2005 Volume 3 Issue 1 Pages 63-70
The Odaiba Marine Park is a typical sightseeing place that represents Tokyo. But unfortunately the Odaiba Marine Park is not in comfortable condition for the people dabbling in seawater, because of the increase of fecal coliforms due to the CSO (Combined Sewer Overflow) system after heavy rain.
Tokyo Metropolitan Government started the ocean area purification experiment with EBARA Corporation. The filtration and the ultraviolet ray disinfection were adopted for the seawater purification process.
The purification zone in the Odaiba Marine Park was partitioned with two oil fences, and the water from the purification plant was continuously drained off, at 5,000m3/day for three consecutive months.
The purified seawater was discharged from July to October in 2003.
Moreover, the effectiveness of photoreactivation, seen as the most challenging task when adopting disinfection by ultraviolet ray, is reported as the preliminary study conducted in 2002. The model tests, using seawater mixed with untreated sewage resulted in either a lower photoreactivation rate of the coliform groups, or further inactivation of the groups.
This suggests that the coliform groups of the freshwater-origin are affected by salt density in the seawater with inhibition of the photoreactivation.
