Mechanistic understanding of simultaneous energy and phosphorous recovery in a single anaerobic reactor: Path to resource-recovery based wastewater treatment

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Water and wastewater collection and treatment are energy intensive and costly processes. Given the deteriorated state of Canadian wastewater treatment systems and aging water infrastructure generally, a transition towards more sustainable resource-recovery based wastewater management is urgently needed. Liu's research group developed anaerobic digestion (AD) processes for simultaneous energy and phosphorus (P) recovery within AD reactors, a process patented as SPRING. This was achieved using a modified upflow anaerobic sludge blanket (UASB) reactor, operated under mesophilic and thermophilic conditions, treating both source-diverted brown and blackwater. High methane production and organic loading rates were achieved for both water types far exceeding previously reported yields. Most significant was P recovery in the form of precipitates in the anaerobic granular sludge without chemical addition. Further studies are needed to identify the roles of key engineering design and operation parameters in the development of functional microbial communities and explore process limitations and optimisation options. The long-term goal of the proposed DG program is to integrate sustainable resource-recovery based wastewater treatment using AD innovations in sewage management in Canada and abroad. The short-term objective of the proposed program is to explore the link between key ecology and metabolic functions and engineering parameters, and to develop cost-effective design and operation strategies for AD energy and P recovery, leading to more sustainable wastewater management. The proposed research will address two aims: A) Elucidate the mechanisms associated with the SPRING process by exploring key engineering factors influencing wastewater energy and P recovery and studying interactions of the microbiota under selected engineering operation conditions and associated localised chemical conditions for P recovery; and B) Redesign the SPRING process by linking microbial processes to engineering design to optimise wastewater energy and P recovery based on key engineering parameters identified in Aim A and to assess new AD operation strategies and designs for Canadian conditions. The proposed program will provide the scientific foundation for resource-recovery based biological wastewater treatments, guide solutions that can gradually displace the conventional energy-intensive practices, serve new promising local and international markets and address escalating capital and operating costs due to the ever-increasing stringency in discharge requirements. It will support pioneering activities considered by developers and Canadian municipalities/utilities, so that communities can aspire to net zero water, energy and residuals in water services, through resource-recovery based treatment technologies that do not discharge wastewater via leakage or outfalls but recover fit-for-reuse water, improving receiving water quality and lowering greenhouse gas (GHG) emissions.