Sludge disintegration by zonation for the production of carbon source for low C/N wastewater treatment

This paper studied excess sludge was disintegated by ozonation oxidation and solubilized organic substances from the excess sludge was used as carbon source for denitrification in an A/O system. The mechanism of sludge ozonation process was investigated. At less than 0.04gO(3)/gTSS, the bacteria began to be broken down. Greater than 0.04 gO(3)/g TSS, ozone was used to oxidize the bio-macromolecules released from the sludge into small molecules. At levels higher than 0.24 g O(3)/g TSS, the small organic molecular was oxidized by ozone. When the optimal ozone dose of 0.2gO(3)/gSS, the concentration of COD, BOD, NH(3)-N and TN in the supernatant increased by 1256.3%, 3210.1%, 232.1%, 241.5% and 275.4% respectively. At C/N=8, the A/O system had high nitrogen removal efficiency. When C/N became Lower, the nitrogen removal efficiency of the A/O system decreaced remarkably. The soluble carbon in supernatant increased by ozoneation oxidation was recirculated back to the A/O system with alkalinity adjusted, which could enhance the TN removal efficiency by 30%.