| The sludge produced by municipal sewage plants contains many different kinds of hazardous substances, which is responsible to the secondary environment pollution. In order to reduce the pollution risk, Pollutant Emission Standards of Municipal Sewage Treatment Plant (GB18918-2002) was developed. It rules that the sludge must be stabilized before further treatment. However, only few sewage plants apply sludge stabilization treatment because of the economical and technological difficulties. As a result, large mounts of sludge is discharged without treatment. It has become a growing trend that sewage plants apply sludge stabilization treatment, since the execution of the Environmental Protection Law is becoming stronger. So it is of great significance to develop a new sludge stabilization technique, which has a low cost, great effects, easy performance and management.Biological stabilization is the most common treatment method because of its low cost and reliability. However, its shortages, such as time-consuming, space-consuming and low efficiency, cause high construction expense and great difficulty of land acquisition in some land-lacking cities. In order to raise the efficiency and to save the construction land, this research applied electrochemical treatment method based on the relevant study on sludge aerobic digestion. By the way of value operation, optimal values of factors were obtained, and the treatment efficiency was improved by chemicals insertion. On the basis of the test results above, electrochemical pretreatment and sludge aerobic digestion were combined, and the effects the different pretreatment brought to the sludge aerobic digestion were analyzed. The results mainly show that: (1) The mixed liquor volatile suspended solid (MLVSS) removal rate of waste activated sludge (18.35~20.50g/L) reached to about 10.5% after 30min electrochemical treatment with RuO2/Ti polar plates when optimum operating conditions were as follows: pH was 11, polar plate spacing was 2.0cm, and voltage was 15V. SCOD of waste activated sludge was increased to 2191 mg/L from 202 mg/L. Simultaneously, the index of TN,TP and NH3-N increased. Thermal stabilization and dewatering performance were reduced.(2) The effect of electrochemical treatment could be greatly improved by adding urea, NaCl and Fenton agent. MLVSS removal efficiency was increased to 13.4% when the dosage of urea was 1.5g/L; MLVSS removal efficiency was increased to 13.9% when the dosage of NaCl was 0.025mol/L.(3) After electrochemical pretreatment under optimum operating conditions, the performance of aerobic digestion was greatly enhanced. The MLVSS removal rate reached to 40.0% after 14 days'aerobic digestion, while the MLVSS removal rate of WAS without any pretreatment just reached to 33.2%, and it reached to 40.2% after 20 days'aerobic digestion.(4) Electrochemical pretreatment by adding urea, Fenton agent will greatly improve the performance of aerobic digestion and sludge stabilization. When adding urea and Fenton before electrochemical pretreatment under optimum operating conditions, the aerobic digestion time could be shortened by 8 and 10 days respectively comparing with the one without pretreatment. It was found the performance of aerobic digestion was the best with Fenton reaction and electrochemical pretreatment. At the end of aerobic digestion, MLVSS removal rate, sludge OUR and TTC-DHA activity values showed that sludge stabilization had reached to the standard.
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