Creation of a combined system for treatment of iron-containing wastewater from etching operations

Abstract

The object of research is the methods of purification of iron-containing wastewater from etching operations, the subject of the study is spent technological solutions of etching and wastewater from the operations of washing enterprises of hardware products. Spent etching solutions are characterized as highly concentrated solutions, and wash water belongs to the category of concentrated solutions containing toxic impurities: heavy metal ions, acids, surfactants. The main problem in the etching area is the processing of used etching solutions. The most progressive creation of combined systems in which the bulk of wastewater is treated in centralized systems with partial return of water to the production process. With such wastewater treatment, the problem arises of reducing the total concentration of iron to less than 1 mg/l. That is why, in accordance with the requirements of environmental legislation on nature management, there is a need for deep additional treatment of such wastewater. The study used the methods of potentiometric titration and chemical deposition, as well as the method of photometric determination. Magnetic cleaning was studied in an experimental magnetic deposition apparatus. The paper presents the results of studies evaluating methods for purifying iron-containing wastewater from etching operations. Improvement is achieved by the creation of technological combined schemes for the purification of iron-containing wastewater, including a magnetic device as an auxiliary element. At the same time, the main volume of wastewater is treated in centralized systems with a partial return of water to the production process. Waste solutions from etching operations are subject to regeneration with return to the production process and partial dosage into the main wastewater stream from washing operations. Deep purification from iron-containing impurities using a magnetic device expands the possibilities of practical implementation of reverse osmosis to obtain «clean» water in centralized systems. This water is applicable for the preparation of process solutions and mixed with industrial water for flushing operations.

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

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

“…Paper [15] considered the improvement of the technological scheme of wastewater treatment of the etching area by implementing technological combined schemes for the treatment of iron-containing wastewater using an auxiliary element of a magnetic device. At the same time, the possibilities of practical implementation of reverse osmosis are expanding.…”

“…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.…”