Anaerobic co-digestion of mechanically biologically treated municipal waste with primary sewage sludge - a feasibility study.

This bench scale study investigated the suitability of MBT material for treatment by anaerobic digestion and the impacts of co-digestion of these wastes with sewage sludge. The results suggest that MBT material is amenable to anaerobic digestion with sewage sludge. The main problems for scale-up are related to the physical composition of the MBT material, the accumulation of heavy metals and other inert contaminants and the impact of both of these factors on final sludge quality. Full-scale trials would be required to assess the long-term impacts of MBT waste on anaerobic digestion, if this form of co-digestion were to be pursued. The material contamination that presents a barrier to the direct recycling of MBT material in land-applications is also a major hurdle in commercial co-digestion. Better quality input material would be likely to result in higher methane yields and fewer restrictions on the utilisation of the product in recycling.