP’s $22 million Phase 1 improvements which included the construction of an expanded and modified blower building with two new blowers and reuse of two existing blowers, two new aeration basins, the retrofit of two existing aeration basins, selector process considerations, aeration piping replacement, return activated sludge (RAS) piping modifications, mixed-liquor recycle (MLR) pump addition, over 1,100 LF of outfall piping upgrades, demolition of an existing trickling filter and associated appurtenances, and site work.

This presentation will:

• Provide a contextual overview of the existing facility and phased improvement planning
• Review unique Phase 1 design elements:

- Use of an intentionally flexible anoxic/anaerobic selector to maximize rated capacity
- Aeration basin FRP partitioning to convert from complete mix basin and create plug flow conditions to maximize capacity and aid foam removal
- Blower selection and reuse of existing blowers
- Probe selection, use, and location for operational control and data acquisition
- Diffuser process selection for improved capacity and O&M access
- Open Channel Mag Meter to maximize capacity
- Preparation for future phases incorporated into the design

• Discussion of bid procedures for contractor responsibility and qualification-based bidding specific to Washington State requirements
• Discuss construction and facility start-up lessons learned