Test of Technology of Galvanochemical Wastewater Treatment for Arsenic Compounds

Summary

The substantiation of perspectivity of application of the galvanochemical method of arsenic removal from wastewater is made. Results of the laboratory study of efficiency of galvanochemical treatment of arsenic-containing model solutions and natural wastewater of an intergrated copper-sulphur plant are presented. It is shown, that application of this technology makes it possible to remove arsenic up to values of Maximum Permissible Concentration (MPC) for water objects. Efficiency and arsenic removal rate depend insignificantly on an initial pH value (in the range of 1,5–9,5). Duration of the galvanochemical treatment ensuring the obtaining of arsenic residual concentrations on a level with MPC depends on its initial concentration in media treated and on a galvanic couple used. The process of arsenic removal progresses with a higher rate when an «iron – copper» galvanic couple is used. When an «iron – crushed coke» galvanic couple is used the duration of treatment necessary for obtaining the arsenic concentration on a level with MPC increases in 2–3 times. Basic flow charts of the galvanochemical treatment of wastewater depending on the initial concentration of arsenic are offered.

Key words

wastewater , arsenic , reagent methods , galvanochemical treatment , toxicity

Problems of removing heavy metals salts from wastewater:
options and solutions

Summary

Many industrial enterprises generate large amounts of wastewater containing salts of various heavy metals and their compounds. Numerous technological options have been developed to extract heavy metals from wastewater: ion exchange and membrane technologies, as well as chemical methods. However, using the first two methods results in the generation of new highly concentrated solutions of toxic components that require subsequent landfilling or solidification. Chemical methods provide for obtaining waste in the form of sludge that also needs processing and landfilling. Consequently, these technologies are often combined. Some methods based on the intensive chemical precipitation in a vortex layer in the presence of seeding material, sand, as a rule, can be considered as an alternative. In this case, products of the process are granules, usually calcium carbonate, with heavy metals or other toxic contaminants bound in the carbonate layer. The developed dynamic water softening system (DSS), designed to remove carbonate hardness from drinking water, was tested for the purpose of removing non-ferrous metals. The results obtained allow us to expect the high efficiency of this method.

Key words

wastewater treatment , reagent methods , heavy metals , dynamic softening system , solubility of hydroxyls, carbonates and sulfides of salts of non-ferrous heavy metals , waste containment