@article{PAR00003319,
  title = {{C}oagulation and ultrafiltration : understanding of the key parameters of the hybrid process},
  author = {{B}arbot, {E}. and {M}oustier, {S}. and {B}ottero, {J}ean-{Y}ves and {M}oulin, {P}.},
  editor = {},
  language = {{ENG}},
  abstract = {{A} hybrid coagulation-ultrafiltration process has been investigated to understand membrane performance. {C}oagulation prior to ultrafiltration is suspected to reduce fouling by decreasing cake resistance, limiting pore blockage and increasing backwash efficiency. {C}oagulation followed by tangential ultrafiltration should gather the beneficial effects of particle growth and cross-flow velocity. {O}ur study aims at determining the key parameters to improve membrane performance, by describing floc behaviour during the hollow fibre ultrafiltration process. {F}locs encounter a wide range of shear stresses that are reproduced through the utilization of different coagulation reactors. {P}erforming a jar-test enables the formation of flocs under soft conditions, whereas {T}aylor-{C}ouette reactors can create the same shear stresses occurring in the hollow fibres or in the pump. {S}ynthetic raw water was made by adding bentonite into tap water. {F}ive organic coagulants (cationic polyelectrolytes) and ferric chloride were selected. {F}loc growth was thoroughly monitored in the different reactors by laser granulometry. {C}oagulation-ultrafiltration experiments revealed different process performance. {T}he effect on the permeate flux depended on the coagulant used: some coagulants have no influence on permeate flux, another enables a 20% increase in permeate flux whereas another coagulant leads to a decrease of 50%. {F}locs formed with ferric chloride do not resist shear stress and consequently have no influence on permeate flux. {T}hese results show the necessity to create large flocs, but the size is not sufficient to explain membrane performance. {E}ven if flocs show a good resistance to shear stress, a high compactness ({D}-f = 3) will lead to a dramatic decrease of permeate flux by increasing the mass transfer resistance of the cake. {O}n the contrary, flocs less resistant to shear stress, then smaller and also more open have no effect on permeate flux. {A}n optimum was quantified for large flocs, resistant enough to shear stress facilitating flow between aggregates.},
  keywords = {{U}ltrafiltration ; {C}oagulation ; {H}ybrid process ; {H}ollow fibre ; {L}aser ; granulometry},
  booktitle = {},
  journal = {{J}ournal of {M}embrane {S}cience},
  volume = {325},
  numero = {2},
  pages = {520--527},
  ISSN = {0376-7388},
  year = {2008},
  DOI = {10.1016/j.memsci.2008.07.054},
  URL = {https://www.documentation.ird.fr/hor/{PAR}00003319},
}