Optimizing Performance of a Side-Stream Enhanced Phosphorus Removal System

In 2019, WERF Published the report "Optimization and Design of a Side-Stream EBPR (S2EPR) Process as a Sustainable Approach for Achieving Stable and Efficient Phosphorus Removal U1RI3/4869". The WERF study goals included the identification of the fundamental mechanisms involved in a RAS fermentation process (S2EBPR) and to develop criteria for effective design and operation of the process. To achieve the objectives, the research team conducted a survey of data from six full-scale facilities, simulated side-stream reactor batch testing, and performed full-scale pilot testing with side-by-side S2EBPR and conventional EBPR processes. The WERF report noted that the Westbank Process configuration was very stable and produced the lowest secondary effluent orthophosphorus concentrations of all plants studied. It was also noted that unique to the Westbank Regional Facility that more than 75% of the time phosphorus uptake was measured in the anoxic zones (Onnish-Hayden et al, 2018). Fluorescent In-situ Hybridization (FISH) and amplicon sequencing found relatively high abundance of Tetrasphaera in the S2EPR configurations. The highest relative abundance of the all the plants studied was found in the Westbank Regional Facility. The WERF researchers postulated that this could be attributed to the addition of primary sludge fermentate to the anaerobic side stream reactor and to the mainstream anoxic zone. It was thought that the fermentate could contain Tetrasphaera that could act as a seed to the mainstream providing a competitive niche to those organisms.