In Japan, reclaimed wastewater has been recycled widely for non-potable urban applications and it is to be used for sprinkling roads to mitigate heat island in urban areas. To assess the heat island mitigation effects of the sprinkling reclaimed wastewater on water retentive pavement, we carried out a survey at Shiodome-District, Tokyo. The temperatures of air and roads, humidity, and WBGT (Wet-bulb globe temperature) were measured and heat flux was estimated to compare the condition of the areas with/without sprinkling. The following results were obtained. 1) Sprinkling reclaimed wastewater decreased the road surface temperature by 8 degrees during the daytime and by 3 degrees at night: temperatures equal to those on planting zones. Nevertheless sprinkling was done only in the daytime, the temperature decrease effect was not only obtained during the daytime: it continued through the night, due to the water retentive pavement. 2) Sprinkling reclaimed wastewater reduced the amount of sensible heat flux and increased that of latent heat flux. These results suggest that sprinkling reclaimed wastewater on water retentive pavement can effectively mitigate the heat island phenomenon.

The existence of pharmaceuticals in the water environment is thought to be a potential problem for aquatic organisms. In this study, we conducted a nationwide survey to clarify the occurrence of 24 selected pharmaceuticals in major Japanese rivers and evaluated their environmental risk to aquatic organisms. We found a total of 22 substances in river waters at concentrations from several nanograms per liter to several micrograms per liter. We found the highest, which was 2.4 μg/L of caffeine, followed by 1.5 μg/L of crotamiton and 1.4 μg/L of sulpiride. We conducted an environmental risk assessment of the 22 pharmaceuticals detected in river water, for which predicted no-effect concentration (PNEC) values for crustacea and algae had been obtained. The measured environmental concentration/PNEC values of four substances, caffeine, carbamazepine, clarithromycin, and ketoprofen, exceeded 0.1 with the maximum value of 9.0 for clarithromycin. As clarithromycin exhibits a high environmental risk to aquatic organisms, particular attention is required.

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Many environmental problems caused by endocrine disruptors (EDs) have been reported. It is reported that EDs flow into sewage treatment plants, and it has been pointed out that these may be shifted from the wastewater treatment process to the sludge treatment process. Little is known about the fate of EDs accumulated in sewage sludge, so we carried out a study to clarify the fate of EDs in sewage sludge treatment processes, especially in an anaerobic digestion process. In this study, nonylphenol (NP) was selected as a target ED. Nonylphenol ethoxylates (NPnEO) or nonylphenoxy acetic acids (NPnEC), which were the precursor of NP, were added to an anaerobic digestion process, and mass balance was investigated. The following results were obtained from the anaerobic digestion experiments. (1) NP1EO was injected to an anaerobic digestion testing apparatus that was operated at a retention time of approximately 28 d and a temperature of 35 degrees C with thickened sludge sampled from an actual wastewater treatment plant. Approximately 40% of the injected NP1EO was converted to NP. (2) NP1EC was injected to an anaerobic digestion testing apparatus with thickened sludge. As a result, almost all injected NP1EC was converted to NP. When NP2EC was injected, NP2EC was not converted to NP until the 20th day.