Flat-plate submerged membrane bioreactor for the treatment of higher-load graywater

Graywater treatment has been the focus when topics of decentralized treatment systems are discussed. In this paper, the treatment of higher-load graywater, a mixture of washing machine and kitchen sink wastewater, was investigated. A 10 L lab-scale submerged membrane bioreactor (subMBR) was operated with a flat-plate membrane for 87 days. Permeate was intermittently withdrawn at constant transmembrane pressure (TMP) induced by water level difference and without pump requirement. The pollutants' removal and membrane behavior were monitored. The COD removal was around 96% and a permeate COD of about 26 mg L-1 was obtained. The total linear alkylbenzene sulfonate (LAS) removal achieved was >99%, indicative of its non-inhibited degradation even at influent concentration of 30.8 mg L-1. The subMBR was operated at almost stable and constant flux of 0.22 m(3) m(-2) d(-1) at a mean HRT of 13.6 h. (C) 2009 Elsevier B.V. All rights reserved.