Simultaneous treatment and single cell protein production from agri-industrial wastewaters using purple phototrophic bacteria or microalgae – A comparison

Resource recovery, preferably as high value products, is becoming an integral part of modern wastewater treatment, with conversion to heterotrophic or phototrophic/photosynthetic microbes a key option to minimise dissipation, and maximise recovery. This study compares the treatment capacities of purple phototrophic bacteria (PPB) and microalgae of five agri-industrial wastewaters (pork, poultry, red meat, dairy and sugar) to recover carbon, nitrogen, and phosphorous as a microbial product. The mediators have different advantages, with PPB offering moderate removals (up to 74% COD, 80% NH4-N, 55% PO4-P) but higher yields (>0.75 gCODremoved gCODadded-1) and a more consistent, PPB dominated (>50%) product, with a higher crude protein product (>0.6 gCP gVSS-1). The microalgae tests achieved a better removal outcome (up to 91%COD, 91% NH4-N, 73%PO4-P), but with poorer quality product, and <30% abundance as algae.