Waste sludge reduction with a pilot-scale membrane bioreactor for point source pollution management

It is an important subject to reduce the amount of waste sludge from small-/middle-scale wastewater facilities for the establishment of point source pollution management. In this work, we focused on the development of sludge decomposition system which did not increase organic loading ratio into wastewater treatment units. The excess sludge produced from wastewater treatment plant of a food factory was decomposed by an aerobic digestion technology with a membrane bioreactor (MBR) system. It was composed of digestion tank (500 L) and a membrane filtration unit (350 L). Sludge was decomposed under the following conditions: 25 g L-1 of MLSS, 36.9 d of HRT, average temperature 32.3°C, and 0.565 kg-SS m-3 d-1 of sludge loading rate. The system decomposed 77.2% of the fed sludge to inorganic carbon, and all of average TOC, CODMn and CODCr in the effluent were less than 50 mg L-1. However, the effluent contained T–N and T–P at 200 mg N L-1 and 150 mg-P L-1, respectively. The quinone profile analysis indicated that the consortia of sludge in the reactor were different from the fed sludge.