リネンサプライ業では，地下水の取水制限，河川・海洋汚染防止等の地球環境保全の観点から，業界の方針として節水に取組み，界面活性剤を含む洗濯排水再利用のニーズが高まってきている．当社は，そのニーズにこたえるため，当該洗濯排水性状に適合した界面活性剤高速分解菌 SD21株を選定した．この SD21株を含んだ界面活性剤分解菌群を高濃度で槽内に保持するために微生物担体，精密ろ過膜を組込んだ，バイオリアクタ構造の採用により，装置のコンパクト化を図った洗濯排水リサイクルシステムの開発に着手した．本報では，その特徴と開発状況を紹介する．

The need for water recycle has grown to save water in environmental protection including restriction on the use of subterranean water and prevention of river and sea pollution, as suggested by the Japan Linen Supply Association, which sought a recycling machine for cleaning up drainage including nonionic surfactants with low biodegradability. We developed a SD21 strain that degrades nonionic surfactants easily and uses nonionic surfactants as the sole carbon source. We developed recycling machine that maintains a high concentration of SD21 strain in the bioreactor using media-added activated sludge process and microfiltration. We introduce the features and examples of pilot plant use for the recycling machine.