Tannery wastewater treatment after activated sludge pre-treatment using electro-oxidation on inactive anodes
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ORIGINAL PAPER
Tannery wastewater treatment after activated sludge pre‑treatment using electro‑oxidation on inactive anodes Tran Le Luu1 Received: 5 January 2020 / Accepted: 25 July 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
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 CO2 and H2O. 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 SnO2/Ti and PbO2/ 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 SnO2/Ti and P bO2/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/cm2. SnO2/Ti anodes gave higher pollutants removal efficiency in base environments, while P bO2/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, SnO2/Ti anodes were found to be more effective than PbO2/Ti anodes in the pollutants removal efficiency and energy consumption of tannery wastewater treatment. Graphic abstract
Electrochemical oxidation
Aerotank
+ Influent
Activated sludge Non-biodegradable compounds Ammonium
Oxidants
Fresh water
Pollutants CO 2+H 2O
Keywords Tannery wastewater · Activated sludge · Electrochemical oxidation · SnO2/Ti · PbO2/Ti
Introduction
* Tran Le Luu [email protected] 1
Master Program in Water Technology, Reuse and Management, Vietnamese German University, Thu Dau Mot, Binh Duong, Vietnam
Tanning is a worldwide manufacturing industry which converts animal hides into leather. In this process, animal hides do not become crispy when cooled nor form wrinkles when moistened or heated (Dinh 2013). Based on using purpose of the leather and process technology, different chemical substances may be used in the tanning process. The
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Vietnamese tanning industry consumes a huge volume of water (35–40 m3/ton) compared with other Southeast Asia countries (30 m3/ton, Lofrano et al. 2013). Although the Vietnamese tanning industry now uses fewer chemicals, technological know-how still remains fragmentary, lacking basic general knowledge. Due to the demand of current markets, the development of the tanning industry is inevitable. However, there are still many issues that remain in the tann
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