Food industry wastewater treatment by ceramic micro- and ultrafiltration membranes

Water scarcity is one of the global problems threatening all living species on Earth. Several solutions have been suggested for resolving the water scarcity. One of these solutions is the treatment of domestic and industrial wastewaters. Treatment and reuse of domestic and industrial wastewaters will significantly contribute to the prevention of the water scarcity. Membrane technology has been used for the treatment of wastewaters and water desalination. Membranes used are generally polymeric membranes. Studies however have been conducted to evaluate the performances of ceramic membranes in wastewater treatment. The goal of this thesis was to prepare tubular ceramic membranes for the treatment of food industry wastewaters. Tubular Al2O3 supports, MF and UF layer coated supports were prepared and used for the treatment of oil containing wastewaters obtained from the different stages in the wastewater treatment facility of the food processing plant. Total suspended solid content (TSS), chemical oxygen demand (COD), color, turbidity and oil content of the wastewaters were determined before and after filtration experiments. Permeate fluxes, TSS, turbidity and color of the permeate samples taken in certain time intervals were also monitored. Permeate fluxes much lower than clean water fluxes of the membrane were observed during the filtration of oily wastewater. In general, increasing cross flow velocity increased the permeate flux while the increase in transmembrane pressure decreased the flux. The lower initial permeate fluxes indicated the rapid membrane fouling by oil and lipids present in the wastewater. Decrease in the fluxes in the course of filtration also pointed out the formation of a fouling layer. Filtration experiments performed using tubular ceramic supports and MF membranes resulted in 97-99 %, 91-98 %, 78-99 % and 63-99 % reductions in TSS, COD, turbidity and color values of the oily wastewater, respectively. No oil could be detected in the permeate samples collected and oil removal efficiencies were found to be 100 % in all experiments. Keywords: ceramic membrane, food industry wastewaters, oil content, filtration, permeate