Following our large presence in the education program out west this week at the BCWWA 2024 Conference, we are headed east in support of the Ontario Water Works Association and the Water Environment Association of Ontario, as they host their joint conference in Niagara Falls from May 5th to 7th! As a gold sponsor of this year’s event, we are also active in the technical program with nine presenters featured in ten sessions.
Monday, May 06
11:00 AM – 11:30 AM
Optimizing Aerobic Digester Design and Operation for Biosolids Stabilization
Presenter: Nico Carunungan
Small wastewater treatment plants receiving less than 10 megaliters per day (MLD) of wastewater produce sufficient quantities of biosolids to require onsite sludge stabilization. Aerobic digestion is a suitable and cost-effective technology candidate for these smaller facilities as it can be easily controlled, has good nitrogen removal capabilities, and is relatively safer to operate and maintain compared to anaerobic digestion. This presentation will discuss how aerobic digestion is an appropriate technological candidate for small wastewater treatment plants requiring biosolids treatment. Sludge stabilization criteria against which digestion performance is measured against include pathogen reduction and vector attraction reduction. Mixing, oxygen transfer, thickening, and temperature are some of the most significant drivers for the proper functioning of an aerobic digestion process. Key design steps for new digesters include tank sizing based on forecasted treatment requirements and site climatic conditions, determining series versus paralmichaelel digester configuration, selecting appropriate aeration equipment (blowers and air diffusers), sludge thickening equipment, and determining how mixing requirements will be achieved. It is essential that process equipment be properly sized and optimally operated to minimize digester life-cycle cost. Sludge should be pre-thickened prior to being aerobically digested to achieve greater levels of performance, although odour generation, heat generation, and foaming can become operational issues when not addressed properly through design. Planning for capital upgrades at existing aerobic digesters involves understanding construction sequencing constraints and the potential need for temporary biosolids treatment during digester shutdowns. It is possible to maintain continued biosolids treatment using a combination of partial stabilization and storage, while sludge trucking to other digester facilities remains an option. Provincial biosolids regulations should be reviewed for compliance if biosolids are intended for land-application. Climate change strategies and greenhouse gas emission (GHG) mitigation requirements are also important considerations in the design and operation of aerobic digesters. In summary, municipalities can consider aerobic digestion as a suitable technological candidate for sludge stabilization at small wastewater treatment plants and subsequently design individual digester systems to meet specific treatment needs.
11:30 AM – 12:00 PM
Blending Asset Management and Engineering Methodologies for Specialized Process Assets
Presenter: Nico Carunungan
Conventional approaches to state of good repair planning at water and wastewater treatment facilities are typically based on physical conditions of assets. However, in-depth reviews of specialized treatment processes are required to provide a practical and integrated approach to achieve service level goals while managing risk and minimizing life cycle costs. In this presentation, we illustrate Associated Engineering’s work with the Region of Waterloo (Region) in creating asset programs for filter assets at sixteen water treatment plants and digester assets at seven wastewater treatment plants across the Region. Asset hierarchies were created using the Region’s standard facility-based asset categories and were supplemented with additional categories and attributes to better facilitate effective asset life cycle management upon integration with the Region’s existing asset management protocol. Ten (10) and fifty (50) year capital and O&M plans were proposed based on the current conditions of existing assets and unique engineering requirements including but not limited to filter media studies, filter underdrain/air scour lateral inspections, aerobic digester diffuser inspections, or anaerobic digester cleanouts and coating applications. Considerations of process redundancy and shutdown requirements for renewal were incorporated into the capital planning and O&M recommendations. Level of Service statements were developed to support performance and lifecycle management to achieve mandated levels of service. The proposed capital and O&M projects and budgets arising from this work provide clearer projections for upcoming filter and digester work at the Region’s treatment facilities. By creating projects under an asset program, the Region can proactively plan for capital and O&M work, thereby ensuring municipal funds are spent efficiently and the risk of treatment service going out of service minimized. Both asset programs will aid the Region in better planning for project work over the life cycles of specialized process equipment.
2:00 PM – 2:30 PM
Identifying WTP Optimization Opportunities via Capacity and Performance Review
Presenter: Anna Comerton
The performance of a WTP can be baselined with a review of historical water quality and operating data. Along with this, the design and operating capacity of individual treatment process units can be estimated in order to identify bottlenecks and performance limiting factors in a process train. This systematic review of historical treatment unit capacity and performance in comparison to design parameters and capacity/performance objectives allows for the identification of WTP optimization opportunities in the short-term with existing infrastructure as well as to inform upgrades and enhancements needed to meet current and future treatment objectives as part of overall facility capital planning and future proofing for potentially changing water quality due to climate change. Confirmation of optimization and upgrade opportunities is often complemented by bench-/pilot- and/or full-scale testing of the proposed operational adjustment and treatment process unit upgrades. Additionally, full-scale stress testing can also provide confirmation of hydraulic and performance capacity limitations. Mixing in anaerobic digesters can limit other water resource recovery facility (WRRF) processes such as dewatering and sludge transfer. Mixing can also be less efficient if operational parameters have changed, for example the solids concentration increased due to implementation of waste activated sludge (WAS) thickening. A properly selected and designed mixing system can also help address other challenges at a WRRF (i.e. poor performing preliminary treatment that result in undesirable materials, like rags) which can cause clogging or excessive settlement in the digester increasing operation and maintenance activities. Beyond the usual anaerobic digester design parameters of achieving a sufficient active volume to enable uniform or consistent heating and volatile solids destruction, effective digester mixing is an important consideration to facilitate the digester in achieving the desired performance, reducing impacts on downstream processes and mitigating operation and maintenance issues. A recent mixing improvement at the Waterloo Wastewater Treatment Plant (WWTP) started as an investigation into sludge transfer between the primary and secondary digesters. Like most facilities, only ~200 mm of driving head was available between the primary digester and its overflow box to the secondary digester. During the commissioning of new rotary drum thickeners (RDTs) for thickening of the WAS, the plant experienced severe clogging in the sludge transfer line, requiring manual intervention by plant staff. As a result, the RDTs have been operating at a reduced capacity since commissioning. After an investigation of digested sludge gravity transfer line hydraulics and maintenance issues with the existing digester mixing system, it was identified that the plant would benefit from a change to hydraulic mixing with a chopper pump that could operate at a higher solids concentration and be able to cut up rags, hair, and other debris. The new hydraulic mixing system has the potential to improve digestion performance, and enable the WRRF to operate with its TWAS process as designed and achieve the most benefit from the existing infrastructure. This will be of particular interest looking to the future as the facility approaches its digester capacity (15-day retention time) and can benefit from operating the digesters with a higher solids concentration.ons as well as to understand the potential of pushing treatment processes to support a retrofit construction upgrade where certain unit processes might need to be taken offline. Case studies from three WTPs will be shared to illustrate the above and demonstrate the benefit of such capacity and performance reviews and associated testing to identify optimization opportunities and in line with getting the most out of existing WTP infrastructure (i.e., making your assets sweat). The case studies will also show examples of deferral of capital expenditures achieved though optimization of existing infrastructure in the interim to longer term upgrades captured through facility capital planning. In brief, this presentation will provide an overview of a structured approach to WTP optimization and facility planning as well as illustrate these concepts with case studies.
3:30 PM – 4:00 PM
Effective Digester Mixing Improves Sludge Transfer – A Case Study from the Waterloo WWTP
Presenter: Michael Blain
Mixing in anaerobic digesters can limit other water resource recovery facility (WRRF) processes such as dewatering and sludge transfer. Mixing can also be less efficient if operational parameters have changed, for example the solids concentration increased due to implementation of waste activated sludge (WAS) thickening. A properly selected and designed mixing system can also help address other challenges at a WRRF (i.e. poor performing preliminary treatment that result in undesirable materials, like rags) which can cause clogging or excessive settlement in the digester increasing operation and maintenance activities. Beyond the usual anaerobic digester design parameters of achieving a sufficient active volume to enable uniform or consistent heating and volatile solids destruction, effective digester mixing is an important consideration to facilitate the digester in achieving the desired performance, reducing impacts on downstream processes and mitigating operation and maintenance issues. A recent mixing improvement at the Waterloo Wastewater Treatment Plant (WWTP) started as an investigation into sludge transfer between the primary and secondary digesters. Like most facilities, only ~200 mm of driving head was available between the primary digester and its overflow box to the secondary digester. During the commissioning of new rotary drum thickeners (RDTs) for thickening of the WAS, the plant experienced severe clogging in the sludge transfer line, requiring manual intervention by plant staff. As a result, the RDTs have been operating at a reduced capacity since commissioning. After an investigation of digested sludge gravity transfer line hydraulics and maintenance issues with the existing digester mixing system, it was identified that the plant would benefit from a change to hydraulic mixing with a chopper pump that could operate at a higher solids concentration and be able to cut up rags, hair, and other debris. The new hydraulic mixing system has the potential to improve digestion performance, and enable the WRRF to operate with its TWAS process as designed and achieve the most benefit from the existing infrastructure. This will be of particular interest looking to the future as the facility approaches its digester capacity (15-day retention time) and can benefit from operating the digesters with a higher solids concentration.
Tuesday, May 7th
9:00 AM – 9:30 AM
Ultra-low and non-reactive phosphorus removal – does it make sense?
Presenter: Amitesh Malhotra
Point source control regulates phosphorus (P) in wastewater discharge since P is usually the limiting nutrient for algal growth related to eutrophication, especially in fresh waters. Eutrophication is known to cause a number of adverse effects to the environment. Today, there is an increased understanding of a climate change/eutrophication feedback loop, and this evidence amplifies the need for nutrient removal technologies that have minimal CO2 equivalent footprints to effectively interrupt this loop. To control ecological degradation, there has been increasing demand to achieve extremely low effluent Total-P due to more stringent discharge limits imposed on wastewater treatment plants (WWTPs). Mass-based effluent limits and tighter numerical concentration-based limits create new challenges for municipalities discharging to the Great Lakes and other sensitive bodies of water, such as Lake Simcoe. Proposed voluntary effluent targets for Total-P in the Grand River watershed are 0.15 mg/L and 0.30 mg/L (monthly averages) for WWTPs with tertiary filters and with secondary treatment, respectively. The long-term load target for Lake Simcoe is 44 tonnes P per year. However, some P-limited surface waters are susceptible to algal blooms even at these low levels, which can potentially lead to even more stringent water quality goals and standards. A long-term sustainable solution for addressing P-based eutrophication is to remove P from water and wastewater streams and recover it for beneficial reuse, e.g., as struvite. However, existing processes can struggle to consistently achieve increasingly lower TP standards. A key factor contributing to this difficulty is that existing processes cannot remove all P fractions, in particular non-reactive P (NRP), which poses a challenge for P removal and recovery. There are concerns that meeting stricter P levels in the effluent of expanding WWTPs might not be possible without looking at advanced technologies that can achieve ultralow P removal and/or remove NRP, especially in areas where the receiver is considered Policy 2 for P. To better understand the concerns regarding ultralow level P/NRP removal, this paper identifies technologies, discuss their advantages and disadvantages as well as technology trade-offs (for example, potentially increased greenhouse gas emissions), and provide critical insights into technology advancements to enhance P removal and recovery.
9:00 AM – 9:30 AM
Infrastructure Gap and Funding – Barriers and Opportunities
Presenter: Vincent Laplante
As we settle into the new reality of building and rehabilitating water and wastewater infrastructure in Ontario in the post-pandemic market, barriers and opportunities present themselves. The well-worn design-bid-build approach is becoming more challenging to successfully execute with increased market pricing volatility, staff shortages and longer manufacturing times for key components in our infrastructure projects. This requires reflection on how we deliver projects to better serve the public in terms of project duration, overall pricing and a more equitable sharing of the project risks amongst all parties involved (e.g. owner, consultant, contractor and suppliers). With these market pressures, it appears that additional capital is unexpectedly required to fund new and upgrade existing infrastructure. Although an unwelcomed additional financial pressure on already strapped municipal budgets, this increased capital need is also an opportunity to review how to fund and deliver projects. On the funding side, municipalities have few levers to use to obtain additional budgets, such as metering revenue, development funding and debt-funding. An approach that is often underutilized or not used is the use of grants and fund programs provided by the Federal and Provincial governments. On the delivery side, various and credible alternate project delivery approaches do exist to the traditional design-bid-build approach that could also provide some relief This presentation will provide a brief review of available funding opportunities and programs, along with suggestions on how to rethink packaging and delivery of infrastructure renewal programs to align with specific funding program requirements. This presentation will also explore the latest alternate project delivery methods to meet project drivers (e.g. lower overall project cost, lower project risk, faster implementation timeline, retain control over key design elements). Case studies will be presented to illustrate the concepts presented.
9:00 AM – 9:30 AM
Small Wastewater Systems – Unique Challenges and Opportunities for Right Sized Solutions
Presenter: Paula Steel
Small wastewater treatment plants (WWTPs), defined as those with design flows of less than 500 m3/day, can have a significant impact on the quality of life within the community they service, as well as on the receiving environment. Changing regulations, stringent effluent limits, updates to codes and standards and climate change are resulting in the modification, replacement, or expansion of existing small WWTPs or the requirement to implement new greenfield facilities. Small WWTPs are designed, constructed, and managed to achieve the same environmental performance objectives as larger conventional WWTPs, yet a small treatment plant is not and must not be regarded simply as a scaled down version of a larger installation. Small WWTPs, typically categorized as decentralized wastewater treatment systems, can be a feasible alternative for communities. Decentralized treatment can be a cost-effective way to meet treatment objectives while mitigating large capital, operations and maintenance costs compared to centralized facilities but also can provide opportunities for growth, business and job opportunities within the community. Similarly, these facilities can be green and sustainable by benefiting water quality and availability, using energy and land wisely, and responding to growth while preserving green space. Unique challenges experienced by small WWTPs include variable organic and fluctuating hydraulic loadings, limited financial resources, attracting or retaining qualified operations staff and potentially remote locations, while being required to meet the same or stricter regulatory requirements as conventional WWTPs, including the management of sludge and biosolids. This makes small treatment systems complex to design, construct, operate, maintain and manage. Solutions that may be effective in other larger facilities may not be as effective in small systems. Designers need to carefully consider many factors when choosing solutions that are suitable for each small system. This presentation will address the unique considerations for planning, design, and implementation of small WWTPs, and illustrate through case studies how these challenges can be addressed.
9:30 AM – 10:00 AM
Impact of Emerging Contaminants on WTP Treatment Design and Monitoring
Presenter: Anna Comerton
The science around the monitoring, treatment and health impacts of emerging contaminants continues to evolve and understanding the impact on water system monitoring, operation and design is important. In recent years, media and public attention have focused on emerging contaminants (such pre- and polyfluorinated substances (PFAS) following EPA announcement of new drinking water health advisory levels in 2023, and microplastics), updated drinking water guidelines (such as lead following the 2019 Health Canada guideline update) and other drinking water concerns (such as March 2023 W5 episode on asbestos cement pipes). In consideration of the above, it is important for anticipated new and updated guidelines to be understood in maintaining public trust and reviewing the robustness of water systems to manage these contaminants as well as implementing appropriate adjustments to water quality monitoring programs. A brief overview of the guideline development process along with recent and anticipated drinking water guidelines will be provided including harmful algal blooms (HAB), manganese aluminum, lead and corrosion, and PFAS. Treatment strategies along with examples to address the above following a holistic approach will be provided. Finally, it is important to understand the raw water source, including potential impacts from climate change, through a good source water quality monitoring plan to understand the impact of emerging contaminants and updated drinking water guidelines as well a to inform the appropriate treatment strategy accordingly. In brief, this presentation will provide an overview of current and upcoming drinking water guidelines, a review of treatment approaches to manage emerging contaminants, and recommendations on related water source monitoring.
11:00 AM – 11:30 AM
Unlocking sustainability at water and water resource recovery treatment facilities
Presenter: Elia Edwards
In an era defined by climate uncertainty and ecological awareness, understanding what it truly means to employ ‘green’ and sustainable solutions at water and water resource recovery treatment facilities is paramount. This landscape is evolving rapidly across Canada, driven by the pressing need for efficient resource management, environmental conservation, and climate resilience. Employing ‘green’ and sustainable solutions goes beyond adopting renewable energy sources or recycling; it encompasses a holistic approach to optimizing operations, infrastructure, and community well-being. The imperative to explore and implement ‘green’ or sustainable solutions in the context of water and water resource recovery treatment facilities has never been more critical. This presentation aims to unravel the multifaceted dimensions of sustainability in the municipal water and water resource recovery treatment space, shedding light on what it truly means to employ ‘green’ solutions. This presentation will delve into the intricacies of sustainable practices, examining their diverse applications across the water and water resource recovery treatment lifecycles. Key focal points include energy efficiency, resource recovery, infrastructure resilience, community engagement, and regulatory compliance. Through case studies, best practices, and lessons learned, this presentation will offer insights for professionals striving to align their operations with sustainable principles and solutions. It will also provide a roadmap for owners, consultants, researchers, manufacturers, contractors, policy makers, and funding agencies to collaborate effectively in the pursuit of a more resilient and environmentally responsible water and water resource recovery treatment sector.
11:30 AM – 12:00 PM
The City of Edmonton’s Sustainable Utility – Blatchford District Energy System
Presenters: Ruben Arellano and Thomas Hummel
Following the closure of the Edmonton City Centre Airport, the City of Edmonton has approved a redevelopment plan for the 536-acre parcel of land. The City’s Vision is that “Blatchford will be home to up to 30,000 Edmontonians living, working and learning in a sustainable community that uses 100 percent renewable energy, is carbon neutral, significantly reduces its ecological footprint, and empowers residents to pursue a range of sustainable lifestyle choices.” The overall District Energy System design utilizes inter-connected nodes of centralized heat pumps distributing ambient-temperature water to heat pumps in each building. This allows for sharing between buildings and flexibility for connection of additional energy sources in a staged build-out over time. Geoexchange, sewer heat exchange, auxiliary boilers and cooling-towers, Solar PV as a low-GHG electricity source, are included in the overall design concept. Combining the benefits of building energy efficiency, energy sharing within the system, and highly efficient heat pumps, results in greenhouse gas reductions at 75% below that of business as usual. The 3 MW Energy Centre for Phase 1 was commissioned in Q4 2019 with an initial 1 MW of HP capacity, and a 570 borehole geoexchange field under the future storm water retention pond as it’s renewable energy source. More than 1 km of large-diameter HDPE DPS has a planned 57 service connections. The City of Edmonton has established the Blatchford Renewable Energy Utility to own and operate the system. Blatchford has been recognized locally, nationally, and internationally, with awards including those from: Association of Consulting Engineering Companies – Canada; Canadian Home Builders’ Association; Consulting Engineers of Alberta; Federation of Canadian Municipalities; and most recently International Federation of Consulting Engineers (FIDIC). This presentation will discuss the assessment, design, and implementation of this innovative and forward-thinking utility project that provides low-carbon heating and cooling service to an urban in-fill, master-planned, sustainable community.
