ABSTRACT
Proper disposal of sludges generated from the treatment of industrial wastewater has been a difficult problem to rapidly developing society. Typically many such sludges find their way into a landfill system. Solid wastes placed in a landfill undergo a number of physical, chemical, and biological changes, such as, anaerobic biodegradation of high molecular weight organic compounds to simple compounds, typically methane and organic acids; percolation of rainwater, stormwater, agricultural runoff, and other liquids through the sludge mass; dissolution and leaching of organic and inorganic materials and movement of leachate through the fill in the direction of hydraulic gradient; and transport and escape of gases through and out of the fill. Generation and containment of the leachate has been a major concern during the past two decades because of the potential of these leachates ultimately finding their way into the nearby groundwater table and polluting the groundwater with chemical species in dissolved or suspended form. 1 , 2 Some of these chemicals, for example, metals and refractory organics, such as pesticides or PCBs are extremely hazardous to human health. From this perspective, unless proper care is taken, every landfill is a potential hazardous waste site.
