Immersed membrane bioreactors for nitrate removal from drinking water: Cost and feasibility

摘要

Brine disposal remains a key consideration when employing ion exchange (IEX) for nitrate removal. To circumvent this issue, research was conducted into developing an immersed membrane bioreactor (MBR) as a replacement for ion exchange. This paper compares the economics of the two process options whilst also considering MBR for brine treatment. At a blend flow rate of 3000 m~3.d~(-1), total life cycle costs were ￡0.095,0.128 and 0.064.m~(-3) for IEX, MBR and IEX with brine recycle MBR respectively. Capital and O&M costs associated with MBR were extremely sensitive to membrane price variation. For blend flows >700 m~3.d~(-3), IEX with brine recycle MBR proved the most cost effective option (total life cycle cost ￡0.044-0.087.m~(-3),1500-30000 m~3.d~(-1)) when assuming similar hydrodynamic efficiencies to the IEX replacement MBR. Further cost reductions (≤17%) can be found by operating Brine recycle MBR at higher salinity (～100 g NaCl.L~(-1)), provided an appropriate halo-tolerant community can be established.