Co-disposal alternatives of various municipal wastewater treatment-plant sludges with refuse

In this study, the effect of various wastewater treatment-plant sludges on anaerobic solid waste degradation in simulated landfill reactors was investigated. The wastewater treatment-plant sludges were directly co-disposed with solid waste in the laboratory to determine an alternative method for sludge digestion and disposal. Three types of sludges, including primary settling sludge, secondary settling sludge (waste-activated sludge) and a mixture of primary and waste-activated sludge, were supplied from a municipal wastewater treatment plant located in Istanbul. Four laboratory-scale digesters were designed, constructed and placed in a temperature-controlled water bath, and loaded with sludge and solid waste at a ratio of 1:7. All indicator parameters for both sludge receival and control reactors followed a similar trend. However, the stabilization of solid waste in the reactor receiving the mixture of primary settling and waste-activated sludges was faster, as indicated by the total gas production and COD removal data. (C) 2002 Elsevier Science Ltd. All rights reserved.