Tool to realize a recycling society

Realizing a carbon neutral society to prevent global warming and a sustainable society such as a recycling society is now an urgent task. Biomass such as organic waste contains a lot of water and is suitable for reduction through methane fermentation and energy recovery as biogas. However, about 20 to 30 days are required for this process and the reduction rate is low.

Kajima has been working on this issue since 1990’s and developed a anaerobic digestion technology for highly efficient decomposition. After many trials and errors, we completed our proprietary thermophilic packed-bed anaerobic digestion system called Methacules. Methacules is a system installed a packed bed serving as a living place for microorganisms to shorten the processing period by utilizing thermophilic methanogens which have a high decomposition rate. These steps allow the system to efficiently decompose organic substances including solids within a short time and minimize residue.

Methacules is now applying food waste, garbage, and other waste at about 15 locations in Japan. Among other operations, Methacules is used in a facility to recycle Shochu lees at KIRISHIMA SHUZO, which is one of Japan’s largest food waste recycle facilities. Methacules treats 1,200 tons of Shochu lees daily to reduce the amount of industrial waste to 20% and recycles 48,000 m3 of recovered biogas having a methane concentration of about 60% as fuel used for distillation and other purposes at their Shochu brewery. KIRISHIMA SHUZO also generates electricity from surplus biogas and sells electrical power to Kyushu Electric Power Company for supply to about 1,000 households.

Kajima has prepared the waste processing database and experiment facilities and built a framework to provide an optimal system for organic waste and wastewater that can vary depending on the customer. In addition, we have kept developing technologies to satisfy customer needs and are constantly evolving Methacules. We will expand the applications of this system that serves as a tool to contribute to solving recently increasing environment-related challenges such as ESG investment and SDGs both inside and outside Japan.