Study On Excess Sludge Minimization With In-Situ Ozonization-SBR Process

The treatment and disposal of excess sludge has becomed a trouble to wastewater treatment plant because of its large amount, high treatment cost and secondary pollution. Therefore, the technique of sludge reduction attracts more attention in the environment protection. Cell-lysis can achieve the sludge reduction by crack the cells of the sludge-constiuting microbes and releasing the materials within cell, which can be used by microorganism as substrates. Nowadays, cell-lysis is studied by many people to reduce the excess sludge due to its advantages.Several conventional cell-lysis techniques, including H2O2treatment, 60 centigrade thermometer and basic condition, 120 centigrade thermometer and basic condition, 120 centigrade thermometer treatment, ozone treatment and anaerobic treatment, were compared by lab-scale experiment, by comparing the effect of sludge reduction and change of sludge activity of those techniques. The optimum cel-lysis technique was selected depending on the treatment effect, and studied its influence factors and process in order to investigate the optimum cell-lysis techniqe of sludge reduction and provide some references for excess sludge reduction produced by domestic wastewater treatment. The results of this study were shown as follows:(1)By comparing different cell-lysis processes and anaerobic treatment , it was found that H2O2, 60 centigrade thermometer and basic condition, 120 centigrade thermometer and basic condition, 120 centigrade thermometer treatment had good solubilization effency of sludge but with poor activity. Ozone crashed 8.42% of sludge with the 88.2% remaining activity. Ozone treatment was selected as optimum cell-lysis technique.(2)The results of experiments in influence factors showed that the more ozone dose, the higher sludge removal rate, while there was an optimum ozone dose, i.e. 22.04mg/L.Because when the ozone dose passed 22.04mg/L, the change ratio of MLSS became slowly. When the sludge concentration was lower, it was easier to reduce the sludge by ozone because lower sludge concentration maked larger contact area between sludge and ozone and the sludge was easier...