Introduction

Result in General

List of CSO controll technologies SPIRIT21

Development and Evaluation of CSO Control Technologies ; SPIRIT21(Intorduction)

The early sewer systems were built in Japan as combined systems, which played an important role in urban development. In recent years, significant pollution of receiving waters by combined sewer overflows (CSOs) conveying large oil balls was reported and the Ministry of Land, Infrastructure and Transport (MLIT) addressed this issue by establishing a CSO Study Committee with a mandate to report on CSO control. This study was followed by publications of Guidelines of CSO control by the Japan Sewage Works .Association.

To develop appropriate technologies for sewage works, MLIT initiated a project called Sewage Project, Integrated and Revolutionary Technology for the 21st Century, or SPIRIT 21. As the first theme, the project conducted research during 2002-05 in the following areas of CSO treatment and instrumentation: (a) debris removal (mostly by screening), (b) high rate filtration, (c) coagulation and separation, and (d) disinfection, and (e) measurement and control instrumentation. 24 technologies were proposed in all by the private industry and proceeded to field test in 13 cities. All technologies have been evaluated successfully and proposed for use in practical applications. For example, upflow filters employing special filter media and operated with or without coagulant addition, achieved suspended solids removals up to 70%, at surface load rates up to 1000 m/day, bromine disinfection was found feasible for use in CSO disinfection, with the main advantage of short reaction times.

The project is operated in partnership of five groups: (a) MLIT - defined and promoted the project theme, (b) Academic institutions - provide technical advice for evaluation of R&D plans and results, and conduct basic research, (c) Municipalities - provide demonstration sites and advice, (d) Private sector - propose/supply technologies, and fund and operate projects, and (e) JIWET coordinates and manages the project. The results indicate that project will be successful in providing CSO control technologies to Japanese municipalities addressing CSO problems.