Experiences with anaerobic digestion of wheat starch processing waste

Abstract An anaerobic digester for the treatment of soluble wheat starch has been running for over 10 years. The experiences gained during this period are reported. The initial design encountered problems associated with holding o optimum biomass concentrations. A series of experiments were carried out using additions of buffer and various solids separation processes. An ultra-filtration plant was installed in 1980. Further difficulties were encountered as the load increased and resulted in an excess of volatile acids. A new digester was installed in 1982 making four digesters in all. The ultrafiltration plant is c connected to each digester in turn for 24 h and the plant ran well, with stable conditions for the next 4 years. Further increase in load from the factory during 1985 necessitated a fifth digester and experiments were carried out on a two-stage system to see if it was possible to update the existing system without reconstruction. These promising results are discussed. It is concluded that anaerobic digestion has been successful, saving over £100k p.a. whilst producing £30k p.a. worth of useable energy.