2864 Introduction The increasing problems associated with recalcitrant com- pounds removal from the effluents and their strict discharge standards required advanced and effective technologies 1,2 . The cost-effective andenvironmental-friendly approach would be suitable to serve the purpose. From the literature survey, the versatile applications of the advanced oxidation processes (AOPs) among physicochemical processes are one of the most suitable and widely adopted choices 2,3 . The hydroxyl radicals (  OH) are the main reactive species in the AOPs. These radicals effectively degrade the variety of recalcitrant compounds 3–5 . The Fenton-based processes are the most effective and widely recognized AOPs for the treatment of a wide variety of pollutants 2–4 . Applications of the Fenton-based approaches Although, the applications of the Fenton process are wide and versatile due to its fast degradation rate and simplicity in operation 6,7 . However, the conventional Fenton process has ATIPC – 2020 Special Issue J. Indian Chem. Soc., Vol. 97, No. 12b, December 2020, pp. 2864-2866 Degradation of recalcitrant compounds from the industrial effluents by Fenton-based approaches: A review Mohd Salim Mahtab* a , Izharul Haq Farooqi a and Anwar Khursheed b a Department of Civil Engineering, Z. H. College of Engineering and Technology, Aligarh Muslim University, Aligarh-202 002, Uttar Pradesh, India b Department of Civil Engineering, College of Engineering, King Saud University, Riyadh-11421, KSA *E- mail: msmahtab@zhcet.ac.in Manuscript received online 11 December 2020, accepted 31 December 2020 The huge generation of industrial effluents and their inefficient treatments make the environment and public health in dan- ger. The variety of pollutants present in the effluents depending upon the type of industry from which they are coming out, which are highly toxic and recalcitrant. Biological (conventional) treatment methods fail for their effective degradation and min- eralization. Wastewaters characterize by such compounds need cutting-edge and innovative technologies for their effective degradation and removal. In this review, we have highlighted some of the most preferable treatment methods with their mecha- nisms and applications in the context of wastewater containing recalcitrant compounds. It has been reported in the literature that Fenton-based approaches are one of the most efficient and versatile processes for degradation/mineralization of recalci- trant compounds. However, despite several advantages, some disadvantages are associated with these processeswhich make complications for their full-scale applications. Hence, we have to appropriately select the treatment options, which could be efficient enough and serve the overall purpose. Keywords: Advanced oxidation processes, electro-Fenton, Fenton process, photo-Fenton, recalcitrant compounds. some limitations, and to overcome those drawbacks various advanced Fenton-based approaches are developed and fur- ther improvements are underway to obtain sustainable solu- tions. Some of the Fenton-based approaches are summa- rized here as follows: Fenton process H. J. H. Fenton has first discovered the Fenton process in 1894 8 , and its main development was proposed by Haber and Weiss 9,10 . The reagents utilized in the reaction are Fe 2+ and H 2 O 2 , which produce the highly reactive hydroxyl radi- cals (  OH) under acidic conditions. The generated radicals rapidly and non-selectively degrade the variety of pollutants, which are non-biodegradable and recalcitrant 11 . The best treatment efficacy of the Fenton process was observed at the pH range of 2–4 12 . The hydroxyl radicals formed by the reaction of Fe 2+ and H 2 O 2 as shown in reaction (1) 11,13 : Fe 2+ + H 2 O 2  Fe 3+ +  OH + OH – (1) The other reactive species like HO  2 also formed and Fe 2+