About Necessity of Revision of Standard Silicon Content in Potable Water

Summary

Substantiation for increasing the value of allowable concentration of silicon dissolved in potable water is made; it will bring the domestic normative documents into accord with international standards, ensure more rational use of resources. In Russia the maximum allowable concentration of silicon is established in SanPiN for anthropogenic silicon and silicon used for water treatment that’s why the limitation on the use of natural water containing natural silicon is unlegitimate. The literary review of water desiliconization technologies is done. Data on reduction in content of dissolved silicon in the course of deferrization and demanganization of underground water with generation of coagels, reciprocal precipitation and sorption on ferriferous deposits generated are presented. In the course of intraformational deposition, reduction in silicon content up to 35–50% is reached.

Key words

potable water , ground water , aquifer , silicon , intraformational deposition

Assessment of the Sanitary Hazard Degree of Silicon Compounds in Natural and Potable Water

Summary

The survey of literature on the role of silicon in the human body, its toxicokinetics is conducted; the critical analysis of scientific substantiation of hygienic standards of maximum concentration of silicon compounds in natural and potable water is made. The attention is paid to the absence of standards concerning the silicon content in water in the foreign standard specifications because of non-actuality of the problem. It is proposed to cancel the standard of limit content of silicon in the domestic normative base in connection with the absence of its proper reasonableness.

Key words

potable water , maximum permissible concentration , silicon , normative , hardness , salt-content

Purification of underground water containing high concentrations of silicon, iron and manganese

Summary

The aspects of purification of underground water containing high concentrations of silicon, iron and manganese are considered. Different forms of silicon present in water are analyzed and the basic physics and chemistry of desilication are presented. The implementation of the technology of comprehensive purification of water containing high concentrations of silicon, iron and manganese is described. Through the example of three operating water treatment plants the negative effect of silicon on de-ironing and demanganation processes is shown. Two factors are accentuated that enhance the negative effect: the presence of organic admixtures in raw water and, possibly, higher degree of polymerization. Taking into account the application character of studies this presumption demands further study. The developed technology provides for water purification to drinking standard by every parameter. For the implementation of the technology dosing a great many of five types of chemicals (NaOH, Mg salts, NaClO, coagulant, flocculant) is required as well as large volume of sludge is subject to utilization. For this reason this technology is recommended for use only when an alternative water source is unavailable.

Key words

ground water , coagulation , iron , manganese , silicon , colloids , chemical precipitation , magnesium silicate