English
norskEffect of ethanol distillery effluent on the water quality of the receiving waters of Lake Malawi during the rainy season
Sammendrag
A
study
was
carried
out
in
Dwangwa
area
of
Nkhotakota
d
i
str
i
ct
in
Malawi
to
determine
the
effect
of
ethanol
distillery
effluent
from
the
Ethanol
Company
on
the
water
quality
of
the
receiving
waters
of
Lake
Malawi.
Water
samples
were
collected
from
six sites
located
along
Dwangwa
River
,
in
the
effluent
ponds
and
in
the
lake
at
week
intervals
for
8
weeks.
The
samples
were
analysed
for
BOD,
COD,
DO,
pH,
alkalinity,
acidity,
turbidity,
a
mm
onia,
nitrate,
phosphorous,
potassium,
calcium
and
chlorophyll.
Concentration
levels
of
pollutants,
BOD,
COD,
DO
and
alkalinity
generally
decreased
from
the
source
downstream
to
the
lake
with
a
few
exceptions.
This
was
attributed
to
the
dilution
factor
and
evaporation
of
some
components.
Concentration
levels
in
the
receiving
waters
were
found
to
be
within
the
tolerable
limits
except
for
ammonia.
On
average
the
levels
of
DO,
BOD,
pH,
Chlorophyll,
Nitrate,
Phosphorous
and
Ammonia
were
6.24
ppm,
30.54
mg/l,
7.48,
5
.
05
ppm,
0.29
ppm,
0.22
ppm
and
2.1
ppm
respectively.
The
levels
detected
for
ammonia
were
generally
ranging
between
the
suggested
toxic
concentration
of
0.6
and
2
mg/l,
for
most
of the
species
in
water
(Smith
and
Piper,
1975).
However,
concentration
of
pollutants
in
the
effluent
was
found
to
be higher
than
the
acceptable
limits.
It
was
therefore
concluded
that
the
ethanol
effluent
from
the
factory
was
potentially
hazardous
to the
aquatic
life
in
the
receiving
waters