Biofilm development during the start-up period of anaerobic biofilm reactors: the biofilm Archaea community is highly dependent on the support material

Abstract

To evaluate the impact of the nature of the support material on its colonization by a methanogenic consortium, four substrata made of different materials: polyvinyl chloride, 2 polyethylene and polypropylene were tested during the start-up of lab-scale fixed-film reactors. The reactor performances were evaluated and compared together with the analysis of the biofilms. Biofilm growth was quantified and the structure of bacterial and archaeal communities were characterized by molecular fingerprinting profiles (capillary electrophoresis-single strand conformation polymorphism). The composition of the inoculum was shown to have a major impact on the bacterial composition of the biofilm, whatever the nature of the support material or the organic loading rate applied to the reactors during the start-up period. In contrast, the biofilm archaeal populations were independent of the inoculum used but highly dependent on the support material. Supports favouring Archaea colonization, the limiting factor in the overall process, should be preferred.

Figure 1

Evolution over time of methane yield during experiments C1 (A: •, PE; ▴, PP; , Gompertz PE; , Gompertz PP), C2 (B: ▴, PVC; •, Bf30; , Gompertz PVC; , Gompertz Bf30), C3 (C: ▴, PVC bis; •, PP bis; , Gompertz PVC bis; , Gompertz PP bis) and C4 (D: ▴, PE bis; •, Bf30 bis; , Gompertz PE bis; , Gompertz Bf30 bis).

Figure 2

Principal component analysis ordination plot from archaeal (A) and bacterial (B) CE-SSCP profiles of adhered communities. The physical distances between points are proportional to the genetic distances of community profiles.