Abstract
The removal of refractory dissolved organic carbon (R-DOC) in secondary treated water from a rural sewage treatment plant was studied using a hybrid-type constructed wetland system with a zeolite substratum from Jun. 2006 to Dec. 2008. Secondary treated water from a rural sewage treatment plant was supplied to this system. Average removal rates (%) of COD, DOC and E260 were 52, 43 and 22, respectively, during the experimental period by this system. R-DOC predominated in the secondary treated water and the ratio of R-DOC to total-DOC fluctuated from 53 to 84%. R-DOC was removed 38-66% after passing through the system in 2006. Result of DOM fractionation, hydrophilic acids (HiA) and hydrophobic acid (AHS) accounted for 30-40% of the total-DOM. The bases (BaS) was 19-27% and the hydrophobic neutrals ( HoN) and the hydrophilic neutrals (HiN) were present at only trace amount. The component ratio in R-DOM was similar to the total-DOM. No special removed fraction was observed in this study.
