Capillary nanofiltration coupled with powdered activated carbon adsorption for high quality water reuse

Direct capillary nanofiltration was tested for reclamation of tertiary effluent from a municipal wastewater treatment plant. This process can be regarded as a promising treatment alternative for high quality water reuse applications when combined with powdered activated carbon for enhanced removal of organic compounds. The nanofiltration was operated at flux levels between 20 and 25 L/(m² h) at a transmembrane pressure difference of 2–3 bar for approximately 4,000 operating hours. The study was conducted with PAC doses in the range from 0 to 50 mg/L. The plant removal for DOC ranged from 88–98%. The sulfate retention of the membrane filtration process was between 87 and 96%. The process provided a consistently high permeate quality with respect to organic and inorganic key parameters.