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Research Publications (Engineering and Built Environment)

Permanent URI for this collectionhttp://ir-dev.dut.ac.za/handle/10321/215

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Author: search.filters.author.Rathilal, SudeshSubject: search.filters.subject.Coagulation

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    Response surface optimization of oil refinery wastewater treatment process
    (GRAWW, 2019-03) Rathilal, Sudesh; Tetteh, Emmanuel Kweinor; Assis, Shan
    In this paper, a laboratory dissolved air flotation (DAF) process was employed for the removal of chemical oxidation demand (COD), soap oil and grease (SOG), total suspended solids (TSS) and turbidity from oil refinery wastewater (ORW) using polyferric sulfate. The optimization was carried out by response surface methodology Box-Behnken design to evaluate the interactive effects of three main independent process parameters (pH, coagulant dosage and flotation time) on the removal of the COD, SOG, TSS, and turbidity. The quadratic model fitted very well with the experimental data at regression coefficients (R2) of values of 0.9986; 0.9992; 0.9847; 0.9858 for COD, SOG, TSS, and turbidity respectively. Under the optimum conditions of coagulant dose of 48 mgL-1, pH (5) and flotation time (17 min), the maximum removal of COD, SOG, TSS, and turbidity were 86%, 92%, 84% and 85% respectively were obtained. The removal efficiencies showed a high significance of the model correlations at 95% confidence level. This demonstrated that the addition of the polymeric sulfate can enhance the treatability performance of the ORW.
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    Application of organic coagulants in water and wastewater treatment
    (IntechOpen, 2019-04-03) Tetteh, Emmanuel Kweinor; Rathilal, Sudesh
    Coagulation is an essential mechanism that occurs in most conventional water and wastewater treatment plants. This occurs in a physical purification unit involving transport processes and the addition of coagulants for chemical reactions, charge neutralization, and formation of smaller flocs to agglomerate into larger flocs. This enhances the effective removal of recalcitrant contaminants by downstream processes. However, poor treatment of wastewater might have a high negative impact on biodiversity and the environment in general. This chapter seeks to address the limitation of employing inorganic coagulants by evaluating the efficiency of organic coagulants and exploring the factors and mechanism governing coagulation in a physiochemical treatment process of water and wastewater resources. The effect of pH, coagulant type and dosage to ease the high sludge production and discharge of residual metals into the downstream waters is addressed. The emerging of organic coagulants and technology to mitigate the performance and recovery of mineral coagulants from wastewater treatment residual is been proposed.