Assessment of a fast method to predict the biochemical methane potential based on biodegradable COD obtained by fractionation respirometric tests

Abstract

The biochemical methane potential test (BMP) is the most common analytical technique to predict the performance of anaerobic digesters. However, this assay is time-consuming (from 20 to over than 100 days) and consequently impractical when it is necessary to obtain a quick result. Several methods are available for faster BMP prediction but, unfortunately, there is still a lack of a clear alternative. Current aerobic tests underestimate the BMP of substrates since they only detect the easily biodegradable COD. In this context, the potential of COD fractionation respirometric assays, which allow the determination of the particulate slowly biodegradable fraction, was evaluated here as an alternative to early predict the BMP of substrates. Seven different origin waste streams were tested and the anaerobically biodegraded organic matter (CODmet) was compared with the different COD fractions. When considering adapted microorganisms, the appropriate operational conditions and the required biodegradation time, the differences between the CODmet, determined through BMP tests, and the biodegradable COD (CODb) obtained by respirometry, were not significant (CODmet (57.8026 ± 21.2875) and CODb (55.6491 ± 21.3417), t (5) = 0.189, p = 0.853). Therefore, results suggest that the BMP of a substrate might be early predicted from its CODb in only few hours. This methodology was validated by the performance of an inter-laboratory studyconsidering four additional substratesThis research was supported by the Spanish Government (AEI) through the TREASURE project [CTQ 2017-83225-C2-1-R]. Moreover, authors would like to thank the EU and the AEI for funding, in the frame of the collaborative international Consortium AquaVal project, [PCIN-2017-047], financed under the ERA-NET WaterWorks2015 Co-funded Call. This ERA-NET is an integral part of the 2016 Joint Activities developed by the Water Challenges for a Changing World Joint Programme Initiative (Water JPI). Authors from the USC belong to the Galician Competitive Research Group GRC ED431C 2017/29. All these programs are co-funded by the FEDER (EU). Lucia Argiz is a Xunta de Galicia Fellow, Axudas de Apoio á Etapa Predoutoral (ED481A-2019/083), grant cofounded by the operative program FSE Galicia 2014–2020. In addition, this work was funded by the Chilean Government through the projects FONDECYT 1180650 and ANID/FONDAP/15130015. Marisol Belmonte belongs to LABMAI-Facultad de Ingeniería, HUB-Ambiental UPLA and UPLAguas Research GroupS