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With less availability of land and loss of crops by pest, the use of pesticide such as Atrazine is increasing significantly. Atrazine is a member of s-triazine group herbicides and is a probable human carcinogen (Group 2B). Atrazine is resistant in the environment and, as a result, causes serious environmental problems. Moreover, it penetrates through the surface and subsurface water bodies as well as groundwater due to its excessive usage and high persistence and mobility. In general, several methods, such as adsorption, incineration, oxidation-reduction, photolysis, hydrolysis, dehalogenation, reverse osmosis, and chemical degradation, are available for removing Atrazine from contaminated water and wastewater; however, these methods are very costly, have many performance problems, produce a lot of toxic intermediates which are very harmful and dangerous, and cannot completely mineralize Atrazine. Biodegradation is an economically viable technology which leads to complete degradation and mineralization of Atrazine and produce simple compounds, such as carbon dioxide, water, nitrogen, and organic materials. Biological methods having enzymatic system that which is Atrazine used as carbon, nitrogen and energy source and completely mineralization occur, also submerged aerated filters to their treatment mechanism greatly contributed to reduce treatment cost. In this study potential of Biological Aerated Filter (BAF) in Atrazine removal from aquatic environment, at 4 concentration of Atrazine and 3 hydraulic retention times (HRTs) was evaluated. Based on the results Atrazine degradation potential of the mixed aerobic consortium was evaluated under various Atrazine concentrations and HRTs. It was shown that maximum efficiency in Atrazine and Soluble Chemical Oxygen Demand (SCOD) removal was 97.9% and 98.3%, respectively. Also stover-kincannon model have very good fitness (R2 > 99%) in loading Atrazine in this biofilter. Submerged aerated filter, a good performance in the removal of toxic and sustainable organic. High degradation rate of Atrazine at comparatively high Atrazine concentration might be due to the effect of concentration gradient. At high concentration gradient, the pollutant has a higher chance to be exposed to and/or penetrate through the cell which is essential for biodegradation. Co-metabolic process is used for bioremediation of most persistence contaminants, such as Atrazine. In co-metabolic processes, by utilizing primary carbon source or nitrogen source, microbes produce enzymes or cofactor during microbial activities which are responsible for degradation of the secondary substrates (toxic compounds, Atrazine). Also, the contaminants degrade in this process in order to trace concentrations. Cometabolism process was effective in Atrazine degradation process and aerobic mixed biofilm culture was observed to be suitable for the treatment of Atrazine from aqueous solutions. The present study investigated the ability of an BAf to remove Atrazine from aqueous environment. The BAF was operated at 3 different aerobic retention times in order to determine the optimum retention time for the highest Atrazine and COD removal.

Keywords: Atrazine, Herbicide, Biodegradation, Submerged Aerated Filter, Biological Filter

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