Sewage Treatment Triad: Better, Faster, Cheaper?
May 10, 2021
It is often mistakenly assumed that one of the triads must be sacrificed in favour of the other two. But with the right combination of innovative technology and mutually beneficial contract mechanism, all three can be consistently achieved. In today’s article, we will be focusing on the technology selection.
Across Western Canada, there are hundreds of lagoon systems that operate under a Code of Practice and discharge to the headwaters of prairie watersheds over a short period of time. In addition, the Fisheries Act includes the Wastewater Systems Effluent Regulations (WSER) that impose additional effluent quality criteria not covered within a Code of Practice. As household, industrial and commercial wastewater volumes continue to grow, many of these systems have reached their treatment and storage capacity. These limits may be encountered in some or all of their anaerobic, facultative or storage cells, with the solutions often coming down to expansion or replacement. Increasingly, we are finding that optimization can offer a superior answer.
We’ve looked at a number of treatment systems that are available within optimization strategy, including:
- Lagoon Expansion: increasing the footprint of anaerobic, facultative and storage lagoon infrastructure to improve performance under the existing Code of Practice;
- Membrane Bioreactors for Wastewater Discharge: installation of a modular membrane biofilm system (ie. Veolia’s Biosep™, Suez’s Leapmbr™ or Bishop’s BioCord™) within the existing lagoons to improve contaminant removal;
- Aerated Lagoons: augmenting oxygen levels to extend the effectiveness of facultative processes to overcome lower temperatures and reduced solar energy;
- Submerged Activated Growth Reactor (SAGR): installation of a post-lagoon fully-aerated buried stone bed (ie. Nexom™) to improve removal of ammonia and reduce vulnerability to colder temperatures;
- Biological Nutrient Removal (BNR) reactors: traditional rectangular (ie. Banff WWTP) or concentric-ring (ie. Jasper WWTP);
- Filtration Screening System: mechanical system (ie. Baleen™) for primary removal of grit, suspended solids, oil and grease upstream of aerated lagoons;
- Moving Bed Biofilm Reactor (MBBR): a modular attached-growth treatment process using palm-sized plastic media and aeration system (ie. Sapphire™) to remove BOD and nutrients;
- Membrane Straddle Plant for Reclaimed Water Quality: insertion of a small-footprint modular membrane system (ie. Swirltex™) and repurposing the existing lagoon infrastructure to optimize performance and reduce the footprint of agricultural land required for increase lagoon sizes; and,
- Algae cultivation: harvesting of residual nutrients within engineered controlled-growth media (ie. Symbiotic BiotekTM)
By fine-tuning the technology selection, integrating low-carbon power sources and maximizing the beneficial reuse of treated effluent/biosolids, it is possible to significantly improve the quality of effluent and enhance the downstream receiving environment. Key factors in selecting a technology include: modularization (to reduce field construction costs and improve build quality); energy-efficiency (by using real-time process control to respond to variable inflows); robustness (reduced vulnerability to process upsets); and reliability (selection of quality materials with proven low life-cycle costs). Often our analysis combines experience-based CAPEX and OPEX estimates, emphasis on mature supply chains and confirmation of timely troubleshooting and repair services.