Recovery of reusable water from sewage using aerated flat-sheet membranes

Continuous developments and advances in membrane technology allow recovering to large extent reusable water from untraditional water sources, such as municipal effluents. In this paper, operational results and preliminary cost-analysis of a microfiltration (MF) process used for raw sewage and secondary effluent polishing are given. The research was conducted with a 22 sandwich-type flat-sheet membrane module (0.45 μm and 4.5 m²) employing aeration for fouling control. During raw sewage filtration the majority of the organics were retained (effluent COD < 90 mg/L and SS ∼ 0 mg/L). However, the fluxes were significantly lower [∼7 L/(m² h)] compared to those achieved during secondary effluent filtration [∼29 L/(m² h)] (at TMP 0.14 bar). In the second case, aeration was found to be suitable mean for fouling control. The total costs (capital and operational) for water recovery from raw sewage and secondary effluent were estimated to be in the order of 2 and 0.75 €/m³ respectively.