Electrocoagulation/electroflotation as a combined process for the laundry wastewater purification and reuse

Abstract

The purpose of this work is to purify wastewater from industrial laundries and return them to the washing process. By means of the methods of electrocoagulation and electroflotation, laboratory and pilot studies on the wastewater treatment were carried out using aluminium electrodes. The process of wastewater treatment has been studied in dependence on treatment time, temperature, pH and current density. The effectiveness of the cleaning process under different values of operating parameters of the reactor was estimated as the percentage of color, turbidity and surfactant removal from the wastewater. As a result of laboratory studies, the optimum values of the operating parameters of the reactor at 90% removal of contamination were the following: current density value as 5.26 mA/cm2, pH as 5.5 and 5 min processing time. The consumption of electrical energy in this case amounted to 1.25 kW h/ m3. The quality control of the purified water was carried out according to such additional parameters as total suspended solids, chemical oxygen demand, total organic carbon, and the content of metal ions and phosphate and nitrate anions in the water. The study of the wastewater treatment in a pilot plant with laboratory values of operating parameters showed the reproducibility of the purification results for the controlled parameters of water quality and suitability of the water for reuse. The washing performed with purified water was estimated by the whiteness index for bed linen and was not inferior to the traditional washing with water from a source of water supply.