Abdolmotaleb Seid Mohammadi
1, Azam Mobarakian
2, Fatemeh Taherkhan
2, Ghorban Asgari
2*1 Social Determinants of Health Research Center, Department of Environmental Health Engineering, School of Public Health, Hamadan University of Medical Sciences, Hamadan, IR Iran
2 Department of Environmental Health Engineering, School of Public Health, Hamadan University of Medical Sciences, Hamadan, IR Iran
Abstract
Chitosan, a biodegradable polymer, is used as an eco-friendly coagulant in a wide variety of applications in water and wastewater
treatment. The present study aimed to investigate the effect of chitosan as a coagulant aid combined with poly aluminum chloride (PAC)
to enhance coagulating efficiency for bentonite suspensions. A conventional jar test apparatus was used for the tests. The effect of various
operational parameters, such as initial pH of the solution (5-9.5), dosage of chitosan (0.5-3.5 mg/L), dosage of PAC (5-35 mg/L) and initial
turbidity (50-200 NTU) were investigated. The maximum turbidity removal rates were obtained as pH 8.5 for PAC and pH 7.5 for combined
PAC and chitosan (CPC). The coagulating efficiency of bentonite using PAC and CPA was found to decrease with an increase in the pH value
of the solutions. The maximum turbidity removal rate was achieved in coagulating by PAC (30 mg/L) alone, and PAC (20 mg/L) combined
with chitosan (2.5 mg/L) as coagulant aid with the removal rate of 87% and 96%, respectively. The optimum dosage of chitosan required
to obtain the highest removal rate was 2.5 mg/L. Hence, using chitosan as a coagulant aid can not only reduce the required amount of
coagulant (35%) but can also enhance the removal turbidity efficiency.