International Journal of Environment Science and Technology
Center for Environment and Energy Research and Studies (CEERS)
Vol. 12, No. 9, 2015, pp. 3039-3046
Bioline Code: st15286
Full paper language: English
Document type: Research Article
Document available free of charge
International Journal of Environment Science and Technology, Vol. 12, No. 9, 2015, pp. 3039-3046
© Copyright 2015 - International Journal of Environment Science and Technology
Iron flocculation stimulates biogas production in Microthrix parvicella-spiked wastewater sludge|
Pradhan, S. K.; Torvinen, E.; Siljanen, H. M. P.; Pessi, M. & Heinonen-Tanski, H.
Municipal wastewater sludge has been used for
fertiliser and biogas production for several decades.
Chemical compounds such as iron and aluminium are
common coagulants used in wastewater treatment plants to
remove suspended solids, phosphorus and micro-organisms.
This laboratory study explores whether ferric chloride
(FeCl3 as PIX-111) or aluminium chloride (AlCl3 as
PAX-18) flocculation could stimulate biogas production in
wastewater sludge contaminated with Microthrix parvicella.
In a fermentation process run in three replicates,
cumulative methane production was in average about 25 %
higher using the iron flocculated sludge than using the
aluminium flocculated sludge; this difference was statistically
significant (P<0.05) in the subsequent runs of the
semi-continuous process. In all runs, the iron flocculated
sludge produced less (P<0.05) hydrogen sulphide in the
biogas than the aluminium flocculated sludge. The numbers
of M. parvicella stayed at the similar levels throughout the
process. It is concluded that biogas production is higher
and more stable with iron coagulant in comparison with
aluminium coagulant, presumably due to the reduced formation
of hydrogen sulphide. Thus, iron coagulants seem
to be better than aluminium coagulants to stimulate the
methane production process. Both coagulants significantly
suppressed multiplication of M. parvicella in the biogas
reactor, i.e. they did not evoke foaming in this experiment.
Aluminium; Biogas; Iron; Microthrix; Wastewater; Sludge
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