title: Characteristics of extracellular polymeric substances from sludge and biofilm in a simultaneous nitrification and denitrification system under high salinity stress.
abstract: The composition and distribution of extracellular polymeric substance (EPS) both from suspended sludge and attached biofilm were investigated in a simultaneous nitrification and denitrification (SND) system with the increase of the salinity from 1.0 to 3.0 %. Fourier-transform infrared (FTIR) spectroscopy and three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectroscopy were used to examine proteins (PN), polysaccharides (PS) and humic substances (HS) present in EPS. High total nitrogen removal (above 83.9 %) via SND was obtained in the salinity range of 1.0-2.5 %. Total EPS in the sludge increased from 150.2 to 200.6 mg/gVSS with the increase of salinity from 1.0 to 3.0 %, whereas the corresponding values in the biofilm achieved the maximum of 288.6 mg/g VSS at 2.0 % salinity. Dominant composition of EPS was detected as HS in both sludge and biofilm, having the percentages of 50.6-68.6 and 41.1-69.9 % in total EPS, respectively. Both PN and PS contents in soluble EPS (S-EPS), loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS) of sludge and biofilm increased with the increased salinity. The FTIR spectrum and 3D-EEM fluorescence spectroscopy of S-EPS, LB-EPS and TB-EPS in the sludge and biofilm showed the changes of functional groups and conformations of the compositions in EPS with the increase of salinity. The results demonstrated that the characteristics of EPS varied from sludge to biofilm. The obtained results could provide a better understanding of the salinity effect on the EPS characteristics in a SND system.
authors.affiliation: Key Lab of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao, 266100, China.
authors.forename: Linting
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Key Lab of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao, 266100, China. szlszl@ouc.edu.cn.|College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, China. szlszl@ouc.edu.cn.
authors.forename: Zonglian
authors.initials: Z
authors.lastname: She
authors.affiliation: Key Lab of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao, 266100, China.|College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, China.
authors.forename: Chunji
authors.initials: C
authors.lastname: Jin
authors.affiliation: Key Lab of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao, 266100, China.|College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, China.
authors.forename: Shiying
authors.initials: S
authors.lastname: Yang
authors.affiliation: Key Lab of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao, 266100, China.|College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Guo
authors.affiliation: Key Lab of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao, 266100, China.|College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, China.
authors.forename: Yangguo
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Key Lab of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao, 266100, China.|College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, China.
authors.forename: Mengchun
authors.initials: M
authors.lastname: Gao
mesh_terms: D018441:Biofilms; D058440:Denitrification; D058465:Nitrification; D011108:Polymers / Q000737:chemistry*; D054712:Salinity; D012722:Sewage / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013312:Stress, Physiological
chemical_list: D011108:Polymers; D012722:Sewage
keywords: Biofilm; Extracellular polymeric substances (EPS); Salinity; Simultaneous nitrification and denitrification (SND); Sludge