title: Sub-critical fouling in a membrane bioreactor for municipal wastewater treatment: experimental investigation and mathematical modelling.
abstract: Fouling is a major limitation for the application of membrane bioreactors (MBRs) in municipal wastewater treatment; the critical flux concept represents a valid tool for process optimisation in planning fouling control strategies. The paper presents the results obtained on a large pilot MBR equipped with a plate-and-frame ultrafiltration membrane. The experimental assessment of flux criticality was carried out by flux-stepping tests showing the positive impact of liquid temperature on the value of the critical threshold. The reliability of short-term tests was then verified over a long period by determining the time of sustainability, t(sust), of six different sub-critical fluxes ranging between 17 and 30Lm(-2)h(-1). An exponential fitting was observed in terms of fouling rate both before and after t(sust), though fouling after t(sust) is likely to be ascribed not only to cake formation. Finally, a new mathematical formulation was proposed according to the local flux approach to model the sub-critical TMP transients. The model involves both bound and free forms of EPS and, once experimentally calibrated, it provided a fair prediction of the TMP jump.
authors.affiliation: Dipartimento di Ingegneria Civile ed Ambientale, Università degli Studi di Trento, Via Mesiano, 77, 38050 Trento, Italy. giuseppe.guglielmi@ing.unitn.it
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Guglielmi
authors.forename: Devendra Prakash
authors.initials: DP
authors.lastname: Saroj
authors.forename: Daniele
authors.initials: D
authors.lastname: Chiarani
authors.forename: Gianni
authors.initials: G
authors.lastname: Andreottola
mesh_terms: D019149:Bioreactors; D002138:Calibration; D008567:Membranes, Artificial; D008962:Models, Theoretical; D010865:Pilot Projects; D011108:Polymers; D011312:Pressure; D013997:Time Factors; D014462:Ultrafiltration / Q000379:methods*; D018508:Water Purification / Q000379:methods*
chemical_list: D008567:Membranes, Artificial; D011108:Polymers