Tannery wastewater treatment after activated sludge pre-treatment using electro-oxidation on inactive anodes

Abstract

Currently, electrochemical oxidation is a very efficient method to treat many types of wastewaters. Under the effects of electrical current, toxic or non-biodegradable substances will be oxidized to become biodegradable or completely oxidized to CO 2 and H 2 O. With the strengthening of environmental discharge legislations, tannery wastewater may have a negative effect on the environment because of its high pollution levels. In this study, for the first time, the tannery wastewater treatment after the activated sludge process digestion was carried out using electrochemical oxidation by SnO 2 /Ti and PbO 2 / Ti inactive anodes. Effects of current density, pH, stirring rate and reaction time on the pollutants removal efficiencies of tannery wastewater were studied. The results showed that SnO 2 /Ti and PbO 2 /Ti anodes can effectively remove over 80.0% of the color, chemical oxygen demand and total nitrogen in tannery wastewater after 90 min of reaction time at a current density of 66.7 mA/cm 2. SnO 2 /Ti anodes gave higher pollutants removal efficiency in base environments, while PbO 2 /Ti anodes offered higher pollutants removal efficiency in acidic environments. The current density and stirring rates significantly affected pollutant removal efficiencies, and the concentration of pollutants in the effluent decreased as reaction time was increased. In general, SnO 2 /Ti anodes were found to be more effective than PbO 2 /Ti anodes in the pollutants removal efficiency and energy consumption of tannery wastewater treatment.

Evaluation of the Light/Dark Cycle and Concentration of Tannery Wastewater in the Production of Biomass and Metabolites of Industrial Interest from Microalgae and Cyanobacteria

“…Goswami and Mazumder [41] reported the typical characterization of tannery wastewater, in which COD concentrations of 500-11,500 mg L −1 and total Kjeldahl nitrogen (TKN) of 200-550 mg L −1 were observed. Regarding pH, results of acidic pH between 3.4 ± 0.0351 and 5.96 ± 0.0351 [42][43][44] and basic pH between 8.0 ± 0.4 and 11.64 ± 0.53 have been reported [45][46][47]. In this work, the pH values were acidic, with values of 4.7 ± 0.12.…”

Obtaining Granules from Waste Tannery Shavings and Mineral Additives by Wet Pulp Granulation

“…In further work, Pietrelli et al [ 16 ] developed a most convenient approach to deal with these powders, generated as a by-product when chromium-containing tannery waste is treated with plasma pyrolysis and managed to recover the heavy metals they contain. The paper by Luu [ 17 ] explores tannery wastewater treatment after the activated sludge process digestion was carried out using electrochemical oxidation by SnO 2 /Ti and PbO 2 /Ti inactive anodes.…”