MATHEMATICAL ANALYSIS OF THE SORPTION PROCESS OF MINE WATER PURIFICATION

Abstract

Contaminated mine water with a large amount of salts makes underground and surface water sources unsuitable for household and drinking needs. Already in 2016, there was a shortage of drinking water in the Rostov region. Water from surface sources does not meet the hygienic requirements for chemical parameters in 36.1% of the samples taken. Water from underground sources in terms of color, turbidity, total hardness, dry residue, content of iron ions, manganese, hydrogen sulfide, nitrates, ammonia, chlorides, sulfates, magnesium, sodium did not meet the required standards in 72.2% of cases. Due to the need for huge expenses for the purification of highly mineralized waters and the poor development of cheap technologies for the neutralization of large volumes, attempts to purify discharged or flowing mine waters to a safe level turn out to be practically fruitless. In this article, studies were carried out to reduce the concentration of dissolved ions of heavy metals (iron, manganese, copper and zinc) in mine wastewater by sorption in a static mode (charring) using rice husk biochar with electromagnetic treatment. The authors proposed a method for pre-treatment of the sorbent from rice husk biochar in an electromagnetic field at a process activation unit. The results of laboratory tests confirmed the high efficiency of the sorbent for the removal of heavy metal ions from mine waters. On the basis of the results obtained, optimization of the sorption purification of mine waters in the mode of carbonization was carried out using the method of mathematical planning of the experiment (full factorial experiment FFE 2k). The factors most influencing the efficiency of mine wastewater treatment from iron and zinc ions have been identified. With a probability of 0.95, the proposed models are adequate, and they can be used to describe the sorption process when using the studied sorbent to remove heavy metal ions (iron, zinc, etc.), while the optimal concentration of the sorbent from rice husks is within 0.5 mg/l. With an increase and decrease in the concentration of the sorbent above the optimal values, the efficiency of sorption decreases, and this affects the iron to a greater extent. In general, the obtained sorbent has a chemical composition similar to that of activated carbon (the most widely used sorbent for water purification), but at the same time it is a cheap production waste, which confirms its efficiency, both technological and economic, when used to purify natural and waste water. With the introduction of the proposed treatment scheme for mine water treatment facilities, it is expected that the concentrations of dissolved heavy metal ions, in particular, iron, zinc, manganese, will decrease to the concentration of the discharge into the reservoir.