Pyrolysis of biodegradable wastes using microwaves

The pyrolysis of biodegradable wastes using microwaves was studied as a potential technology to divert waste streams from landfill by converting the biomass into a high-value char, with a potential market as a co-firing media in pulverised fuel power stations. It is demonstrated that pyrolysis can be achieved using inherent moisture as the microwave absorbing phase and that complete char formation can be attained. The efficiency of the process is dependent on the microwave cavity used and it was found that microwave pyrolysis is governed primarily by the rate at which energy is supplied to the waste material. When the heating rate is maximised, the calorific value of the produced pyrolysis gases is greater than the total microwave energy required, meaning that the process is potentially self-sustaining. The dielectric properties of other waste materials are presented and these are used to identify the prevalent design criteria for translating the pyrolysis process to pilot scale.