Evaluating Drying Potential of Different Sludge Types: Effect of Sludge Organic Content and Commonly Used Chemical Additives

Abstract

Drying of residual treatment sludge is one of prerequisites in final disposal of this hazardous material. In this study, sludge drying potential (SDP) of different sludge types (DST) and the effect of organic content and commonly used chemical additives, including polyelectrolyte and lime, on SDP were investigated in a full-scale municipal wastewater treatment plant (WWTP). Freshly collected sludge samples were used in all experiments, which were conducted in onsite laboratory of sludge treatment facility. Studied sludge types were composed of raw biological sludge (RBS), raw primary sludge (RPS), mixed sludge (MS), dewatered sludge (DS), and limed sludge (LS). Halogen radiation was used for sludge drying. Organic content of sludge was represented by total organic carbon (TOC), dissolved organic carbon (DOC), and lost on ignition (LOI) parameters. Relations and interactions among the SDR(s) of DST(s) were statistically determined using independent samples t-test. The effect of organic content and chemicals additives on SDP was also statistically analyzed using linear regression model. Results of the study imply that each surveyed sludge type had a different SDP. Furthermore, organic composition of sludge and chemical additives had a significant impact on SDP.