| The large increase of wastewater discharge in China has imposed an demand on new and efficient wastewater treatment technologies to reduce adverse environmental impacts. The large production of excess sludge from biological treatment will become increasingly more. In this study, efficient degradation of coking wastewater and sludge reduction are focused, and a novel fluidized bed membrane bioreactor (MBR) combined was used as a core biological treatment unit. Beside, Fenton oxidation technology was also used to oxidize the excess sludge, as well as to degradate some coking wastewater organics so that sludge could be realized.The process of coking wastewater treatment in MBR with and without Fenton oxidation showed that both of system had good effluent quality and high efficiency of coking wastewater treatment. However, MBR without Fenton oxidation need continuous sludge discharge to maintain stable operation, while simultaneous treatment of wastewater and excess sludge was achieved in the MBR with Fenton oxidation process, sludge yielding (0.0023 g·MLVSS·(g·COD)-1) approached zero and the decreasing of sludge activity was slight.The effect of DO on the performance of simultaneous nitrification and denitrification (SND) was studied. It was found that lower DO concentration is advantageous to SND on condition that nitrification was not affected. The optimized removal of TN was 91.9% in condition of sludge concentration at 7800 - 8200 mg·L-1, DO at 0.8 mg·L-1. In addition, the higher influent C/N and appropriate increase of F/M was advantageous to SND efficiency. Through batch test, it showed that microbial used organic matter as the priority at high substrate concentration, and an increasing speed of SND with the decrease of substrate concentration. Results also showed that denitrification was the limitation step in the SND process. The nitrification and denitrification process in MBR was simulated, and the possibility of simultaneous mineralization and nitrification happened was also analyzed. Under the conditions of SND, the denitrification seemed to be rate-limiting step.The mechanism study of Fenton oxidation using sequencing batch reactor showed that, the solubilization of excess sludge was divided into two phases. The first was mainly to break cells, which could be shown by the rapid decrease of sludge concentration and increase of dissolved organic matter concentration in the solution; second stage was mainly for the oxidation of dissolved organic matter, which could be shown by the decrease of dissolved organic matter concentration after increasing to the maximum. The optimized condition of sludge disintegration is pH = 3.0, H2O2 of 8000 mg·L-1, H2O2/Fe2+ = 40 : 1, reaction time of 90 min. Continuous operation of MBR with and without Fenton oxidation showed that both of them had high efficiency of organic matter degradation. Considering the additional organics and TN introduced into systems by the Fenton oxidation process, the system with the sludge Fenton oxidation had higher organic and TN loads. The removal total mount of COD and TN in Fenton oxidation system was higher than the MBR. The average sludge yield of the MBR with and with out Fenton oxidation was 0.006 g·MLSS·(g·COD)-1 and 0.15 g·MLSS·(g·COD)-1, respectively. The study showed that small quantity of activated sludge Fenton oxidation and recycled into MBR was significantly effective for the minimization of excess sludge production as well as for the enhancement of TN removal.The varation of the membrane flux was tested as well, and it was found that the membrane flux reduced about 40% during the initial 7 d. The membrane flux in the low sludge concentration of membrane modules was higher than that of the high sludge concentration of membrane modules. And SCOD was an important factors which influenced the membrane flux. Through the analysis of membrane fouling mechanism, using the appropriate chemical cleaning methods, the loss of membrane flux of 50% could be recovered after repeated washing five times.
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