The disruption of microbial cells in urban excess sludge to release the intracellular organics is an important step for improving the efficiency of anaerobic digestion. So

excess sludge was employed to investigate the disruption behavior of the microbial cells within the sludge by means of DC and AC corona discharge. The Soluble Chemical Oxygen Demand（SCOD） of the sludge sample was measured to evaluate the disruption performance of the cells

and the effects of DC voltage magnitude

polarity and AC voltage frequency on the performance were discussed. The results indicated that the microbial cells could be disrupted by either DC or AC corona

which leaded to the increase in SCOD. With the application of DC corona

the growth rate of SCOD decreased from 15.6% to 6.8% as the positive DC voltage increased from 1 k V to 5 k V

whereas the growth rate of SCOD increased from 0.1% to 21.4% as the negative DC voltage grew from-1 k V to-5 k V. With the application of AC corona

the increase rate of SCOD showed a close relationship to frequency and magnitude. AC corona exhibited a better treatment performance compared with DC corona. It is suggested that the disruption of the cells

as well as the release of intracellular organics

is due to the generation of oxidative species

such as hydroxyl radical and ozone within the corona discharge. The microphysical processes of cells disruption and extracellular organics degradation varies as a function of the parameters of corona discharge

which leads to the variation of SCOD increase rate.