International Journal for Research in Engineering Application & Management (IJREAM) ISSN : 2454-9150 Vol-05, Issue-12, Mar 2020 14 | IJREAMV05I1260005 DOI : 10.35291/2454-9150.2020.0160 © 2020, IJREAM All Rights Reserved. UV-TiO 2 process for Landfill Leachate Treatment: Optimization by Response Surface Methodology * Mohd Salim Mahtab, # Izharul Haq Farooqi * Research Scholar, # Professor, Department of Civil Engineering, Aligarh Muslim University, Aligarh, India, *mohdsalimmahtab@gmail.com, # farooqi_izhar@yahoo.com Abstract - Landfill leachate contains variety of organic compounds, some are recalcitrant in nature. Those compounds are difficult to convert into inorganic compounds by conventional biological methods. For which, advanced oxidation processes (AOPs) plays very crucial role for their treatment. Among AOPs, photocatalytic degradation process was employed in the present study. In this method, ultraviolet (UV) irradiation with photocatalyst titanium dioxide (TiO 2 ) is producing highly reactive hydroxyl radicals (HO°). The generated (HO°) are highly reactive and non-selective in nature, which converts complex organic compounds into simple harmless inorganic compounds. In the present study, experiments were designed by Central Composite Design (CCD) method in Response Surface Methodology (RSM) approach by using Design Expert-10 software and performed the experiments accordingly. In the (CCD) method, three factors were adopted, i.e. reaction time, TiO 2 dosage and dilution factor (D.F) with one response, percentage chemical oxygen demand (COD) removal. Using the multivariate effect of the factors, the optimization conditions were achieved for UV-TiO 2 process for landfill leachate treatment. At optimized conditions more than 60% COD removal were achieved and the experimental results were in agreement with the predicted value with R 2 = 0.91. It is noticeable from the results, UV assisted TiO 2 photo catalysis could be useful for high strength wastewater treatment. From the results, it is analyzed that beyond a certain limit of the parameters, the organic contaminants removal decreased. The UV-TiO 2 photo catalysis system suggested may be an economical method for landfill leachate treatment. This process also helps in enhancing the biodegradability of landfill leachate. Keywords — Central Composite Design, Chemical oxygen demand, Landfill leachate, Photocatalytic degradation, Response surface methodology, Titanium dioxide I. INTRODUCTION In India the generation of municipal solid waste is about 62 million tons per year, having an annual average growth rate of 4% [1].The rapid urbanization and population explosion are the main culprits behind the severity of Municipal solid waste (MSW) problem. The anticipated population of India in 2051 would be 1823 million having a MSW generation of about 300 million tons per annum [2].Hence, proper disposal of the MSW is the need of hour. The different disposal methods that are primarily adopted for MSW involve, composting, incineration, recycling and landfilling. Landfilling is one of the most widely applied methods of municipal solid waste disposal all over the world. However, the generation of highly contaminated leachate is an unavoidable and undesirable effect of the existing practice of waste management [3]. This highly toxic leachate is formed when the rain falls over the landfill and percolates down, combining with the decomposed waste under different biological, physical and chemical conditions [4]. The refractory nature of the contaminants, high COD, presence of various recalcitrant compounds, heavy metals and other toxicants make its remediation a difficult task [5]. Due to the diverse nature of the leachate the conventional biological treatments face various drawbacks. Hence, a generalized treatment does not exist. However numerous kinds of physical and chemical treatment processes have been developed in the last decades such as Chemical Oxidation, Coagulation–Flocculation, Electrochemical treatment etc. which are adopted in combination with the biological treatments in order to optimize the total treatment efficiency. Despite its drawbacks, biological treatment is still the best treatment method for young and intermediate leachates because of their high biodegradability (BOD 5 /COD ˃0.4) and lower molecular weight fraction. They show good elimination efficiency, are relatively cost effective and uncomplicated in nature. However, these treatments prove to be ineffective when it comes to mature leachate because of their refractory nature i.e. (BOD 5 /COD˂0.2), greater