Water reclamation with membrane bioreactors

The City of San Diego was awarded a grant from the Bureau of Reclamation to investigate the feasibility of using Membrane Bioreactors (MBRs) for water reclamation. Based on the findings of the first phase of the project (Adham et al., 1998), the project team concluded that a parallel comparison of commercially available MBR systems needed to be evaluated at pilot-scale. Two submerged MBR systems were evaluated at the Aqua 2000 Research Center in Escondido, California. The project was designed to evaluate the MBR performance treating municipal wastewater and the feasibility of using the MBR permeate as a feed source for thin film composite reverse osmosis (RO) membranes. The first part of the project was dedicated to operating both MBRs in a nitrification and denitrification mode. After completion of Part 1 of the project, both MBR systems were retrofitted and operated in a nitrification only mode. Throughout both parts of the study, the effluent from each MBR was fed to two separate, single stage RO pilot systems. Both MBR systems showed high BOD removal with values below the detection limit, and significant TOC reduction. The effluent turbidities from the MBRs were consistently less than 0.1 NTU. Both MBRs also produced a high quality effluent that could be used by thin film composite RO membranes with minimal fouling.