Nippon Paper Industries Co., Ltd. (President: Masatomo Nakamura) commenced full-scale operation of one of Japan's largest methane fermentation treatment facilities in January this year, at Iwakuni Mill (Iwakuni, Yamaguchi). Effluent containing organic matter is generated in the kraft pulp manufacturing process. The treatment facility is capable of processing 2,400m3 of kraft pulp effluent a day in a reaction tank of 1,200m3. When converted to heavy oil, the amount of methane gas generated is equivalent to 2,000kl each year. (The amount of energy consumed by about 1,000 households)

 

Unlike the conventional aerobic treatment, methane fermentation treatment requires almost no energy. Moreover, the organic matter contained in effluent can be converted to methane gas, which can be used as an alternative for heavy oil. Consequently, this approach has gathered attention as a treatment method that generates energy from effluent. And while carbon dioxide gas is generated as an end product with conventional treatment methods, methane fermentation treatment offers the additional advantage of generating only minimal quantities of carbon dioxide gas, since methane gas is the main discharge. As such, the method has already been used for effluent treatment at domestic beer factories and other food-related production facilities. However, the concentration of organic matter contained in discharge generated at paper mills is low, making efficient treatment difficult. This has slowed the adoption of the treatment method in the paper and pulp industry.

 

Aided by "Support for Development of Technology for Rationalization of Energy Use (Development of Methane Fermentation Treatment Technology from Black Liquor Concentrated Water for Rationalization of Energy Use)" by the Ministry of Economy, Trade and Industry, Nippon Paper Industries has developed technologies for the practical application of effluent treatment by methane fermentation and conducted demonstration tests using actual equipment. The first-phase demonstration test started in 2004 at Yufutsu Mill (Tomakomai, Hokkaido), with a second phase demonstration test launched at Iwakuni Mill in 2005. Now, full-scale operation of an actual facility has finally begun. (Total development costs were 1.1 billion yen.) Yufutsu Mill is the second and Iwakuni Mill is the third facility in the world to adopt methane fermentation treatment for kraft pulp effluent. In Japan, Yufutsu Mill is the first and Iwakuni Mill is the second to adopt the method, and both facilities are among the nation's largest.

 

Based on the Nippon Paper Group's Environmental Charter, Nippon Paper Industries is committed to energy conservation and sustainable activities for harmonizing with nature. "Methane fermentation treatment of kraft pulp effluent" is a resource conservation technology that enables the effective application of unused effluent content. The Company will continue to develop conservation technologies and help build a sustainable society.