Waste Management & Research 78 Waste Manage Res 2004: 22-2: 78–92 Printed in UK – all right reserved Copyright © ISWA 2004

Modelling leachate quality and quantity in municipal solid waste landfills The operational phase of landfills may last for 20 years or more. Significant changes in leachate quality and generation rate may occur during this operational period. A mathemati-cal model has been developed to simulate the landfill leachate behaviour and distributions of moisture and leachate constit-uents through the landfill, taking into consideration the effects of time-dependent landfill development on the hydraulic characteristics of waste and composition of leachate. The model incorporates governing equations that describe proc-esses influencing the leachate production and biochemical processes taking place during the stabilization of wastes, including leachate flow, dissolution, acidogenesis and meth-anogenesis. To model the hydraulic property changes occur