Modeling Nonionic Polyacrylamide Flocculation Using Population Balances

基於群體平衡模型的非離子聚丙烯酰胺絮凝過程模擬

10.6937/TWC.202009/PP_68(3).0008

史志鵬(ZHI-PENG SHI)；張根廣(GEN-GUANG ZHANG)；何婷婷(TING-TING HE)；張宇卓(YU-ZHUO ZHANG)

Aggregation ； Breakage ； Micro-flocs ； Macro-flocs ； CFD ； Bridging effect ； 絮凝 ； 分裂 ； 絮凝體 ； 絮凝團 ； CFD ； 橋聯作用

台灣水利

68卷3期（2020 / 09 / 01）

87 - 97

英文

Nonionic polyacrylamide is widely used as a flocculant in wastewater treatment, but current knowledge is limited to empirical observations on how they work. A population balance model for flocculation of particle suspension by nonionic polyacrylamide under quiescent flow condition was presented. The model takes particles aggregation, flocs breakage and flocs restructure into account. It was found that the process of flocculation is a dynamic and nonlinear process in which particles, micro-flocs and macro-flocs are constantly seeking equilibrium through aggregation and breakage. The size of micro-flocs and macro-flocs was obtained respectively in the flocculation of sediment and nonionic polyacrylamide. Moreover, bridging effect of nonionic polyacrylamide is the main reason for the faster increase of settling velocity. When the experimental results from literature were tested, the model which combined with population balance equations and computational fluid dynamics predicted the experimental behavior of flocculation both adequately and directly in three dimensions. The proposed model is the first time to reproduce the process of flocculation in three dimensions, and the model is more rational and general to predict the process of flocculation in wastewater treatment.

非離子聚丙烯酰胺廣泛應用於水處理中。然而在實際應用過程中，側重於經驗性的方法。本文結合群體平衡理論對非離子聚丙烯酰胺在靜水中的絮凝過程進行了有效的計算模擬。該理論模型考慮到了絮凝過程中顆粒或絮凝體之間的絮凝、分裂和重組等因素。結果表明：絮凝的過程是顆粒、絮凝體和絮凝團之間通過絮凝和分裂的方式不斷尋求平衡的動態非線性過程。結合之前的試驗結果，絮凝體和絮凝團的有效範圍得以確認；分析認為基於非離子聚丙烯酰胺的橋聯機理是絮凝體（團）沈速不斷遞增的主要原因。群體平衡模型結合計算流體動力學的方法首次在三維尺度上有效的再現絮凝的過程。同時，相對於其他計算方法，該方法是壹種更加實用和通用的方法。

1. Bertin, D.,Cotabarren, I.,Pina, J.,Bucala, V.(2016).Population balance discretization for growth, attrition, aggregation, breakage and nucleation.Computers and Chemical Engineering,84,132-150.
2. Erabit, N.,Ndoye, F.T.,Alvarez, G.,Flick, D.(2015).A population balance model integrating some specificitties of the β-lactoglobulin thermally-induced aggregation.Journal of Food Engineering,144,66-76.
3. Flesch, J.C.,Spicer, P.T.,Pratsinis, S.E.(1999).Laminar and turbulent shear-induced flocculation of fractal aggregates.Aiche Journal,45(5),1114-1124.
4. Golzarijalal, M.,Ashtiani, F.Z.,Dabir, B.(2018).Modeling of microalgal shear-induced flocculation and sedimentation using a coupled CFD-population balance approach.Biotechnology Progress,34(1),160-174.
5. Gregory, J.,Barany, S.(2011).Adsorption and flocculation by polymers and polymer mixtures.Advances in Colloid and Interface Science,169(1),1-12.
6. Hatashi, K.,Watano, S.(2019).Novel population balance model for granule aggregation and breakage in fluidized bed granulation and drying.Powder Technology,342,664-675.
7. Heath, A.R.,Bahri, P.A.,Fawell, P.D.,Farrow, J.B.(2006).Polymer flocculation of calcite: population balance model.AIChE Journal,52(5),1641.
8. Kohler, M.H.,Bordin, J.R.,Barbosa, M.C.(2019).Ion flocculation in water: From bulk to nanoporous membrane desalination.Journal of Molecular Liquids,277,516-521.
9. Lee, B.J.,Toorman, E.,Molz, F.J.,Wang, J.(2011).A twoclass population balance equation yielding bimodal flocculation of marine or estuarine sediments.Water Research,45,2131-2145.
10. Li, Z.L.,Zhang, D.J.,Lu, P.L.(2017).Population balance model and calibration method for simulating the time evolution of floc size distribution of activated sludge flocculation.Desalination and Water Treatment,67,41-50.
11. Manning, A.J.,Dyer, K.R.(2007).Mass settling flux of fine sediments in Northern European estuaries: measurement and prediction.Marine Geology,245,107-122.
12. Mishra, S.,Sen, G.,Rani, G.U.(2011).Microwave assisted synthesis of polyacrylamide grafted agar (Ag-g-PAM) and its application as flocculant for wastewater treatment.International Journal of Biological Macromolecules,49(4),591-598.
13. Qin, J.Y.,Wang, H.N.,Qin, C.(2018)。The role of sodium carbonate in PAM coagulation-flocculation for oil acidized wastewater treatment。Water Science and Technology，77(11)，2677-2686。
14. Rassamdana, H.,Sahimi, M.(1996).Asphalt flocculation and deposition.2. Formation and growth of fractal aggregates.Aiche Journal,42(12),3318-3332.
15. Runkana, V.,Somasundaran, P.,Kapur, P.C.(2006).A population balance model for flocculation of colloidal suspensions by polymer bridging.Chemical Engineering Science,61(1),182-191.
16. Sang, Y.Z.,Englezos, P.(2012).Flocculation of precipitated calcium carbonate (PCC) by cationic tapioca starch with different charge densities. II: Population balance modeling.Colloids and Surfaces a-Physicochemical and Engineering Aspects,414,520-526.
17. Sen, G.,Ghosh, S.,Jha, U.(2011).Hydrolyzed polyacrylamide grafted carboxymethylstarch (Hyd. CMS-g-PAM): An efficient flocculant for the treatment of textile industry wastewater.Chemical Engineering Journal,171(2),495-501.
18. Shi, Z.P.,Zhang, G.G.,Pei, G.L.(2016).Predicting the Floc Characteristics and Settling Velocity of Flocs Under Various Polyacrylamide Concentration Treatments.Taiwan Water Conservancy,63(3),92-100.
19. Singh, M.,Kaur, G(2018).Convergence analysis of finite volume scheme for nonlinear aggregation population balance equation.Math Meth Appl Sci,42,3236-3254.
20. Singh, M.,Vuil, K.,Kaur, G.,Bart, H.J.(2019).Effect of different discretizations on the numerical solition of 2D aggregation population balance equation.Powder Technology,342,972-984.
21. Smoluchowski, M.V.V., 1917. "Mathematical theory of the kinetics of the coagulation of colloidal solutions", Z. Phys.Chem, 92: 129-168.
22. Stuart, M.A.C.,Fleer, G.J.(1996).Adsorbed polymer layers in nonequilibrium situations.Annual Reviews of Materials Science,26,463-500.
23. Sun, Z.Y.,Wang, A.M.,Bai, N.(2015).Treatment of Coking Wastewater with Modified Fly Ash Combined with Cationic Polyacrylamide.Bulletin of the chinese ceramic society,34(12),3606-3609.
24. Thomas, D.N.,Judd, S.J.,Fawcett, N.(1999).Flocculation modelling: A review.Water Research,33(7),1579-1592.
25. Vajihinejad, V.,Soares, J.B.P.(2018).Monitoring polymer flocculation in oil sands tailings: A population balance model approach.Chemical Engineering Journal,346,447-457.
26. Vlieghe, M.,Saudejaud, C.C.,Line, A.,Frances, C.(2016).QMOM-based population balance model involving a fractal dimension for the flocculation of latex particles.Chemical Engineering Science,155,65-82.
27. Wang, X.(2016).Population balance modeling of precipitated calcium carbonate (PCC) flocculation induced by cationic starches.International Journal of Mineral Processing,148,9-14.
28. Zeng, Y.B.,Yang, C.Z.,Zhang, J.D.(2007).Feasibility investigation of oily wastewater treatment by combination of zinc and PAM in coagulation/flocculation.Journal of Hazardous Materials,147(3),991-996.
29. Zerradi, H.,Mizani, S.,Loulijat, H.,Dezairi, A.,Quaskit, S.(2016).Population balance equation model to predict the effects of aggregation kinetics on the thermal conductivity of nanofluids.Journal of Molecular Liquids,218,373-383.
30. Zou, W.J.,Cao, Y.J.,Sun, C.B.,Zhang, Z.J.(2016)。Mechanism of action of polyacrylamide in selective flocculation flotation of fine coal。Chinese Journal of Engineering，38(3)，299-305。