Waste Conversion Reactor: Pyrolysis, Gasification and Hydrothermal Pathways What is a waste conversion reactor? A waste conversion reactor is a vessel that transforms low-value or hazardous refuse, biomass, plastic or sludge into energy or chemicals, and it is defined by which of four pathways it uses: pyrolysis, heating in the absence of oxygen at 400-700°C to yield pyrolysis oil, gas and char; gasification at 700-1200°C to make syngas of 10-30 MJ per normal cubic metre;