Oxidant Multi-Injection in Supercritical Water Oxidation of Wastewaters

Supercritical Water Oxidation (SCWO) process with oxidant multi-injection was studied in a continuous flow system where the same amount of oxidant feed is split between two points, a first injection at inlet of reactor and a second one located at three different positions along the reactor. At the same operation conditions, this multi-injection configuration presented advantages compared with those obtained with a single oxidant entry. Moreover, oxidant dosage in a SCWO reactor is a key aspect in energy management. In this work, experiments were performed to find the best oxidant dosage to obtain the maximum organic conversion and to improve the thermal control of the process. Experimental study have been carried out using two different feeds, N,N-Dimethylformamide (DMF) as a model compound for nitrogen containing hydrocarbons in wastewaters and Biocut 35® cutting fluid as an industrial organic wastewater. All experiments were carried out at 250 bar, an oxygen coefficient n = 1 and temperature between 400 °C and 450 °C. Each experiment was carried out at five different residence times (2, 4, 6, 8 and 10 seconds).