Recovering biomethane and nutrients from anaerobic
digestion of water hyacinth (Eichhornia crassipes) and its
co-digestion with fruit and vegetable waste
M. A. Hernández-Shek, L. S. Cadavid-Rodríguez, I. V. Bolaños and
A. C. Agudelo-Henao
ABSTRACT
The potential to recover bioenergy from anaerobic digestion of water hyacinth (WH) and from its
co-digestion with fruit and vegetable waste (FVW) was investigated. Initially, biogas and methane
production were studied using the biochemical methane potential (BMP) test at 2 g volatile solids
(VS) L
1
of substrate concentration, both in the digestion of WH alone and in its co-digestion with
FVW (WH-FVW ratio of 70:30). Subsequently, the biogas production was optimized in terms of total
solids (TS) concentration, testing 4 and 6% of TS. The BMP test showed a biogas yield of 0.114 m
3
biogas kg
1
VS
added
for WH alone. On the other hand, the biogas potential from the WH-FVW co-
digestion was 0.141 m
3
biogas kg
1
VS
added
, showing an increase of 23% compared to that of WH
alone. Maximum biogas production of 0.230 m
3
biogas kg
1
VS
added
was obtained at 4% of TS in the
co-digestion of WH-FVW. Using semi-continuously stirred tank reactors, 1.3 m
3
biogas yield kg
1
VS
added
was produced using an organic loading rate of 2 kg VS m
3
d
1
and hydraulic retention time
of 15 days. It was also found that a WH-FVW ratio of 80:20 improved the process in terms of pH
stability. Additionally, it was found that nitrogen can be recovered in the liquid effluent with a
potential for use as a liquid fertilizer.
M. A. Hernández-Shek (corresponding author)
COLCIENCIAS-Universidad Nacional de Colombia,
Carrera 32 No. 12-00, Palmira,
Colombia
and
Institut National des Sciences Appliquées de
Toulouse,
135 Avenue de Rangueil, 31400 Toulouse,
France
E-mail: mahernandezsh@unal.edu.co
L. S. Cadavid-Rodríguez
I. V. Bolaños
Departamento de Ingeniería, Universidad Nacional
de Colombia,
Carrera 32 No. 12-00, Palmira,
Colombia
A. C. Agudelo-Henao
Departamento de Ciencias Básicas, Universidad
Nacional de Colombia,
Carrera 32 No. 12-00, Palmira,
Colombia
Key words | anaerobic digestion, biochemical methane potential (BMP), fruit and vegetable waste,
renewable energy, water hyacinth
INTRODUCTION
Water hyacinth (Eichhornia crassipes) is an aquatic plant
belonging to the pickerelweed family (Pontederiaceae).
Native to Brazil, it occurs in several waterways and water
storages in most countries of the world. It is a free-floating
aquatic plant well known for its production abilities and
removal of pollutants from water and as a reservoir of
both energy and nutrients (O’Sullivan et al. ). This
plant is considered as a noxious weed. According to
(Malik ), it can quickly grow to very high densities
(over 60 kg m
2
), even to completely clog water bodies,
which leads to serious problems in the preservation of
water ecosystems and human activities like fishing, naviga-
tion, irrigation and power generation (Fernández et al.
; Epstein ). In order to control its aggressive
growth, various efforts have been made, based on weed
management methods such as physical removal, chemical
methods (application of herbicides) and release of biological
control agents. However, water hyacinth (WH) has success-
fully resisted all attempts to its eradication (Malik ).
Direct landfilling of biodegradable material from
municipal solid waste (MSW), as in the case of Colombia,
poses lasting detrimental impacts to the environment and
human health. Among the major issues are the consequen-
tial emissions of greenhouse gases to the atmosphere and
water and soil contamination (Nguyen et al. ). Accord-
ing to the Ministry of Environment and Housing and
Territorial Development (MAVDT ), on average MSW
in Colombia contain an important fraction of biodegradable
material, about 65% (wet weight), and the generation rate of
this waste is increasing in time.
Several efforts have been made in order to give effective
solutions to these problems. In the case of WH, recent
research has been focused not only on control methods but
also on the utilization of technologies with significant
355 © IWA Publishing 2016 Water Science & Technology | 73.2 | 2016
doi: 10.2166/wst.2015.501