Conditioning of resuspension excess sludge with chemical oxidation technology: The respective performance of filtration and expression stage in compression dewatering

Abstract

Excess sludge has a high yield, rich in organic matter and high water content. The combinational method from chemical oxidation treatment and secondary mechanical dehydration is a powerful approach to further reduce the moisture content of the sludge. This work mainly studies the physicochemical properties of resuspension excess sludge (RES) with the treatment of chemical oxidation, the samples are processed by the compression filter device in a laboratory scale, and the three-stage Terzaghi-Voigt model was used to characterize the expression stage dewatering of samples. The experimental results indicate that: i) The improvement of the dewaterability of resuspension excess sludge is due to moderate chemical oxidation, which is related to the mode of migration and mineralization of organic substances in the stratified structure of the extracellular polymer substance (EPS). ii) When the protein in supernatant + slime is more mineralized than moved in, the dewaterability of the sample is improved. iii) The change of moisture removal for ternary consolidation was very consistent with the change of SRF in the filtration stage (ρ = 0.95, p < 0.01). Based on the results, we discuss how chemical oxidation affects the dewatering performance of filtration and expression stages in the solid-liquid separation. This means that the surface characteristics of the sludge particle and the liquid properties play critical roles in solid-liquid separation mechanism.