Third-world areas are facing a two-fold problem in terms of
how the organic waste streams can be handled and how they can be provided with
predictable and decentralised energy. This research paper is a comparative
kinetic evaluation of the anaerobic co-digestion of cow dung (CD) with 2
different high-carbon feedstuffs, cassava peel (CP) and water hyacinth (WH), on
the stability, performance, and fuel quality of biogas produced under
mesophilic batch anaerobic digestion. Three digestion systems were operated for
30 days: cow dung alone (CD), cow dung with cassava peel (CD+CP), and cow dung
with water hyacinth (CD+WH). Daily monitoring of temperature, pH, total
dissolved solids (TDS), electrical conductivity (EC), and gas yield provided
insights into microbial activity and substrate behaviour. All digesters
maintained constant mesophilic conditions (25 - 32 °C) and buffered pH values
(7.2 - 8.9) for most of the retention period, with a final decline (≈5.2 - 6.1)
marking substrate depletion. Co‑digestion markedly improved biogas
productivity compared to mono‑digestion. The CD+WH blend
produced 4,810 L of biogas (72.8% increase),
with steady gas release linked to the gradual breakdown of lignocellulosic
material. The CD+CP blend achieved the highest yield at 5,042 L (81.1%
increase), driven by the rapid fermentation of cassava starch. Gas composition
analysis showed methane concentrations peaking at 61.0% in CD+CP, compared with
52.0% in CD alone. However, all raw gases contained critically high hydrogen
sulfide (5,000 - 8,000 ppm). A low-cost, locally designed and fabricated
iron-oxide scrubber used during this work successfully eliminated H2S by
reducing the concentration from about 8000 ppm to 0 ppm. Post-scrubbing
flammability tests confirmed high-quality fuel, with co‑digested
gases producing strong blue flames characteristic of methane-rich biogas.
Beyond energy recovery, the study also demonstrated the agronomic value of the
digester effluents. The nutrient-rich slurry was applied as fertiliser to
plants, improving soil quality and supporting healthy growth, thereby closing
the resource loop between waste management, energy generation, and agriculture.
In addition to energy recovery, the nutrient-rich digester effluents were
applied as fertiliser, improving soil quality and supporting plant growth. The
findings demonstrate that co-digestion of cow dung with cassava peel or water
hyacinth enhances biogas yield, methane content, and process stability while
generating valuable organic fertiliser. This integrated approach supports
decentralised renewable energy and sustainable agriculture in biomass-rich
regions.
Author(s) Details
Stephen Oyelami
Centre for Gas, Refining and Petrochemical Engineering, University of Port
Harcourt, Nigeria.
Otaraku J. Ipeghan
Centre for Gas, Refining and Petrochemical Engineering, University of Port
Harcourt, Nigeria.
Akuma Oji
Centre for Gas, Refining and Petrochemical Engineering, University of Port
Harcourt, Nigeria.
Please see the link:- https://doi.org/10.9734/bpi/erpra/v12/6953
