A Hydraulic Model for Estimating Specific Surface Area in Landfill

Abstract

The kinetics of waste degradation in landfill is believed to be influenced by the available surface area, but detailed hypothesis testing has been hampered by lack of methods for estimating surface area. In this paper a new theory for water transport and storage in landfill is developed, with equations for estimating specific surface area of refuse and of suspended solids in leachate. The analysis was motivated by the need to develop scale-up equations relating methane production rate per litre of leachate to rate per tonne of bulk refuse. Two such equations are derived. The first, using surface area as the key scale-up parameter, gives unrealistic values; the second, using liquid volume, gives results in excellent agreement with gas pumping trials. This may indicate that methanogens in landfill are freely suspended individuals or flocs rather than film type bacteria that depend on mechanical support surfaces.