Estimation of Hydrolysis Parameters in Full-Scale Anerobic Digesters

Batstone, D. J. and Tait, S. ORCID: and Starrenburg, D. (2008) Estimation of Hydrolysis Parameters in Full-Scale Anerobic Digesters. Biotechnology and Bioengineering, 102 (5). pp. 1513-1520. ISSN 0006-3592


In hydrolysis-limited anerobic systems, the key parameters describing degradation are degradability extent (fd), and the lumped apparent first order coefficient (khyd). These are often measured in biological methane potential (BMP) tests. Using modern techniques, it should also be possible to estimate these parameters in full-scale systems, especially where inputs are dynamic. In this study, we evaluated fd and khyd values and uncertainty based on nonlinear parameter estimation from (i) BMP tests and (ii) effluent gas and solids from two full-scale digesters fed with highly variable feed flows and concentrations (up to 6 kg COD m−3 day−1). The substrate was thermally hydrolyzed activated sludge, and the inoculum for BMP tests was from the full-scale digesters. While identifiability of both parameters in the BMP tests was generally good, only fd could be well identified using continuous data. For khyd using continuous data, normally only a lower limit could be found (upper was unbounded). In addition, parameters as estimated on different outputs (VS and gasflow) and two different digesters were consistent, with an fd value of 0.45–0.55, and a khyd value of >5 day−1. Gradual changes in fd over the 450 days could be related to upstream changes. fd values as estimated in BMP tests were consistent (if conservative) with continuous estimates, with a fd in BMP of 0.4–0.5. khyd values were an order of magnitude lower (0.15–0.25 day−1 vs. >5 day−1), and this translated to very poor model performance when BMP-estimated values were used in the continuous model. This means that while BMP testing may be used for project feasibility analysis, values obtained should not be used for dynamic modeling. The parameter confidence regions found were highly nonlinear, especially for continuous systems, indicating that iterative or sampling techniques are required for an estimate of real parameter uncertainty.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Faculty/School / Institute/Centre: No Faculty
Faculty/School / Institute/Centre: No Faculty
Date Deposited: 22 Feb 2022 03:15
Last Modified: 22 Feb 2022 03:15
Uncontrolled Keywords: Activated sludge; ADM1; Anerobic; Hydrolysis; SRT; Thermal hydrolysis
Fields of Research (2008): 09 Engineering > 0907 Environmental Engineering > 090702 Environmental Engineering Modelling
09 Engineering > 0907 Environmental Engineering > 090701 Environmental Engineering Design
Fields of Research (2020): 40 ENGINEERING > 4004 Chemical engineering > 400410 Wastewater treatment processes
40 ENGINEERING > 4004 Chemical engineering > 400403 Chemical engineering design
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