doi: 10.17113/ftb.55.02.17.5080

Biogas Production from Brewer’s Yeast Using an Anaerobic Sequencing Batch Reactor

Gregor Drago Zupančič^1,2, Mario Panjičko¹ and Bruno Zelić³*

¹Sustainable Technologies Development Centre Ltd, Dragutina Golika 63, HR-10000 Zagreb, Croatia
²National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia
³University of Zagreb, Faculty of Chemical Engineering and Technology, Marulićev trg 19, HR-10000 Zagreb, Croatia

Article history:
Received November 24, 2016
Accepted February 24, 2017

Key words:
anaerobic digestion, ASBR, biogas, brewer’s yeast

Summary:
Renewable energy sources are becoming increasingly important in the beverage and food industries. In the brewing industry, a significant percentage of the used raw materials finishes the process as secondary resource or waste. The research on the anaerobic digestion of brewer’s yeast has been scarce until recent years. One of the reasons for this is its use as a secondary resource in the food industry and as cattle feed. Additionally, market value of brewer’s yeast is higher than its energy value. Due to the increase of energy prices, brewer’s yeast has become of interest as energy substrate despite its difficult degradability in anaerobic conditions. The anaerobic co-digestion of brewer’s yeast and anaerobically treated brewery wastewater was studied using a pilot-scale anaerobic sequencing batch reactor (ASBR) seeded with granular biomass. The experiments showed very good and stable operation with an organic loading rate of up to 8.0 kg/(m3·day), and with a maximum achieved organic loading rate of 13.6 kg/(m3·day) in a single cycle. A specific biogas productivity of over 0.430 m3/kg of the total chemical oxygen demand (COD) inserted, and total COD removal efficiencies of over 90 % were achieved. This study suggests that the brewer’s yeast can be successfully digested in an ASBR without adverse effects on the biogas production from brewer’s yeast/wastewater mixtures of up to 8 % (by volume). By using the brewer’s yeast in the ASBR process, the biogas production from brewery wastewater could be increased by 50 %.

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