Treatment of domestic wastewater using microfiltration for reuse of wastewater

This study was conducted to evaluate the applicability of microfiltration in treating domestic wastewater for reuse. A hollow fiber microfiltration membrane was used in the pilot test. The pore size of the membrane was 0.1 mu m and effective surface area was 20 m(2). The maximum capacity of the pilot plant was 10m(3)/d. The microfiltration system could be operated for 120 days without any cleaning procedure. It was found that agitation in the membrane tank had an effect on fouling prevention. In particular, the bi-directional agitation significantly reduced fouling. Chemical cleaning was effective in recovering of permeate flux and resistance, but in spite of chemical cleaning, fouling slowly progressed. According to the particle size distribution, in the membrane tank particles were transformed into smaller size by agitator-induced shear force. Based on mass balance analysis, about 60% of dissolved TOC mass removal in the system was attributed to biodegradation, indicating its important role. But suspended solids and colloidal matter were removed by the sieve mechanism of the membrane. Effluent quality was found to be lower than 30 mg/L of GOD, 10 mg/L of BOD, 10 mg/L of TOC, 1 NTU of turbidity and 2 mg/L of SS, respectively. It satisfies the standard for wastewater reuse.