Analysis of wet oxidation process after initial thermohydrolysis of excess sewage sludge

The authors propose a new technique to analyse a complex process of wet oxidation of excess sewage sludge by separating thermohydrolysis that results in the separation of sewage sludge into hydrolysates: solid and liquid products, from the basic process of oxidation of the two products. Wet oxidation kinetics was studied at different temperatures of both products based on the measurement of total organic carbon during the process with the use of a PARR high-pressure reactor. Decomposition of the liquid product leads to the formation of non-degradable and gaseous final products, while degradation of the solid product—via an intermediate liquid product—also leads to the formation of final and gaseous products. Solution of the kinetic equations that describe the dependence of relative organic carbon concentration on time is well illustrated by experimental results. On the basis of fitting theoretical curves to the experimental results, the kinetic parameters of the process were determined.