Disintegration of Biological Sludge by Electro-oxidation Process with Different Electrode Couples

This study deals with disintegration of biological sludge by electro-oxidation process for the purpose of improving anaerobic biodegradability of sludge. A pair of titanium (Ti) electrode and a pair of titanium electrodes coated with RuO2 (Ti/RuO2) used for both anode and cathode and their effects on anaerobic sludge bio-processing were investigated. Process conditions were optimized by response surface methodology. Disintegration degree (DD) parameter was used as system response. Optimum conditions were found to be 20 V for 30 min for both electrode couples. DD = 13.9% was achieved for Ti electrodes application, addition of supporting electrolyte (10 g/L Na2SO4) improved disintegration the performance of sludge (DD = 17.3%). Ti/RuO2 electrodes provided higher DD values and the highest DD were determined as 16.6% and 10 g/L Na2SO4 supporting electrolyte addition increased the DD value to 20.4%. Biochemical methane potential (BMP) test results suggest that electro-oxidation enhanced the anaerobic biodegradability of sludge. Electro-oxidation with Ti/RuO2 electrodes allowed more methane gas formation in BMP test. Disintegrated sludge with the pair of Ti and Ti/RuO2 electrodes provided 11.8% and 34.1% higher methane production comparing to the raw sludge at the end of the 40 days of incubation, respectively.