Resource recovery as irrigation water and struvite from forward osmosis-based anaerobic microfiltration-membrane bioreactors treating slaughterhouse wastewater

Abstract

Sustainable wastewater management by resource recovery from wastewater is essential due to increasing resource and water scarcity. Therefore, while studies are conducted to improve conventional treatment systems, new technologies are also needed to recover water and nutrients. Anaerobic microfiltration osmotic membrane bioreactors (AnMF-OMBRs) and up-flow anaerobic sludge blanket microfiltration osmotic membrane bioreactors (UASB MF-OMBRs) are innovative technologies for high-effluent quality and resource recovery. The microfiltration (MF) permeates of these systems containing high amounts of salt, nitrogen, and phosphorus, provide an opportunity for resource recovery. Membrane processes, like nanofiltration (NF) and reverse osmosis (RO), are among the feasible options for resource recovery from MF permeates of these systems. This study aims to recover water and nutrients from the MF permeates of AnMF-OMBR and UASB MF-OMBR treating slaughterhouse wastewater by using NF or RO. Based on the results, only the RO permeates were found to be suitable for irrigation. Then, chemical precipitation was applied to the RO concentrate to evaluate the potential for struvite. >99 % PO43- recovery was achieved at all pH values while the optimum struvite precipitation was detected at pH 9. From 1 L of RO concentrate, 11.9 g of struvite could be recovered. The cost analysis showed that the specific produced permeate cost of NF systems (0.123-2.30 US$ m(-3)) was slightly lower than that of RO systems (0.430-2.64 US$ m(-3)). Consequently, the RO was effectively applied to MF permeates of forward osmosis (FO)-based anaerobic microfiltration osmotic membrane bioreactors (AnMF-MBRs) to recover water and struvite simultaneously.