Investigation of Biogas Production by Co-Digestion of Brewery Wastewater and Brewery Spent Yeast
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Date
2019-06-09
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Addis Ababa University
Abstract
Production of biogas through anaerobic digestion of organic waste materials provides an
alternative environmentally friendly renewable energy. In this study, biogas production from codigestion of
brewery
wastewater, spent
yeast
and
brewery
sludge
in
five
mix
ratios
was
evaluated
under
mesophilic condition (35 ℃, 37 ℃, 39 ℃) using a batch digester for 21 days. For all
substrates, total solids (TS), biological oxygen demand (BOD), chemical oxygen demand (COD),
temperature (T), total nitrogen (TN), total phosphorus (TP), and pH were measured before and
after digestion. For the experimental design, different mix ratios of yeast and wastewater by
volume (0 %, 1 %, 6 %, 11 %, 100 %) were adopted for all the anaerobic digestion employed. All
measured physico-chemical parameters of the sample substrate significantly varied before and
after anaerobic digestion AD. Gas production was measured for all the samples periodically
starting from fourth day of digestion experiment and went to zero at about 21 days in all substrates.
Assessment of cumulative biogas production revealed that substrate in a mix ratio of 1 %,
temperature 37 ℃, pH 6.5 (3417 mL/800 mL sample) spent and 6 %, 37 ℃, 6.5 (3325.5 mL/800
mL sample) showed the highest biogas production and the lowest was in 11 % volume ratio, 35 ℃
temperature and pH of 5 (2173 mL/800 mL sample) and 11 %, 39 ℃, 5 pH suggesting the first
mix ratio of the two substrates is an optimal mix to yield better biogas. Overall the results indicated
that biogas yield and TS, BOD, COD reduction can be significantly enhanced when brewery spent
yeast and brewery wastewater are co-digested.
Description
Keywords
Biogas, Co-digestion, anaerobic digestion, BOD, COD, TS, TN, TP, spent yeast