title: Biological control of biofilms on membranes by metazoans.
abstract: Traditionally, chemical and physical methods have been used to control biofouling on membranes by inactivating and removing the biofouling layer. Alternatively, the permeability can be increased using biological methods while accepting the presence of the biofouling layer. We have investigated two different types of metazoans for this purpose, the oligochaete Aelosoma hemprichi and the nematode Plectus aquatilis. The addition of these grazing metazoans in biofilm-controlled membrane systems resulted in a flux increase of 50% in presence of the oligochaetes (Aelosoma hemprichi), and a flux increase of 119-164% in presence of the nematodes (Plectus aquatilis) in comparison to the control system operated without metazoans. The change in flux resulted from (1) a change in the biofilm structure, from a homogeneous, cake-like biofilm to a more heterogeneous, porous structure and (2) a significant reduction in the thickness of the basal layer. Pyrosequencing data showed that due to the addition of the predators, also the community composition of the biofilm in terms of protists and bacteria was strongly affected. The results have implications for a range of membrane processes, including ultrafiltration for potable water production, membrane bioreactors and reverse osmosis.
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Process Engineering, Dübendorf, Switzerland.
authors.forename: Theresa
authors.initials: T
authors.lastname: Klein
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Process Engineering, Dübendorf, Switzerland.
authors.forename: David
authors.initials: D
authors.lastname: Zihlmann
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Process Engineering, Dübendorf, Switzerland; Institute of Environmental Engineering, ETH Zürich, Zürich, Switzerland.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Derlon
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Process Engineering, Dübendorf, Switzerland.
authors.forename: Carl
authors.initials: C
authors.lastname: Isaacson
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Process Engineering, Dübendorf, Switzerland.
authors.forename: Ilona
authors.initials: I
authors.lastname: Szivak
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Process Engineering, Dübendorf, Switzerland; Institute of Environmental Engineering, ETH Zürich, Zürich, Switzerland.
authors.forename: David G
authors.initials: DG
authors.lastname: Weissbrodt
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Process Engineering, Dübendorf, Switzerland. Electronic address: wouter.pronk@eawag.ch.
authors.forename: Wouter
authors.initials: W
authors.lastname: Pronk
mesh_terms: D000818:Animals; D001419:Bacteria / Q000235:genetics; D018441:Biofilms / Q000254:growth & development*; D057219:Biofouling / Q000517:prevention & control; D061046:Biological Control Agents; D056890:Eukaryota / Q000235:genetics; D008567:Membranes, Artificial; D009348:Nematoda; D009835:Oligochaeta; D011235:Predatory Behavior
chemical_list: D061046:Biological Control Agents; D008567:Membranes, Artificial
keywords: Basal layer; Biofouling; Biological control; Flux increase; Gravity driven membrane; Nematodes; Oligochaetes