Hybrid membrane bioreactor application for decentralized treatment and reuse

Abstract

Membrane bioreactor (MBR) technology is worldwide recognized, and it is also being applied for reuse purposes. The addition of biofilm support media has already been suggested as pure biofilm as well as hybrid membrane bioreactors (HMBR) in order to get more efficient, compact and stable systems. An original HMBR vertical configuration is here proposed for its feasibility as decentralized treatment, implementing submerged fixed bed biofilm support media (self-produced plastic nets filling the top part of the reactor) and submerged microfiltration membranes (collocated below the support media). The demonstrative treatment plant, tested at increasing loading rates (0.36-1.71 kg COD m^-3d^-1), was able to treat municipal wastewater without need of primary settling thus awarding high compactness as required to decentralized treatments. The system maintained good overall performances at increasing loading rates with special regard to organic matter and ammonium removal. Denitrification and total nitrogen removal were slightly affected by the loading rate's increase, until reaching stabilization to the new loading conditions. HMBR reliability in terms of stable effluent quality and the average characteristics of the effluent (among the others: [COD]<55 mgL-1, [SS]<4mgL-1, [TN]<10 mgL-1, turbidity<2 NTU) allow for discharge in sensitive areas as well as for reuse.