Domestic wastewater treatment using immobilized sludge fluidized-bed reactors

Bench-scale fluidized-bed reactors using the immobilized activated sludge p rocess were studied for the treatment of domestic wastewater. Different int ermittent aeration patterns were investigated in order to improve the total nitrogen (TN) removal. The best TN removal at 74.4% was achieved at an HRT of 6 hours (with corresponding BOD loading rate of 0.766 kg/m(3)/d) and an aeration-pattern of 1,3 (the hours of aeration and non-aeration time cycle ). The removal efficiencies for organic carbon, NH4+-N, TKN and TSS were no t affected and remained at more than 90%. Simultaneous organic carbon and n itrogen removal was accomplished in a single immobilized sludge reactor. Th e impact of various influent feed patterns on the treatment was examined. T he continuous feed pattern was recommended as it ensured good TN removal wi thout any adverse impacts on the removal of organic carbon, NH4+-N TKN and TSS. The immobilized sludge beads exhibited satisfactory mechanical stabili ty without apparent breakage over the 180-day experiment period.