There is growing concern for the applicability of Escherichia coli as a fecal indicator bacterium in the water environment because E. coli has been reported to regrow in a variety of environments. We investigated longitudinal variation in E. coli counts along a small channel which receives the effluent of treated wastewater. The two fecal indicator bacteria, E. coli and Enterococci, were enumerated, and these bacterial fluxes were calculated from bacteria counts and river flow. As a result, the flux of E. coli was larger downstream of the effluent site than the sum of the fluxes upstream and in the effluent. A high E. coli count was detected in the riverbed sediment of a downstream site. In addition, pulsed-field gel electrophoresis revealed that the genotypes of E. coli isolated from the upstream water, periphyton, and riverbed sediment samples were concordant (similarity = 1.0) . These results indicate that E. coli survived and accumulated in riverbed periphyton and sediment and that E. coli may regrow in a small stream that is strongly affected by treated wastewater. When we assess the fecal pollution in rivers, it is necessary to consider the possibility of E. coli regrowth.

The main objectives of this study were to investigate 1) the occurrence of polyfluoroalkyl phosphate esters (PAPs) in cosmetics and 2) the behavior of PAPs in wastewater treatment plants (WWTPs) and 3) to estimate of the inflow load contributed by cosmetics. Cosmetic samples (n =23) were purchased in Japan and other countries, and field surveys in WWTPs (n =5) were conducted in August 2016. The total concentration of three types of diPAPs (6:2diPAP, 6:2/8:2diPAP, 8:2diPAP) detected in cosmetics were in the range of 1,030 to 58,500,000 ng g-wet^-1. Fourteen diPAPs were detected in cosmetic samples by liquid chromatography mass spectrometry (LC-MS/MS) . The concentrations of the three diPAPs were 479 ng L^-1 in primary sedimentation tank sludge, 123 ng L^-1 in biological reaction tank effluent, and 269 ng L^-1 in return sludge. The total mass of the three diPAPs decreased in the biological reaction tank. The inflow load contributed by cosmetics was estimated from information on amount to use and population. The inflow load of Σ3 diPAPs ranged from 67 to 1,180 mg day^-1, which contributed 14±2% of the total load. The findings reported in this study suggested that special attention should be paid to the above kinds of new emerging pollutants.

Field observation was conducted to study the influence of nitrification restrained water in an estuary. In particular, the transport of ammonium nitrogen before and after nitrification restraint was investigated. It was found that the mixing and dispersion along the flow in a semitidal period dilute the concentration of ammonium nitrogen; therefore, the increase in nutrient concentration in the downstream area was not clear under the restrained nitrification treatment at the sewage treatment plant. On the other hand, the effluent water body flowed out to near the seaweed cultivation area. Then, the effluent water body moved upstream near the upper tidal area of 4 to 5 km from the river mouth. In addition, on the basis of past research regarding the effects of the removal of ammonium nitrogen on salinity and suspended solids, the transport of ammonium nitrogen in estuaries was considered. The results indicate that high salinity blocks the adsorption of ammonium nitrogen on suspended solids, and the potential for the accumulation of deposits including ammonium nitrogen out of a tidal river was shown. Consequently, ammonium nitrogen derived from the effluent water may be transported offshore without removal by adsorption on suspended solids.