Industrial membrane processes in the treatment of process waters and liquors

摘要

A review on pulp and paper industrial membrane processes using a variety of modulesnand processes is presented. Membranes are mostly used today to purify processnwaters and to recover coating colours. Ultrafiltration using tubular membrane modulesnor cross-rotational (CR) filtration has been widely applied for the purification of process waters.nThe reuse of UF membrane permeate has decreased the fresh water consumption to lowernthan 6m3/t of paper in some paper machines. Some industrial membrane processes alsonrecover valuable products from different streams (e.g lignosulphonates). Membranes arenalso combined with biological degradation processes in some paper mills. Nanofiltration hasnbeen used to purify the effluents discharged from the activated sludge process. At least twonreverse osmosis plants purify river water to be used as raw water in the mill. Furthermore,nadvantages of different membrane modules and the current ways to treat membranenconcentrate are discussed.