Electrochemical Recovery of Coagulants in the Processes of Wastewater Treatment of Textile Enterprises.

Flotation technologies for wastewater treatment of textile enterprises have become very widespread. This raises the issue of wastewater treatment waste containing resistant organic compounds, such as synthetic dyes and surfactants. These substances account for the bulk of sewage pollution from textile factories. The purpose of the research was to study the electrochemical destruction of biologically stable organic substances in the liquid phase of the flotation sludge and to develop on this basis the technology for regenerating the coagulant solution to return to the wastewater treatment process. The research was carried out on the model solutions and samples of the flotation sludge of the operating flotation plants. It was found that the rate of oxidation of organic dyes is practically independent of the pH value. In the oxidation of surfactants, the maximum effect was observed at pH <= 4. The degree of electrochemical destruction of dyes exceeds 90%. At the same time, the electricity consumption is 10...12 Watt/h per 1g of the oxidized substances. The efficiency of electrochemical destruction of surfactants is not more than 55...65%, with specific electricity consumption of 12...15 Watt h/g. Further studies were aimed at intensifying the process of electrochemical oxidation of surfactants using the addition of chlorides and homogeneous catalysts. It was established that the degree of oxidation of the organic substances essentially depends on the dose of the catalyst. The effective dose of the catalyst - the ion Fe3+ is associated with the content of chlorides in the processed flotation sludge and is in the range of 60...100 mg/I. The degree of electrochemical destruction of surfactants in the presence of ferric iron salts is up to 96%. At the same time, the specific electricity consumption for the destruction of resistant organic substances by chemical oxygen demand (COD) is in the range of 5-12 kWh / (kg of COD). The method of electrochemical destruction makes it possible to regenerate the coagulant, reduce the mass of waste removed outside the enterprises, and significantly reduce the supply of resistant organic compounds to the environment.