Optimizing Coagulation Process for Low to High Turbidity Waters Using Aluminum and Iron Salts | Science Publications

American Journal of Environmental Sciences

Nasser Mehrdadi¹  Akbar Baghvand¹  Ali D. Zand¹  Abdolreza Karbassi¹ 

关键词: Coagulation process;    turbidity removal;    ferric chloride;    aluminum sulfate;    synthetic water;   

DOI  :  10.3844/ajessp.2010.442.448

学科分类：环境科学（综合）

来源: Science Publications

【 摘 要 】

Problem statement: Turbid waters, containing colloidal particles, are normally treated bycoagulation-flocculation followed by clarification. Ferric chloride and alum, which are the mostcommon types of coagulants in water treatment plants of Iran as well as many other countries, wereinvestigated with the aim of determining their capabilities to reduce turbidity of drinking water.Turbidity was added as kaolin. Optimization of coagulation process may assure removal of turbidityto a level below water quality standards in most cases. Approach: In this study, the effectiveness ofaluminum sulfate and ferric chloride was evaluated at different pH values and coagulant dosage tofind optimal operational conditions for low to high turbidity waters. The influence of lime, as acoagulant aid, on coagulation process was also studied. A set of jar test experiments was conducted tofind the optimal pH and coagulant dosage. Results: Results demonstrated that coagulation processcan assure turbidity removal from low to medium turbidity waters effectively, using relatively lowlevels of aluminum sulfate and ferric chloride (10-20 mg L^?1). Turbidity removal efficiency stillremained high when the initial turbidities of water were increased to 500 and 1000 NTU.Conclusion/Recommendations: Results showed that turbidity removal is dependent on pH,coagulant dosage, as well as initial turbidity of water for both used coagulants. The highest turbidityremoval efficiency was within 82.9-99.0% for alum and 92.9-99.4% for ferric chloride over theapplied range of turbidity. Turbidity removal efficiency was higher for ferric chloride compared toaluminum sulfate at optimum conditions. Both applied coagulants demonstrated promisingperformance in turbidity removal from water. The results of the current study can be used as abaseline data for drinking water treatment facilities which uses these two types of coagulants.

【 授权许可】

Unknown