Article High performance electrocoagulation process in treating palm oil mill effluent using high current intensity application ☆ Mohd Nasrullah 1 , A.W. Zularisam 1, ⁎, Santhana Krishnan 1 , Mimi Sakinah 1 , Lakhveer Singh 2 , Yap Wing Fen 3 1 Faculty of Engineering Technology, Universiti Malaysia Pahang (UMP), Lebuhraya Tun Razak, Gambang, 26300 Kuantan, Pahang, Malaysia 2 Department of Biological and Ecological Engineering, Oregon State University, Corvallis, OR 97333, USA 3 Department of Physics, Faculty of Science, Universiti Putra Malaysia (UPM), Serdang 43400, Selangor, Malaysia abstract article info Article history: Received 17 October 2017 Received in revised form 9 June 2018 Accepted 2 July 2018 Available online 11 October 2018 Electrocoagulation process using high current intensity to treat palm oil mill effluent (POME) was investigated in this study. Various operating parameters such as electrolysis time, inter-electrode distance and initial pH were carried out to determine the efficient process condition on the removal of chemical oxygen demand (COD), biological oxygen demand (BOD) and suspended solids (SS). The highest treatment was achieved at 50 min with the removal efficiencies for COD, BOD and SS obtained as 85%, 83%, and 84%, respectively. More than 50 min treatment showed the fluctuated trends of removal efficiencies which can be considered insignificant. The application of higher current resulted in higher removals of organics while the gas bubbles also assisted in removing the pollutant particles by floatation. In an inter-electrode distance study, the removal efficiency decreased when inter-electrode distance was either higher or lower than 10 mm due to the increase of solution resistance and the decrease of anode active surface area. In initial pH study, it was found that high removal efficiencies were achieved in slightly acidic POME sample rather than in neutral or basic condition. An electrocoagulation process by using the optimum operating parameters was able to remove COD, BOD and SS up to 95%, 94% and 96% respectively. The experimental results confirm that application of high current intensity in electrocoagulation provided high treatment efficiency at a reduced reaction time. © 2018 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved. Keywords: Electrochemistry Environment Electrocoagulation Palm oil mill effluent High current intensity 1. Introduction Palm oil industry in this country has grown by leaps and bounds over the last few decades making Malaysia one of the largest crude palm oil producers in the world. However, the increasing production and processing of oil palm and its derivatives have generated consider- able wastes, termed as palm oil mill effluent (POME) that adversely af- fects human and aquatic life [1]. Every year, this country alone generates approximately 43.29 million cubic metres of POME [2]. This excessive industrial wastewater must be treated well to reach the discharge stan- dard in order to protect the environment. Various studies have been performed for the treatment and disposal method for POME such as ponding system, aerobic and anaerobic methods [3]. Not only for POME treatment, but also this biological treatment is a conventionally practiced method to treat most kinds of wastewater [4]. For example, different microorganisms and techniques have been tested to valorize olive mill wastewater, which is the wastewater that has pollutant con- centration similar to POME [5]. However, these biological treatment methods require a proper maintenance as well as periodic monitoring since the processes solely rely on microorganisms to degrade the high molecular weight fraction of wastewater [6]. Moreover, these methods need a particular attention and commitment by expert and are also time-consuming. Besides that, these biological treatments also take a longer hydraulic retention time and need a huge investment in land for pond and digesters [7]. Thereby, it is necessary to find other method or technique as an alternative to the conventional treatment system in order to comply with the requirements and regulations of safe waste- water discharge [8]. The alternative method must include various factors such as more convenient to operate, short retention time, ease of installation, energy efficiency, cost effective, widely applicable on the various pollutant ranges, less labour and less maintenance. An advanced electrochemistry-coagulation process, known as electrocoagulation is an alternative treatment method to remove the pollutant from wastewater. Electrocoagulation method has potential to treat POME as it is a stand-alone portable treatment with the ability to remove a wide range of pollutants. This treatment method was tested successfully for treating phenolic wastewater [9], olive mill wastewater [10], sewage [11], drilling fluids wastewater [12], tannery wastewater [13], poultry slaughterhouse wastewater [14], textile wastewater [15], chicken industry wastewater [16], removal of lead [17] and phosphate recovery from sludge anaerobic supernatant [18]. Other than low man- agement cost, this method is also safe and natural environmentally Chinese Journal of Chemical Engineering 27 (2019) 208–217 ☆ Supported by Universiti Malaysia Pahang Research Grant (RDU1803143). ⁎ Corresponding author. E-mail address: zularisam@ump.edu.my (A.W. Zularisam). https://doi.org/10.1016/j.cjche.2018.07.021 1004-9541/© 2018 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved. Contents lists available at ScienceDirect Chinese Journal of Chemical Engineering journal homepage: www.elsevier.com/locate/CJChE