Abstract:
Woven-fiber microfiltration (WFMF) membrane was investigated as onsite treatment technology
for water and wastewater treatment. In this regard, flat sheet woven-fiber microfiltration
(WFMF) membrane was submerged in septic tank as membrane based septic tank (MBST) for
wastewater treatment. Objective was to reduce fouling frequency and prolong filtration time by
operating laboratory scaled MBST at three filtration-relaxation modes (FRM) of 30min-10min,
45min-15min and 60min-20min corresponding to 36, 24 and 18 cycles/day, operated at 8 LMH flux.
The average fouling rate (dTMP/dt) was found to be 17, 10 and 15 kPa/day respectively. Results
revealed that 45min-15min to be optimum FRM while the variation in removal efficiencies of
COD, TSS and NH4-N was 55-78, 60-85 and 30-40% respectively. Flat sheet WFMF membrane
was also evaluated for water treatment having turbidity 25±5, TSS 200±50 and fecal coliform
120±20 using optimized FRM. The removal efficiencies for turbidity, TSS and fecal coliform
were 78-89, 56-65 and 92-99% respectively. The treated water needed further disinfection to be
within limits of WHO drinking water quality standard. Physical and chemical cleaning was
applied separately on membrane and it was found that pore blockage resistance which caused
irreversible fouling may only be controlled by chemical cleaning
