In the latest revision in 2004, the 3rd edition, the Water Safety Plans (WSP) was newly introduced into the World Health Organization (WHO) Guidelines for Drinking Water Quality. The Hazard analysis and critical control point (HACCP) is a basic concept that underlies the WSPs, and is also known as the product quality management method in the field of food and the medical manufacturing industries. In the amendments of the Drinking Water Quality Standards in Japan, water suppliers are required to reasonably achieve both safe water and efficient water quality management. Therefore, the HACCP concept is focused as an adequate management method covering a whole process of water supply systems, in a systematic way. The purpose of this study is to investigate a practical procedure in introducing the HACCP into water quality management in Japan. In comparison to conventional applications of the HACCP, unmanageable variations of raw water quality, continuous treatment and supply, and numerous standards of water quality items need to be considered. The HACCP system is expected to achieve a quick response to improvements in water quality, accountability towards consumers and a decrease in accidents.

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An automatic coagulant dosage control technology for water purification plants was developed to deal with rapid changes of feed water quality. Control logic was developed to decide coagulant dosage based on aluminum concentration in the mixing tanks. A coagulant-sedimentation process apparatus was installed in December 2010 in a water purification plant, and the coagulant dosage control test using feed water was started. The developed system was confirmed to be effective for managing settled water turbidity and adequacy of coagulant dosage. For actual changes of feed water quality at the water purification plant over more than one year, the developed system was able to maintain settled water turbidity at less than 1.0 mg-kaolin/L in the period of high feed-water turbidity.

The local structures around Zr atoms such as coordination number of oxygen and cations, and the Zr-0 and Zr-Ln (Ln; La, Ce) interatomic distances in the (La1-xCex).2Zr2O7 Pyrochlore compounds (X = 0–0.25), where Ce is a simulation of actinides,were studied by means of extended X-ray absorption fine structure (EXAFS) spectrometry. The local structure determined by EXAFS in this study is discussed in relation to the dissolution behavior of (La1-xCex)2Zr207 (leaching rates of Zr, La and Ce) in an acid solution (pH=1) at 363K reported previously. The difference in the local structure before and after leaching test was also investigated.