Abstract:
Energy is a key factor to socio-economic development. There is clear correlation between energy
consumption and the level of standard of living. On the other hand, human societies produce wastes
that can represent a useful raw material for the production of energy, and recovery of by-products and
component water. In this paper, the potential of Moringa stenopetala seed cake powder which is a byproduct
of the hexane extract of the seed is evaluated for its contribution in biogas production and
brewery wastewater treatment through coagulation. Moringa stenopetala seed cake powder was used
as feedstock in nine serum bottles with a capacity of 2.5 L. The anaerobic digestion was conducted in
triplicate with 10%, 15% and 20% of their working volume inoculated with actively digested biogas
slurry. The experimental findings showed that the composition of methane in all of the digesters is
within the range of 62-72%. The amount of biogas produced over a retention time of 68 days was also
between 6.6 L to 7.7 L. The Physico-chemical characteristics of the seed cake powder revealed the
suitability of the substrate for biogas production. No inhibitory factors were found within the seed
cake powder. However, the total solids percentage of the seed cake powder was about 93% which can
be considered as a drawback in areas which suffer from water drought for large scale application of the
substrate in biogas production. The other application of the seed cake powder studied in this work is to
evaluate its potential for brewery wastewater treatment. The brewing industry is one of the largest
industrial users of water. The wastewater is also characterized by different valuable nutrients.
Recovery of these resources and treatment of the wastewater to reduce the impact on the receiving
water bodies is an important aspect of this research. Moringa stenopetala seed cake powder was found
to be an effective coagulant in reducing total phosphorus, turbidity and total suspended solids from
the brewery effluent achieving an average removal efficiency of more than 90%. A relatively better
efficiency of more than 80% was achieved for COD and BOD. The removal efficiency for total
nitrogen was about 43%, a lower but important figure as coagulation is a physical process. However,
conductivity, total dissolved solids and pH were not significantly affected through the coagulation
process. Better removal efficiency was obtained at a coagulant concentration of 500mg/L. Therefore,
Moringa stenopetala seed cake powder which is a by-product of the hexane extract of the seed can be
managed by using as substrate for biogas production and as coagulant for brewery wastewater
treatment.
Key words: Moringa stenopetala seed cake powder, Biogas, coagulation, Brewery wastewater, average
removal efficiency