Journal of Water Process Engineering xxx (xxxx) xxx Please cite this article as: Özlem Bulca, Journal of Water Process Engineering, https://doi.org/10.1016/j.jwpe.2020.101821 2214-7144/© 2020 Elsevier Ltd. All rights reserved. Performance investigation of the hybrid methods of adsorption or catalytic wet air oxidation subsequent to electrocoagulation in treatment of real textile wastewater and kinetic modelling ¨ Ozlem Bulca, Burcu Palas, Süheyda Atalay, Gülin Ers¨ oz * Chemical Engineering Department, Faculty of Engineering, Ege University, 35100 Bornova, ˙ Izmir, Turkey A R T I C L E INFO Keywords: Adsorption isotherms Catalytic wet air oxidation Electrocoagulation Hybrid treatment Reaction kinetics model ABSTRACT The performances of two hybrid wastewater treatment methods were compared to determine which method is more effective for improving the reusability of textile industry wastewater as irrigation water. In the hybrid treatment processes, either adsorption or catalytic wet air oxidation (CWAO) was performed subsequent to the electrocoagulation. The performances of the adsorption and catalytic wet air oxidation methods were evaluated according to the irrigation water criteria. Rice husk based activated carbon (RHAC) was used as adsorbent and catalyst support material in the adsorption and CWAO, respectively. BiNiO 3 -RHAC catalyst was prepared and used in CWAO process. The irrigation water criteria for total organic carbon (TOC), turbidity, and color were met and 91 % TOC reduction was achieved after the sequential application of electrocoagulation and adsorption. Freundlich isotherm and second order adsorption kinetics were regarded as the most suitable models to ft the adsorption data. The application of electrocoagulation and catalytic wet air oxidation yielded 62 % TOC removal whereas the oxidation reaction followed a two-step second order reaction kinetics. 1. Introduction Water pollution is one of the major ecological problems, which threatens health of all living organisms. The water pollution is generally related to the human activities such as industrial and agricultural ap- plications [1]. Textile, paper, petro chemistry, pharmaceutical, oil, food industries have large amounts of wastewater discharge. According to activities of companies, type of contaminants changes like organic, inorganic, toxic, mutagenic, radioactive etc. [2]. In textile industry, there are different processes such as fber production, dying, bleaching, and washing in which various dyes, solvents, adhesives, detergents, and lubricants are used. Since large amounts of wastewater have been released from the textile mills, development of effective treatment methods is signifcant to minimize the harmful effects of contaminants [3]. Electrocoagulation is one of the outstanding processes for the treat- ment of industrial wastewater and has several advantages over tradi- tional coagulation methods. Electrocoagulation is a simple operation with little requirement for equipment in which no additional chemicals are used for the removal of pollutants [4]. However, electrocoagulation process has several drawbacks including regular replacement of sacri- fcial anodes, cathode passivation due to the oxide flm, electricity consumption, and sludge generation. Though a considerable amount of sludge is generated in electrocoagulation process, the volume of sludge is much less than that produced in chemical coagulation/focculation process [5,6]. Adsorption is another effective treatment method for the removal of both of the organic and inorganic contaminants. Though adsorption is simple and suitable method for the removal of a wide variety of pol- lutants, it is a nondestructive method and the pollutants are transferred from one phase to another. In addition, regeneration ad elimination of the adsorbents increase the operating costs. The performance of the process depends on the type of the adsorbent material and high quality adsorbents may be quite expensive [7]. Therefore, there has been a growing interest in production and application of low cost adsorbents [8]. Activated carbon is one of the most popular adsorbent materials, which is widely used in wastewater treatment applications. For the production of low cost activated carbon, agricultural wastes have been utilized as the carbon source due to their high carbon content and abundancy in nature. In this study, activated carbon adsorbent was * Corresponding author. E-mail addresses: bulcaozlem35@gmail.com ( ¨ O. Bulca), burcu.palas@ege.edu.tr (B. Palas), suheyda.atalay@ege.edu.tr (S. Atalay), gulin.ersoz@ege.edu.tr (G. Ers¨ oz). Contents lists available at ScienceDirect Journal of Water Process Engineering journal homepage: www.elsevier.com/locate/jwpe https://doi.org/10.1016/j.jwpe.2020.101821 Received 28 July 2020; Received in revised form 10 November 2020; Accepted 13 November 2020