This study focusses on a measure to remove dissolved phosphorus and nitrogen from river water flowing into reservoirs. Aquatic treatment is a typical such method, but has the shortcoming that the facilities covering a large area are required. In this paper, we use filamentous algae communities, which have a high multiplication rate compared with other freshwater plants and which can be applied throughout the entire year. We aim to resolve the problem by installing artificial beds for cultivating such filamentous algae communities at places around reservoirs that have little value in terms of other uses. We present specific propositions for facility structure and site selection and clarify the problems expected in putting these proposition into practice.

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Pathogens which have chlorine tolerance were detected in water environment used as sources of drinking water in recent years. This report indicates that the community supplied with the drinking water has the potential risk for outbreaks of waterborne diseases. In this paper, the parameter expressing the human sensitivity against pathogens was proposed. By combining this parameter with conventional dose-response models, the novel outbreak model on waterborne diseases was developed. This model included an age distribution in the community and an existence distribution of pathogens in drinking water. It became obvious by the simulation using this model that the age distribution in the community was an important factor for characterizing outbreaks of waterborne diseases in the community.

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The effect of ammonia on carbohydrate and protein degradation in anaerobic digestion under mesophilic (35°C) conditions was investigated. At the first batch experiment, seed sludge was cultured with dewatered sewage sludge. The carbohydrate degradation rate significantly decreased with increasing the ammonia nitrogen concentration from 900 to 5400mg-N/L. At the second batch experiment, acidogenic bacteria from anaerobic digester fed with glucose was used as a seed sludge. Butyric acid production decreased and ethanol production increased, as the concentration of ammonia nitrogen increased.

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