Deposition Kinetics of Extracellular Polymeric Substances (EPS) on Silica in Monovalent and Divalent Salts
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- 作者：Pingting Zhu ; Guoyu Long ; JinRen Ni ; Meiping Tong
- 刊名：Environmental Science & Technology
- 出版年：2009
- 出版时间：August 1, 2009
- 年：2009
- 卷：43
- 期：15
- 页码：5699-5704
- 全文大小：214K
- 年卷期：v.43,no.15(August 1, 2009)
- ISSN：1520-5851
文摘
The deposition kinetics of extracellular polymeric substances (EPS) on silica surfaces were examined in both monovalent and divalent solutions under a variety of environmentally relevant ionic strength and pH conditions by employing a quartz crystal microbalance with dissipation (QCM-D). Soluble EPS (SEPS) and bound EPS (BEPS) were extracted from four bacterial strains with different characteristics. Maximum favorable deposition rates (kfa) were observed for all EPS at low ionic strengths in both NaCl and CaCl2 solutions. With the increase of ionic strength, kfa decreased due to the simultaneous occurrence of EPS aggregation in solutions. Deposition efficiency (α; the ratio of deposition rates obtained under unfavorable versus corresponding favorable conditions) for all EPS increased with increasing ionic strength in both NaCl and CaCl2 solutions, which agreed with the trends of zeta potentials and was consistent with the classic Derjaguin−Landau−Verwey−Overbeek (DLVO) theory. Comparison of α for SEPS and BEPS extracted from the same strain showed that the trends of α did not totally agree with trends of zeta potentials, indicating the deposition kinetics of EPS on silica surfaces were not only controlled by DLVO interactions, but also non-DLVO forces. Close comparison of α for EPS extracted from different sources showed α increased with increasing proteins to polysaccharides ratio. Subsequent experiments for EPS extracted from the same strain but with different proteins to polysaccharides ratios and from activated sludge also showed that α were largest for EPS with greatest proteins to polysaccharides ratio. Additional experiments for pure protein and solutions with different pure proteins to pure saccharides ratios further corroborated that larger proteins to polysaccharides ratio resulted in greater EPS deposition.