Coagulation characteristics of polyaluminum chlorides PAC-Al30 on humic acid removal from water

Zhang, Panyue; Wu, Zhen; Zhang, Guangming; Zeng, Guangming; Zhang, Haiyan; Li, Juan; Song, Xiangguo; Jianhua, Dong

doi:10.1016/j.seppur.2008.07.008

Cited by 105 publications

(45 citation statements)

References 18 publications

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“…4b). (Chen et al, 2006;Zhang et al, 2008). Because Al 30 species do not react with the ferron reagent within 120 min, they are categorized as Al c by the ferron method (Chen et al, 2007).…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, the development of new coagulation processes that effectively remove suspended and dissolved materials, including viruses, from both neutral and alkaline drinking water sources without the need for pH optimization is highly desired. ]) have been produced, and the influence of PACl basicity on coagulation processes has been investigated (Wang et al, 2002;Yan et al, 2008a,b;Yang et al, 2011;Zhang et al, 2008). For example, Wang et al (2002) reported that turbidity removal at alkaline pH is improved by increases in PACl basicity.…”

Section: Introductionmentioning

confidence: 99%

“…For example, Wang et al (2002) reported that turbidity removal at alkaline pH is improved by increases in PACl basicity. Zhang et al (2008) reported that the coagulation efficiency of PACl increases with increasing basicity: specifically, PACl with a basicity of 2.4 exhibits higher humic acid removal efficiency and lower residual aluminum concentration at a broader pH range and a wider PACl dosage range compared to PACls with basicities of 1.2 and 1.8. In previous work, we compared PACls with basicities of 2.1 and 1.5 in the pH range of 6.…”

Section: Introductionmentioning

confidence: 99%

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Improved virus removal by high-basicity polyaluminum coagulants compared to commercially available aluminum-based coagulants

et al. 2014

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We investigated the effects of basicity, sulfate content, and aluminum hydrolyte species on the ability of polyaluminum chloride (PACl) coagulants to remove F-specific RNA bacteriophages from river water at a pH range of 6-8. An increase in PACl basicity from 1.5 to 2.1 and the absence of sulfate led to a reduction of the amount of monomeric aluminum species (i.e., an increase of the total amount of polymeric aluminum and colloidal aluminum species) in the PACl, to an increase in the colloid charge density of the PACl, or to both and, as a result, to high virus removal efficiency.The efficiency of virus removal at around pH 8 observed with PACl-2.1c, a nonsulfated 2 high-basicity PACl (basicity 2.1-2.2) with a high colloidal aluminum content, was larger than that observed with PACl-2.1b, a nonsulfated high-basicity PACl (basicity 2.1-2.2) with a high polymeric aluminum content. In contrast, although extremely high basicity PACls (e.g., PACl-2.7ns, basicity 2.7) effectively removed turbidity and UV260-absorbing natural organic matter and resulted in a very low residual aluminum concentration, the virus removal ratio with PACl-2.7ns was smaller than the ratio with PACl-2.1c at around pH 8, possibly as a result of a reduction of the colloid charge density of the PACl as the basicity was increased from 2.1 to 2.7. Liquid 27 Al NMR analysis revealed that PACl-2.1c contained Al 30 species, which was not the case for PACl-2.1b or PACl-2.7ns. This result suggests that Al 30 species probably played a major role in virus removal during the coagulation process. In summary, PACl-2.1c, which has high colloidal aluminum content, contains Al 30 species, and has a high colloid charge density, removed viruses more efficiently (>4 log 10 for infectious viruses) than the other aluminum-based coagulants-including commercially available PACls (basicity 1.5-1.8), alum, and PACl-2.7ns-over the entire tested pH (6-8) and coagulant dosage (0.54-5.4 mg-Al/L) ranges.

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“…4b). (Chen et al, 2006;Zhang et al, 2008). Because Al 30 species do not react with the ferron reagent within 120 min, they are categorized as Al c by the ferron method (Chen et al, 2007).…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Improved virus removal by high-basicity polyaluminum coagulants compared to commercially available aluminum-based coagulants

et al. 2014

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“…If the pH is lowered to improve coagulation (Eckenfelder (2000)) and organics' removal, it is often recommended to readjust the pH after the filtration process as compared to pre-filtration. This is due to the fact that some OM may be adsorbed onto the floc that may carry over from the clarification process, and any pre-filtration pH adjustment may then result in the "release" of this OM, which could pass through the filters and contribute to subsequent DBP formation (Delphos and Wesner (2005)), Zhang et al (2008)). …”

Section: Poorer Dewatering Characteristicsmentioning

confidence: 99%

Review of Coagulation’s Rapid Mixing for NOM Removal

Ghernaout¹,

Boucherit²

2015

CHEM

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This review focuses on rapid mixing in the coagulation process for improved natural organic matter (NOM) removal in water treatment. Rapid mixing aims to instantly and efficiently disperse coagulant species into raw water, before flocculation, sedimentation, and filtration processes. Mechanical mixing with a longer retention time cannot guarantee an instantaneous and uniform coagulant dispersion. For this reason, the so-called pump diffusion mixer (PDM) has been proposed. Using various rapid mixing devices to test the sedimentation performance, it is showed that in-line hydraulic jet and static mixers are able to achieve performance equivalent to that of the mechanical mixing type at a lower coagulant dosage. On the other hand, the removal of NOM as disinfection by-products (DBPs) precursor by chemical coagulation (CC) has been extensively studied. It is well reported that enhanced coagulation (EC) by adjusting the pH downwards to 4-5 prior to coagulant addition will encourage the formation of soluble NOM-Al complex from low-turbidity waters. In case of most waters, therefore, acid must be added to maintain the desired coagulation pH for EC, and excess coagulant is required to improve the removal of NOM. However, CC using in-line hydraulic jet mixer such as PDM is a reasonable method for the improvement of coagulation process compared to EC, since it is possible to obtain good removals of NOM as well as turbidity using a lower dosages of coagulant without supplementary addition of chemicals for pH control and thus producing a smaller volume of waste solids.

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“…Al 30 polymer is regarded as another polycation in hydrolytic polyaluminum solutions (Allouche and Taulelle, 2003;Casey, 2006;Chen et al, 2005;Zhang et al, 2008). Our previous research indicated that Al 30 was another high active species in solutions responsible for coagulation/flocculation besides Al 13 (Chen et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Preparation of high concentration polyaluminum chloride with high content of Alb or Alc

Zhao¹,

Zhang²,

Luan³

et al. 2009

Journal of Environmental Sciences

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A novel membrane distillation concentration method was used to prepare high concentration polyaluminum chloride (PACl) with high content of Al b or Al c . 2.52 mol/L PACl 1 with 88% Al b and 2.38 mol/L PACl 2 with 61% Al c were successfully prepared. Three coagulants, AlCl 3 , PACl 1 and PACl 2 were investigated on their hydrolysis behavior and speciation under different conditions. The effects of pH and dilution ratio on Al species distribution were investigated by ferron assay. Experimental result showed that pH had a significant effect on Al species distribution for the three coagulants. Dilution ratio had little effects on Al b and Al c distribution in whole dilution process except the beginning for PACl 1 and PACl 2 . The results indicated that transformation of Al depends largely on their original composition. AlCl 3 was the most unstable coagulant among these three coagulants during hydrolysis process. PACl 1 and PACl 2 with significant amounts of highly charged and stable polynuclear aluminum hydrolysis products were less affected by the hydrolysis conditions and could maintain high speciation stability under various conditions.

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Coagulation characteristics of polyaluminum chlorides PAC-Al30 on humic acid removal from water

Cited by 105 publications

References 18 publications

Improved virus removal by high-basicity polyaluminum coagulants compared to commercially available aluminum-based coagulants

Improved virus removal by high-basicity polyaluminum coagulants compared to commercially available aluminum-based coagulants

Review of Coagulation’s Rapid Mixing for NOM Removal

Preparation of high concentration polyaluminum chloride with high content of Alb or Alc

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