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Background and Objectives: Bioremediation is a process to reduce toxic heavy-metals, such as arsenic, in the environment using microorganisms. This study aimed to isolate arsenic remediating microbial strains from garbage leachates and to evaluate the effects of several factors on bioremediation by isolated strains. Materials and Methods: After isolating arsenic-resistant bacteria from garbage leachates and determining their MIC values, Taguchi design of experiments was used to evaluate the effect of arsenic concentration, pH solution, temperature, and contact time on arsenic bioremediation by isolated bacteria. Results: The results revealed that 3 arsenic-resistant strains of genus Bacillus characterized as KL1, KL4, and KL6 had arsenic bioremediation activity. Based on the results, the highest bioremediation of arsenic by Bacillus sp. KL1 was obtained as 77% after 24 hours at 40°C, pH 5, and 150 ppm concentration. However, the maximum bioremediation of arsenic by KL4 (91.66%) and KL6 (88%) was achieved after 24 hours at 40°C, pH 5, and 60 ppm concentration and at 35°C, 90 ppm concentration, pH 5 after 36 hours, respectively. Conclusion: The results presented here may facilitate improvements in the eliminating arsenic from contaminated sites and reducing environmental pollutions. [ABSTRACT FROM AUTHOR]