An introduction of sewage sludge treatment recycling technology through hydrothermal and anaerobic digestion that does not require fossil fuel

With the keywords zero emission and utilization in mind, we have developed and manufactured a revolutionary sewage sludge recycling full-scale plant, and installed it in Nagasaki, Japan. This plant is designed around hydrothermal treatment and high speed anaerobic digestion technology. Through continuous hydrothermal treatment, the time required for anaerobic digestion is shortened to about 6 days and the dewaterability of the digested sludge is improved to a moisture content of 67%. Compared to conventionally dewatered sludge, the weight can be reduced by as much as about 75%. The mixed sludge can easily be turned into the recycled products (solid fuel, fertilizer). Also it is virtually self-sufficient; it uses its self-generated biogas to cover the thermal energy needs of the plant. Therefore fossil fuel usage and greenhouse gases emission are greatly reduced. This technology is used in the B-DASH project promoted by the Japanese ministry of land, infrastructure, transport and tourism.