Roles of coagulant species and mechanisms on floc characteristics and filterability

Jiao, Ruyuan; Fabris, Rolando; Chow, Christopher W.K.; Drikas, Mary; Leeuwen, John van; Wang, Dongsheng

doi:10.1016/j.chemosphere.2016.02.030

Cited by 31 publications

(11 citation statements)

References 37 publications

(30 reference statements)

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“…In the pilot Water Treatment Plant we have also observed shorter treatment cycles for sweep flocculation, when compared to the other mechanisms studied. In References [39,51] the flocs formed by the charge neutralization mechanism showed better filterability compared to the ones with sweep flocculation.…”

Section: Pilot Water Treatment Plant Trial With Downward Filtration Wmentioning

confidence: 99%

Charge Neutralization Mechanism Efficiency in Water with High Color Turbidity Ratio Using Aluminium Sulfate and Flocculation Index

Cruz

Pimentel

Russo

et al. 2020

Water

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Most of the water supplied in Brazil comes from water streams that may have higher values for apparent color than turbidity. Treatability trials were performed for color and turbidity removal to evaluate the advantages of coagulation during the charge neutralization mechanism when compared to sweep flocculation for water with those characteristics. There were three types of trials: conventional Jar Test with raw water, with and without filtration, and in a pilot Water Treatment Plant, direct downward filtration, with synthetic water. Auxiliary equipment such as Continuous Flocculation Monitoring Equipment (CFME) and image analysis were used to evaluate the growth of flocs. In the Jar Tests experiments, similar levels of color (61.49%) and turbidity (61.30%) removal were observed, with a lower dosage of coagulant (46 mg/L) in the charge neutralization mechanism compared to the ones with sweep flocculation (58.22% for color and 54.73% for turbidity removal with 52 mg/L of aluminium sulfate). Similar results were found on pilot plant. At filtration rates of 180 and 300 m3 m−2 day−1, sweep flocculation mechanism had shorter filtration cycle (<5 m3) compared to other mechanisms. Therefore, a change in the operation of Water Treatment plants that use a coagulant dosage associated with sweep flocculation can bring advantages such as the reduction of coagulant consumption and sludge productions, as well as the increase of chlorine disinfection and filtration cycles.

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Section: Pilot Water Treatment Plant Trial With Downward Filtration Wmentioning

confidence: 99%

Charge Neutralization Mechanism Efficiency in Water with High Color Turbidity Ratio Using Aluminium Sulfate and Flocculation Index

Cruz

Pimentel

Russo

et al. 2020

Water

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“…There are many studies analyzing flocculation with aluminum salts, some of them analyzing floc strength under different shear forces (deflocculation studies) and the reversibility of the flocculation after breakage (reflocculation studies). However, these studies usually focus on model suspensions of kaolin (Cheng et al, 2011;Wang et al, 2011), humic acids (Wang et al, 2009), or a combination of both (Yu et al, 2009;Zhao et al, 2010;Yao et al, 2014;Nan et al, 2016;Wang Z. et al, 2017) and only in some cases with drinking waters (Yao et al, 2015;Jiao et al, 2016). However, the study of flocculation mechanisms in industrial wastewaters are very limited.…”

Section: Introductionmentioning

confidence: 99%

Understanding the Efficiency of Aluminum Coagulants Used in Dissolved Air Flotation (DAF)

2020

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This paper reports on the efficiency of five aluminum coagulants for the treatment of a paper mill wastewater by dissolved air flotation (DAF). The coagulants studied were: alum, a polyaluminum chloride coagulant of high aluminum content and intermediate basicity (PAC-MB), another with intermediate aluminum content and high basicity (PAC-HB), a polyaluminum nitrate sulfate of intermediate aluminum content and basicity (PANS) and one hybrid coagulant formed by the combination of PANS and a mixture of polyamines (PANS-PA). The influence of Al speciation on contaminants removal and the main flocculation mechanisms involved have been analyzed. High removal of suspended solids together with significant removal of dissolved and colloidal material (COD and silica) were obtained, which is required for extended reuse of this process water. PAC-HB was the best product for removing suspended solids (85%) and soluble silica (50%) with a rather limited COD removal (5%), while PANS-PA obtained high turbidity (90%) and silica removal (45%) together with a significant soluble COD removal (15%). Monomeric Al (Al a , Al m) was more efficient in removing suspended solids and soluble COD than polymeric or colloidal Al (Al c , Al u), but the latter was more efficient in removing soluble silica. Results demonstrated that the main flocculation mechanism varies with the aluminum dosage, being predominantly charge neutralization at low dosages and sweep flocculation at high dosages. The floc strength factor however, was very high and similar for all the coagulants and dosages tested (85-90%), as it was mainly determined by the behavior of the pre-flocculated suspended solids present in wastewater. The reflocculation factor varied from 45 to 75% at the lowest dosages to almost zero at the highest dosages, confirming the transition from charge neutralization to sweep flocculation. The flocs formed by PANS-PA had lower strength than the others and it decreased with the dosage while its reflocculation factor was almost zero, even at low dosages. Due to the polyamines present in this coagulant, its flocculation mechanism is through both charge neutralization and patch formation, especially at low dosages, and sweep flocculation and interparticle bridge formation at high dosages.

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“…Flocos são estruturas complexas, irregulares, de composição variável e heterogêneas. Tipos de coagulantes, mecanismos de coagulação e gradientes de mistura são os principais fatores que influenciam na sua formação (JIAO et al, 2016;SELOMULYA et al, 2004;TURCHIULI;FARGUES, 2004).…”

Section: Lista De Figurasunclassified

“…Após a adição do coagulante, bem como a sua mistura, flocos se formam rapidamente e crescem a uma taxa inicial que, entre diversos fatores, depende da concentração de partículas do meio, gradientes de mistura, eficiência das colisões e da ação do coagulante selecionado (JIAO et al, 2016;SELOMULYA et al, 2004).…”

Section: Flocosunclassified

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Microscopia >i<in situ>/i< aplicada ao estudo de tratabilidade de água de consumo usando >i<Opuntia cochenillifera>/i<

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Roles of coagulant species and mechanisms on floc characteristics and filterability

Cited by 31 publications

References 37 publications

Charge Neutralization Mechanism Efficiency in Water with High Color Turbidity Ratio Using Aluminium Sulfate and Flocculation Index

Charge Neutralization Mechanism Efficiency in Water with High Color Turbidity Ratio Using Aluminium Sulfate and Flocculation Index

Understanding the Efficiency of Aluminum Coagulants Used in Dissolved Air Flotation (DAF)

Microscopia >i<in situ>/i< aplicada ao estudo de tratabilidade de água de consumo usando >i<Opuntia cochenillifera>/i<

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