Performance survey of 46 full-scale Danish anaerobic digesters

Martin Hjorth Andersen, Rasmus Hansen Kirkegaard, Per Halkjær Nielsen

Publikation: Konferencebidrag uden forlag/tidsskriftPosterForskning


Background. Anaerobic digestion (AD) is a key technology for a sustainable future and is employed worldwide to produce biogas and degrade organic wastes. The strong emphasis on circular economy at Danish wastewater treatment plants (WWTPs) has had the consequence that many plants utilise AD to treat primary and secondary sludge. Although AD has been extensively studied in lab- and pilot-scale, studies describing full-scale operation of AD at WWTPs are few. An improved understanding of how full-scale ADs are operated and how they perform is important for future optimisation of design and operation.

Research question. The main objective was to learn how the Danish ADs treating wastewater sludge are operated, and investigate whether correlations between performance and microbiology could be identified.

Methods. We conducted a six-year survey of operational data from 46 ADs at 22 Danish WWTPs. Data included feeding sludge flows, gas yield, and operational parameters such as volatile fatty acids, alkalinity and ammonium. The microbial communities (archaea and bacteria) were analysed using 16S rRNA gene amplicon sequencing of all 400+ samples.

Main results. Unexpected difficulties arose when comparing the different plants since the chemical parameters analysed, analytical methods and sensors used, and possibilities for accessing data, varied a lot. The survey proved that there is need for standardisation of chemical analyses and equipment. Data suggested that, in most cases, thermal hydrolysis pre-treatment and thermophilic operating conditions were more efficient than mesophilic single-phase digesters. The lack of standardisation between WWTPs made identification of correlations between performance and microbiology difficult. The bacterial community was more diverse in mesophilic digesters and methanogenesis occurred predominantly through the acetoclastic pathway, while the hydrogenotrophic pathway was prevalent in thermophilic.

Take-home messages. Further research is needed to optimise methane yield and sludge degradation, which are essential parameters for achieving a good circular economy at Danish WWTPs.

Acknowledgements. The Danish wastewater treatment plants are acknowledged for their support with funding, samples and data and the Villum foundation for funding.

1. Kirkegaard, R.H., S.J. McIlroy, J.M. Kristensen, M. Nierychlo, S.M. Karst, M.S. Dueholm, M. Albertsen and P.H. Nielsen (2016): Identifying the abundant and active microorganisms common to full-scale anaerobic digesters.
2. McIlroy, S.J., R.H. Kirkegaard, B. McIlroy, M. Nierychlo, J.M. Kristensen, S.M. Karst, M. Albertsen and P.H. Nielsen (2017): MiDAS 2.0: An ecosystem-specific taxonomy and online database for the organisms of wastewater treatment systems expanded for anaerobic digester groups. Database (in press).
StatusUdgivet - 2017
BegivenhedMicrobial Genomics and Metagenomics Workshop - DOE Joint Genome Institute, Walnut Creek, USA
Varighed: 27 feb. 20173 mar. 2017


WorkshopMicrobial Genomics and Metagenomics Workshop
LokationDOE Joint Genome Institute
By Walnut Creek

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