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Iranian Journal of Environmental Health, Science and Engineering
Iranian Association of Environmental Health (IAEH)
ISSN: p-ISSN: 1735-1979
Vol. 6, No. 4, 2009, pp. 247-252
Bioline Code: se09036
Full paper language: English
Document type: Research Article
Document available free of charge

Iranian Journal of Environmental Health, Science and Engineering, Vol. 6, No. 4, 2009, pp. 247-252

 en Effectiveness Of Chitosan As Natural Coagulant Aid In Treating Turbid Waters
Bina, B.; Mehdinejad, M. H.; Nikaeen, M. & Attar, H. Movahedian

Abstract

During the last decade, there has been a concern about the relation between aluminum residuals in treated water and Alzheimer disease, and more interest has been considered on the development of natural coagulants such as chitosan. Chitosan, a natural linear biopolyaminosaccharide, is obtained by alkaline deacetylation of chitin. The present study was aimed to investigate the effects of alum as coagulant in conjunction with chitosan as coagulant aid on the removal of turbidity, hardness and Escherichia coli check for this species in other resources from water. A conventional jar test apparatus was employed for the tests. The optimum pH was observed between 7 to 7.5 for all turbidities. The optimum doses of alum and chitosan when used in conjunction, were 10mg/L and 1mg/L, 5mg/L and 0.5mg/L, and 5mg/L and 0.5mg/L in low, medium and high turbidities, respectively. Turbidity removal efficiency was resulted between %74.3 to %98.2 by alum in conjunction with chitosan. Residual Al+3 in treated water was less than 0.2 mg/L, meeting the international guidelines. The results showed that turbidity decrease provided also a primary Escherichia coli reduction of 2-4 log units within the first 1 to 2 hr of treatment. Hardness removal efficiency decreased when the total hardness increased from 102 to 476mg/L as CaCO3. At low initial turbidity, chitosan showed marginally better performance on hardness, especially at the ranges of 100 to 210 mg/L as CaCO3. In conclusion, coagulant aid showed a useful method for coagulation process. By using natural coagulants, considerable savings in chemicals and sludge handling cost may be achieved.

Keywords
Chitosan, Coagulant aid, Hardness removal, Escherichia .coli removal, Water treatment

 
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