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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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Subject: 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.
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    The efficiency of chitosan as a coagulant in the treatment of the effluents from the Sugar Industry
    (2015) Pambi, Ritha-Lorette Luti; Musonge, Paul
    Chitosan has been used as a coagulant for industrial wastewater treatment. However, no attention has been given to the coagulation of sugar effluents using this polymer. Two effluent streams from a local sugar refinery, namely the final effluent (FE) and the resin effluent (RE) were treated using chitosan prepared by dissolution in aqueous hydrochloric acid. The optimum chitosan dosage was found to be 138 mg/l and 7.41 mg/l for RE and FE respectively, beyond which, the efficiency of the coagulant decreased. The efficiency of the chitosan was higher under acidic conditions and using sodium hydroxide to adjust the pH negatively affected the performance of the chitosan. The treatment of FE yielded better removal efficiency (97% total suspended solids, 61% colour and 35% chemical oxygen demand) than RE (68% total suspended solids, 30% colour and 15% chemical oxygen demand). This coagulant can be used to pre-treat turbid water for further treatment.
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    Influence of effluent type on the performance of chitosan as a coagulant
    (Akshar Publications, 2014) Pambi, Ritha-Lorette Luti; Musonge, Paul
    The use of chitosan as a bio-polymeric coagulant has continued to attract interest in water treatment due to its biodegradability and non-toxicity. Its ability to treat effluents of high organic content has been investigated in some food processing industries. The focus of the present study is to compare results of the use of chitosan in the treatment of effluent from a Sugar Processing Plant (SPP), with those obtained from the treatment of wastewater from a Milk Processing Plant (MPP) and from a Brewery Processing Plant (BPP), in order to determine the influence of effluent type on the impurities removal efficiency. The treatment of the MPP provided the best removal efficiency (99% suspended solids removal and 70% COD removal) in comparison to the SPP (98% suspended solids removal and 11% COD removal) and BPP (95% suspended solids removal and 50% COD removal). The optimum pH value varied as a function of the type of effluent with BPP= 4.5, SPP = 4.5 and MPP =7. The results indicate that chitosan is not very efficient for the removal of dissolved matter. A relationship between total suspended solids (TSS) and total dissolved solids (TDS) has been developed.