Agriculture Reference
In-Depth Information
L. mauritii
eliminated
Salmonella
and
Escherichia
sp., and the earthworm
gut analysis also proved that
Salmonella
sp. ranging 15-17 × 10
3
CFU/g
and
Escherichia
sp. ranging 10-14 × 10
2
CFU/g were completely elimi-
nated in the gut after 70 days of vermicomposting period (Ganesh Kumar
and Sekaran 2005). Activities by earthworms on sludge reduced levels of
pathogens and odors of putrefaction and accelerated sludge stabilization
(Mitchell 1978; Brown and Mitchell 1981; Hartenstein 1983). The reduc-
tion or removal of these enteric bacterial populations at the end of ver-
micomposting period, correlates with the findings that earthworm's diet
include microorganisms and earthworms ability to selectively digest them
(Bohlen and Edwards 1995; Edwards and Bohlen 1996). Apart from solid
waste management, earthworms are also used in sewage water treatment.
Earthworms promote the growth of 'beneficial decomposer bacteria' in
wastewater and acts as aerators, grinders, crushers, chemical degraders,
and biological stimulators (Dash 1978; Sinha et al. 2002). Earthworms
also granulate the clay particles and increase the hydraulic conductivity
and natural aeration and further grind the silt and sand particles and in-
crease the total specific surface area and thereby enhance adsorption of
the organic and inorganic matter from the wastewater. In addition, earth-
worms body acts as a 'biofilter' and remove the biological oxygen demand
(BOD), chemical oxygen demand (COD), total dissolved solids (TDS) and
total suspended solids (TSS) from wastewater by 90%, 80-90%, 90-92%
and 90-95% respectively by 'ingestion' and biodegradation of organic
wastes, heavy metals, and solids from wastewater and by their 'absorp-
tion' through body walls (Sinha et al. 2008).
Reports reveal that vermicomposting converts the infected biomedical
waste containing various pathogens viz.,
Staphylococcus aureus, Proteus
vulgaris, Pseudomonas pyocyaneae
and
Escherichia coli
to an innocuous
waste containing commensals like
Citrobactor freundii
and aerobic spore
bearing microorganism usually found in the soil and alimentary canal of
earthworms (Umesh et al. 2006). Vermicomposting plays a vital role for
safe management of biomedical wastes and solid wastes generated from
wastewater treatment plants and its bioconversion into valuable composts
free from enteric bacterial populations. Depending on the earthworm spe-
cies, vermicomposting was known to reduce the level of different patho-
gens such as
Salmonella enteriditis, Escherichia coli,
total and faecal coli-
