To verify a statistical model for predicting urban pollutant runoff developed in our previous research, newly obtained runoff data were compared with those predicted by the model. The proposed model previously was a regression model using parameters representing geological, rainfall, and hydrological characteristics. The targeted pollutants were COD, SS, TN, and TP, and their event mean concentrations (EMCs) for each rainfall were predicted. From the comparison, the model was found to predict the EMC to one order of magnitude. Moreover, the yearly mean EMC was evaluated from only the mean and standard deviation of all data for each index. The error ratio of the prediction of the mean of 50 rainfall events was within 50%. Furthermore, in order to consider the possible differences among different catchment areas, the EMC values for three catchment areas newly obtained were compared statistically with nationwide values obtained previously. Significant differences were found for one area out of the three which thus emphasizes the importance of the consideration of catchment area differences. Thereafter, the number of runoff samples in a specific watershed area required to detect the mean EMC difference from the nationwide database was derived statistically. This number was calculated to be 10 at most for detecting more than double or less than half of the database means. Lastly, a modified model that includes watershed area differences using a generalized linear mixed model was proposed.

The concentrations of cyanamide in environmental water have not been reported owing to a lack of its analytical method. We have developed an analytical method for detecting cyanamide in river water and sea water, which includes the derivatization of cyanamide into dansyl-cyanamide, clean-up with a silica gel solid-phase extraction cartridge, and measurement by liquid chromatography/tandem quadrupole mass spectrometry (LC-MS/MS) . The method was applied to the determination of cyanamide concentration in river water at nine different locations in Osaka Prefecture. Cyanamide was detected at all locations, and its concentration ranged from a value below the method detection limit (MDL) to 4.2 ng mL^-1. The concentrations were much lower than the registration standards of agricultural chemicals concerning prevention of damage to aquatic flora and fauna (670 ng mL^-1) , and thus, the risk of cyanamide pollution to aquatic flora and fauna in the rivers was assumed to be negligible.

To achieve power independence and net zero CO₂ emission at sewage treatment plants, a performance evaluation system (PES) was used at five sites with a treatment capacity of 150,000 to 200,000 m³ day^-1, to estimate the power self-sufficiency rate and GHG (Greenhouse Gas) intensity. For power independence, the combination of energy saving and energy production measures was evaluated. When the energy saving measures were introduced at Treatment Plant A, the amount of power consumption decreased to 31,840 kWh day^-1 (reduction of about 20%) , and the power self-sufficiency rate improved to 83%. Moreover, when energy production measures were introduced, the amount of power generation increased to 38,800 kWh day^-1 (increase of about 50%) , and the power self-sufficiency rate was 105%, which was considered to indicate power independence. To promote net zero CO₂ emission, the GHG intensity and offset rate were evaluated. Even at Treatment Plant A, the GHG intensity was calculated to be 0.17 kg m^-3 that net zero CO₂ emission was not reached (offset rate of 48%) . By improving the operation of the incinerator, the GHG intensity may be improved to 0.08 kg m^-3 (offset rate of 70%) . Looking toward the two goals, the power independence and GHG emissions were evaluated, and high potential to realize the envisioned sewage treatment plant was confirmed.

The anaerobic co-digestion of sewage sludge and various types of organic waste produces digestate, which can be used directly as fertilizer. The cultivation of photosynthetic bacteria with digestate is focused on to improve the fertilizer quality. After eight months of enrichment with artificial culture media from a seed of sewage sludge, the accumulation of Rhodospirillaceae, which are known to be photosynthetic bacteria, was observed, and the detection ratio to the total number of reads was 55% by sequencing. Filtered digestate liquor from the anaerobic digestion of sewage sludge was continuously cultivated under light illumination, with the seeding of the enrichment culture only at the beginning. The cultivated liquor had a higher pufM gene copy number, which is an indicator of photosynthetic bacteria. Pot experiments showed that grown komatsuna (Brassica rapa var. perviridis) had significantly higher (t-test, p < 0.05) fresh weight and ratios of chlorophyll and carotenoid. These results confirmed that the cultivation of filtered digestate liquor under light illumination improves the fertilizer quality. On the other hand, the cultivation of digestate by the anaerobic digestion of sewage sludge under light illumination with the seeding of the enrichment culture only at the beginning resulted in no significant difference in pot experiments. This showed that the cultivation of filtered digestate liquor under light illumination is practical.