Modeling of Leachate Recirculation Using Spraying–Vertical Well Systems in Bioreactor Landfills

Abstract

Leachate recirculation in municipal solid waste (MSW) landfills operated as bioreactors offers significant economic and environmental benefits. However, vertical well (VW) recirculation may not be an effective method because gravity will cause the recirculated leachate to flow directly downward to the leachate collection systems at the bottom of the landfill, resulting in a waste of recirculated leachate. One of the solutions to minimize the misapplication of leachate is to enable the leachate to flow in horizontal directions using combined spraying-VW systems, thus enabling it to flow through more MSW. The key objectives of this study were to investigate combined spraying-VW systems, to analyze the effects of applying spraying and VW recirculation systems simultaneously on the leachate migration in landfills, and to estimate some key design parameters (e.g., the steady-state flow rate, the influence radius, and the cumulative leachate volume). In addition, design charts for engineering application were established using a dimensionless variable formulation. The proposed design charts prove both simple and useful.