Fig 1.
Schematic representation of replicate MFC configurations with the two evaluated electrical load conditions (Ref-MFC and MPPT-MFC).
Fig 2.
A) Schematic figure of the anode compartment where the 4 samples (1, 2, 3 and 4) for microbial analyses are represented. Hydrodynamic model results in terms of (B) fluid velocity and (C) shear rate profile distribution.
Fig 3.
Time course of organic matter removal (COD rem) and electrical performance indicators (CE- coulombic efficiency, Current density and Power density) during the experimental period (43 days) in A) Ref-MFC and B) MPPT-MFC.
Table 1.
MFC performances in terms of organic matter and solid removal, current and power generation, and gas production measured for both reactors (Ref-MFC and MPPT-MFC).
Table 2.
16S rRNA gene abundances (Mean values ± SD, n = 2, technical replicates) at the four sampled positions within the Ref-MFC and MPPT-MFC operated at different organic loading rates (OLR).
Table 3.
Observed OTUs and alpha diversity indices, Chao1, Shannon (H’) and phylogenetic diversity (PD) diversity indices in swine manure (SM), Ref-MFC (Ref_1 to Ref_4) and MPPT-MFC (MPPT_1 to MPPT_4).
Fig 4.
A) Venn diagram of the OTU distribution in swine manure and the two MFC configurations (MPPT and Ref). B) Clustering of samples based on weighted Unifrac measures (rarefied at 500 seqs per sample) calculated after phylogenetic reconstruction of detected OTUs. Black dots in the dendrogram show nodes at bootstrap supported levels above 80%. Bar charts show the relative abundance of main bacterial groups (Orders) found in each of the samples. Phyla representing less than 1% of the sequences in a sample have been grouped as Others.
Fig 5.
Phylogenetic relationship of OTUs (97% similarity level) belonging to core communities of SM, Ref-MFC, and MPPT-MFC biofilm samples.
Members of core communities for each sample type are shown as coloured squares next to OTU identifier. Box plots show the relative abundance of OTUs in swine manure (grey), Ref-MFC (blue), and MPPT-MFC (red). * indicate OTUs showing significant differences on relative abundances between SM and MFCs. **indicate OTUs showing significant differences on relative abundances between Ref-MFC and MPPT-MFC.