Woven Fiber Microfiltration (WFMF) introduced in the third chamber of a septic tank as a submerged membrane for domestic wastewater treatment. Concentrations of black water stored in the third chamber were 125±15 mg/L COD, 124±28 mg/L SS and 59±9 mg/L TKN. Results showed that COD removal was 54-78% of which effluent achieved less than 50 mg/L. | Improving effluent quality of septic tank by low cost membrane in Viet Nam