Improvement of the technological treatment scheme of iron-containing wastewater from etching operations

Abstract

The aim of the research is to improve the technological scheme of treatment of iron-containing wastewater from etching operations by creating combined systems, including reagent wastewater treatment, their mutual neutralization, regeneration of etching solutions, deep post-treatment using a magnetic device. The main volume of wastewater is treated in centralized systems with partial return of water to the production process. Spent solutions from etching operations are subject to regeneration with return to the production process and partial dosing into the main wastewater stream from flushing operations. The consumption of commercial HCl is reduced by 50%. The use of hydrogen peroxide can increase the effect of extracting iron from etching solutions by 30% (total purification effect of 70%). Given that deep purification from iron-containing impurities is provided using a magnetic device, the possibilities of practical implementation of reverse osmosis to obtain "pure" water in centralized systems, which can be used for preparation of process solutions and in a mixture with technical water - for flushing operations, increase. In experimental and industrial conditions the expenses of reagents, their concentrations, dosing time are established

Determining rational parameters for the treatment of concentrated wastewater from etching site by using combined systems producing sediments of predefined composition

“…To devise a technological scheme for obtaining sludge for disposal, it is recommended to direct 50 % of the total volume of the etching solution to local regeneration cycles. Regeneration of solutions from etching operations is carried out by treatment with an alkaline reagent and hydrogen peroxide in an acid-oxidizing environment in order to precipitate iron ions in the form of hydroxo compounds [19]. Schematically, this process can be represented as follows:…”

“…-the formation of insoluble Fe 3+ hydroxo compounds when adding an alkaline reagent to pH=4 [15,19].…”

“…Based on the review of the literature [4] and earlier conducted studies, which were verified in papers [15,[18][19][20] and under industrial conditions (Fig. 2), we systematized elements of the technological scheme, which provides for the treatment of concentrated wastewater from the etching area in combined systems with obtaining sediments of predefined composition (Fig.…”

“…To this end, in order to improve the classical technology [19], wastewater should be divided into separate categories according to the parameters of its treatment. It depends on the technological operation (degreasing, etching, washing, etc.)…”