Contents lists available at ScienceDirect Journal of Environmental Management journal homepage: www.elsevier.com/locate/jenvman Adsorption of sugarcane vinasse effluent on bagasse fly ash: A parametric and kinetic study Kudakwashe Engels Chingono a , Edmond Sanganyado b,a,* , Emily Bere a , Bongani Yalala a,** a Applied Chemistry, National University of Science and Technology, Bulawayo, Zimbabwe b Marine Biology Institute, Shantou University, Shantou, Guangdong Province, 515063, China ARTICLE INFO Keywords: Bagasse fly ash Industrial wastewater treatment Low-cost adsorbent Solid waste utilization Biosorption ABSTRACT Sugarcane and bioethanol production produces large amounts of bagasse fly ash and vinasse, which are solid and viscous liquid wastes, respectively. However, these wastes are often disposed into the environment without treatment, thus posing an environmental and public health risk. This study investigated the treatment of vinasse effluent in terms of reduction of chemical oxygen demand (COD) and acidity removal using sugarcane bagasse fly ash. A maximum COD removal efficiency of 72% was obtained using an effluent volume of 100 mL, contact time of 180 min, and shaking speed of 240 rpm. The adsorbent dose and particle sizes were 4.5 g and 90–125 μm, respectively. Furthermore, the potential application of bagasse fly ash as an adsorbent in a sand filtration bed was assessed using a column test. A maximum recovery of 68% was obtained at the 25-min interval. The ad- sorption data was found to fit the Freundlich model best (K f = 2.16 mg g -1 ; R 2 = 0.96), and the kinetics fit the pseudo-second order model (R 2 = 0.98). 1. Introduction Bioethanol production from sugarcane is often commended as a sustainable source of fuel. However, it produces large amounts of vi- nasse and bagasse, which are liquid and solid wastes, respectively (Colin et al., 2016). Vinasse is a complex acidic effluent formed during the distillation stage in the production of bioethanol. It often has high chemical oxygen demand (COD) and biochemical oxygen demand (BOD) that can be as high as 90000–210000 mg L -1 and 45000–100000 mg L -1 , respectively (Fagier et al., 2016). Vinasse is widely used for fertigation since it has high amounts of nutrients such as nitrogen, phosphorus, and sulfate (Christofoletti et al., 2013). However, vinasse effluent has been shown to have mutagenic and genotoxic potential in aquatic and terrestrial organisms such as fish (Correia et al., 2017a, 2017b), onion (Allium cepa)(Garcia et al., 2017), and Rhinocricus padbergi (Diplopoda) (Coelho et al., 2017). Therefore, discharging untreated vinasse into the aquatic and terrestrial environ- ment may pose an environmental risk. Sugarcane bagasse is often burned in the production of bioethanol as a source of energy and this result in the formation of bagasse fly ash (Bhatnagar et al., 2016). The bagasse fly ash has been successfully used as a filler material in the production of concrete in the construction industry (Ríos-Parada et al., 2017). Despite the increase in use in the construction industry, the amount of fly ash produced per year con- tinues to grow (Janoš et al., 2003). Hence, in the past decade additional green applications of fly ash have been explored (Wong et al., 2018). Sugarcane bagasse fly ash contains about 15–35 wt% unburned carbon that could be easily separated and activated to low-cost sorbents for removal and recovery of small molecules (Gonçalves et al., 2016). For example, several studies successfully employed fly ash for the removal of dyes (Caqueret et al., 2012; Wang et al., 2010), organic compounds (Subramanian et al., 2013), and heavy metals (Yadav et al., 2014) in industrial waste. Unlike fly ash from incinerators, bagasse fly ash is more suitable for water treatment because it does not contain high concentrations of toxic metals (Janoš et al., 2003). Recently, 78% of melanoidins were successfully recovered from distillery wastewater using activated carbon derived from bagasse fly ash (Kaushik et al., 2017). Thus, using sugarcane bagasse fly ash as a sorbent is not only important for waste removal but volarization of agro-waste as well. Bioethanol plants in Zimbabwe produce about 60 million liters of anhydrous ethanol each season, with approximately 470 million liters of vinasse effluent (Maqhuzu et al., 2017). In Zimbabwe, vinasse ef- fluent is often discharged into the environment untreated. Furthermore, sugarcane bagasse fly ash is sometimes used for landfilling. Thus, al- though bioethanol production is essential for Zimbabwe to meet its sustainable development goals, the generation and subsequent https://doi.org/10.1016/j.jenvman.2018.07.042 Received 28 April 2018; Received in revised form 9 July 2018; Accepted 14 July 2018 * Corresponding author. Marine Biology Institute, Shantou University, Shantou, Guangdong Province, 515063, China. ** Corresponding author. Applied Chemistry, National University of Science and Technology, Bulawayo, Zimbabwe. E-mail addresses: esang001@ucr.edu, esanganyado@stu.edu.cn (E. Sanganyado), bongani.yalala@nust.ac.zw (B. Yalala). Journal of Environmental Management 224 (2018) 182–190 0301-4797/ © 2018 Elsevier Ltd. All rights reserved. T