Evaluation of Woven Fiber membrane bioreactor efficiency for domestic wastewater treatment

Abtract

Water pollution becomes burning issue in Ho Chi Minh City (HCMC) because a vast of untreated wastewater from domestic and industry daily discharged into water body. Wastewater from a septic tank significantly contributes to the pollution of water because its effluent does not meet the national technical regulation on domestic wastewater before it is discharged. At the same time, high exploitation rate of fresh water resource for domestic, industrial and service activities in HCMC have resulted in the degradation of ground water. Therefore, the reuse and recycle of reclaimed water is recommended as an alternative water resource to solve the water demand, also reduce the water pollution of Ho Chi Minh City in the future. A pilot scale study of Woven Fiber Microfiltration (WFMF) with pore size from 1 – 3 µm in form of flat sheets was applied in the last compartment of a septic tank to improve the quality of the effluent of the septic tank, but not modify the structure of the septic tank that was already built before. The flux of 4 L/m2.h was suggested as a sustainable flux for the working of WFMF in an anaerobic condition in a septic tank. For 68 days with the presence of WFMF in the septic tank, the efficiency of reducing COD was from 20% to 38%. SS removal was high with over 95%, and the concentration of SS of effluent was under 10 mg/L. However, nitrogen and phosphate removal was not effective in anaerobic condition, under 10%. The removal efficiency of coliform was from 68.18% to 99.62%. Organic compounds, suspended solids, and pathogens were significantly reduced in the effluent of a septic tank upgraded by WFMF. However, useful nutrients such as nitrogen and phosphorous were still high in the effluent. To minimize the environmental pollution and overcome the shortage of water exploitation in Ho Chi Minh City, Vietnam, treated effluent after disinfection was recommended for irrigation of parks, flower gardens, and grass golf in this city.

Keyword: domestic wastewater, membrane, Woven Fiber Microfiltration, septic tank.

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