Biogas production from cheese whey wastewater:
laboratory- and full-scale studies
K. Stamatelatou, N. Giantsiou, V. Diamantis, C. Alexandridis,
A. Alexandridis and A. Aivasidis
ABSTRACT
A two-phase system for biogas production from cheese whey wastewater (CWW) was designed,
set up and operated at laboratory and full scale for a whole cheese production season (8–9 months).
The high efficiency and stability of the laboratory-scale system was demonstrated under various
organic loading rates (OLRs) reaching 13 g chemical oxygen demand (COD) L
À1
d
À1
and producing up
to 9 L L
À1
d
À1
of biogas (approximately 55% in methane). The COD removal was above 95% and the
pH was maintained above 6.3 without any chemical addition. The full-scale system was operated at
lower OLRs than its normal capacity, following the good response and high stability in disturbances of
the laboratory-scale unit.
K. Stamatelatou (corresponding author)
N. Giantsiou
V. Diamantis
A. Aivasidis
Department of Environmental Engineering,
Laboratory for Wastewater Management and
Treatment Technologies,
Democritus University of Thrace,
Vas. Sofias 12, 67100 Xanthi,
Greece
E-mail: astamat@env.duth.gr
N. Giantsiou
C. Alexandridis
A. Alexandridis
Sustainable Engineering Ltd,
Thesi Plakoto, P.O. Box 20, 19018 Magoula,
Greece
Key words | biogas, cheese whey wastewater, full scale, two-phase
INTRODUCTION
The food industry is a major production sector generating
large quantities of wastes. Stabilization of wastes is impera-
tive prior to their disposal to the environment according to
national legislation of many countries including Greece. In
the case of wastes of high organic content, such as food
wastes, anaerobic digestion is often the core technology in
the treatment scheme. Although the process development
aims primarily at meeting the environmental specifications
for safe waste disposal, provision could be taken to utilize
the energy produced in the form of biogas.
A typical type of waste produced in agricultural areas of
Greece is cheese whey wastewater (CWW) from cheese
manufacture. There are numerous and small cheese manu-
facturing units scattered in Greece, producing more than
160,000 t of cheese (data for 2007 by Hellenic Statistical
Authority, ELSTAT 2009–2010). There are three main
types of CWW depending on the origin of production:
from (a) primary cheese, (b) secondary ‘soft’ cheese and
(c) washing processes (Prazeres et al. ). The volume of
CWW produced is large (2.5 m
3
CWW are produced per
ton of milk processed). CWW contains mainly lactose (39–
60 g L
À1
) and its chemical oxygen demand (COD) is high
(50–70 g L
À1
). Other constituents are proteins (1.4–8gL
À1
)
and fats (0.99–10.58 g L
À1
)(Prazeres et al. ).
Anaerobic digestion is an alternative technology to
other methods employed in CWW management such as
animal feeding, and protein and other compound recovery
(Prazeres et al. ). The adoption of these options requires
the presence of farmers and industries in the proximity of
the cheese manufacturing plant to minimize transport
costs. On the other hand, a biogas plant could be installed
on-site and the biogas produced could be exploited to
cover the thermal or other energy requirements of the
cheese manufacturing plant.
CWW is rich in lactose, and therefore easily fermentable
to acids and subsequently to biogas. The rapid conversion of
CWW to acids, however, combined with the low alkalinity
of the mixed liquor, causes an abrupt drop in the pH, and
the methanogenic population is adversely affected (Kalyuzh-
nyi et al. ; Janczukowicz et al. ). As a result, the
application of pH control is often regarded as necessary,
via addition of chemicals such as lime (Patel & Madamwar
; Gannoun et al. ), sodium hydroxide (Yang et al.
) and bicarbonate salts (Ergüder et al. ; Frigon
et al. ).
Both single- and multi-stage systems have been studied
for CWW treatment. Single-stage bioreactors should operate
under high hydraulic retention times (HRTs) and/or require
1320 © IWA Publishing 2014 Water Science & Technology | 69.6 | 2014
doi: 10.2166/wst.2014.029
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