Title: Improvement of coagulation-flocculation process for treatment of detergent wastewaters using coagulant aids.
Abstract: In this study, coagulation-flocculation process was used to treat detergent wastewater with ferric chloride as coagulant. The improvement of the process by using polyelectrolytes and clay minerals (montmorillonite and bentonite) as coagulant aids was also investigated. The results of the wastewater characterization showed that the concentration of organic matter expressed as chemical oxygen demand (COD) was as high as 24.3 g/L while the biochemical oxygen demand was low. Chemical treatment can be considered as a suitable option for treatment of detergent wastewater due to the low ratio of BOD5/COD. Coagulation/flocculation and precipitation studies were performed in a conventional jar-test apparatus. The coagulant dosage of ferric chloride ranged between 0.5 g/L and 3 g/L, whereas the concentrations of polyelectrolyte and clay minerals varied between 5-75 mg/L and 25-750 mg/L, respectively. The optimal condition was obtained at the dosage 2 g/L ferric chloride at pH 11 with the COD removal efficiency of 71%. Addition of coagulant aids provided higher removal efficiencies. Using clay minerals at the dose of 500 mg/L with ferric chloride provided 84% of COD removal and the removal efficiency of COD increased with using polyelectrolyte, resulting in an efficiency of 87%. The maximum removal efficiency was obtained with the addition of polyelectrolyte and it was found that the ferric chloride combination with coagulant aids, at certain pH and agitation speed, provided higher removal efficiencies compared to coagulation with ferric chloride alone.
Publication Year: 2010
Publication Date: 2010-01-01
Language: en
Type: article
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Cited By Count: 70
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