title: Aluminum-induced changes in properties and fouling propensity of DOM solutions revealed by UV-vis absorbance spectral parameters.
abstract: The integration of pre-coagulation with ultrafiltration (UF) is expected to not only reduce membrane fouling but also improve natural organic matter (NOM) removal. However, it is difficult to determine the proper coagulant dosage for different water qualities. The objective of this study was to probe the potential of UV-vis spectroscopic analysis to reveal the coagulant-induced changes in the fouling potentials of dissolved organic matter (DOM) and to determine the optimal coagulant dosage. The Zeta potentials (ZPs) and average particle size of the four DOM solutions (Aldrich humic acid (AHA), AHA-sodium alginate (SA), AHA-bovine serum albumin (BSA) and AHA-dextran (DEX)) coagulated with aluminum chloride (AlCl3) were measured. Results showed that increasing the aluminum coagulant dosage induced the aggregation of DOM. Meanwhile, the addition of aluminum coagulant resulted in an increase in DSlope(325-375) (the slope of the log-transformed absorbance spectra from 325 to 375 nm) and a decrease in S(275-295) (the slope of the log-transformed absorption coefficient from 275 to 295 nm) and SR (the ratio of Slope(275-295) and Slope(350-400)). The variations of these spectral parameters (i.e., DSlope(325-375), S(275-295) and SR) correlated well with the aluminum-caused changes in ZPs and average particle size. This implies that spectral parameters have the potential to indicate DOM aggregation. In addition, good correlations of spectral parameters and membrane fouling behaviors (i.e., unified membrane fouling index (UMFI)) suggest that the changes in DSlope(325-375), S(275-295) and SR were indicative of the aluminum-caused alterations of fouling potentials of all DOM solutions. Interestingly, the optimal dosage of aluminum (40 μM for AHA, AHA-BSA, and AHA-DEX) was obtained based on the relation between spectral parameters and fouling behaviors. Overall, the spectroscopic analysis, particularly for the utilization of spectral parameters, provided a convenient approach for the exploration of combined coagulation and UF systems for DOM removal.
authors.affiliation: School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510275, China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou, 510275, China.
authors.forename: Minghao
authors.initials: M
authors.lastname: Zhou
authors.affiliation: School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510275, China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou, 510275, China. Electronic address: mengfg@mail.sysu.edu.cn.
authors.forename: Fangang
authors.initials: F
authors.lastname: Meng
mesh_terms: D000327:Adsorption; D000464:Alginates / Q000737:chemistry; D000465:Algorithms; D000535:Aluminum / Q000737:chemistry*; D017607:Aluminum Compounds / Q000737:chemistry*; D000818:Animals; D057219:Biofouling; D002417:Cattle; D003911:Dextrans / Q000737:chemistry; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D006812:Humic Substances / Q000032:analysis; D007700:Kinetics; D008567:Membranes, Artificial; D009930:Organic Chemicals / Q000737:chemistry*; D010316:Particle Size; D012710:Serum Albumin, Bovine / Q000737:chemistry; D012996:Solutions / Q000737:chemistry*; D013053:Spectrophotometry / Q000379:methods*; D014462:Ultrafiltration / Q000295:instrumentation / Q000379:methods; D018508:Water Purification / Q000295:instrumentation / Q000379:methods
chemical_list: D000464:Alginates; D017607:Aluminum Compounds; D003911:Dextrans; D006603:Hexuronic Acids; D006812:Humic Substances; D008567:Membranes, Artificial; D009930:Organic Chemicals; D012996:Solutions; D012710:Serum Albumin, Bovine; D020723:Glucuronic Acid; D000535:Aluminum
keywords: Coagulation; Dissolved organic matter (DOM); Membrane filtration; Membrane fouling; Water treatment