Optimal Waste Decomposition—Landfill as Treatment Process

Abstract

Landfills can be regarded as uncontrolled anaerobic digestors. An increasingly popular landfill management technique involves moisture addition and/or leachate recycle which can enhance stabilization, increase gas production, and improve leachate quality. Leachate recycle operations have not been guided by theory. In this paper, the optimal control theory is applied to managing waste decomposition in landfills through leachate recycle. The technique minimizes net present value cost of landfill postclosure operations while satisfying landfill liner safety constraints. The optimal control method specifies leachate recycle rates through the landfill lifetime and the optimal leachate collection and distribution system capacities. The approach is applied to a simplified model of waste decomposition in a typical excavated cell landfill with composite liner.