Research On Optimization Of Technological Parameters For Oily Sludge Treatment Based On Supercritical Water Oxidation

Supercritical water oxidation(SCWO) is a new oxidation process that can destroy the basic carbon chain structures of organic matters. A hydrogen peroxide-ozone system will be established when gas oxidizing agent is dissolved in supercritical water, thus creating a good environment for oxygenolysis of organic matters. Organic matters in waste sludge can be degraded into simple harmless water, CO, CO2 and other small molecule compounds through oxygenolysis.In this experiment, real oily sludge and oily sludge in simulated refining process were chosen to make supercritical reactions with hydrogen peroxide on the independently designed reactor. The optimal supercritical reaction parameters for oily sludge treatment were studied. Moreover, the mechanism of oily sludge treatment based on SCWO was explored preliminarily.Results showed that SCWO can remove as high as 95% COD in oily sludge under 420 ℃, 24 MPa, pH=10 and 1000 mg/L COD. In addition, existence of HCHO or NaHCO3 in the supercritical reaction system can improve removal rate of organic matters significantly. Under the same reaction conditions, adding few HCHO can remove more than 98% COD in sludge and the COD in reaction residues is lower than 15 mg/L. When exploring the reaction mechanism, it is found that acetic acid and CO will be produced during the supercritical reaction. They are detected in reaction residues and served as intermediate products of the reaction.To sum up, SCWO under 420 ℃-440 ℃, 24 MPa-30 MPa, 10 min-15 min reaction time, 4-7 of oxidant/ hydrogen peroxide and hydrogen peroxide/chemical demands as well as 2000 mg/L-6000 mg/L COD in oily sludge can remove at least 95% COD in oily sludge.