Impact of shear stress and pH changes on floc size and removal of dissolved organic matter (DOM)

Slavik, Irene; Müller, S.; Mokosch, Regina; Azongbilla, Joseph Abanga; Uhl, Wolfgang

doi:10.1016/j.watres.2012.09.033

Cited by 47 publications

(35 citation statements)

References 39 publications

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“…Many researches [7,8] found that it was difficult for the broken flocs to fully return to their size before breakage, and repeated breakage of flocs resulted in lower re-growth ability [9]. The re-growth of flocs after exposure to high shear forces was found limited for waters coagulated with aluminium sulfate (alum), ferric sulfate and cationic polyelectrolyte [10].…”

Section: Introductionmentioning

confidence: 99%

Investigation of the property of kaolin–alum flocs at acidic pH

Gregory

Liu

et al. 2014

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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Section: Introductionmentioning

confidence: 99%

Investigation of the property of kaolin–alum flocs at acidic pH

Gregory

Liu

et al. 2014

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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“…S5). This may introduce some repulsion in algal flocs and weaken the adsorptive binding in algal flocs, which leads to the low floc stability (Slavik et al, 2012).…”

Section: Floc Stabilitymentioning

confidence: 99%

Removal of Microcystis aeruginosa using cationic starch modified soils

et al. 2016

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a b s t r a c tA cheap and biodegradable modifier, cationic starch (CS), was used to turn local soils into effective flocculants for Microcystis aeruginosa (M. aeruginosa) removal. The isoelectric point of soil particles was remarkably increased from pH 0.5 to 11.8 after modification with CS, which made CS modified soil particles positively charged and obtain algal flocculation ability. At the soil concentration of 100 mg/L, when the CS modifier was 10 mg/L, 86% of M. aeruginosa cells were removed within 30 min. Lower or higher CS dosage led to limited algal removal. About 71% and 45% of M. aeruginosa cells were removed within 30 min when CS was 5 mg/L and 80 mg/L, respectively. This is because only part of algal cells combined with CS modified soil particles through charge neutralization at low dosage, while flocs formed at high CS dosage were positively charged which prevents further aggregation among the flocs. The floc stability was quantified by a floc breakage index under applied shear force. Algal flocs formed at acid and alkaline conditions were more prone to be broken than those at the neutral condition. The cost and biodegradability concerns may be largely reduced through the use of CS modified local soils. For field applications, other practical issues (e.g., re-suspension) should be further studied by jointly using other methods.

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“…On the other hand, pH change may influence average particles size of coagulated OSPW [28,29], implying that 10 mg alum/L is no longer a minimum concentration that complies with the MF criteria. Therefore, before conducting Run 5, zeta potential and average particle size of OSPW treated with 10 mg alum/L at pH 10 were examined.…”

Section: Filtration Performancesmentioning

confidence: 99%