ABSTRACT
An outbreak of Cryptosporidium infection from tap water has triggered the implementation of stricter controls for the turbidity of filtered water in Japan. Accordingly, a growing number of water purification plants have begun to measure the number of particles, which is more closely correlated to this kind of protozoan than turbidity. With this background we have developed a high-sensitivity turbidimeter based on the particle counting method that supports both turbidity measurement and particle counting to realize a compact and low-cost monitoring system of filtered water. This paper explains the basic principles of the turbidimeter, which uses both forward-angle light scattering and light obscuration methods in series and determines the turbidity from particle counting by applying Mie's theory of light scattering. In basic experiments on turbidity standards such as kaolin solution and formazine solution, we verified that the turbidimeter could determine the particle counts and turbidity of filtered water with sufficient accuracy.
Subject(s)
Environmental Monitoring/methods , Optics and Photonics , Water Supply/standards , Animals , Cryptosporidium , Filtration , Nephelometry and Turbidimetry , Particle Size , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
The 1995 Hyogoken-nanbu (Kobe) earthquake of January 17 caused severe damage to water supply systems, especially to water pipelines. More than 4,000 incidents of damage to distribution pipes were identified and their pertinent data recorded in the Hanshin area. A total of 1.2 million customers was without water for at most 90 days in Kobe city. We investigated damage to water distribution pipes i the cities of Kobe, Ashiya, Nishinomiya, Takarazuka, Amagasaki and Osaka and the town of Hokudan-cho on AwajishimaIsland, and analyzed the collected data by using the Geographical Information System (GIS).. A database was built for damaged pipes, distribution networks, geological data of the surface layer, degree of liquefaction seismic intensity. This paper describes various modes of damage to the distribution pipes observed in this earthquake and causes revealed by this investigation.(AU)
