Contents lists available at ScienceDirect Journal of Environmental Management journal homepage: www.elsevier.com/locate/jenvman Research article Feasibility analysis of homogenizer coupled solar photo Fenton process for waste activated sludge reduction V. Godvin Sharmila a , S. Adish Kumar a , J. Rajesh Banu a,* , Ick Tae Yeom b , Ganesh Dattatraya Saratale c a Department of Civil Engineering, Anna University Regional Campus-Tirunelveli, Tirunelveli, Tamilnadu, 627007, India b Department of Civil and Environmental Engineering, Sungkyunkwan University, Suwon, South Korea c Department of Food Science and Biotechnology, Dongguk University-Seoul, Ilsandong-gu, Goyang-si, Gyeonggi-do 10326, Republic of Korea ARTICLE INFO Keywords: Waste activated sludge Fenton oxidation Solar Homogenizer Cost analysis ABSTRACT In this study, an attempt has been made to reduce the sludge using novel homogenizer coupled solar photo Fenton (HPF) process. At an optimum pH of 3 and Fe 2+ to H 2 O 2 dosage of 1:6, PF process yielded 63.7% solids reduction at a time interval of 45 min. Coupling of homogenizers with photo Fenton (PF) process effectively enhanced treatment efficiency. When homogenizer (specific energy - 1150.694 kJ/kg TS) was coupled with PF, a sharp increase in solid reduction 73.5% and decrease in reaction time (20 min) were observed. Cost benefit analysis revealed the efficiency of HPF process and achieved a net cost of 15.59 USD whereas PF achieved a negative net cost of -82.69 USD. Based on the above study it can be concluded that coupling of homogenizers with PF not only increased its efficiency but also make it field applicable. 1. Introduction The wastewater treatment plant produces tremendous quantity of biosolids. This emergent biosolids i.e., the waste activated sludge (WAS) comprises of pathogens, biodegradable materials and other traces of organic and inorganic compounds (Kavitha et al., 2014). This WAS has potential to affect the environment and human health. Various treatment techniques have been adopted to reduce the quantity of generated WAS such as biological treatment such as anaerobic and aerobic treatment (Banu et al., 2018a) and conventional treatment such as landfill and composting (Kavitha et al., 2016a). Even though there is a generation of bioenergy, the above common method requires high area, high energy and more time (Poh et al., 2009). Research has been made to reduce sludge quantity by alternative techniques. Among al- ternative technology, advanced oxidation plays an important role now- a-days (Amudha et al., 2016). Advanced oxidation process has gained attention due to the usage of solar radiation for treatment which is an eco-friendly method (Tsydenova et al., 2015). Solar radiation is the pollution free renewable form of energy source with high abundant natural energy. Solar photo Fenton process is one among the advanced oxidation process involved in efficient degradation of organics. Its utilization in the field of sludge treatment gives non-toxic by-products. It has following advantages such as better degradation efficiency, toxic less treatment, consumes less energy e.t.c., (Rathod et al., 2012). During solar photo Fenton process, Fe 2+ act as catalysts stimulating oxidation reaction of hydrogen per- oxide leads to the generation of hydroxyl radical (Kavitha et al., 2016b). This generated hydroxyl radical has high oxidative potential involved in the degradation process. Recently, combinative treatment in field of AOP is gaining attention (Dewil et al., 2017). Homogenizer is a mechanical device used by many researchers to pretreat the sludge (Kavitha et al., 2014; Kannah et al., 2017; Tamilarasan et al., 2017). Homogenizer works in the principle of rotor stator effect and it can capable of reducing and dispersing the waste activated sludge (Kavitha et al., 2016a). Poor sludge reduction and greater energy consumption limits the usage of homogenizer as a sole agent to reduce solids (Bagal and Gogate, 2014). However, it is successfully employed by many researchers to reduce solids by com- bining the process with other agents (Rai et al., 2009; Poornima et al., 2014; Zhang et al., 2012). Hence in the present study, coupling of homogenizers with photo Fenton (PF) is used to improve the efficiency of sludge management process. Mainly mechanical treatment such as ultrasonic and homogenizer method generating acoustic and hydro- dynamic cavitation plays a vital role in enhancing the hydroxyl radical generation in addition to organic disintegration (Saharan et al., 2012; Gong et al., 2015). https://doi.org/10.1016/j.jenvman.2019.03.013 Received 10 October 2018; Received in revised form 25 February 2019; Accepted 3 March 2019 * Corresponding author. Department of Civil Engineering, Anna University Regional Campus-Tirunelveli, Tirunelveli, Tamilnadu, 627007, India. E-mail address: rajeshces@gmail.com (J.R. Banu). Journal of Environmental Management 238 (2019) 251–256 0301-4797/ © 2019 Elsevier Ltd. All rights reserved. T