Assessing the role of biochemical methane potential tests in determining anaerobic degradability rate and extent

Jensen, P. D., Ge, H. and Batstone, D. J. (2011) Assessing the role of biochemical methane potential tests in determining anaerobic degradability rate and extent. Water Science and Technology, 64 4: 880-886. doi:10.2166/wst.2011.662


Author Jensen, P. D.
Ge, H.
Batstone, D. J.
Title Assessing the role of biochemical methane potential tests in determining anaerobic degradability rate and extent
Journal name Water Science and Technology   Check publisher's open access policy
ISSN 0273-1223
1996-9732
Publication date 2011
Sub-type Article (original research)
DOI 10.2166/wst.2011.662
Volume 64
Issue 4
Start page 880
End page 886
Total pages 7
Place of publication London, U.K.
Publisher IWA Publishing
Collection year 2012
Language eng
Formatted abstract
The biodegradability and bioavailability of hydrolysis-limited substrates under anaerobic (and aerobic) conditions can be represented by two key parameters – degradability (fd), or the percentage that can be effectively be destroyed during digestion, and first order hydrolysis coefficient (khyd), or the speed at which material breaks down. Biochemical methane potential (BMP) testing uses a batch test (in triplicate), and by fitting against a first order model, can fit both parameters in the same test. BMP testing is now being widely used for anaerobic process feasibility and design purposes, and standardisation efforts are ongoing. In this paper, we address a number of key issues relating to the test method and its analysis. This includes proposal of a new fitting and parameter estimation method, evaluation of the impact of inoculum to substrate ratio on fitted parameters, and comparison to performance in continuous systems. The new parameter estimation technique provides an estimate of parameter uncertainty and correlation, and is clearly more suitable than model transformation and linear regression. An inoculum volume ratio of at least 50% (2:1 on VS basis) was required on a cellulose substrate to use methane production as primary indicator, as found by comparing methane production and solubilisation of cellulose. Finally, on a typical material, waste activated sludge, the batch test was slightly conservative in terms of degradability and rate, indicating a bias in the BMP test. The test is a cost-effective and capable method to evaluate potential substrates, but it should be noted that it is generally conservative, especially if sub-optimal inoculum is used.
Keyword Anaerobic digestion
Biochemical methane potential (BMP)
Degradability
Hydrolysis rate
Cellulose
Digestion
Inoculum
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2012 Collection
Advanced Water Management Centre Publications
 
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