WCW26

Utilities must prioritize large inventories of linear assets to develop defensible capital plans. The task is complicated by the volume and variability of data that must be considered. This joint investigation by New Castle County, DE (NCC) and Jacobs evaluates how different risk scoring formulas influence pipe asset prioritization in rehabilitation programs. The study compares the traditional risk = LOF × COF methodology, which multiplies likelihood of failure (LOF) and consequence of failure (COF) into a single value, with alternative additive approaches.
Our objectives were to evaluate how each scoring method affects rehab prioritization, 10‑year rehabilitation schedules and budgets, and identify the risk prioritization methodology best aligning with NCC’s operational goals and risk tolerance.
This study reflects ongoing collaboration between NCC and Jacobs to create risk scores and manage their sewer and stormwater assets. Analysis incorporates NCC’s GIS asset inventory, work order history, and condition assessments. Additionally, remaining useful life (RUL) estimates and cost estimates were generated, and a predictive AI model was used to flag pipes with high potential defect acceleration using an acceleration factor (AF). NCC is reviewing modeled results and comparing them with field observations, maintenance trends, and planned rehabilitation.
Three prioritization techniques were compared using identical datasets and business rules and differing prioritization techniques.

• Traditional: Single risk value calculated using LOF × COF
• Alternative 1: Refined priority value calculated as COF + 2×LOF 
• Alternative 2: Refined priority value calculated as COF + 2×LOF + AF

When LOF or COF scores were missing, substitutes were made using percent‑life‑used or a peer comparison of pipes within the same basin and age range, for the same material and diameter. For comparison purposes, a 10‑year program was constructed under equal annual budget assumptions, filling each year with the highest‑priority assets.


Findings:
Assessing the Options
When assessing the possible prioritization outcomes, the scoring methods produced meaningfully different prioritization spreads. Traditional LOF × COF provided an irregular range of possible outcomes while the additive options created a more normalized range of outcomes. When assessing the prioritization outcomes, we focused on two hypothetical example pipes.
Comparing Outcomes Using NCC Data
The three prioritization methodologies have been applied across NCC’s full pipe inventory, generating priority scores for every asset. To validate these modeled results, NCC selected a representative subset of pipes to apply manual, engineering‑judgment‑based prioritization, drawing on institutional knowledge. This manually ranked set will serve as a ground‑truth benchmark. The study then compares the modeled priorities to both NCC’s hand‑assigned rankings and NCC’s planned rehabilitation projects to evaluate alignment, highlight discrepancies, and identify opportunities to refine the risk scoring approach.
Significance
Choice of risk formula has direct implications on rehab prioritization, construction workload, budget stability, and long‑term system performance. For NCC, adopting COF + 2×LOF+AF offers tangible benefits: it highlights condition‑driven assets that require timely intervention while still assessing criticality, targets pipe defect degradation, and supports proactive rehabilitation. More broadly, this study provides a replicable, transparent method for utilities to reevaluate their risk modeling and integrate rehabilitation-centric prioritization into capital planning and budgeting.

The Fish Creek Wastewater Treatment Plant (WWTP) Upgrade represents one of Calgary’s most significant treatment modernization efforts in recent years, driven by increasingly stringent effluent requirements and the need to reestablish treatment capacity for a rapidly growing service area. Advancing this complex program from a high‑level concept to a coordinated, tender‑ready design package required a structured, collaborative, and iterative approach that aligned process decisions, facility upgrades, and constructability considerations across multiple design stages. This presentation traces the key steps that shaped the project’s development from conceptual design, through preliminary and detailed design, and into the issued for tender (IFT) ready documents.
Rather than detailing each technical component of the upgrade, the presentation highlights how early evaluations – such as biological nutrient removal process selection, peak flow management requirements, and updated hydraulic modelling – guided downstream decisions related to site layout, tankage configuration, and integration with the existing operating plant. This early-stage coordination and selections established the foundation for design development and ensured that treatment objectives, regulatory needs, and expected future loading conditions were consistently carried throughout the project.
A critical component of the design progression was the structured Value Management (VM) process, which brought together City staff, the consultant design team, the construction manager, and independent reviewers to assess the design at key milestones and to provide design alternatives for consideration. Recommendations from the VM workshops helped refine process choices, optimize capital investments, and improve operational reliability. This collaborative environment accelerated alignment on major design drivers, such as biological nutrient removal configuration, primary and secondary treatment upgrades, filtration strategy, sludge handling improvements, and energy recovery opportunities, and ensured that the evolving IFT documentation reflected an optimized and coordinated project.
Attendees will gain insight into the practical challenges encountered as the project advanced through design, including navigating site constraints, maintaining plant operations during construction, coordinating multidisciplinary technical inputs, and balancing scope, schedule, and interested party expectations. This case study provides a clear and realistic look at how intentional planning, iterative evaluation, and strong team collaboration can successfully advance a major wastewater treatment plant upgrade, ultimately enabling utilities to implement complex upgrades with reduced risk and improved confidence.

This case study details the retrofit of an existing Rotating Biological Contactor (RBC) system to a Moving Bed Biofilm Reactor (MBBR) configuration for Wabaseemoong Independent Nations, located near the Ontario–Manitoba border. The upgrade addressed stringent effluent requirements—TSS <25 mg/L, cBOD₅ <25 mg/L, and TAN <10 mg/L—within a design flow of 438 m³/d, while minimizing civil works and footprint. The solution leveraged existing headworks and secondary clarification, incorporating twelve stainless steel coarse-bubble diffusers per tank to optimize oxygen transfer and reduce maintenance associated with membrane replacement. Media backflow prevention was achieved through influent piping modifications. The MBBR provided intensified nitrification and BOD removal within the RBC basins, ensuring compliance with nutrient limits and operational simplicity. Commissioned in January 2024, the system demonstrated stable performance and energy efficiency, validating MBBR retrofits as a cost-effective approach for decentralized wastewater treatment facilities

Carbon capture and storage (CCS) is a critical strategy for mitigating CO₂ emissions from carbon-intensive industries, with amine-based post-combustion capture (PCC) being the most widely applied technology. However, PCC generates amine-rich wastewater containing ammonia, amines, nitrosamines, and sulfate, posing significant environmental and health risks and requiring effective treatment before discharge. This study experimentally compared two biological treatment configurations for synthetic PCC wastewater: pre-denitrification–nitrification and pre-denitrification–anammox, to evaluate the feasibility of replacing conventional nitrification with anammox. The pre-denitrification–nitrification system was operated in sequencing batch reactors (SBRs) at a 2-day hydraulic retention time (HRT) under low organic loading (COD/N ≈ 3.5) without nutrient adjustment. Influent monoethanolamine (MEA) and diethanolamine (DEA) concentrations were gradually increased up to 3000 mg/L. The system achieved effective amine biodegradation in the anoxic stage and high ammonium and COD removal. However, the introduction of a diluted pilot-scale MEA-rich stream (~10,000 mg/L total amines) resulted in incomplete amine degradation, nitrite accumulation, and inhibition of nitrite-oxidizing bacteria. In parallel, mature anammox granules were stabilized for over 180 days, achieving 87.4% ammonium removal and a nitrogen removal rate of 187 mg N L⁻¹ d⁻¹. Although batch tests showed partial MEA and DEA degradation by heterotrophic denitrifiers, the integrated pre-denitrification–anammox system failed after coupling due to rapid loss of anammox activity under continuous exposure to residual COD and amines. Overall, the results indicate that pre-denitrification–anammox is unsuitable for amine-rich PCC wastewater without effective pretreatment, and alternative configurations such as partial denitrification–anammox or simultaneous nitritation, denitrification, and anammox (SNAD) are recommended.

The Saskatoon Wastewater Treatment Plant is piloting the Mobile Organic Biofilm (MOB) process as a strategy for process intensification within its biological nutrient removal system. Initial piloting demonstrated improved nitrification reliability and reduced secondary clarifier solids loading, leading to refinement of the operating strategy to better balance suspended and attached growth.
In the second year, the pilot focused on sustained low solids retention time (SRT) operation to intentionally shift ammonia oxidation capacity toward the biofilm fraction. By operating at lower mixed liquor suspended solids (MLSS) concentrations, the team aimed to strengthen biofilm development, reduce solids loading to the secondary clarifiers, and increase overall system resilience.
A key objective was to evaluate system behaviours during extended cold-weather conditions. Low-SRT operation reduced suspended nitrifier populations and increased reliance on attached growth on the mobile carriers. This operating strategy provided insight into how much nitrification capacity could be maintained within the biofilm fraction and how the system responded under varying seasonal and loading conditions.
Results from the second year highlight the operational opportunities and constraints associated with low-SRT operation, including the importance of managing dissolved oxygen, solids inventory, and carrier distribution to maintain consistent performance.
This presentation will share second-year performance results, lessons learned from winter and low-SRT operation, and key considerations for full-scale implementation of the MOB process as a long-term capacity and resilience strategy.

Water Resource Recovery Facilities (WRRFs) face increasing pressure to meet stringent nutrient limits, reduce energy consumption, minimize chemical usage, and accommodate growth within limited footprints. 
 
Low dissolved oxygen (DO~0.3-0.5 mg/L) operation is a promising method to reduce aeration energy and support sustainable biological nutrient removal (BNR) pathways, such as simultaneous nitrification-denitrification (SND).  SND is particularly advantageous for carbon-limited plants, as it can free carbon once used in nitrogen removal and divert it to enhanced biological phosphorus removal (EBPR), which significantly reduces reliance on coagulants (e.g., ferric or alum). Total nitrogen (TN) removal offers benefits such as reduced alkalinity demand (e.g., caustic) and lower biomass yield, especially when SND lowers the use of exogenous carbon.  
 
Biofilm technologies are well known to increase process capacity. Unlike conventional biofilm systems such as integrated fixed film activated sludge (IFAS), moving bed biofilm reactor (MBBR), or membrane aerated biofilm reactor (MABR), mobile media (MM) can be uniquely integrated with low dissolved oxygen (DO) aeration strategies due to their small size and low mixing energy requirements.  They also require minimal retrofitting, limited to rotary screening for media recovery. 
 
In addition to significant capacity improvements, process modeling indicates integration of MM to a low DO process significantly enhances SND, achieving 3-4 mg/L greater TN removal than suspended sludge alone.  With MM, dropping the DO from 2.0 mg/L to 0.5 mg/L resulted in a decrease in effluent phosphorus from 1.2 mg P/L to 0.1 mg P/L, attributed to decrease in nitrate return in the return activated sludge (RAS) stream.  
 
Further, the biofilm potentially buffers seasonal kinetic variability (i.e., degree of acclimation). Low DO operation presents challenges at cold temperatures (10-13˚C), as very long aerobic solids retention times (SRTs) are required for full nitrification. While microbial acclimation to low DO may overcome these limitations, adaptation is not guaranteed and can introduce treatment and operational challenges.  With a biofilm, nitrification activity by the biofilm increases when the suspended sludge performance worsens. 
 
Our study combines process modeling and pilot-scale system operation to evaluate the potential for intensification and the synergistic effects of MM and low DO operation on nutrient removal performance and stability. To test the modeling-informed hypotheses, pilot-scale research is being conducted at the Boulder WRRF (Colorado, USA) using a 400-gallon reactor system treating primary effluent. Currently, a comparative study of activated sludge and hybrid MM systems is being performed using sequencing batch reactors. Next, a plug flow configuration will be evaluated. This research will offer a compelling nutrient removal roadmap for WRRFs needing to meet nutrient limits while advancing towards sustainability goals.

Effective headworks screening is the foundation of reliable and cost-efficient wastewater treatment. Our presentation, Wastewater Screen Technologies and Design Considerations, provides a comprehensive and practical guide to selecting and designing screening systems that maximize protection of downstream processes, extend equipment life, and reduce long-term operating costs.
 
Drawing on data from the UK Water Industry Research’s internationally recognized National Screen Evaluation Facility, we will demonstrate how Screenings Capture Ratio (SCR) directly impacts plant performance and operational efficiency. Attendees will gain a clear understanding of the comparative effectiveness of screen types—including center flow, through flow, multi-rake, and step screens—and how SCR influences debris removal, maintenance demands, and sludge quality.
 
Beyond theory, the session emphasizes real-world application. We highlight design standards for screen velocities, explore velocity adjustment strategies, and share proven approaches to minimizing headloss and eliminating bypass. Attendees will see how advanced design features—such as stainless steel construction, non-submerged components, replaceable wear tracks, and fully enclosed housings—optimize safety, reliability, and odor control.
 
We will also address the full screening process by examining screenings handling systems, including washing, compacting, dewatering, and transport technologies, ensuring that participants leave with a complete understanding of both front-end screening and downstream solids management.
 
The presentation concludes with case examples across municipal and industrial applications—from membrane bioreactors (MBR) and combined sewer overflows (CSO) to septage receiving stations and industrial intakes—demonstrating the versatility of modern screen designs.
 
By blending technical rigor with practical insights, this session equips decision-makers, designers, and operators with the knowledge needed to select the right technology, ensure regulatory compliance, and deliver long-term operational savings.

Ashbridges Bay WWTP in Toronto is anticipated to reach an average daily flow of 818 megalitres per day (ML/d) in 2054. Due to space limitation for future expansion, intensification of existing secondary treatment is required. 
Different technologies were explored to intensify the existing trains, including S2EBPR. S2EBPR would intensify secondary treatment through promoting enhanced biological phosphorus removal (EBPR); the process increases readily biodegradable substrate to enhance floc-forming microorganisms such as phosphate accumulating organisms (PAOs). The facility typically achieves phosphorus removal through chemical precipitation in grit and primary treatment with dosing ferrous chloride.
The City of Toronto along with Jacobs has piloted S2EBPR in an existing secondary treatment train. One of the existing eleven activated sludge aeration tanks is modified to evaluate the potential for secondary treatment intensification by S2EBPR to increase the process capacity. 
Multiple modifications were completed on Aeration Tank 2 (AT2) to achieve required operational conditions for S2EBPR: 

• Converting upstream passes of the AT2 to fermentation cells
• Extending return activated sludge (RAS) distribution system from the main RAS header to distribute RAS flow between the fermentation and anaerobic cell appropriately 
• Converting underflow to overflow baffles between the fermentation and anaerobic cells to retain sludge in the fermentation cells and direct supernatant flow from fermentation to the next cells 
• Installing mixers and oxidation-reduction potential (ORP) probe in the fermentation cells to enhance and monitor fermentation

An intense sampling program was conducted from February to September 2025 to evaluate the process performance. Three testing periods were performed with intense substrate/nutrients profile and settling testing to evaluate the impact of S2EBR implementation on process performance and capacity. Flow to AT2 was increase from approximately 10% of total plant influent in Phase 1 to approximately 16% of total plant influent in Phase 3.
The trial results show that fermentation and EBPR began developing about one month into Period 1. S2EBPR performance improved in Period 2 due to higher solids retention in the fermentation cells from increased RAS flow; this produced higher rbCOD concentrations and greater phosphorus release, indicating stronger PAO activity. Effluent ortho‑phosphate remained below 0.5 mg‑P/L in Periods 1 and 2, supported in part by ferrous dosing. In Period 3, phosphorus release increased further, suggesting enhanced PAO activity after ferrous dosing to AT2 stopped. Although effluent phosphorus rose slightly, it generally remained below 0.5 mg‑P/L.
A key objective of the trial was to assess process intensification potential. Settling tests showed clear shifts in sludge characteristics, including formation of dense sludge (>3 m/h) and partial granulation (>9 m/h). Granule fractions peaked at 35% in July when SVI was 82 mL/g, then declined in August due to increased flow and no ferrous dosing. S2EBPR significantly reduced AT2 SVI (80–105 mL/g) compared to a control train (AT6), where SVI ranged from 110–180 mL/g at similar or higher flows. Ferrous dosing strongly improved AT6 settleability but had a weaker effect on AT2.
Overall, the trial demonstrated that S2EBPR promotes dense sludge formation, increases secondary treatment capacity, and reduces reliance on costly ferrous chemicals. With appropriate bioreactor design and operational adjustments, process intensification can be achieved with S2EBPR.

Conventional municipal wastewater aeration relies heavily on the activated sludge method, in which blowers or compressors force air through small bubble diffusers at the bottoms of aeration basins. These bubbles slowly rise to the surface, transferring oxygen in the process, and allow microorganisms to digest the carbonaceous matter in the waste stream.  Recently, a new technology is being developed, termed a Confined Tube Aerator (CTA). Here, a pump draws water from a basin and forces it through a Venturi aspirator, where air may be naturally entrained. This multiphase mixture then travels to a coiled tube where oxygen may be transferred without stratification. The proposed technology has strong potential for cold‑climate operation, smaller physical footprint, and reduced operational requirements, making treatment feasible where conventional, lagoon-based systems are impractical.
The efficiency of a CTA system is highly dependent on the losses in the Venturi aspirator itself. Typically, assessment of Venturi aeration efficiency relies on testing, where Dissolved Oxygen (DO) content and pump power draw are used to evaluate standard metrics such as Standard Oxygen Transfer Rate (SOTR) and Standard Aeration Efficiency (SAE). However, these tests are time consuming and costly, and a new metric is proposed herein to use thermodynamic principles to gauge relative improvements in Venturi injector performance. This metric, called the Venturi Efficacy (VE), relies on motive water flow rate, inlet and outlet Venturi pressure, and ingested air flow rates, along with statistical measurements of bubble sizes to provide a relative measurement of the ratio of interfacial surface area flux to entropy generation within the Venturi injector.
The goal of this study is to compare calculated Venturi Efficacy measurement with SAE measurements using aeration tests. To perform each test, sodium sulfite is used to scrub a large 1000L tank of water of oxygen. Then, aeration is performed to saturated levels using a CTA assembly, with varying pump speeds and outlet valve position, the latter drastically affecting back pressure and hence, air injection. SOTR and SAE measurements were obtained for each test and compared in a relative manner to VE calculations.
Preliminary results show that system parameters including bubble size, air and water flow rates, and thermodynamic analysis of entropy generation can be used to assess a Venturi injector performance, relative to a baseline. This approach has the potential to decrease CTA system testing costs as compared to traditional aeration testing.

The introduction of dosed vertical flow biofilters, DVFBs, a form of submerged constructed wetland for municipal wastewater treatment, have proven successful in cold climate regions of northern Europe, principally in Austria, Germany, Denmark and Poland.   This technology should not be confused with the very successful French system for use in temperate climates.  The primary differences between cold climates and temperate climates are the survival of plants during the winter in temperate climates and the dormancy of plants during the winter in cold climates; and, the fact that surface water will freeze.  Only submerged constructed wetlands are used in cold climates to avoid complexities associated with freezing.  The Canadian environment is a cold climate.  Initial attempts in using DVFB technology in Canada for treatment of municipal wastewater, while still in the development stage, are promising.
 
Computer modelling (simulation) of the combined hydraulics and treatment processes inherent to the DVFB technology have had limited success.   The flow through the filter bed of a DVFB is a complex mixture of saturated and unsaturated flow that can be successfully modelled despite its complexity.  But, while the treatment processes are generally known, their kinetics have not been accurately identified and models which attempt to combine the simulation of hydraulics with the treatment processes have not been able to reliably reproduce observations of flow or quality of treatment.  Consequently, most design activity relies on the growing body of information from those installations which are performing satisfactorily.
 
The combined hydraulic and treatment kinetics (CHTK) model described uses a combination of the accurate identification of the treatment processes and associated kinetics, an understanding of the hydraulics of the dosing process together with the experience and knowledge gained from successful DVFB facilities in Europe that are enshrined in the form of national guidelines and standards.  Procedures to implement the CHTK model have been developed.
 
The potential for successfully using DVFB technology throughout Canada, a cold climate, is greatly increased with the use of the CHTK model.

Lagoon facilities in Canada are facing more stringent effluent requirements for BOD, TSS, and nutrient removal. This presentation will demonstrate an updated approach for lagoon-based wastewater treatment and will provide a comparison of past lagoon design standards to current ones and introduce advanced lagoon technologies that can be implemented for nutrient removal strategies. In-depth case studies will be included to showcase how lagoons in cold climates are being successfully updated to effectively meet current and future effluent requirements.
Attendees will:

• Learn how lagoon technology has evolved to meet changing effluent standards for BOD, TSS and Nutrient removal.
• Gain insight into the value of process modelling for designing efficient and effective lagoon- based treatment systems for Canada’s effluent requirements. 

Understand how traditional lagoon systems were designed and their typical treatment performance. 

In 2022, the Town of Lumsden replaced its aging lagoon system with a modern Class 3 mechanical wastewater treatment facility, demonstrating how innovative design and strategic planning can deliver sustainable, cost‑effective infrastructure within tight regulatory and financial constraints. Designed to serve 2,500 residents in Stage 1 and 3,700 in Stage 2, the new plant provides a scalable treatment solution tailored for growing small communities seeking enhanced environmental protection.
 
The project included construction of a new main lift station, headworks building, process building, and a community‑focused odor control strategy. The liquid treatment train incorporates screening, grit removal, two sequencing batch reactors (SBRs), and UV disinfection. Solids management systems include sludge pumping and storage, rotary drum thickening, dual aerobic/anoxic digesters, centrifuge dewatering, and dedicated biosolids storage. Chemical treatment, aluminum sulfate for phosphorus removal, polymer for thickening and dewatering, and sodium carbonate for alkalinity, supports reliable, optimized performance. Since commissioning, the facility has consistently met all provincial effluent requirements, including CBOD₅, TSS, ammonia, E. coli, total nitrogen, phosphorus, and acute lethality parameters.
 
This presentation will walk through the project lifecycle, from planning and design through construction and commissioning, highlighting key challenges, lessons learned, and successes. The Lumsden WWTP showcases Stantec’s modular approach to capacity planning, with an initial two‑basin SBR system that meets current needs while streamlining future expansion for a growing community.

Machine learning (ML) is increasingly applied in Water Resource Recovery Facilities (WRRFs) to improve operational decision-making, yet most implementations remain fragmented and highly dependent on either large historical datasets or narrowly defined use cases. This work presents a unified fit-for-purpose perspective on scalable ML applications for WRRFs through two complementary case studies addressing both data-rich and data-scarce operational challenges.
The first case study focuses on influent flow forecasting for proactive plant-wide optimization. Accurate forecasts enable improved chemical dosing, staffing, maintenance planning, and mitigation of wet-weather impacts in combined sewer systems. An ensemble ML framework integrating Random Forest (RF), eXtreme Gradient Boosting (XGBoost), Long Short-Term Memory (LSTM), and Gated Recurrent Unit (GRU) models via a meta-learner was developed to leverage the usually available influent flow historical data and provide robust forecasts up to seven days ahead. Tested across 30 WRRFs (2022–2024) with average daily flows ranging from 0.3 to 146 MGD and peak flows approaching 300 MGD, the framework achieved average Mean Absolute Percentage Error (MAPE) below 11% and Nash–Sutcliffe Efficiency (NSE) around 50% for 7-day forecasts, including during extreme wet-weather events. Adaptive preprocessing tailored to dataset characteristics proved critical for consistent performance across diverse facilities.
The second case study addresses data scarcity through a new soft-sensing paradigm for monitoring biological processes without relying on historical plant data. Probabilistic ML models are trained exclusively on synthetic datasets generated from uncertainty-aware mechanistic simulations, producing priors over plausible process behavior. During deployment, predictions are refined through Bayesian updating using sparse laboratory or online measurements without model retraining. Demonstrated for real-time monitoring of both ammonia concentrations and the amount of simultaneous nitrification–denitrification (SND), the framework achieved 90% empirical coverage of true values in simulations and is currently being validated on pilot-scale using only occasional nitrogen measurements.
Together, these case studies illustrate how ML can support both predictive planning and real-time process insight across WRRFs with varying levels of data availability. By combining state-of-the-art ML methods, synthetic-data-driven probabilistic modeling, and Bayesian updating, this work outlines a scalable pathway toward uncertainty-aware digital monitoring and decision support in wastewater treatment systems.