Ultimate disposal of wastewater sludges is one of the most concerning steps of sludge management. As an alternative disposal, reuse of sludge as a soil conditioner or fertilizer has had some success. Another alternative is the addition of sludge to the solid waste landfills. Many researchers have studied the effects of sludge addition to the solid waste stabilization in landfills. However, part of the researchers found positive effects, while others found either negative effects or no effects at all. This study investigates the remaining stabilization potential of the solid waste retrieved from an operating landfill by sludge addition. Determination of the remaining stabilization potential of landfilled solid waste is an important issue in solid waste management. In this study, the further stabilization of landfilled solid waste is achieved by the addition of anaerobically digested sludge to the solid waste with different sludge to waste ratios. Four 10-litre laboratory-scale batch digesters operated under constant temperature of 34°C are used in the experiments. One of the digesters was the control unit operated without any sludge addition. The other three digesters had different sludge to waste ratios; 1:9, 1:6, 1:4 (on wet basis) respectively, in order to find the optimum ratio for the solid waste stabilization. The comparison of gas production and quality and other indicator parameters provided an opportunity to determine the remaining stabilization potential and its significance. The results are translated in terms of conventional landfill practices, as well as emerging technologies for innovative sludge management.

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