en تخصصي Special Original articles <div dir="ltr" style="text-align: justify;"><strong><em><span style="letter-spacing:.1pt;"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">Introduction</span></span></span></em></strong><strong><span style="letter-spacing:.1pt;"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">:</span></span></span></strong><span style="letter-spacing:.1pt;"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;"> Since some dyes and their metabolites have toxicity and carcinogenicity potential, and are dangerous to the health of different living creatures, discharge of untreated wastewaters containing large concentrations of dye compounds into water resources is one of the important environmental problems. Therefore, in this research, the <span style="color:black;">efficiency of chemical coagulation process was investigated using ferric chloride coagulant </span></span>to remove Direct Red 23 dye from colored wastewater.</span></span><br> <strong><em><span style="letter-spacing:.1pt;"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">Materials and Methods:</span></span></span></em></strong><span style="letter-spacing:.1pt;"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;"> In the experiments, a Jartest device was used and the effect of different parameters including the dose of the coagulant (20-200 mg/L), pH (3-10), and initial concentration of the dye (25-200 mg/L) on the efficiency of chemical coagulation process for removal of the dye was examined. Further, the final pH of the wastewater was investigated and the optimal conditions were determined.</span></span></span><br> <strong><em><span style="letter-spacing:.1pt;"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">Results:</span></span></span></em></strong><span style="letter-spacing:.1pt;"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;"> The results indicated that the optimal dose of ferric chloride coagulant for Direct Red 23 dye removal of 97.7% is 40 mg/L at the optimal pH of 7. With increase in the dose of the coagulant, the dye removal efficiency increased, while the final pH of the wastewater decreased. Under constant conditions, with increase in the dye concentration, the dye removal efficiency diminished. </span></span></span><br> <strong><em><span style="letter-spacing:.1pt;"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">Conclusion:</span></span></span></em></strong><span style="letter-spacing:.1pt;"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;"> Chemical coagulation by ferric chloride is a very effective and fast method for removal of direct dye from colored wastewater.</span></span></span></div> Dye, Removal, Coagulation 333 339 http://jehsd.ssu.ac.ir/browse.php?a_code=A-10-1-55&slc_lang=en&sid=1 Arash Dalvand No Environmental Science and Technology Research Center, Department of Environmental Health Engineering, School of Public Health, Shahid Sadoughi University of Medical Sciences, Yazd, Iran. Mohammad Hassan Ehrampoush No Environmental Science and Technology Research Center, Department of Environmental Health Engineering, School of Public Health, Shahid Sadoughi University of Medical Sciences, Yazd, Iran. Mohammad Taghi Ghaneian No Environmental Science and Technology Research Center, Department of Environmental Health Engineering, School of Public Health, Shahid Sadoughi University of Medical Sciences, Yazd, Iran. Mehdi Mokhtari No Environmental Science and Technology Research Center, Department of Environmental Health Engineering, School of Public Health, Shahid Sadoughi University of Medical Sciences, Yazd, Iran. Ali Asghar Ebrahimi No Environmental Science and Technology Research Center, Department of Environmental Health Engineering, School of Public Health, Shahid Sadoughi University of Medical Sciences, Yazd, Iran. Roya Malek Ahmadi No Environmental Science and Technology Research Center, Department of Environmental Health Engineering, School of Public Health, Shahid Sadoughi University of Medical Sciences, Yazd, Iran. Amir Hossein Mahvi ahmahvi@yahoo.com Yes Department of Environmental Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.