The structural and functional properties of polysaccharide foulants in membrane fouling
Graphical abstract
Introduction
Membrane separation technology has been extensively applied in water and wastewater treatment thanks to its high efficiency and energy saving (Oinuma et al., 1994; Sheikholeslami, 1999; Matin et al., 2020). However, the fouling problem is always one of the main challenges for the application of membrane technique (Yu et al., 2019; Zhang and Jiang, 2019). Membrane fouling refers to the phenomenon that suspended particulate colloidal particles or dissolved macromolecules of organic matter are deposited on the surface of the membrane or adsorbed in the membrane pores in the process of membrane separation, resulting in the reduction or blockage of the membrane pores and irreversible decrease of membrane flux. Although various roles of organic foulant in membrane systems have been increasingly recognized, consensus cannot be reached if we don’t have enough knowledge about the fundamental structural features of organic foulants (Wang et al., 2017; Khan et al., 2020). Polysaccharide is the most common component of organic foulants, with extremely high molecular weight as well as gel properties and compositional diversity. Previous studies reveal that extracellular polymeric substances (EPS) often affect the properties and functions of activated sludge as well as the membrane separation process (Ji et al., 2020; Teng et al., 2020). Because of its unique structure with intermolecular cross-linking chains, polysaccharide is easy to cause more serious membrane fouling than other substances in EPS (Barzeev et al., 2015; Meng et al., 2015b; Meng and Liu, 2016). Usually, the fouling propensities of organic foulants are attributed to their functional groups, which are believed to play a significant role between foulant-foulant interaction and foulant-membrane interaction. However, recent studies have shown that the fouling tendencies of polysaccharides depend on not only their functional groups but also other properties such as spatial configuration and the morphology of foulants (Farias et al., 2014; Meng et al., 2020).
Polysaccharide shows an extensive diversity of nature and properties and such original characteristic may be an important reason leading to the controversy in understanding the mechanisms of membrane fouling. For example, Meng et al. (2018) demonstrated the fouling propensities of polysaccharide were structurally different by testing two different polysaccharides and their mixtures. In order to give a clear explanation to the fouling problem, it is crucial to establish a detailed database of reference polysaccharides from important categories. The mathematical model which has received much attention from researchers recently can be an efficient method in exploring fouling mechanism and it is very important to find a suitable fouling model for membrane filtration process.
Many more recent methods include artificial neural network (ANN), genetic programming (GP) models, membrane pore blocking models and cake layer models for evaluating membrane fouling mechanisms (Griffiths et al., 2014). However, most of them have some problems, such as the lacking of application method, high workload and high demand for computing facilities. Nowadays, the two models above the Hermia are the most widely used, but they still have such problems as that the conclusions are inconsistent and the application is unclear. In order to discuss the applicability and accuracy of the two models and interpret the membrane fouling problems and technical obstacles caused by polysaccharides, seven representative polysaccharides samples were employed as models for the present experiment. Above-mentioned polysaccharides are widespread in feed water in membrane system due to its wide application in food and textile industry. In this work, we investigated the relationship between flux decline and polysaccharide properties in UF-crossflow, and polysaccharide-Ca2+ interactions were probed to reveal the underlying membrane fouling mechanisms. Two models with different mass-transfer processes at typical feed water, Hermia’s mathematic model and resistance-in-series model, were used as polysaccharide analysis models. Our study represents the effort to delineate polysaccharides which can be classified into different categories and to explain their fouling properties on UF performance.
Section snippets
Experiment materials
Commercial polyethersulfone (PES) ultrafiltration membrane, AMFOR INC, Beijing, molecular weight cut off (MWCO) 20 kDa, effective surface area of 42 cm2; calcium chloride, Beijing Chemical Plant, AR; BSA224S precision electronic balance, Sartorius; ultra-pure water system (referred in this experiment), Millipore Simplicity; RP-1DN magnetic stirrer, As One; GS6202 electronic balance, Shinko Denshi; CF042A filter plant, Sterlitech; KH–500B ultrasonic cleaner, Kunshan Hechuang ultrasonic
The fouling mechanism of various polysaccharides
The filtration curves of different polysaccharides are shown in Fig. 1. It can be seen that agarose and starch led to continuous permeation decline over the whole filtration period. Under the same operation condition, the least flux decline during the 120min filtration test can be seen when the feed contained agarose only; while for the most flux decline, the feed contained starch. Agarose is known to be peculiarly gelatinous, but the gels are fragile and easily get synaeresis due to the
Conclusion
Although remarkable progress has been made in recent years, questions related to membrane fouling mechanism and related technique challenges haven’t been properly addressed. The current study investigated the effect of classic different polysaccharides and Ca2+ concentrations on the membrane fouling during ultrafiltration. Seven different structural and functional features of polysaccharide samples were studied, drawing the same conclusion that the formation of the spatial structure of
Credit author statement
Xianghao Meng: Conceptualization, Methodology, Experiment, Data curation, Investigation, Writing – original draft & revision. Duoji Luosang: Experiment, Data curation, Investigation. Shujuan Meng: Writing – review & editing, Formal analysis, Funding acquisition. Rui Wang, Wenhong Fan, Dawei Liang, Xiaohu Li, Qian Zhao and Linyan Yang: Formal analysis, Visualization,
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
This work was financially supported by grants from the National Natural Science Foundation of China [No. 51808019].
References (41)
- et al.
Pectin as a rheology modifier: origin, structure, commercial production and rheology
Carbohydr. Polym.
(2017) - et al.
Effects of membrane fouling on solute rejection during membrane filtration of activated sludge
Process Biochem.
(2001) - et al.
The rheology of K+-κ-carrageenan as a weak gel
Carbohydr. Polym.
(2002) - et al.
Spatial and temporal evolution of organic foulant layers on reverse osmosis membranes in wastewater reuse applications
Water Res.
(2014) - et al.
A combined network model for membrane fouling
J. Colloid Interface Sci.
(2014) - et al.
Fouling kinetics and associated dynamics of structural modifications
Colloid. Surface. Physicochem. Eng. Aspect.
(1998) - et al.
Influence of inorganic scalants and natural organic matter on nanofiltration membrane fouling
J. Membr. Sci.
(2007) - et al.
A Self-Sustaining Synergetic Microalgal-Bacterial Granular Sludge Process towards Energy-Efficient and Environmentally Sustainable Municipal Wastewater Treatment
(2020) - et al.
A comparison of variations in blocking mechanisms of membrane-fouling models for estimating flux during water treatment
Chemosphere
(2020) - et al.
Influence of mixing temperature on xanthan conformation and interaction of xanthan–guar gum in dilute aqueous solutions
Food Res. Int.
(2006)
Intermolecular interactions of polysaccharides in membrane fouling during microfiltration
Water Res.
Alginate block fractions and their effects on membrane fouling
Water Res.
Transparent exopolymer particles (TEP)-associated membrane fouling at different Na+ concentrations
Water Res.
The Role of Transparent Exopolymer Particles (TEP) in Membrane Fouling: A Critical Review
Ultrafiltration behaviors of alginate blocks at various calcium concentrations
Water Res.
Ultrafiltration behaviors of alginate blocks at various calcium concentrations
Water Res.
New pretreatment systems using membrane separation technology
Desalination
A comparative study of Indian rice starches using different modification model solutions
Lwt - Food Science and Technology
Fouling mitigation in membrane processes: report on a workshop held January 26–29, 1999, technion — Israel institute of technology, Haifa, Israel☆
Desalination
A new approach for modeling flux variation in membrane filtration and experimental verification
Water Res.
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