For
commercial
biogas
production
in
India,
cattle
waste
(dung)
is
the
prime
source.
Following
are
the
major
operations
for
biogas
production
:
(i)
dung
and
water
arc
mixed
in
1:
1
ratio,
so
that
inorganic
particles
(or
rajkans)
are
maintained
at
10%
level
(dung
usually
has
20%
rajkans);
(ii)
dung
feeding
rate
is
maintained
at
3,500
kg!
day,
although
it
may
vary
with
the
size
of
the
digester.
In
addition
to
dung,
the
input
may
include
the
following:
(i)
recycling
of
2%
share
of
fresh
slurry,
(ii)
use
of
night
soil
(3%
of
fresh
slurry),
(iii)
use
of
wastes
from
kitchens
and
(iv)
use
of
calcium
amm
nitrate
(1%
of
fresh
slurry).
It
has
been
shown
that
the
production
of
biogas
can
be
increased
from
38'6
litres/kg
of
input
(when
only
dung
is
used)
to
59,
6
litres/kg
(when
dung
is
combined
with
other
inputs).
These
other
inputs
prove
useful
in
growth
and
multiplication
of
bacteria,
which
help
in
anaerobic
digestion.
The
optimum
temperature
for
biogas
production
ranges
from
3S<>C
to
38°C,
which
is
achieved
sometimes
through
the
use
of
solar
panels.
The
pH
of
slurry
is
maintained
at
7
(neutral
medium).
