Seasonal variation characteristics of reclaimed wastewater quality in combined household wastewater treatment facilities for individual houses in rural area

Abstract

  The reclaimed wastewater quality in 34 treatment facilities of combined household wastewater for individual houses were investigated in the rural area in Ehime Prefecture, in Japan, in September or October, 2007. The mean values of SS·BOD· COD·T-P·T-N were 3.3 mg·L^-1, 4.0 mg·L^-1, 17.9 mg·L^-1, 19.2 mg·L^-1, 3.11 mg·L^-1, respectively. The T-N concentrations decreased when the return flow devices were continuously operated. The COD·T-N concentrations decreased when it was shorter period since the cleaning, including back washing and sludge carry out. Based on the results and the former results obtained in February or March, 2007, the availability, limitation and the better management practices of the treatment systems were also discussed.