The electrochemical coupling system was used on the pretreatment of coking waste water with high organic loading and biological inhibition. The sludge-derived activated carbon(AC) particle electrodes were prepared from in-site sludge and characterized

indicating that surface oxygen groups contained hydroxyl

ether

carbonyl

carboxyl

etc.

which could accelerate catalytic reaction. The effects of cathode aeration were investigated and degradation mechanism of organic contaminants was analyzed. The results showed that aeration was beneficial to open-loop reaction. Based on the Central-Composite response surface method

the separate action and interaction effects of impressed voltage

initial pH

aeration rate

and AC filling ratio were evaluated

and COD removal rate was used as the evaluation index. The significance of influencing factors followed the order:AC filling ratio > initial pH > aeration rate > impressed voltage

and the most significant interaction occurred between initial pH and aeration rate. The optimal conditions were determined to be impressed voltage 15 V

pH 5.8

aeration rate 12.4 ml·min-1

AC filling ratio 50%

and reaction time 45 min. Then COD removal rate reached 46.8%. Under optimal conditions

COD of the treated waste water decreased from 4700 mg·L-1 to 2500 mg·L-1

and chroma removal rate was 50% with low energy consumption of 0.971 kW·h·(kg COD)-1. And B/C increased from 0.05 to 0.37

indicating the biochemical properties were improved. Therefore

the electrochemical technique can efficiently pretreat the coking waste water and improve its biodegradability.