ビタミンB_<12>資源調査 : (V)ビタミンB_<12>資源としての都市屎尿消化法の考察

概要

論文の詳細を見る
Inquiries were sent to 490 cities of Japan on the surplus amount of night soil and how it is treated. The answers received from 312 cities were summarized as following : In rural cities of population more than 50,000,surplus night soil is utilized as fertilizer for neighbouring farmers. About 65% of the cities in Japan have more or less surplus night soil. In 27 cities surplus night soil is discarded in the sea, and in 10 cities it is discurded in mountains or plains. In 6 cities which have sewage treatment plants, collected night soil is poured into a sewage canal. In 13 cities the methane fermentation process is employed, in 13 other cities plants for the process are under construction, in 11 cities a concrete plan has already been completed, and in 28 cities treatment is under contemplation. In short, digestion process seems to become polular for the treatment of night soil. Vitamin B_<12> contained in the bacterial cell fraction obtained by centrifuging the effluents from digesting tanks is presumed to be 9 kg annually in the plants already constructed, 6 kg in those under construction, and 8 kg in those under contemplation.