title: Calcium ion on membrane fouling reduction and bioflocculation promotion in membrane bioreactor at high salt shock.
abstract: Fouling propensity of activated sludge in membrane bioreactor (MBR) is closely related to the disturbance of a salt shock. In this work, the characteristics of membrane fouling and bioflocculation were compared in two laboratory-scale MBRs (one with calcium addition, MBR-Ca, the other without, MBR-C) with a transient salt shock. Particle size distributions, zeta potential, relative hydrophobicity, modified fouling index, the content of polysaccharides, proteins and calcium ions in different layers of sludge were monitored prior to, during and after the salt shock. Comparison with MBR-C showed that the recovery time and fouling rate of MBR-Ca were reduced by 50% and 34%, respectively. Remarkable variations of sludge properties in terms of bioflocculation, such as larger particle sizes, higher relative hydrophobicity and zeta potential, lower polysaccharides in supernatant, higher proteins/polysaccharides ratio in slime and loose bound extracellular polymeric substances, were observed in MBR-Ca after the salt shock.
authors.affiliation: School of Chemical Engineering, Northeast Dianli University, Jilin 132012, Jilin, PR China; Department of Civil, Environmental, and Construction Engineering, Texas Tech University, Boston, Lubbock, TX 79409-1023, USA.
authors.forename: Haifeng
authors.initials: H
authors.lastname: Zhang
authors.affiliation: School of Chemical Engineering, Northeast Dianli University, Jilin 132012, Jilin, PR China.
authors.forename: Xue
authors.initials: X
authors.lastname: Fan
authors.affiliation: School of Chemical Engineering, Northeast Dianli University, Jilin 132012, Jilin, PR China.
authors.forename: Bin
authors.initials: B
authors.lastname: Wang
authors.affiliation: Department of Civil, Environmental, and Construction Engineering, Texas Tech University, Boston, Lubbock, TX 79409-1023, USA. Electronic address: lianfa.song@ttu.edu.
authors.forename: Lianfa
authors.initials: L
authors.lastname: Song
mesh_terms: D019149:Bioreactors; D002118:Calcium / Q000737:chemistry*; D004867:Equipment Design; D005374:Filtration; D007477:Ions; D008567:Membranes, Artificial; D010316:Particle Size; D011108:Polymers; D011134:Polysaccharides / Q000737:chemistry; D012492:Salts / Q000737:chemistry*; D012722:Sewage; D012965:Sodium Chloride; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D007477:Ions; D008567:Membranes, Artificial; D011108:Polymers; D011134:Polysaccharides; D012492:Salts; D012722:Sewage; D012965:Sodium Chloride; D002118:Calcium
keywords: Bioflocculation; Calcium ion; Membrane bioreactor; Membrane fouling rate; Salt shock