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IWRA World Water Congress 2008 Montpellier France
1. Water availability, use and management
Author(s): Inom Sh. Normatov
Ilhomiddin M. Rakhimov
Nurkhon S. Karomatulloeva
Inom Normatov, Ilkhom Rakhimov, Nurkhon Karomatulloeva

Keyword(s): chloride,coagulation,ozonization

AbstractIn condition of Tajikistan, in connection with great population percentage in the river valleys and allocation of main industrial objects in this zone, the influence factors of anthropogenic character gain the special description and actuality. The traditional technological schemes of preparation of potable water, consisting of pre-chlorination, working out by coagulants, filtering and disinfections by chloride decrease total content of organic admixture to about 50%. In the modern technologies of water preparation one of the sharp problems is formation of additional chloride organic products during chlorination of water, which has instant organic substance. Presence in water Cu; Mn; Zn; Al; Fe increase the content of trighalogentmethans in 2-3 times; and Pb in 5.6 times. As a result, during chlorination there are formed trichlormetan, chloride vinegar acid, chloracetone, polychlorinated phenols and chlorates. It is known that chlorate alongside with chlorite causes hemolytic anemia of animals. During water chlorination there is formed mutagen combination MX (3-chlor-4- dichlormethil-5 hydroxi-2(5H)-phuranole), presented in potable water in concentration of 2-87 ng/dm3. In this respect, the great attention should be paid to coagulation unit while working out the modern technological schemes of water preparing.For the last time the most interest attracts such strong gaseous oxidant as ozone. This is caused, first of all, by the fact that during it’s using no adding admixtures are inserted into flows. And what is the most important, disinfection’s matter ozone acts in 15-20 times faster, than chlorine. Ozone is produced on the place of utilization. Ozonization promotes water oxygen saturation. Perspective is the technology, using non-aerated filters with fixed heterophase active biomass and with ethanol as a carbon. It allows reaching the filtration speed up to 10 m3/m2 * h and reducing nitrates ratio from 40-65 to 15-17 mg/dm3, ammonium from 2-3 to 0.02 mg/dm3. According to the results of the last years’ research, we can state that coagulation method, based on using natural powdery silicates as additives and basic coagulating reagent – aluminium sulphate is perspective and promising. For example, clinoptilolite bringing into clearing water together with coagulant in correlation of 1:1 allows increasing to clear water from turbidity for 73 %, from chromacity for 55 %, and from sedimentary aluminium for 65 %, comparing with traditional coagulation method. Aluminium hydroxide, precipitated onto grained material, extracts fluorine effectively out of water. Therefore, water defluorination is implemented by means of using the sand, ceramzite, crushed clinoptilolite, processed by saline aluminium. Maximal aluminium capacity has alumo modified clinoptilolite (0.5-0.10 mg/g), which in its natural shape does not extract fluorine. Thus, in order to achieve high indexes for potable water quality and to realise the WHO conceptions it is necessary to strengthen research and practical work in modernization of traditional and working out of modern water preparation technologies. There should be applied local alum silicate material of Tajikistan Republic.
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