Comparison of Variable and Constant Loading for Mesophilic Food Waste Digestion in a Long-Term Experiment

He Song, Yue Zhang, Sigrid Kusch-Brandt and Charles J. Banks
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He Song: Biomass Group, College of Engineering, Nanjing Agricultural University, 40 Dianjiangtai Road, Nanjing 210031, China
Yue Zhang: Water and Environmental Engineering Group, University of Southampton, Southampton SO16 7QF, UK
Sigrid Kusch-Brandt: Water and Environmental Engineering Group, University of Southampton, Southampton SO16 7QF, UK
Charles J. Banks: Water and Environmental Engineering Group, University of Southampton, Southampton SO16 7QF, UK

Energies, 2020, vol. 13, issue 5, 1-14

Abstract: Operators of commercial anaerobic digestion (AD) plants frequently note the challenge of transferring research results to an industrial setting, especially in matching well-controlled laboratory studies at a constant organic loading rate (OLR) with full-scale digesters subject to day-to-day variation in loadings. This study compared the performance of food waste digesters at fluctuating and constant OLR. In a long-term experiment over nearly three years, variable daily OLR with a range as wide as 0 to 10.0 g VS L −1 day −1 (weekly average 5.0 g VS L −1 day −1 ) were applied to one laboratory-scale digester, while a pair of control digesters was operated at a constant daily loading of 5.0 g VS L −1 day −1 . Different schemes of trace elements (TE) supplementation were also tested to examine how they contributed to process stability. Variable loading had no adverse impact on biogas production or operational stability when 11 TE species were dosed. When TE addition was limited to cobalt and selenium, the stability of the variable-load digester was well maintained for nearly 300 days before the experiment was terminated, while the control digesters required re-supplementation with other TE species to reverse an accumulation of volatile fatty acids. This work demonstrated that variation in daily OLR across quite a wide range of applied loadings is possible with no adverse effects on methane production or stability of food waste digestion, giving confidence in the transferability of research findings. The positive effect of variable OLR on TE requirement requires further investigation considering its practical significance for AD industry.

Keywords: variable loading; food waste; anaerobic digestion; trace elements; cobalt; selenium; process stability (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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