Organic wastes can be derived from MSW (Organic Fraction of Municipal Solid Waste OFSW) or directly from source (eg. food processing waste). DP offers a range of technologies for the conversion of organic wastes to energy. In general, the treatment of organic materials using thermal disintegration and biological treatment techniques are more environmentally friendly and efficient than landfill or incineration. However, this is also dependent on the waste characteristics. Of the biological treatment options, anaerobic digestion, followed by aerobic stabilization and biogas production allows co-generation of electrical and thermal energy, as well as production of high quality natural fertilizer. Anaerobic digestion is a natural process in which organic matter is decomposed by micro-organisms in the absence of oxygen. Organics from separately collected or source-sorted waste are the ideal feedstock for this technology. The options of ‘dry’ or ‘wet’ digestion techniques have different advantages.
DP offers the most efficient ‘semi-dry’ technique with the ADOS System (Anaerobic Digestion of Organic Slurry) and the less efficient but less costly DAD (Dry Anaerobic Digestion) technique, developed over the last 20 years by leading waste management experts IUT GmbH. Some fuels such as poultry litter or manures may in fact be better suited to a combustion technology, depending on quantities, fuel characteristics and specific requirement outputs.
Depending on the specifics of the organic waste, and the type, quality and quantity of energy required, different technologies may be more suitable. Similarly, depending on the waste characteristics, different waste handling processes may need to be designed into the plant at the outset. For example, for treatment with anaerobic digestion, waste from meat sources such as slaughterhouses needs to be hygienised before digestion, whilst the digestate will need to be adjusted for the chemical composition of the feedstock.