Synergistic effect of sono-photocatalytic processes on sludge disintegration.

Abstract

The synergistic effect of the combination of sono-photocatalytic oxidation and Fenton reagents was investigated on sewage sludge disintegration. In this context, the simultaneous effect of ultrasound (US) and UV irradiation was studied with variable parameters such as the duration of photocatalysis, catalyst amount and different UV light. The optimum amount of TiO2 and Fenton reagent determined in the sono-photocatalytic process was kept constant. Different combinations of advanced oxidation processes (AOPs) showed different degree of disintegration (DD). While H2O2 added to sono-photocatalytic application with TiO2 contributed to the increase of DD, iron addition caused a decrease in DD. This decrease was more in Fe2+ use than Fe0. DD was determined as 18.35%, 20.60% and 32.58% in TiO2/UVA, TiO2/H2O2/UVA, and TiO2/H2O2/UVA/US processes, respectively. In TiO2/UVB process DD was found to be 17.60%, while it reached 30.34% in TiO2/UVB/US, 43.82% in TiO2/CFP/UVB/US and 52.81% in TiO2/MFP/UVB/ US. In the kinetic study, it was determined that all processes comply with zeroth order kinetics. The use of ultrasound in all processes increased the germination percentage, which expresses the toxicity of the sludge, up to 100%. After sono-photocatalytic disintegration, the sludge volume decreased by 19.2% to 60% according to values of volumeweighted average. It was concluded that the sono-photocatalytic process has an important effect on sludge disintegration,which is an effective method for sludge minimization. In addition, it was determined that the synergistic effect of fenton reagents added to the process was strong and the combined use of these two processes increased the DD value from 17.60% to 52.81%.