Enhancement of dewatering performance and effective degradation of petroleum hydrocarbons in biological oily sludge using atmospheric pressure plasma jet.

The presence of petroleum hydrocarbon components (PHCs) in biological oily sludge increases the toxicity of the sludge and makes dewatering even more difficult. In this study, an atmospheric pressure plasma jet (APPJ) technology was used for treating biological oily sludge. The results showed that under specific conditions-a sludge/water ratio of 1:100, a discharge power of 440 W, and a 60-min treatment-the degradation rate of PHCs reached 36.3 %. APPJ can convert larger molecule PHCs and extracellular polymeric substances, thereby reducing the particle size and viscosity of the sludge. Meanwhile, the sludge volume was reduced and the sludge dewatering efficiency was improved. The hydroxyl radical and superoxide radical generated by APPJ were the main active species involved in the degradation process. This work provides a novel strategy for the reduction of biological oily sludge and the synergistic removal of PHCs along with the sludge.