Ferrous Sulphate From Titanium Dioxide Industry For The Treatment Of Petroleum Refinery Wastewater
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Date
2016-02
Authors
Tan, Yee Lynn
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Coagulation-flocculation treatment method is widely used in industrial processes. The efficiency of coagulation-flocculation process is determined by the coagulant dosage, pH, temperature, ionic strength, nature and concentration of organic matter, the surface charge and several other factors. FeSO4 (coagulant) is not well documented in the treatment of petroleum refinery wastewater (PRW). Therefore, in this research, capability of FeSO4 in the treatment of PRW was studied. The removal/reduction efficiencies for color, total suspended solids (TSS), turbidity and chemical oxygen demand (COD) were calculated. The coagulation-flocculation process can be monitored through the measurement of the electrophoretic mobility and the determination of zeta potential. In this study, the interaction between FeSO4 and the negatively charged colloidal particles in PRW and the mechanisms involved in the coagulation-flocculation process were studied. Different behaviors of PRW particles with FeSO4 depending on the pH and the dosage of the FeSO4 were demonstrated. It was found out that at very low pH (pH 2), charge neutralization is responsible for the particle aggregation and at high pH (pH ˃ 8) sweep flocculation mechanism is responsible for the particle aggregation. At high pH and high coagulant dosages, FeSO4 formed solid iron(II) hydroxide and colloidal particles were ‘swept out’ from PRW and settled to the bottom. Response surface methodology was applied by using face centered composite design (FCCD) to find the best combination of pH and coagulant dosage that result in maximum color removal, TSS removal, turbidity removal and COD reduction. The quadratic models developed indicated the optimum operating conditions for WW16 to be 623 mg/L of FeSO4 at pH 11, with 73.2% color removal, 96.6% TSS removal, 79.4% turbidity removal and 42.7% COD reduction. The optimum operating conditions for T1269 to be pH 12 and 1088 mg/L of FeSO4. The color removal of 72.6%, TSS removal of 56.4%, turbidity removal of 88.0% and COD reduction of 16.3% were demonstrated.
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Keywords
Wastewater