In this study, the effect of adding clay minerals and/or wastewater treatment-plant sludge (WWS) to organic fraction of municipal solid waste (OFMSW) in simulated landfill reactors was investigated. The clay minerals and/or WWS were directly co-disposed with solid waste in the laboratory to determine an alternative and effective method for, sludge and solid waste, digestion and disposal. As well as to increase biogases released and improve the quality of the leachate. Two types of models have been used, bench scale models and pilot scale models. The WWS used was a mixture of primary and waste-activated sludge. sludges were supplied from Zinien, a municipal wastewater treatment plant located in Giza. A powdered montmorillonite clay were prepared and supplied. Two sets, each of seven bench scale models were designed and placed in a temperature