Centralized Water Supply Systems Research Articles

Anion chromatography and redox photometry in potable water analysis

Anion chromatography with ANIEKS-N selective ion exchanger and redox photometry with an antimony(V) ionic associate as selective oxidizing agent were suggested for determination of low concentrations of toxic (F−, Br−, NO2−, NO3−) and biogenic (SeO32−, I−) ions in some potable waters available from central water supply systems and mineral water springs.

Removal of Arsenic from Groundwater using Point-of-use Reverse Osmosis and Distilling Devices

Ground water in both the northeastern and southwestern coast areas of Taiwan may contain high concentrations of arsenic. Since no central water supply system is available in some of those areas, point-of-use (POU) water purification devices are considered as an option for providing safe drinking water. In this study, removal of arsenic, using two types of POU purification devices, reverse osmosis (RO) systems and distillers, was investigated. Three commercially available RO systems and two distillers were selected to test their removal efficiency of arsenic from synthetic and real ground water. Experimental results of the three RO systems using synthetic ground water showed that only one system had good removal efficiency for arsenic. In subsequent experiments using real ground water with 0.7 mg l−1 arsenic, only one RO system was able to meet the drinking water standard after producing about 1,000 l of treated water. For the distilling systems, 99% of the arsenic was removed from both synthetic and real ground water. The arsenic concentrations in the finished water of both distillers were all below the standard for drinking water. Although systems with higher arsenic removal efficiency seemed to have better removal of total dissolved solids (TDS), no correlation could be found after analysis.

Brackish water RO desalination plant in the Gaza Strip

Besides some sweet water wells, there are two known sources of potable water in the Gaza Strip area: brackish water from wells which have become saline due to dry seasons and overpumping and Mediterranean seawater. Both must be desalinated, but the brackish water source is preferable because of the lower investment required for maintenance and treatment. Reverse osmosis is the preferred desalination process mainly due to low energy consumption, easier start-up and operation, flexibility in construction and utilization of electrical energy as the only energy source. Since Gaza has no central water supply system for the time being, subregional systems were considered for immediate implementation. At first plant of 60 m 3/h capacity to desalinate brackish water of 3250 ppm TDS was built and is operating in the town of Deir El-Balah.

ECONOMIC DESIGN OF CENTRAL WATER SUPPLY SYSTEMS FOR MEDIUM SIZED TOWNS1

ABSTRACT. Adequate and good‐quality water supply for medium sized towns is costly when there are insufficient quantity and low quality of groundwater or surface water. In a central water supply system serving a number of towns, the economies of scale may permit a sufficient and good‐quality supply at lesser rates. Such a system has the flexibility of supplying rural population through small service lines. The system may be an interbasin or intrabasin conveyance depending on the location of a suitable water source and the economics of the supply network. Seven cost elements are pertinent to the optimum or least‐cost design of network consisting of pipelines and pumping stations. The relevant cost functions are based on the available data gathered from various sources. Water conveyance costs are calculated for various flow rates, pipeline diameters, flow variabilities, static heads, and interest rates, thus providing a measure of sensitivity of the conveyance cost to such variations. The economies of scale, the sensitivity of optimum unit conveyance costs, and variations in unit costs with change in cost functions are useful in making a feasibility study for a proposed conveyance system.