Abstract
This paper presents the results of a comprehensive study of water scale found in water distribution system of Taliouine city in the south of Morocco. Physico-chemical properties of drinking water supplied to the city were evaluated. The data showed a high level of soluble salt in water. Concentrations were calcium 108 - 143 mg/1, magnesium 80 - 96 mg/1, bicarbonate 660 - 750 mg/l and hardness degree 660 - 690 mg CaCO3/l. The water samples contain high amounts of minerals in the form of ions, especially the metals calcium and bicarbonate, which precipitated out and caused problems in water conducting or storing vessels like pipes. Scales were removed from the inside of two old pipes which transported drinking and hot water in the downtown of Taliouine city. Scale samples were investigated by XRF, XRD, SEM, DTA, TGA and SEM’s analytical techniques. This study was able to identify scales formed in pipes of water distribution systems. It was found that water scale in this city contains 53% of calcium oxide and 43% of organic matter. The XRD and SEM results revealed that calcite was the main crystalline structure in drinking water scale. Nevertheless, scale deposited in hot water pipe is well crystalline with peaks corresponding mostly to aragonite (88%) along with calcite (12%). The thermal behavior of scale samples confirms that calcium carbonate was the main compound in the scale samples. Further studies are needed to find an efficient antiscale in drinking water of this city.
Highlights
Water distribution system is a key to public health
The physico-chemical analysis of drinking water in the Taliouine downtown shows that it contains high amounts of minerals ions especially calcium cation and bicarbonate anions
These minerals ions precipitate and cause problems in both drinking and hot water piping. Such ionic deposits leading to the formation of scale on the inside of the pipes are harmful because, first, they lead to a gradual clogging of pipes and, secondly, they promote and facilitate the implementation and development the biofilm microorganisms
Summary
Water distribution system is a key to public health. Water distribution network cannot be considered as an inert system. Many reactions take place and solid deposit is formed on the walls of the water distribution equipments. These deposits cause serious technical and economic consequences such as total or partial obstruction of pipes leading to a decrease in flow rate; reduction of heat transfer, obstruction of the drains, thermal loss of effectiveness in boilers or heat exchangers, the filling of the filters, etc. We were interested to study water scale found in water distribution system in the downtown of Taliouine. Changing pipes transporting water from time to time is necessary because the scale formed in their interior wall decreased their diameter leading to poor performance. Several analytical techniques were used: X-ray fluorescence (XRF), X-ray diffraction (XRD), differential thermal analysis (DTA), thermogravimetry (TG) and Scanning electron microscopy (SEM) in order to identify and characterize scale samples
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