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Water Res. 2018 May 1;134:181-191. doi: 10.1016/j.watres.2018.02.001. Epub 2018 Feb 7.

Performance and genome-centric metagenomics of thermophilic single and two-stage anaerobic digesters treating cheese wastes.

Author information

1
Department for Sustainable Food Process - DiSTAS, Catholic University of the Sacred Heart, 29122 Piacenza, Italy; Department of Environmental Engineering, Technical University of Denmark, 2800 Kongens Lyngby, Denmark.
2
Department of Biology, University of Padua, 35131 Padua, Italy.
3
Department of Environmental Engineering, Technical University of Denmark, 2800 Kongens Lyngby, Denmark.
4
Department of Environmental Engineering, Technical University of Denmark, 2800 Kongens Lyngby, Denmark. Electronic address: panak@env.dtu.dk.
5
Department for Sustainable Food Process - DiSTAS, Catholic University of the Sacred Heart, 29122 Piacenza, Italy.

Abstract

The present research is the first comprehensive study regarding the thermophilic anaerobic degradation of cheese wastewater, which combines the evaluation of different reactor configurations (i.e. single and two-stage continuous stirred tank reactors) on the process efficiency and the in-depth characterization of the microbial community structure using genome-centric metagenomics. Both reactor configurations showed acidification problems under the tested organic loading rates (OLRs) of 3.6 and 2.4 g COD/L-reactor day and the hydraulic retention time (HRT) of 15 days. However, the two-stage design reached a methane yield equal to 95% of the theoretical value, in contrast with the single stage configuration, which reached a maximum of 33% of the theoretical methane yield. The metagenomic analysis identified 22 new population genomes and revealed that the microbial compositions between the two configurations were remarkably different, demonstrating a higher methanogenic biodiversity in the two-stage configuration. In fact, the acidogenic reactor of the serial configuration was almost solely composed by the lactose degrader Bifidobacterium crudilactis UC0001. The predictive functional analyses of the main population genomes highlighted specific metabolic pathways responsible for the AD process and the mechanisms of main intermediates production. Particularly, the acetate accumulation experienced by the single stage configuration was mainly correlated to the low abundant syntrophic acetate oxidizer Tepidanaerobacter acetatoxydans UC0018 and to the absence of aceticlastic methanogens.

KEYWORDS:

Acidogenesis; Dairy wastes; Metagenomics; Methanogens; Syntrophisms; Thermophilic anaerobic digestion

PMID:
29427960
DOI:
10.1016/j.watres.2018.02.001
[Indexed for MEDLINE]
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