Simple water purifier comprising 6 columns where high-temperature oak charcoal was filled was constructed as prototype. Rain water, artificial cistern water and artificial water to which Fe³⁺, Cu²⁺, methylene blue pigment (MB) were added were continuously applied to the columns. Using none energy, the unit allowed water to be deal with at a rate of 120 litter per hour. At the stage of final water purification water with pH 6.7, which was filtered through the columns, was obtained. To the extent that the amount of the water reached 170 litter after the application of water was started, dissolution was noted with the Na⁺, K⁺, Mg²⁺ and Mn²⁺ which originated from the constituents in the cells of the high-temp. charcoal. NH₄⁺, Cl^-, NO₃^- and SO₄^2- were successful in passing through the columns. On the other hand, Fe³⁺, Cu²⁺, MB, bacteria 78%, and coliform 50% were adsorbed on the said charcoal. By adding a distillated bamboo-vinegar liquid to the crude liquid of the artificial cistern water and its final purified water, pasteurization effect of bacteria and coliform was examined. From this result, it is explained that the effect, which was noted with the 5% bamboo-vinegar liquid concentration to a certain degree, was utterly low with the land 2% liquids. However combination of utilization of this unit and employment of the bamboo-vinegar liquid was far from sufficiency in complying with the standard required for a drinking water system for practical use.

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Haloacetic acids (HAAs) in wastewater effluents from the wastewater treatment plants which are located along the Tama River system and in river waters of the river system were examined. The fate of HAAs in wastewater treatment processes was investigated. The mean concentrations of dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) in wastewater effluents were 0.81, 4.2 μg·l^-1, respectively. In the case of river water samples, DCAA was detected in very low concentrations, while TCAA was almost always detected with the concentration range from 0.2 to 1 μg·l^-1. The removal of HAAs in river water treatment facilities using the gravel bed contact-purification method was insignificant. Tap water would be one of the major sources of HAAs in wastewater influents, while the contributions of industrial wastewater were not negligible. The mean removal ratios of DCAA and TCAA by activated sludge process in aeration tank were 97% and 29%, respectively. These results can be explained by the difference in the degradability of different species of HAAs. The amount of TCAA produced by the chlorination carried out in wastewater treatment plants was insignificant compared with that remaining after the biological treatment at almost all plants examined, though a high formation of HAAs was observed in the case of an exceptional treatment plant.

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Mine wastewater and hot spring water flow into the Toyohira River, a source of water for Sapporo City. Since the concentrations of components contained in such water change with the flow regime of the river, water quality management is considered a difficult challenge. The authors focused on the dynamic state of arsenic compounds, and found that hot spring water contains these arsenic compounds in dissolved state at high concentrations and that the characteristics of pulled runoff change from point source pollution (dilution pollution) to non point source pollution (runoff load increase pollution) in the flow process of the river. This change seems to closely involve water storage in dams, and we gathered that arsenic as a component of hot spring water entering the Toyohira River accumulates in dam sediment by absorption in silt and clay and that the runoff and re-dissolution of silt and clay at times of high flow rate causes the runoff and return of arsenic to the river. It was revealed that sediment in dams is a potential source of arsenic pollution.

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Coagulation foam separation with dispersed air using milk casein as a collector and a frother is an effective method to remove suspended substances in water. Harmful algae, which proliferate as outbreaks in many lakes and ponds, are considered suspended organic substances. Hence, the applicability of this method for algal removal is promising. In this study, removal of algae by coagulation and foam using polyaluminum chloride (PAC) and casein was examined.
Highly effective processing was achieved within 10 min by adjusting pH and dosages of PAC and casein. The most important consideration in the foam separation process is adding the proper amount of casein, which functions as both collector and frother. The removal efficiency of Microcystis aeruginosa, Selenastram capriornutum, and Chlorella pyreniodosa was over 97% when PAC and casein were added at a dosage of 3 mg-Al·l^-1 and 15 mg·l^-1, respectively at pH 7-8. The percentage of liquid volume of collapsed foam in the total amount of algal suspension was about 2%. Approximately 100% of the added PAC and casein were recovered from the treated water. These results prove that this novel method has a high efficiency and applicability in removing algae from aquatic blooms.

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