Direct water reclamation from sewage using ceramic tight ultra- and nanofiltration

• Sewer mining using ceramic tight ultra- (CUF) and nanofiltration (CNF) was studied.
• Efficient cleaning of CUF and CNF membranes during sewage filtration was achieved.
• Hydraulic backwash did not benefit the performance of the CUF/CNF fed with sewage.
• CNF was proven to be suitable as RO pre-treatment during the sewage filtration.

Sewage is a nutrient rich reliable water source that is rather consistent in quality, volume and temperature, and is available in large amounts in urban areas. Decentralised reclamation of water including its constituents from municipal sewage, further referred to as sewer mining, is a concept in which municipal sewage is considered a resource instead of a waste stream.In this research, water reclamation in the sewer mining concept was studied using ceramic tight ultra- (UF) and ceramic nanofiltration (NF). In our current approach, ceramic membrane filtration is proposed as pre-treatment for reverse osmosis (RO) to produce demineralised water for industries from municipal sewage. The objectives of this research are to study (i) the membrane performance, (ii) the organic matter and ion rejection, and (iii) the biofouling potential of RO using permeate water from the ceramic filtration.The application of ceramic tight UF and ceramic NF for direct treatment of domestic sewage has been demonstrated in this study. The cross flow ceramic tight UF and NF fed with filtered sewage, can be operated for 1–4 days without any cleaning required. The membrane performance remained high with chemical cleaning with NaClO (0.1%) and HCl (0.1 mol L−1) solutions. On average about 81% of organic matter was rejected by both ceramic tight UF and NF membranes. Finally, the pressure drop increase in the MFS fed with ceramic NF permeate was low during an operation of 14 days. These results were comparable with the increase in pressure drop of an MFS fed with Dutch drinking water.