WCW26

Granular media filters are at the heart of many water treatment plants and often the final barrier for particle removal. Although water treatment plants may vary in size and complexity, all granular media filters require backwash to recover the filter media after producing a batch of water. Filter Operators typically monitor and trend filter effluent quality and filter capacity. These two items are used by the Operator to determine if a filter is working well or not. To ensure efficient, sustained filter performance a third item should be added. The third item is monitoring and trending the backwash pressure. Unchecked, the backwash pressure across the filter can increase until the filter underdrain system becomes over-pressured and eventually fails. Even with a substantially plugged filter underdrain, the filter effluent quality and filter capacity may remain acceptable. Acceptable, until the filter underdrain fails! While a UFRV decrease or a filter effluent turbidity spike are readily noticeable, gradually increasing backwash pressure is silent.

Membrane failures in water and wastewater treatment systems often appear sudden, yet they typically result from progressive and detectable mechanisms. This presentation shares practical insights from conducting comprehensive membrane autopsies designed to uncover the root causes of performance decline. Using standardized procedures and analytical protocols, the work evaluates fouling layers, chemical deposits, structural damage, and operational histories to build a clear diagnostic profile for each membrane element. The results consistently reveal multi‑factor interactions—such as feedwater variability, pretreatment gaps, cleaning inefficiencies, and operational stress—that drive premature failure. By translating autopsy findings into actionable recommendations, utilities have achieved measurable improvements in flux recovery, cleaning effectiveness, and membrane lifespan. Attendees will gain a deeper understanding of how autopsy‑driven decision‑making strengthens asset management, reduces unplanned downtime, and supports more resilient treatment operations.

Reverse osmosis and nanofiltration (RO/NF) is widely recognized as one of the most effective processes for removing problematic water constituents from drinking water. However, the non-selective nature of RO/NF membranes also strips beneficial ions and CO₂ buffering capacity, resulting in permeate with low pH, and indices inferring relatively unstable water in the distribution system.
To produce stable finished water, RO/NF post-treatment stabilization/remineralization is beneficial. Common industry approaches include bypass streams, chemical dosing, and calcite/limestone contactors, each presenting distinct trade-offs in capital investment, operational complexity, maintenance requirements, and long-term consumable costs.
This presentation compares these stabilization strategies using real-world performance data from multiple full-scale RO/NF facilities. Key metrics evaluated include achievable index and pH targets, alkalinity and hardness remineralization, chemical and consumable costs, and operator involvement over years of operation.
Findings highlight which approaches deliver the best balance of water quality, reliability, and cost for different plant sizes and source-water conditions, providing actionable guidance for designers and operators seeking to optimize RO/NF post-treatment systems.

Many small and remote communities across Canada, including numerous First Nations, rely on legacy slow sand filtration systems that are structurally sound but strained by changing source water conditions, maintenance needs, and community growth. This presentation examines practical upgrade strategies that support the continued use of these facilities while improving system capacity, resilience, and operational efficiency.


Focusing on the intersection of established natural treatment processes and adaptable modern technologies, this session will highlight how enhancements such as pre-ozonation, roughing filtration, and surface-wash retrofits can improve biological performance, stabilize operations, and eliminate the need for sand replacement.


Case studies from MS Filter projects across Canada will feature observed performance outcomes, implications for long-term maintenance, and benefits for communities seeking to optimize existing infrastructure without the expense of full system replacement. Slow sand systems are sound, robust and sustainable. With customized upgrades, these systems will stand the test of time.