Application of air–cathode pipe reactor to simultaneously suppress sulphate reduction and accelerate COD oxidation in synthetic wastewater

While bio-corrosion causes severe damage to sewer pipeline, removal of organics in wastewater treatment plants consume substantial energy and is costly. Accepting the electrons from degrading organics by sulphate will produce sulphide – the culprit of corrosion. In this experiment, electrodes were tested for its ability to reduce sulphide formation by transferring electrons to outside the water. Two bench-scale pipe reactors, one with and the other without electrodes were fed with acetate based synthetic wastewater (800 mg/l COD) and sulphate (39 mg/l). In all cases, electrodes were found to suppress sulphate reduction; for low sulphate feed, the average reduction was 2 compared to 4 mg/l and for high sulphate feed it was 20 compared to 68 mg/l. In addition electrodes assisted higher COD removal; the average removal during low sulphate feed was 200 compared to 300 mg/l, but during high sulphate feed they were 300 compared to 450 mg/l.