Role of mixing conditions on coagulation performance and flocs breakage formed by magnesium hydroxide

Zhao, Jianhai; Su, Runxi; Guo, Xiexian; Li, Wenpu; Feng, Na

doi:10.1016/j.jtice.2013.12.014

Cited by 23 publications

(5 citation statements)

References 30 publications

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“…Generally, the formation of larger flocs is considered favorable for reducing the resultant residual turbidity [33]. However, minimum residual turbidity in the present study (Figure 7) was obtained not when the gigantic flocs were formed ((III) in Figures 5 and 6) but when chitosan was used as the coagulant aid in combination with PACl ((III) in Figures 5 and 6).…”

Section: Effects Of Chitosan As Coagulant Aid On the Removal Of Kaoli...contrasting

confidence: 52%

Optimum Conditions for Enhancing Chitosan-Assisted Coagulation in Drinking Water Treatment

Takaara,

Kurumada

2023

Sustainability

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Coagulant aids are useful chemicals that enhance the efficiency of coagulation sedimentation treatment. For this purpose, it is necessary to choose safe chemicals to avoid various risks to the health of those who use the treated water. The use of chitosan, an abundant natural polysaccharide, as a coagulant aid is significant not only for safe water treatment but also for the effective utilization of unused natural water resources, which are mostly wasted. We experimentally determined the optimal treatment conditions for using chitosan as a coagulant aid in water treatment. The most efficient use was identified as adding chitosan at the stage of rapid stirring after the addition of coagulant accelerated initial dispersion. When used with the main coagulant polyaluminum chloride (PACl), the optimal concentration of chitosan was 0.8 mg L−1, as estimated using the ζ potential showing isoelectricity at the optimal chitosan concentration. Determining the chitosan concentration using the minimum ζ potential was also valid for estimating the optimum concentration of chitosan, which is an extension of the method used at much higher turbidity, as seen in wastewater. Thus, the ζ potential-based prediction of the optimum chitosan concentration was effective even when the effect of sweep coagulation, which is normally induced at higher turbidity, was negligible. The superiority of using the coagulant PACl in combination with chitosan as the coagulant aid was demonstrated by comparing the in situ-observed coagulation process to cases with other coagulants and coagulant aids using direct time-series observation of the coagulation process. The use of chitosan with PACl was found to make the flocs easier to remove because it resulted in the largest mass fraction of the resultant floc sedimentation on the bottom of the vessel. In this study, using the PACl coagulant in combination with chitosan as the coagulant aid was found to be as viable as using the current popular combination of aluminum sulfate and polyacrylamide. Replacing polyacrylamide with chitosan contributed to reducing the potential risk to the health of those to use the treated water.

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Section: Effects Of Chitosan As Coagulant Aid On the Removal Of Kaoli...contrasting

confidence: 52%

Optimum Conditions for Enhancing Chitosan-Assisted Coagulation in Drinking Water Treatment

Takaara,

Kurumada

2023

Sustainability

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“…8 In general, a jar test with standard procedure is used to explore the inuence of shear rate on oc size and structure. [9][10][11] Yu et al found that an increase in shear rate generated smaller oc size in the jar test. 12 However, Colomer et al demonstrated that a higher shear rate resulted in a larger oc size for both an oscillating grid and a ask on a shaker table.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of kaolin floc characteristics during coagulation process: a case study with a continuous flow device

et al. 2016

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“…As the mixing speed increased from 75-125 rpm, the absorbance also increased. A high shear rate tends to break flocs generated during the coagulation/flocculation process (Zhao et al, 2014). The removal of lignin occurs at every combination of polyDADMAC and calcium lactate dosage ( Figure 12).…”

Section: Response Surface Methodological Approach For Optimization Ofmentioning

confidence: 99%

Coagulation/flocculation of lignin aqueous solution in single stage mixing tank system: Modeling and optimization by response surface methodology

Zahrim

Nasimah

Hilal

2015

Journal of Environmental Chemical Engineering

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Lignin particles contribute to color pollution in river water and treating this type of pollution biologically is difficult. In this study, the treatment of a model solution containing lignin using a single mixing tank system approach with poly-diallyldimethyl ammonium chloride (polyDADMAC) as destabiliser was carried out. The effect of various flocculants i.e. calcium lactate, magnesium hydroxide and anionic polyacrylamide (APAM) were investigated. Calcium lactate performed better than magnesium hydroxide and anionic polyacrylamide as flocculants. The coagulation/flocculation with polyDADMACcalcium lactate removed lignin through a complex mechanism: the adsorptive-charge neutralizationprecipitation-bridging mechanism. Response surface methodology (RSM) study indicated that strong interaction in the coagulation/flocculation of lignin occurred between the initial pH-polyDADMAC dosage, initial pH-calcium lactate dosage and polyDADMAC-calcium lactate dosage. The highest lignin removal achieved was between 50-68%. The removal behavior depended on the initial lignin concentration in the solution. The results showed that lignin removal from aqueous solution is possible in a single stage mixing tank by utilizing polyDADMAC-calcium lactate as a dual coagulant. The method mentioned here will potentially be useful for the treatment of lignin containing wastewater from several industrial processes such as palm oil mill, pulp and paper, olive mill etc.

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Role of mixing conditions on coagulation performance and flocs breakage formed by magnesium hydroxide

Cited by 23 publications

References 30 publications

Optimum Conditions for Enhancing Chitosan-Assisted Coagulation in Drinking Water Treatment

Optimum Conditions for Enhancing Chitosan-Assisted Coagulation in Drinking Water Treatment

Evaluation of kaolin floc characteristics during coagulation process: a case study with a continuous flow device

Coagulation/flocculation of lignin aqueous solution in single stage mixing tank system: Modeling and optimization by response surface methodology

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