(a) A number of landfill investigation studies have suggested that the stabilization of waste proceeds in five sequential and distinct phases. During these phases, the rate and characteristics of leachate produced and gas generated from a landfill are not only dissimilar, but also reflect the microbially mediated processes taking place inside the landfill. What are these five phases and please explain the major features of these phases in a typical municipal solid waste landfill.

(b) One of your colleagues suggests to build a landfill leachate treatment plant with energy recovery technology from the treatment process, like those energy recovery scheme in treating municipal wastewater. What is your view? Please state your reason(s).