In the rectangular agitated in-vessel composting bioreactor, the waste is placed in the infeed conveyor. The extraction conveyor moves to mix the compost at regular intervals so as the material remain porous and stable before discharging it in the outfeed conveyor (FAO, 2003). To prevent heating up and aerate the compost material, oxygen is supplied by forced aeration through the plenum and blowers at the bottom of the bed. After a retention time of 6-12 days in the bin, the material is windrowed for 1-2 months i.e. the curing period until stability is reached. The horizontal rectangular tank is well suited for sewage sludge, MSW and mixtures of MSW and sludge (Tchobanoglous et al., 2002).