Effect of pH and temperature on sludge ozonation performance

Abstract

Processing and disposal of excess sludge from rubber industry is one of the most serious problems encountered in terms of environment, finance and technology so that it accounts for 30%-50 % of the total expense of rubber industry wastewater treatment. A number of processes include thermal energy, alkaline, high pressure, mechanical disintegration, acidification and ultrasound have been investigated for decomposition and pre-treating waste sludges. However, the disintegration/reduction of sludge by these treatments is limited. Ozonation, which is based on hydroxyl radical (OH.) generation is an emerging treatment alternative for sludge disintegration and reduction. The objective of this research is to evaluate the efficiency of ozonation process for disintegration of sludge from a rubber industry wastewater treatment plant. Biological sludge was collected from Shorubber wastewater treatment plant in Jejawi, Arau (Perlis) which has conventional activated sludge plant. Ozonation experiments were carried out in a single-stage flow-through reactor system, in which ozone was continuously introduced through a porous fritted diffuser. The result indicated that the optimum sludge reduction by ozonation was 50 % at ozonation time of 5 minutes. Factors influencing the decomposition of ozone in water are temperature, pH, environment and concentrations of dissolved matter.