Electrodialysis desalination and limiting concentration of highly mineralized waters

Abstract

We study the regularities of the process of desalination of sodium chloride solutions with a limiting concentration of 10.2 to 37.7 g/dm3, which simulate chloride wastewater of some mining enterprises. We use an electrodializerconcentrator with advanced design developed at A.V. Dumansky Institute of Colloid Chemistry and Water Chemistry of the NASU. The need to develop such device is caused by the necessity of the deep concentration of concentrates obtained during the wastewater treatment in order to facilitate their further processing into secondary material resources. The electrodialyzers produced by the industry are unsuitable for a significant concentration, since the concentration chambers in such devices and the desalination chambers are pumped with the initial solution. This leads to a significant reduction in the concentration of the resulting brine. Studies have shown that the use of the specified electrodializer-concentrator allowed one to obtain for 100 min from solutions with a concentration of 10.2, 18.8, and 37.7 g/dm³ Cl-ion diluents containing them, respectively, 0.2, 0.6, and 1.0 g/dm³ and to concentrate the brine by 10.6, 6.7, and 4.0 times, respectively. Based on this research and the experience gained at the Institute in the field of mine water treatment, a basic block diagram of the mine water treatment is developed. It is based on a combination of advanced electroodialysis and reverse osmosis. The complex processing of substances removed during the mine water treatment involves their use in relevant industries; additional desalination diluent can be used for technical purposes, and its excess is discharged into reservoirs.