International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 7, Issue 9, September 2017) 623 Photocatalytic Degradation of Pulp & Paper Mill Wastewater Using ZnO Photocatalyst Abhishek Mahajan 1 , Kulbir Singh Nain 2 , Rajesh Kumar Lohchab 3 1,2 Department of Civil Engineering, Maharishi Markandeshwar University, Mullana-Ambala, 133207, (Haryana) 2,3 Department of Environmental Science & Engineering, Guru Jambeshwar University of Science and Technology, Hisar-125001 (Haryana) Abstract— To reduce the pollutants from the effluent heterogeneous photocatalysis process is the environment friendly process. In degrading bio-recalcitrant compounds the photocatalytic process has proved to be superior to various conventional treatment processes. During the photocatalytic degradation, the transfer of hazardous contaminants from one form to another do not takes place and complete degradation of contaminants takes place. Due to the use of Artificial UV light and Semiconductor as a catalyst, this process is quite. The application of Photocatalytic process at industrial scale is possible in India. So Photocatalysis is attractive and cost- effective option in our country. With varying parameters like pH, irradiation time, catalyst dose and UV light intensity the degradation process is studied. Under the optimum pH of the solution (7.0 pH), catalyst dose of 1.2 g/500ml after 6 hr conditions 97%, 90% and 83% degradation in BOD, COD & Colour was observed. Keywords— Photocatalysis, ZnO, Pulp & Paper Mill Effluent, Artificial UV. I. INTRODUCTION The wastewater discharge from various industries like agricultural fertilizers, chemical industries, landfills etc. remains global concern as the discharge of contaminants from them results in contamination of water bodies. The conventional treatment processes faces the most challenging problem in removal of trace & Toxic contaminants as the presence of such pollutants in them. As per environmental point of view the public concern is growing in developing the modern techniques to overcome technical shortage in treatment of such toxic and trace elements with low cost. The untreated effluent discharge from industries and agricultural processes like fertilizers and other chemicals are the main threat & problem to the environment. During treatment processes like chlorination large number of compounds can transform themselves into harmful substances. In pulp & paper wastewater the main interest of consideration is decolouration, now a days. The treatment of pulp & paper mill wastewater by physical, chemical & biological methods are difficult due to presence of toxic pollutants.[1] The conventional methods has too many limitations as they convert the contaminant from one stage to other but the initial problem remains unsolved. So to overcome these problems advanced treatment methods are developed.[2] The paper industry is the type of industry that use huge amount of water and chemicals. So decolourization of pulp & paper mill waste water is very interesting subject as we can save more amount of water and these industries produces large amount of pollutants so the decolourization of waste water of Pulp and paper mill wastewater is overall beneficial. Pulp and paper industry is one of the major aquatic pollution causing source in India. These pollutants can cause various diseases like cancer and can cause Mutations in aquatic life.[3] [4] The pollutants released as the result of various processes in the form of Black Liquor which contains high BOD & COD values.[5] A. Photocatalysis Photo-catalysis is the light based acceleration of photoreaction in presence of semiconductor as catalyst. In Photocatalysis the electron hole pairs are generated and the activity of photo reaction depends on the generation of E-H pair which helps in generation of free radical which undergo the other secondary reaction processes. Photo catalysis involves the use of non-toxic semiconductor catalyst such as TiO2, ZnO. [6] Semiconductors have various kinds of properties due to which they are uses in photo catalysis such as they can absorb light, the excited state life time and characteristic of charge transport. [7] Conventional treatment methods such as Oxidation, biological treatment, activated carbon adsorption etc. has too many limitations so the Photocatalysis treatment shows many advantages over these conventional methods. In a typical photo-catalytic system, on the surface of photocatalyst the photo induced transformation occurs. [8] Basically the photocatalytic reaction involves formation of Electron – Hole pair in semiconductor and its deposition over the organic matter. The catalyst initially absorbs light of different colour based on the band gap energy of the semiconductor.