PROCESS STUDIES ON EFFICIENCY OF COMMERCIAL flAT POLYETHERSULFONE (PES) WATER PURIFICATION MEMBRANES ON FISH PROCESS WASTEWATER TREATMENT THROUGH MEMBRANE BIOREACTOR (MBR) TECHNOLOGY
Membrane bioreactor (MBR) technology is a waste water treatment technique that combines biological activated sludge process (ASP) and membrane filtration. This study was conducted to test and compare the performance of two commercial flat polyethersulfone (PES) membranes submerged in a membrane bioreactor (MBR) for treatment of wastewater from fish processing industry. Waste water sample was collected from Makindi fish farm processing unit. The sample was transferred to JKUAT-chemistry laboratory and analyzed for biological oxygen demand(BOD), chemical oxygen demand (COD), dissolved oxygen (DO), pH, conductivity, total dissolved solid (TDS), dry mass, phosphate and nitrate levels. Nitrates and phosphates were analyzed at wavelength of 220nm and 830 nm respectively using UV/Visible spectrophotometer (Model:UV- 1800) from (Germany). A small lab scale MBR unit fitted with a denitrification tank and an aeration tank constituting two submerged membrane modules was used. The feed water was pumped into the denitrification tank for reduction of nitrate levels, then was pumped to the MBR reactor tank for treatment process. The MBR operating conditions were optimized and maintained throughout the treatment process. The level of dissolved oxygen (DO) in the MBR range was 4.0-7.0mg/L. The MLSS and food microorganism (F/M) ratio was (0.4-3.0g/L) and (0.4-0.8) kg COD/ (Kg MLSS.d) respectively. The MBR had water permeability (WP) level in the range of 146.6±9(L/m2hbar) and 119.8±20(L/m2hbar) for mobdule 1 and 2 respectively. High quality efluent was produced with over 90% removal of COD achieved. Nitrate, ammonia and phosphate levels were significantly reduced with (t observed > t calculated) for paired T-test (at 95 % confidence level). The commercial flat PES water purification membranes were found to be efficient for production of high quality effluent that can be recycled for irrigation in agricultural fields located within the surrounding area and for aquaculture.