Influence of flocs breakage process on membrane fouling in coagulation/ultrafiltration process—Effect of additional coagulant of poly-aluminum chloride and polyacrylamide

Yao, Meng; Nan, Jun; Chen, Ting; Zhan, Dechen; Li, Qinggui; Wang, Zhenbei; Li, Haoyu

doi:10.1016/j.memsci.2015.05.018

Cited by 57 publications

(18 citation statements)

References 54 publications

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“…It may be due to the fact that the pore size in the cake layer formed by flocs with additional coagulant is much larger than the one without precoagulation process. Yao et al . showed that membrane fouling was remarkably alleviated by precoagulation process which they attributed to the incompact structure of cake layer formed on the membrane surface.…”

Section: Resultsmentioning

confidence: 99%

Performance evaluation and antifouling analyses of cellulose acetate/nanodiamond nanocomposite membranes in water treatment

Etemadi

Yegani

Babaeipour

2017

J of Applied Polymer Sci

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In this study, nanocomposite membranes based on cellulose acetate (CA) and nanodiamond (ND) were prepared by applying phase inversion methods. In order to achieve efficient dispersion and more hydrophilic NDs, they were functionalized via heat treatment (ND-COOH). The prepared nanocomposite membranes were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), contact angle, porosity measurement, tensile strength, and abrasion resistance techniques. Furthermore, the governing fouling mechanisms were determined by using classic models as well as combined fouling models. Moreover, the effect of precoagulation with polyaluminum chloride (PAC) on the humic acid (HA) filtration was investigated. The obtained results showed that in the presence of ND-COOH, the abrasion resistance of nanocomposite CA membrane was three times higher than that of pristine CA membrane. Besides, the nanocomposite membranes with 0.5 wt % of raw and functionalized ND exhibited excellent hydrophilicity and PWF. The analysis of fouling mechanism based on Hermia's model revealed that the cake formation is prevailing mechanism for CA and CA/ND (0.5 wt %) membranes while for CA/ND-COOH (0.5 wt %) membrane, experimental results are fitted by combined cake filtration-complete blocking (CFCB) model. It confirms that pretreatment with PAC can significantly mitigate fouling and improve HA removal.

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Section: Resultsmentioning

confidence: 99%

Performance evaluation and antifouling analyses of cellulose acetate/nanodiamond nanocomposite membranes in water treatment

Etemadi

Yegani

Babaeipour

2017

J of Applied Polymer Sci

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“…Based on previous UF studies [33,[38][39][40], which demonstrated that increasing coagulant dose improves backwash effectiveness, it can be argued that Δ n is expected to decrease with increasing coagulant dose (i.e., UF backwash effectiveness improves and UF fouling is reduced as coagulant dose increases) up to a critical threshold above which Δ n is not appreciably affected.…”

Section: Coagulant Dose Adjustment Strategy and Control Logic 22mentioning

confidence: 99%

“…Previous studies have concluded that varying operational parameters such as backwash frequency can significantly increase UF operational duration before the need for CIP [29][30][31]. There is also a body of work regarding coagulant use for UF feed pre-treatment demonstrating improved UF product quality and reduced UF fouling [32][33][34][35][36][37][38]. It is generally accepted that coagulant dosing promotes the formation of flocs (i.e., aggregation of fine particles and colloidal matter) which improves both UF and MF membrane filtration and hydraulic cleaning [33,38,39].…”

Section: Introductionmentioning

confidence: 99%

“…There is also a body of work regarding coagulant use for UF feed pre-treatment demonstrating improved UF product quality and reduced UF fouling [32][33][34][35][36][37][38]. It is generally accepted that coagulant dosing promotes the formation of flocs (i.e., aggregation of fine particles and colloidal matter) which improves both UF and MF membrane filtration and hydraulic cleaning [33,38,39]. Also, UF pore plugging and irreversible fouling have been reported to decrease with increasing coagulant dose up to an optimal maximum limit [40] beyond which there is little added benefit.…”

Section: Introductionmentioning

confidence: 99%

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Self-adaptive cycle-to-cycle control of in-line coagulant dosing in ultrafiltration for pre-treatment of reverse osmosis feed water

Gao

Rahardianto

et al. 2017

Desalination

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Real-time self-adaptive approach to in-line UF coagulant dosing was developed and field demonstrated for integrated UF-RO seawater desalination. A novel coagulant dose controller was designed and successfully implemented in a pilot UF-RO seawater desalination plant. The coagulant controller, which tracks the UF resistance during filtration and backwash, adjusts coagulant dose to the UF feed with the objective of reducing the incremental cycle-to-cycle UF post-backwash (PB) resistance change (i.e., Δ n). Real-time tracking the above UF resistance metrics, as well as the rate of change of Δ n with coagulant dose, enabled the controller to quantify the progression of both irreversible fouling and UF backwash effectiveness. The above information was then utilized by the controller to make the appropriate coagulant adjustment. Field tests of the proposed self-adaptive coagulant dosing approach demonstrated measurable coagulant dose reduction while maintaining robust UF operation even during periods of both mild and severe water quality degradation. The approach to real-time coagulant dose control developed in the present work should be suitable for both seawater and brackish water UF treatment and has the potential of providing both effective UF operation as well as reduction in coagulant use.

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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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Influence of flocs breakage process on membrane fouling in coagulation/ultrafiltration process—Effect of additional coagulant of poly-aluminum chloride and polyacrylamide

Cited by 57 publications

References 54 publications

Performance evaluation and antifouling analyses of cellulose acetate/nanodiamond nanocomposite membranes in water treatment

Performance evaluation and antifouling analyses of cellulose acetate/nanodiamond nanocomposite membranes in water treatment

Self-adaptive cycle-to-cycle control of in-line coagulant dosing in ultrafiltration for pre-treatment of reverse osmosis feed water

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

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