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Biological treatment of wastewater from urea plants of Kuwait
0361-3658/X5 $3.00 + 0.00 Pergamon Press Ltd.
BIOLOGICAL
TREATMENT
FROM UREA
M.S.
Khalafawi**,
OF WASTEWATER
PLANTS
M.N.
OF
KUWAIT
El-Khawaga*,
and
H.S.
Pal**
ABSTRACT
A qualitative the
bydrolyzer
(PIC)
effluent
a routine
analysis
10 heavy
plant,
hydroll-zer
biological in
average were
growth, vas
studies
kere
and urea
the
hence
undertaken
or
urea
a
6-11 parameters
results.
ammonia
of
and urea
respectively.
removing
the in
The
urea
and ammonia
batch
sg-stem
vith
high
optimize
combined
sometimes
better
optimum
rates
than
levels
-
sustain of
of
Kinetic
denitrification
nitrification,
bio-oxidation the
to
efficiency.
nitrification
nitrogen
that
medium
treatment
The observed and
indicated
deficient
de-
rates
corresponding
Mere
rates
reported
literature.
be completely
retention j0
the
for
to
In a continuous could
in
su pplementation
biodegradation.
to
the
of
optimization
of
at
coupled
samples,
a set
of
130 mg/l,
was a nutritionally
urea
of
process
aimed
Company
systems.
a prerequisite
nitrifichtion, comparable
were
in
measurements
analysis despite
pollutants
wastewater
concentration
treatment
nutrients
of
100 and
studies
effluent
microbial
in
that
the
Biological
flow
determination
statistical
the
Industries
involved
and
and continuous
hjdrolyzer
the
effluent
of
Petrochemical
task
showed
treatment
batch
study
collection
for
metals,
The results hJ-drolyzer
the
This
and intensive
comprehensive
the
of
was uudert.aken.
with
and
and quantitative
time
of
biological
removed 20-24
from
hours
treatment the
system
hydrolyzer
and a solids
urea
and ammonia
effluent
retention
at
time
a h)-draulic
in
excess
days.
in
Ihe
average’concentrations
the
final
respectively;
the
*
Petrochemical
xy
Kuwait
effluent total
Institute
of
were dissolved
Industries for
0.3,
ammonia, 0.21,
solids Company,
Scientific
nitrite,
0.4 were
and 0.0
nitrate mg/l,
450 mg/l.
Kuwait. Research,
Kuwait.
and
of
104
M. S. Khalafawi
et cl/
INTRODUCTION
Petrochemical fertilizer Capital
complex
located
the
complex
city,
exploiting
Industries
the
The complex
Natural
capacity
of
3000
the in
1974,
MT/D,
2500
for
an effluent
to
a clean
keep
between to role in
the
be of
suitable
which
whenever
industrial
sector
significant
started
in
cooperation
utilizing
the
last
industrial
five
field
years
industrial of
in-plant
treatment
several
The
for
subject
of
in
the
cooperation
organizations
applied
this
to
limits
vater
the
programmes
specialists
solutions
paper
this
Researches
her
find
seems of
research
Scientific
to
abatement measures,
importance
of
scientists
the
course
the
with
authorities
abatement
of
strength
technologies
pollution
experience
KISR
problems.
pollution
academic
high
compliance
for
the
respectively.
generate
for
make use
one
total
400 MT/D,
steps
In this
Institute
with
know-how
PIC realizing
Kuwait
experience
to
and
role.
with
the
academic
and
production.
local
the
of
plants,
the
wastewater
possible.
oil
plant
by
the
object
no exception.Im
imposed
satisfies
Kuwait,
Urea
invariably
practicable
environment,
place
Acid
progressive
best
the
achieve
suitable
factories
of
of
three
Sulphuric
and PIC is
followed
a nitrogenous
the
a by-product
regulations
the
has
1965 vith
MT./D, 500 MT/D and
wastes,
PIC has
by implementing
),
50 Km. South in
is
one
fertilizer
discharge
searching
Shuaiba,
Ammonia plants,
and
nitrogenous
effluent
and
four
plant
Nitrogenous aqueous
at
( PIC
was started
Gas which
comprises
Ammonium Sulphate
Company
*as
(KISR) and
for
one
of
the
some these
prcgrammes. T t Of Lrea
Plants
The effluent 500 mgl-
ammonia
forestry
area,
the
In
1980
the
caused
caused
by the
the
first of
The resultant adding for urea.
extra
the
However,
that from
area the
decreasing
these system
are product
effluent during
due
180
‘C.
recycled
outlet operation
Sabahia in
ammoniacal population
adour there.
was commissioned
decompose
The hydrolyzer as per
loads
the
the
urea
in
reaction
following
reaction;
2NH3 + co*
---L
of
the
compounds
NH3 and COP. and at
the
nitrogenous to
to
as much as
to
progressing
hydrolyzer
into
originally
was sent
The high
in
gases
treated
at
+ H20
urea
It
a urea
18 Kg/cm*
NH2(CO)NH2
contained
urea.
Shuaiba.
complains
effluent
under
plants
mgl-
nuisance
step
addition
place
urea
10,000
several
wastewater
takes
outlet and
15 Km. North
effluent
which
Wastewater
to
about
the
urea
18 ton/d
hydrolyger these
limits
plants
to
in
average.
are
60 mgl-
were
not
be processed
again
The design ammonia always
and
limits 200 mgl-
achieved,
Biological
and due more of
to
the
increasing
strongly.
investigate
methods.
Although
compounds, the
most
proved this
the
there
study
the
of
1981
optimization
with
treating
as
and
several
project Research treatment
removing
nitrogenous
methods
reports
industrial et
study
of
quantitative
was undertaken,
as
have
it
is
conclusively
wastewaters
al;
1979;
routine
and and
intensive
four
after
the
a course
pollutant
work
by
Bridle
of
et
al.,
analysis
for
the
process
outlet
flor
urea
measurements
wastewater
samples
The wastewdter
respectively.
optimization
in of
loads
involved
collection
hours,
a comprehensive and
the-pollutants
meanwhile,
pollutants
to
for
treatment
Bridle
minimize
before
known
study
biological
1977;
of
subjected
by the
raised
levels
Scientific
nitrogenous
to
eight
them were
method,
assessment
of
parameters
methods
biological
was carried Ihis
were
and
effluent
intervals
the
research for
and urea
complains
these
).
A qualit,ative
roupled
several
( Adams and Eckenfelder,
Luthy,
plants.
are
the
suppress
Institute
ammonia
feasible
feasibility
hydrolyzer
of
selected
economically
method
1980;
removal
area,
to
A joint
was necessary. PIC and Kuwait
the
Sabahia step
between
105
of Wastewater
at
a further
compounds
was established to
popElation
Consequently
nitrogenous
Treatment
the
periods,
determinarion the
average
at
samples of
results
11 of
follows,
TABLE (
1
)
INTENSIVE ANALYSES FZSULTS OF HYDROLYZER WATER
Parameter
Post-Optimization
Pre-Optimization
PH
9.08
9.55
Na3
mg/l
187
10
Urea
mg/l
247
70
TDS
mg/1
475
61
COD
me/1
1200
BOD
mg/1
CN
mg/l
ND
ND
H2S TOC
mg/1
ND
ND
mg/l
92
23
25
SiO2
mg/l
3-D
ND
Oil
mg/l
ND
ND
ND
=
Not
detectable
However
the
pollutant
taken
before
and after
scope
of
nitrogenous
table
(2)
the
the
loads
process
loads
to
were
taken
optimization be considered
as
the
periods in
the
average to study
of
give as
90
more shown
readings wider in
106
et al.
M. S. Khalafawi
TABLE
( 2 )
ASSESSMENT OF POLLUTANTS IN ~DROLYZER
Period
Concentration
Pre-Optimization
(July,
( Nov.,
19P2
* Average
of
Cu,
hydrolyzer as
it
Load
t/day
Urea
NH3
Crea
342
437
0.56
0.71
109
129
0.16
0.20
90 readings
Fe,
from
routine
an intensive
Cr,
Ni,
effluent
is
/
)
Meanwhile Cd,
mg/l
NJ3
1982 )
Post-Optimization
for
\VAIER *
analysis
Mn, Pb,
is
originally
almost
steam
shift
for
MO, Zn,
totally
condensate
samples.
heavy
metals
and Mg and
deficient water
of
vas
carried
indicated all
that
these
introduced
to
elements
the
hydrolyzer
process. The assessment effluent
has
-
the
study
following
results
indicated
that
the
urea
hydrolyzer
characteristics.
Low concentrations
of
TSS,
CN, H2S,
SiO2,
Oil,
color
and
toxic
met,als. -
High
-
Unsuitable
-
Nutritionally
-
concentrations for
Requires metals
direct
supplementation for
are,
urea
biological
is
as
Crea
follows
and
and
TDS.
treatment
is
required.
effluent. with
inorganic
phosphorous
and
trace
nitrogenous
compounds
treatment.
processes
biodegradation,
A summary
respectively.
NH3, urea, reuse
unbalanced
The biological removal
of
of
the
encountered
in
nitrification reactions
and
involved
denitrification in
these
processes
processes
,
Biodegradation
co(NA2J2
+
2NH3
b
NO2
>
NO 3
+
co2
Nitrification %l4
+
NO2
+0.502
sH4
+
1.5
2
o2
O2
e
NO3
+
H20
+
2H +
+
2H +
+
H20
Biological
Treatment
107
of Wastewater
Denitrification NO3 + 0.33
NO3 + 0.83
CH3OH
~
0. 5N2 + 0.5C0,
three
batch
with
ammonia
experiments
factors
with
the
in
the
degrading
in
these
employed
for
fying of
bacteria
in
the the
and
Effect
activated
MLSS -
+ OH -
in
the
efficiency
the
hydrolyzer
was undertaken effluent
to
the
normally
of expected
to
Fig
activated
was usually
and the
8.80
results from
in
the
from
1.6
seed
indicate
was
required
an
Figure
acclimation
of
that
an initial
final
bacteria
when it
population.
on the
obtained
was efficient
observed
bacterial
The
sludge
plant
value
(1)
nitri-
the
rate
of
2.24
batch.
by the mg YO 3
same subculturing method -1 %” >k - h -I ,o - S - g
(2).
cultures
mentioned
above
serx-ed
as
seed
in
the
experiments.
at
30 ‘C.
to
85,
118,
mg NH3 - N -
that of
both
The concentration
treatment
experiment
rate
stage,
be nitrified
ponding 2.73
to
The study
that
specific
denitrifying
more
than
nitrification
concentration.
:
Nitrification
Nitrification studied
into
hydrolyzer
adjusted
subculturing
denitrification last
lag
sludge. by
h -I of
Of Ammoniaon
could
study
relative
actual
denitrification,
the
a typical
The acclimated folloring
time
enrich
Acclimation
were
indicated
improved
mg hH3 - N g-l
improT-ed
the
insight
nutrients.
wastewater
of
for
the
inorganic
two media
gain above
processes.
with
municipal
to
results
nitrification
3.16
in
+ 1. 167H20
effluent.
nitrification
the
to
mentioned
or
A distinct
period
highlits
designed
experiments
local
urea.
acclimation
adopted
+ irH-
systems.
these
missing
hyrdolyzer
Ardyia
were
medium
Preliminary from
were
CO2 + 0.5H20
:-
affecting
the
and urea in
steps continuous
processes
a synthetic
supplemented
in
studies
biological
and the
levels
and
N2 + 0.5
WORK
These
water
biological
studies
three
either
H20
)
Static
the
+ 0.67
CH3OH
EXPERIMENTAL
of
NO2
NO2 + 0.5
batch
1.
,
0.5
These static
CH30H
rates
at
different
The results
(Fig.
rithin
40 hrs.
24 -
li15, g -’
118 mg/l under
and
227
MLSS -
test
mg/l
h -’
ammonia the
3)
,
exert
concentrations shokrd
that
85 -
The ni:rifica;ion ammonia
kerc
respectirely.
of
;Immoni,l kere
115 me/l ra:es,
7.OLi. Thus,
an inhibitor>-
conditions
of
5.35,2,7 it
influence
temperature
tan on
dtnd be roncludc,d the
tind biomass
rate
108
r
Fig
( 2
)
Il.
Srcond
Iknilrification
Time
48
( h )
72
culture
Subculture
in batch
96
in synthetic
0
\
h
y=j
\
*
48
*\-
.
'Time ( h )
24
.
medium at, ‘IO ‘C.
‘;-r 72
200
XJO
0
_ 100
-
.
400
M. S. Khalafawi
Fig.
( 3 ) Sitrification
Rates
et al.
of
Different
\Hj Concentrations
240
220
180
160
<
140
E” i
120
9 c z 100
80
60
40
20
0
. 8
16
24 Time
32 ( hours
)
40
48
56
Biological
Effect
Of Urea
OnNitrification
The results could
be
KLSS 9.4
degraded
g -I
rate
was 7.9
urea
in
Effect
the of
medium has
-1
g
delayed
temperatures,
15,
and
the
total
hence
it
was concluded
and urea
biodegradation.
Effect
KLSS -
Nitrification
MISS -
h -’
respectively.
conentration the
as ammonia,
same with
PO4 is and Effect
of
medium
also
for
could
Nitrate
per
respectively.
of
urea -1 g
rate
was
Biodegradation
studied
(
and
at
Fig.
13.56
at
15, is
30 and
the
with
alone
6.34
Hovever,
when urea of
rates
g -I
were
6.43,
the
and
for
nitrification
same with
was introduced
biodegradation
- urea
14.0
respectively,
mg/r;H3 - N -
can
urea
MLSS- h-l
:-
were
It
that
N -
temperature
and 6.55
urea
different
-
Biodegradation
ammonia
:-
5 ) indicate
40 ‘C.
optimum
and were
rates
three
mg urea
and NfI3 - N ) removal
nitrification
On Denitrification
received
of
nitrate
methanol
mg NO - N. 3 in
be denitrified
denitrification
- N -
be
PO4
g -’
wit,h were
found
concluded
that
biodegradation
of
-
the
same to
be
2 mg/l
100 mg/l
3x3
urea.
Two levels
methanol
were
PO4 conentrations. the
104 mg/l
mg urea
process.
and Urea
and Urea
the
different
required
100 mg/l
nitrification
30 ‘C.
rates
2 and 6 mg/l
8.66
and NH3 - N ) removal
17.95,
h -’
that
that
of
The results
7.51,
Of PO4 On Nitrification
concentration
( urea
the
( urea
g -’
III
For ammonia alone, however, the nitrification _ h -1 This means that the presence of .
45 ‘C.
were
nitrogen
mg N -
a rate
processes
30 and
rates
and 7.88
4 ) indicate at
on Nitrification
The two biological
biodegradation
(Fig.
h -l.
mg NE3 - N -
Temperature
in
16 hours nitrogen
MLSS -
of Wastewater
:-
shown within
The total
h -l.
mg N -
Treatment
rates
were
:were
as
The results 25 hours, 5.95
tested
electron
(
( Fig. but
and 7.34
165
donor
and 265 mg/l). in
6 ) shows
265 mg/l
The
a concentration that
165 mg/l
NO3 needed
33 hours.
mg NO3 - N -
g -I
XLSS -
salt
of
3 mg NO3
h -’
The
112
M. S. Khalafawi
er al.
< N
. c_
-
z
T
( I,%
)
iH';
0
12 Time
.
( h )
36
my/l
Concentration
24
mg/l
Urea Concentration
A N0-5
mg/l
Concentration
0
Time
40
Temp.
24
0.71
MLSS
and urea biodegradation
Ml3
on niLrification
0
Fig.(T) Kffrrt of tcmpclr;lI.ure
g/l
( h )
4x
Oc.
72
1
x s m R
k20
0
70
140
210
280
350
490
-= kY -
560
630 -
114
M. S. Khalafawi
Effect
Of Temperature
On Denitrification
Denitrification results
( Fig.
here
7)
g -1
NO3 - N -
we find Of PO,
on the
denitrification
best
showed
plant
conditions,
phosphate
and
of
denitrification
rates of
successive
of
substrate
indicating
the
experiments
Effect
of
Fig.(ll) at
20 h,
urea
the
was reduced increased
to
rates
16 h
BRT
g -’
MLSS .
were
that
for
the
in
each
the
Fig.
feed.
8.
The results and
The observed
increase
successive
nitrifying
Process
biodegradation
respectively.
cultures
up to
efficiences
the
twelvth
Thus,
under
in
batch
the
rate
thereby
and denitrifying served
On the
effluent day
the
total
as
the
seed
in
concentration
the of
(urea
and
urea the
HRT was maintained
however,
than
was an HRT of 30 days.
removal 22.4
HRT
progressively
concentration
ammonia) -1 and MLSS . h
) and
when the
experiment,
was more
:-
( 100 mg/l
ammonia
SRT value
g -’
when the
ammonia day,
whereas
mg NH3 - N. respectively.
days, for
Removal
seventh
conditions
nitrogen
Of Nitrogen
six
observed
The estimated
17.9
shown
to
simulate
supplemental
into
and urea
Time On Rate
the
h-l,
feed,
to
below.
16 hours,
for
as
a progressive in
of
1CO v/c.
20 h was desirable. oxidation
the
designed
In order
& IO ),
acclimated
) were
up to
undetectable.
are
Figs.(9
These
shows
( 160 mg/l
study
enrichment
Retention
removal
PO4 is
essentially
incorporated
demonstrate
described
Hydraulic
was used
denitrification
a stepwise
were
nitrification
in
concentrations
6 mg/l
that
experiments.
were the
of
shown
populations.
mg
Again,
temperature.
PO4 different
studies
batch
during
removal and
4.14
:-
effluent
batches
nitrification
bacterial
in
nutrients
are
and
The
conditions.
continuous
employed
three
of
System
hydrolyzer
configurations of
4.32,
respectively.
NO3 indicated
test
obtained
inorganic
1.19,
45 ‘C.
denitrification
effect
325 mg/l the
scale
results
were
optimum
15, 30 and 45 ‘C.
at
:-
On Continuous
The bench the
30 and
the
of under
Studies
confirm
rates
15,
the
testing
,
30 ‘C
studied
the
On Denitrification
concentration
2.
at
is
:-
were
that
h -1
30 ‘C.
Effect
At
rates
NJSS -
that
et NI.
at
Bio-
20 and
mg Total-
N
Biological Treatment
of Wastewater
115
116
M. S. Khalafawi et cd.
/
/
1
-
Biological
Process
Fig.(s)
Vitrification
or Reactor
A -
Treatment
of Wastewater
configurations
denitrification
Vitrification
or
Denitrification
Process.
Alkali
Feed
Denitrificdtion
Sludge
El - Nirrification
Recycle
- Drnitrifichrisn
Pr,~rr;s
I It;
Biological
Treatment
of Wastewater
119
M. S. Khalafawi PI NI
.
I. .i ./
.I
.I \. ./ . . \
Biological
Nitrification This and
salt
Biodegradation
one
treatment
of
efficiencies the
and Urea
medium
The results
step
containing
for
urea
mg N . g -I
Vitrification
with
the
Parallel
to
Captor
sponges g/l
rate -
one
stage
one
day
to
Ihe
!8.47
mg
run at
sha..s
similar
at
Treatment This
shohn
in
nitrification employed.
Fig
in
Growth
and
removal
was
System growth
( Fig.
growth
13 ) show
as rell
system
The average
suspended
(urea
system.
that
as for
a 100%
ammonia.
and ammonia
) was 21.26
days
steady
.
Growth
state
Urea
the
g/l.
a reactor
contained
( Fig.
incretse
14)
from
treatment.
steady -1 h .
of
141-354 shows
66 s
*as
the
mg/l
that
on the
calculated
atrached of
nirrhte.
lhe
mg NO
3
Biodegradation,
recycle
the
the second
The SHT exceeded
state
conditions,
was 2j.l
The aerobic
using
50
to
be
System
removal
treatment
liquor
in
KLSS concentration
a 14 1 fermentogfor
The mixed
out
at
experimental
for
2.
to
of
PlL-‘S
the
:-
The feed
was 0.32
equilibruim in
combined 8 -
respectively,
an attached
the
was carried
commenced
Attached
100 $ efficiency
Tuo Step
85 ‘$,
urea.
treatment
conditions.
urea
System
( Fig.8_1).
12-19
an dverage
denirrification
in
for
Growth
YES
. g -’
in
g/l
nitrogen
denirrification
NOj - ?j
Using iias
system average
of
Denitrification
of
average
and ammonia)
Attached
The results
treatment
$ during rate
(urea
identical
0.36
total
efficiency
85-88
d,,yc.
the
experiment,
be achieved for
step
the
denitrification
with
30 days.
Suepended
treatment and
that
(Fig.8_1)
105 mg/l
h -I.
in
nitrate
and
100 ?L and
in
preceeding
could
The bio-oxidation
of
were
was run under
compared
mg N . g -’ ?ILSS
This
show
nitrogen
Biodegradation
the
than
efficiency
Denitrification
total
System
an R 1 fermentor
ammonia
12)
Growth
!&SS-h-l.
The YRT was more removal
for
and Urea
VLSS was 0.31
of
and ammonia
rate
Suspended
employed
( Fig.
121
of Wastewater
in
100 mg/l
a 19 day run
bio-oxidation
14.56
Treatment
- N
growth
O.j4@
g/l.
al-erage . g -l
Nitrification
rrite
i: Denitrification
with
the
step
urea
biodegradation
involved
ratio
to
feed
process
configuration and
a 4 1 fermentor rate
17
of
-1 . . 11
MISS
was attempted
denitrification,
system Fig.
was
2
:
1.
kas
M. S. Khalafawi
122
I . I
.
/
I I.
/J \ ) /
??
et a/.
1lWl’ =
!!,I
t1 I
tllt’l’
-
t’o
Ii
= = = =
MISS
t ttrr ‘I’emp. t1.0.
%.
0967
30
24.20
0.31
w/l
11
K/l
124
M. S. Khalafawi
ef al
i t
I
/ 4’ / I
Biological
Treatment
of Wastewater
12.5
126
M. S. Khalafawi
The that
results
of
the
efficiency
although
and
denitrification
the
high
the
of
ammonia
III an attached in
this
case
of
were
however,
contained
( Fig.
70 mg/l
not
17 ).
the
where
the
was
two
steady
thereby
16)
indicate
as may be
seen
by
effluent. times
state
100 74 ( 13th
nitrate-11
( Fig.
YBS 100 %, nitrification
satisfactory,
in
system,
and nitrification
treatment
bio-oxidation
and nitrate
growth
was used
growth
urea
efficiencies
levels
bio-oxidation
suspended
ef al.
more
biomass
efficiency
to
22nd
indicating
of
day).
than urea
The effluent,
ineffi&nt
denitrification. Three Step Treatment Denitrification. This the
process
for
treatment
the
ratio
treatment, of
eighth
:
2
\ILSS
tiring rate
. h -l.
dnd the
15 days for
the
is
Shotin
of
18)
2
ratio
denitrification
ammonia,
urrd
unlikel?
in
Table
dnd TS3. a biological
that
steady
the
( davs and
1.
during
Remora1 treatment
the
show of
q-24),
lhis
ereddy
a 99 -
TDS was not system.
at
and
the
seven
On the
the
methanol
step in
lasting
till
irate
period
100 Ci removal efficient,
in
22.47
resulted
days
a recycle
overall
) vas
post-denitrification 4 :
initial
efficiency
ammonia
a situation
results
treatment:
post-denitri-
satisfactory.
was introduced
(urea
to
data
during
state
the
of
(N)
was operated was not
step
day,
The
by employing
system
The sequence
100 5: denitrifitation
efficiency,
3.
gro*_th 3.
treatment
\tas raised
The performance in
and
biodegradation
efficiency
nitrogen
24th
Nitrification
: 1 was used.
indicate
trso step
in
of
total
On the
recpcle
in
( Fig.
resulted
8 -
and ammonia
denitrification
which
attached
Fig.
a post-denitrification
day,
oxidation
in
ratio
when the
1,
was doubled, system.
urea
A recycle
The results of
the
shown
(DN)
(DN).
Biodegradation.
involved
configuration
pre-denitrification fication
Urea
dose
the bio-
mg N . g *ds
the the
deleted treakdobn
i9rh
(days
day. 9 -
rffirienc?which
-1
is
24) for
not
Biological
Treatment
of Wastewater
. ,
0
1
M. S. Khal;ifaw
<‘Itrl.
Biological
Treatment
129
of Wastewater
5
88
m -
130
M. S. Khalafawi
Pcrform,;nce
Data
For
Integrated
( mg/l
\x
Biological
3
rrea SO
so:
)
Y.D.
S‘.D.
0.4
S.-n.
0.23 3.1
Turbidity
(SrC)
Eic?2
1.1
87
5.2
1.;
by.3
1.52
-12.1,
I.35
222
24.6
=
Y.D.
I’ot
detectable
of
Pollutant
Comparison
5.5 100
8.5
222
Cl
75.4
V.D.
@.Ol
Oil
;00
451
477
TSS
( ci )
19.7
0.3
160.3
12.6
TDS
Remora1 Efficiency
!mg/l)
100
ROD5
C>-stem
Effluent Concentration
Feed Concentration
parxneter
cl ui
Cl -31.3
32.3
Biodegradation
Rates
With
Data
Reported
In Literature. The in
the
rates
range
of
of
7 -
denitrification
in
The bio-oxidation ammonia 22.47 of
in
mg
these
Table
the
mg
the
range
rates
for
wastewater
N.
g -I
results
total
were
MISS
with
observed
during
NH - N. g -’ 3 of 3 - 7.3 mg nitrogen
from
. h -1
the
data
may be pointed
out
9 -
in
NO3 -
14 in
in
study
h -I
N.
for
MLSS
studies
studies.
h-l.
.
by urea
batch
the
were
and
g -I
contributed
continuous
reported
this
.
MLSS
and
and
17.9
-
A comparison
literature
is
shown
in
4. It
expressed and
nitrification
10.6
in
terms
of
denitrification
fication which
would
rates is
could
totally
the
fication nitrification
become
even to
of
the
rates
are rates
‘C.
observed
results the
higher. the
urea,
used
by the at
of
which
in
The
by other van’t
30 ‘C
of
any
nitrifying was set
investigators.
Hoff-Arrhenius are
not
unexpected.
of
nitrithe
other
generates
study
were
high
nature or
itself
study
nitrification
observed
specific this
this
rates
nitrogenous
with
temperature
normally
governed
the MLSS)
carbohydrates
was enriched
incubation
20-25
proteins,
except
biomass
the
if
attributed
substrates active
Furthermore, and not
be
devoid
biodegradable Thus,
that
MLVSS ( and not
ammonia. bacteria. at Since
law,
feed
easily
the
30 ‘C. nitrihigh
Biological
Quality
of
Treated
Effluent
The quality
of
biological
treatment
stantial the
effluent,
This
data
7.14
mg of
mgofT0 had
to
treated
( Table
reduction
in
there
alkalinity
is
3 be neutralized It
rates.
is
for
be required
for
acid
minimize
the
With
Bio-Oxidation
mg of 3.75
if
by
toial
three
there
pollution
nitrite
was a sub-
the
is
produced
boiler
OR -
biological
reclaimed
per
ions
oxidation
water
is
treatment
feed
(IDS).
produced,
The excess
a tertiary
in
solids
nitrogen
oprimum
step
pardmeters
dissolved
1980).
to
the
mg all-alinit>-
al.,
TDS level
to
be
step
bould
quality.
4
Of Pollutant Data
the
water,
131
although
maintain
that
feed
TABLE Comparison
et to
evident
as boiler
in
and
(Mivaji
therefore
that
and other
each
utilized
with
reuse to
urea
ltas no reduction
- X denitrified
produced
3 ) shows
since
of Wastewater
effluent
ammonia,
was expected
employed
Treatment
Reported
Biodegradation
Rates
In Literature.
Rate Source
(mg N . g -’ MLVSS . h-l unless otherwise stated)
vitrification 0.85
h’ong-Chong
1.07
Bridle
1.5
-
0.83 7.0
3.0 -
al
Bungaard
7.7
-
and Caruso
et
et
(1980) al.
(1980)
EPA (19i5)
8.8
(batch
16.6
(Pure
17.9
-
22.47
-
1.6
studies)
This
NH40H) *
Study
Rridle
(continuous
studies)
This
et
* al.
study
(1979)
*
Denitrification 1.22
Panzer
4 4.04 3 -
*
Rate
**
Total
et
al.
(1981)
EPA (1975) Yonteith 7.3
(batch
expressed l’Bj
studies)
as mg
and Urea-N
This
N . g -I oxidation
?ILSS rate
.
et
al.
study
h-l.
expressed
as *
(1980)
(1977)
132
M. S. Khalafawi et ul.
CONCLUSION
1.
The urea
effluent
of
from
significant
color,
oil
or
sustain
biological levels
plant
sludge
under
stages Kuwaiti
be more
identical
conditions.
Despite
than
ammonia
too
be
the
free turbidity,
and urea.
nutritionally of
unbalanced
this
essential
to
wastewarer
trace
metals
a prerequisite
from
inoculum
involving
for
the
local
with and
urea
for
the
municipal
-
treatment.
of
efficiencies biological
conventional
wastekater
biological
a combination
treatment
An attached than
in growth
suspended
aerobic
excess system
grokth
and of
99 9r
prored
s?-stem
under
conditions.
high
accomplish
solids,
denitrification.
obtained
accomplish
efficient
dissolved
to
and
treatment
could
experimental
5. cannot
appears
hydrolyzer
or
Supplementation
was a suitable
A biological
4.
to
donor)
the
relatively
is
it
of is
phosphate,
nitrification
Activated
anoxic
effluent
inorganic
(electron
treatment
other
out
as
suspended
activity. of
biodegradation,
3.
of
hydrolyzer
coming
wastewater,
compounds
toxic
optimum methanol
wastewater
a unique
amounts
This
2.
plants
PIC is
treatment
d reduction
efficiencies, in
the
the
dissolved
biological
solids
of
system file
II>-drol?-rrr
effluent.
It
h.
is
technically
of
PIC by resorting
of
Kuwait
for
and to
irrigation
or
to
feasible a total
produce a second
reno~afo
biological
a qualit>grade
to
of
the
hydro1!.7c’r
tretitment reclaimed
industrial
wdrer
water.
in
tile rh,~t
ef’fluc:nt
en\-ironment could
be used
REFERENCES
1ddms , (‘.E.
and W.W. Eckenfelder,
for
high
strength
Control Bridle,
T.R.,
Federation
D.C.
scale
W.K.
of
coke
12
:
Rungadrd,
Climenhage
Journal
T.R.,
D.
of
design
Journal
of
approach
Water
Pollution
413-21.
and A.
Stelzig.
Water
1979.
Operation
industrial
Pollution
and B.E.
Control
dank.
wastewaters.
Bangsbo
wastewater
and 0. from
International f‘nvironmental
1980.
Progress
Nitrogen
Hoybye.
rendering
Congress
Protection
for
Nitrification
of
waste
a full-
treatment
Federation
51:127-119
Biological
nitrogen
Water
Technology(Toronto)
in
control
667-80
E., of
1977.
denitrification
Bedford
plant
:
49
nitrification
plant, Bridle,
Jr.
ammonia wastewaters,
1980.
Adranced
plants.
Paper
on Wastewater,
Agency
Stockholm,
( FPA, VS.\). Office
Control,
biological
presented
1975.
treaiment at
3rd
February
Process
G-R
Design
%nual
of
Technology
Transfer,
hashington
coking
and coal
gasification
waste-
D.C. Luthy,
1981.
Treatment
waters.
Journal
R.
‘ii:-a j i , Y.,
M. Ivasaki
by step Yonteith,
M.D.,
Pi,n/er,
M.
in
combined
hong-(‘hong,
Komao*s~
wastewater stage
S.(‘. for
of
Pollution (‘aruso.
the
1980.
Senske.
rechnology
removal
12:195-202.
Industrial
baste
Progress
1977.
control
of
Industrial
Canada.
hastes
of
Improved
1981.
of
(‘control
Proceedings
reactor.
Services,
Sutton.
53:325-19.
nitrogen
denitrification.
,lnd G.E.
Water
and
fication
Water
nirrification,‘denitrificaTion
of
G.Y.
Biological
in
biological
Federation
in
Water
12:12:-141.
(‘.P.,
Journal
and P.M.
for
rontrol
1980.
Progress
Bridle
sources
Pollution
Sekigawa.
process.
T.R.
Technology
coal Water
and Y.
feed
carbon
of of
Federation
Biological nitrogen Biological horkshops,
performance
rannery
wste.
ii:lii4-39. oxidation
compounds
in
of
coke
pl,~nl
a single
Vitrification/llenitriI‘nrironmental
Protection
BIOLOGICAL
TREATMENT
FROM UREA
M.S.
Khalafawi**,
OF WASTEWATER
PLANTS
M.N.
OF
KUWAIT
El-Khawaga*,
and
H.S.
Pal**
ABSTRACT
A qualitative the
bydrolyzer
(PIC)
effluent
a routine
analysis
10 heavy
plant,
hydroll-zer
biological in
average were
growth, vas
studies
kere
and urea
the
hence
undertaken
or
urea
a
6-11 parameters
results.
ammonia
of
and urea
respectively.
removing
the in
The
urea
and ammonia
batch
sg-stem
vith
high
optimize
combined
sometimes
better
optimum
rates
than
levels
-
sustain of
of
Kinetic
denitrification
nitrification,
bio-oxidation the
to
efficiency.
nitrification
nitrogen
that
medium
treatment
The observed and
indicated
deficient
de-
rates
corresponding
Mere
rates
reported
literature.
be completely
retention j0
the
for
to
In a continuous could
in
su pplementation
biodegradation.
to
the
of
optimization
of
at
coupled
samples,
a set
of
130 mg/l,
was a nutritionally
urea
of
process
aimed
Company
systems.
a prerequisite
nitrifichtion, comparable
were
in
measurements
analysis despite
pollutants
wastewater
concentration
treatment
nutrients
of
100 and
studies
effluent
microbial
in
that
the
Biological
flow
determination
statistical
the
Industries
involved
and
and continuous
hjdrolyzer
the
effluent
of
Petrochemical
task
showed
treatment
batch
study
collection
for
metals,
The results hJ-drolyzer
the
This
and intensive
comprehensive
the
of
was uudert.aken.
with
and
and quantitative
time
of
biological
removed 20-24
from
hours
treatment the
system
hydrolyzer
and a solids
urea
and ammonia
effluent
retention
at
time
a h)-draulic
in
excess
days.
in
Ihe
average’concentrations
the
final
respectively;
the
*
Petrochemical
xy
Kuwait
effluent total
Institute
of
were dissolved
Industries for
0.3,
ammonia, 0.21,
solids Company,
Scientific
nitrite,
0.4 were
and 0.0
nitrate mg/l,
450 mg/l.
Kuwait. Research,
Kuwait.
and
of
104
M. S. Khalafawi
et cl/
INTRODUCTION
Petrochemical fertilizer Capital
complex
located
the
complex
city,
exploiting
Industries
the
The complex
Natural
capacity
of
3000
the in
1974,
MT/D,
2500
for
an effluent
to
a clean
keep
between to role in
the
be of
suitable
which
whenever
industrial
sector
significant
started
in
cooperation
utilizing
the
last
industrial
five
field
years
industrial of
in-plant
treatment
several
The
for
subject
of
in
the
cooperation
organizations
applied
this
to
limits
vater
the
programmes
specialists
solutions
paper
this
Researches
her
find
seems of
research
Scientific
to
abatement measures,
importance
of
scientists
the
course
the
with
authorities
abatement
of
strength
technologies
pollution
experience
KISR
problems.
pollution
academic
high
compliance
for
the
respectively.
generate
for
make use
one
total
400 MT/D,
steps
In this
Institute
with
know-how
PIC realizing
Kuwait
experience
to
and
role.
with
the
academic
and
production.
local
the
of
plants,
the
wastewater
possible.
oil
plant
by
the
object
no exception.Im
imposed
satisfies
Kuwait,
Urea
invariably
practicable
environment,
place
Acid
progressive
best
the
achieve
suitable
factories
of
of
three
Sulphuric
and PIC is
followed
a nitrogenous
the
a by-product
regulations
the
has
1965 vith
MT./D, 500 MT/D and
wastes,
PIC has
by implementing
),
50 Km. South in
is
one
fertilizer
discharge
searching
Shuaiba,
Ammonia plants,
and
nitrogenous
effluent
and
four
plant
Nitrogenous aqueous
at
( PIC
was started
Gas which
comprises
Ammonium Sulphate
Company
*as
(KISR) and
for
one
of
the
some these
prcgrammes. T t Of Lrea
Plants
The effluent 500 mgl-
ammonia
forestry
area,
the
In
1980
the
caused
caused
by the
the
first of
The resultant adding for urea.
extra
the
However,
that from
area the
decreasing
these system
are product
effluent during
due
180
‘C.
recycled
outlet operation
Sabahia in
ammoniacal population
adour there.
was commissioned
decompose
The hydrolyzer as per
loads
the
the
urea
in
reaction
following
reaction;
2NH3 + co*
---L
of
the
compounds
NH3 and COP. and at
the
nitrogenous to
to
as much as
to
progressing
hydrolyzer
into
originally
was sent
The high
in
gases
treated
at
+ H20
urea
It
a urea
18 Kg/cm*
NH2(CO)NH2
contained
urea.
Shuaiba.
complains
effluent
under
plants
mgl-
nuisance
step
addition
place
urea
10,000
several
wastewater
takes
outlet and
15 Km. North
effluent
which
Wastewater
to
about
the
urea
18 ton/d
hydrolyger these
limits
plants
to
in
average.
are
60 mgl-
were
not
be processed
again
The design ammonia always
and
limits 200 mgl-
achieved,
Biological
and due more of
to
the
increasing
strongly.
investigate
methods.
Although
compounds, the
most
proved this
the
there
study
the
of
1981
optimization
with
treating
as
and
several
project Research treatment
removing
nitrogenous
methods
reports
industrial et
study
of
quantitative
was undertaken,
as
have
it
is
conclusively
wastewaters
al;
1979;
routine
and and
intensive
four
after
the
a course
pollutant
work
by
Bridle
of
et
al.,
analysis
for
the
process
outlet
flor
urea
measurements
wastewater
samples
The wastewdter
respectively.
optimization
in of
loads
involved
collection
hours,
a comprehensive and
the-pollutants
meanwhile,
pollutants
to
for
treatment
Bridle
minimize
before
known
study
biological
1977;
of
subjected
by the
raised
levels
Scientific
nitrogenous
to
eight
them were
method,
assessment
of
parameters
methods
biological
was carried Ihis
were
and
effluent
intervals
the
research for
and urea
complains
these
).
A qualit,ative
roupled
several
( Adams and Eckenfelder,
Luthy,
plants.
are
the
suppress
Institute
ammonia
feasible
feasibility
hydrolyzer
of
selected
economically
method
1980;
removal
area,
to
A joint
was necessary. PIC and Kuwait
the
Sabahia step
between
105
of Wastewater
at
a further
compounds
was established to
popElation
Consequently
nitrogenous
Treatment
the
periods,
determinarion the
average
at
samples of
results
11 of
follows,
TABLE (
1
)
INTENSIVE ANALYSES FZSULTS OF HYDROLYZER WATER
Parameter
Post-Optimization
Pre-Optimization
PH
9.08
9.55
Na3
mg/l
187
10
Urea
mg/l
247
70
TDS
mg/1
475
61
COD
me/1
1200
BOD
mg/1
CN
mg/l
ND
ND
H2S TOC
mg/1
ND
ND
mg/l
92
23
25
SiO2
mg/l
3-D
ND
Oil
mg/l
ND
ND
ND
=
Not
detectable
However
the
pollutant
taken
before
and after
scope
of
nitrogenous
table
(2)
the
the
loads
process
loads
to
were
taken
optimization be considered
as
the
periods in
the
average to study
of
give as
90
more shown
readings wider in
106
et al.
M. S. Khalafawi
TABLE
( 2 )
ASSESSMENT OF POLLUTANTS IN ~DROLYZER
Period
Concentration
Pre-Optimization
(July,
( Nov.,
19P2
* Average
of
Cu,
hydrolyzer as
it
Load
t/day
Urea
NH3
Crea
342
437
0.56
0.71
109
129
0.16
0.20
90 readings
Fe,
from
routine
an intensive
Cr,
Ni,
effluent
is
/
)
Meanwhile Cd,
mg/l
NJ3
1982 )
Post-Optimization
for
\VAIER *
analysis
Mn, Pb,
is
originally
almost
steam
shift
for
MO, Zn,
totally
condensate
samples.
heavy
metals
and Mg and
deficient water
of
vas
carried
indicated all
that
these
introduced
to
elements
the
hydrolyzer
process. The assessment effluent
has
-
the
study
following
results
indicated
that
the
urea
hydrolyzer
characteristics.
Low concentrations
of
TSS,
CN, H2S,
SiO2,
Oil,
color
and
toxic
met,als. -
High
-
Unsuitable
-
Nutritionally
-
concentrations for
Requires metals
direct
supplementation for
are,
urea
biological
is
as
Crea
follows
and
and
TDS.
treatment
is
required.
effluent. with
inorganic
phosphorous
and
trace
nitrogenous
compounds
treatment.
processes
biodegradation,
A summary
respectively.
NH3, urea, reuse
unbalanced
The biological removal
of
of
the
encountered
in
nitrification reactions
and
involved
denitrification in
these
processes
processes
,
Biodegradation
co(NA2J2
+
2NH3
b
NO2
>
NO 3
+
co2
Nitrification %l4
+
NO2
+0.502
sH4
+
1.5
2
o2
O2
e
NO3
+
H20
+
2H +
+
2H +
+
H20
Biological
Treatment
107
of Wastewater
Denitrification NO3 + 0.33
NO3 + 0.83
CH3OH
~
0. 5N2 + 0.5C0,
three
batch
with
ammonia
experiments
factors
with
the
in
the
degrading
in
these
employed
for
fying of
bacteria
in
the the
and
Effect
activated
MLSS -
+ OH -
in
the
efficiency
the
hydrolyzer
was undertaken effluent
to
the
normally
of expected
to
Fig
activated
was usually
and the
8.80
results from
in
the
from
1.6
seed
indicate
was
required
an
Figure
acclimation
of
that
an initial
final
bacteria
when it
population.
on the
obtained
was efficient
observed
bacterial
The
sludge
plant
value
(1)
nitri-
the
rate
of
2.24
batch.
by the mg YO 3
same subculturing method -1 %” >k - h -I ,o - S - g
(2).
cultures
mentioned
above
serx-ed
as
seed
in
the
experiments.
at
30 ‘C.
to
85,
118,
mg NH3 - N -
that of
both
The concentration
treatment
experiment
rate
stage,
be nitrified
ponding 2.73
to
The study
that
specific
denitrifying
more
than
nitrification
concentration.
:
Nitrification
Nitrification studied
into
hydrolyzer
adjusted
subculturing
denitrification last
lag
sludge. by
h -I of
Of Ammoniaon
could
study
relative
actual
denitrification,
the
a typical
The acclimated folloring
time
enrich
Acclimation
were
indicated
improved
mg hH3 - N g-l
improT-ed
the
insight
nutrients.
wastewater
of
for
the
inorganic
two media
gain above
processes.
with
municipal
to
results
nitrification
3.16
in
+ 1. 167H20
effluent.
nitrification
the
to
mentioned
or
A distinct
period
highlits
designed
experiments
local
urea.
acclimation
adopted
+ irH-
systems.
these
missing
hyrdolyzer
Ardyia
were
medium
Preliminary from
were
CO2 + 0.5H20
:-
affecting
the
and urea in
steps continuous
processes
a synthetic
supplemented
in
studies
biological
and the
levels
and
N2 + 0.5
WORK
These
water
biological
studies
three
either
H20
)
Static
the
+ 0.67
CH3OH
EXPERIMENTAL
of
NO2
NO2 + 0.5
batch
1.
,
0.5
These static
CH30H
rates
at
different
The results
(Fig.
rithin
40 hrs.
24 -
li15, g -’
118 mg/l under
and
227
MLSS -
test
mg/l
h -’
ammonia the
3)
,
exert
concentrations shokrd
that
85 -
The ni:rifica;ion ammonia
kerc
respectirely.
of
;Immoni,l kere
115 me/l ra:es,
7.OLi. Thus,
an inhibitor>-
conditions
of
5.35,2,7 it
influence
temperature
tan on
dtnd be roncludc,d the
tind biomass
rate
108
r
Fig
( 2
)
Il.
Srcond
Iknilrification
Time
48
( h )
72
culture
Subculture
in batch
96
in synthetic
0
\
h
y=j
\
*
48
*\-
.
'Time ( h )
24
.
medium at, ‘IO ‘C.
‘;-r 72
200
XJO
0
_ 100
-
.
400
M. S. Khalafawi
Fig.
( 3 ) Sitrification
Rates
et al.
of
Different
\Hj Concentrations
240
220
180
160
<
140
E” i
120
9 c z 100
80
60
40
20
0
. 8
16
24 Time
32 ( hours
)
40
48
56
Biological
Effect
Of Urea
OnNitrification
The results could
be
KLSS 9.4
degraded
g -I
rate
was 7.9
urea
in
Effect
the of
medium has
-1
g
delayed
temperatures,
15,
and
the
total
hence
it
was concluded
and urea
biodegradation.
Effect
KLSS -
Nitrification
MISS -
h -’
respectively.
conentration the
as ammonia,
same with
PO4 is and Effect
of
medium
also
for
could
Nitrate
per
respectively.
of
urea -1 g
rate
was
Biodegradation
studied
(
and
at
Fig.
13.56
at
15, is
30 and
the
with
alone
6.34
Hovever,
when urea of
rates
g -I
were
6.43,
the
and
for
nitrification
same with
was introduced
biodegradation
- urea
14.0
respectively,
mg/r;H3 - N -
can
urea
MLSS- h-l
:-
were
It
that
N -
temperature
and 6.55
urea
different
-
Biodegradation
ammonia
:-
5 ) indicate
40 ‘C.
optimum
and were
rates
three
mg urea
and NfI3 - N ) removal
nitrification
On Denitrification
received
of
nitrate
methanol
mg NO - N. 3 in
be denitrified
denitrification
- N -
be
PO4
g -’
wit,h were
found
concluded
that
biodegradation
of
-
the
same to
be
2 mg/l
100 mg/l
3x3
urea.
Two levels
methanol
were
PO4 conentrations. the
104 mg/l
mg urea
process.
and Urea
and Urea
the
different
required
100 mg/l
nitrification
30 ‘C.
rates
2 and 6 mg/l
8.66
and NH3 - N ) removal
17.95,
h -’
that
that
of
The results
7.51,
Of PO4 On Nitrification
concentration
( urea
the
( urea
g -’
III
For ammonia alone, however, the nitrification _ h -1 This means that the presence of .
45 ‘C.
were
nitrogen
mg N -
a rate
processes
30 and
rates
and 7.88
4 ) indicate at
on Nitrification
The two biological
biodegradation
(Fig.
h -l.
mg NE3 - N -
Temperature
in
16 hours nitrogen
MLSS -
of Wastewater
:-
shown within
The total
h -l.
mg N -
Treatment
rates
were
:were
as
The results 25 hours, 5.95
tested
electron
(
( Fig. but
and 7.34
165
donor
and 265 mg/l). in
6 ) shows
265 mg/l
The
a concentration that
165 mg/l
NO3 needed
33 hours.
mg NO3 - N -
g -I
XLSS -
salt
of
3 mg NO3
h -’
The
112
M. S. Khalafawi
er al.
< N
. c_
-
z
T
( I,%
)
iH';
0
12 Time
.
( h )
36
my/l
Concentration
24
mg/l
Urea Concentration
A N0-5
mg/l
Concentration
0
Time
40
Temp.
24
0.71
MLSS
and urea biodegradation
Ml3
on niLrification
0
Fig.(T) Kffrrt of tcmpclr;lI.ure
g/l
( h )
4x
Oc.
72
1
x s m R
k20
0
70
140
210
280
350
490
-= kY -
560
630 -
114
M. S. Khalafawi
Effect
Of Temperature
On Denitrification
Denitrification results
( Fig.
here
7)
g -1
NO3 - N -
we find Of PO,
on the
denitrification
best
showed
plant
conditions,
phosphate
and
of
denitrification
rates of
successive
of
substrate
indicating
the
experiments
Effect
of
Fig.(ll) at
20 h,
urea
the
was reduced increased
to
rates
16 h
BRT
g -’
MLSS .
were
that
for
the
in
each
the
Fig.
feed.
8.
The results and
The observed
increase
successive
nitrifying
Process
biodegradation
respectively.
cultures
up to
efficiences
the
twelvth
Thus,
under
in
batch
the
rate
thereby
and denitrifying served
On the
effluent day
the
total
as
the
seed
in
concentration
the of
(urea
and
urea the
HRT was maintained
however,
than
was an HRT of 30 days.
removal 22.4
HRT
progressively
concentration
ammonia) -1 and MLSS . h
) and
when the
experiment,
was more
:-
( 100 mg/l
ammonia
SRT value
g -’
when the
ammonia day,
whereas
mg NH3 - N. respectively.
days, for
Removal
seventh
conditions
nitrogen
Of Nitrogen
six
observed
The estimated
17.9
shown
to
simulate
supplemental
into
and urea
Time On Rate
the
h-l,
feed,
to
below.
16 hours,
for
as
a progressive in
of
1CO v/c.
20 h was desirable. oxidation
the
designed
In order
& IO ),
acclimated
) were
up to
undetectable.
are
Figs.(9
These
shows
( 160 mg/l
study
enrichment
Retention
removal
PO4 is
essentially
incorporated
demonstrate
described
Hydraulic
was used
denitrification
a stepwise
were
nitrification
in
concentrations
6 mg/l
that
experiments.
were the
of
shown
populations.
mg
Again,
temperature.
PO4 different
studies
batch
during
removal and
4.14
:-
effluent
batches
nitrification
bacterial
in
nutrients
are
and
The
conditions.
continuous
employed
three
of
System
hydrolyzer
configurations of
4.32,
respectively.
NO3 indicated
test
obtained
inorganic
1.19,
45 ‘C.
denitrification
effect
325 mg/l the
scale
results
were
optimum
15, 30 and 45 ‘C.
at
:-
On Continuous
The bench the
30 and
the
of under
Studies
confirm
rates
15,
the
testing
,
30 ‘C
studied
the
On Denitrification
concentration
2.
at
is
:-
were
that
h -1
30 ‘C.
Effect
At
rates
NJSS -
that
et NI.
at
Bio-
20 and
mg Total-
N
Biological Treatment
of Wastewater
115
116
M. S. Khalafawi et cd.
/
/
1
-
Biological
Process
Fig.(s)
Vitrification
or Reactor
A -
Treatment
of Wastewater
configurations
denitrification
Vitrification
or
Denitrification
Process.
Alkali
Feed
Denitrificdtion
Sludge
El - Nirrification
Recycle
- Drnitrifichrisn
Pr,~rr;s
I It;
Biological
Treatment
of Wastewater
119
M. S. Khalafawi PI NI
.
I. .i ./
.I
.I \. ./ . . \
Biological
Nitrification This and
salt
Biodegradation
one
treatment
of
efficiencies the
and Urea
medium
The results
step
containing
for
urea
mg N . g -I
Vitrification
with
the
Parallel
to
Captor
sponges g/l
rate -
one
stage
one
day
to
Ihe
!8.47
mg
run at
sha..s
similar
at
Treatment This
shohn
in
nitrification employed.
Fig
in
Growth
and
removal
was
System growth
( Fig.
growth
13 ) show
as rell
system
The average
suspended
(urea
system.
that
as for
a 100%
ammonia.
and ammonia
) was 21.26
days
steady
.
Growth
state
Urea
the
g/l.
a reactor
contained
( Fig.
incretse
14)
from
treatment.
steady -1 h .
of
141-354 shows
66 s
*as
the
mg/l
that
on the
calculated
atrached of
nirrhte.
lhe
mg NO
3
Biodegradation,
recycle
the
the second
The SHT exceeded
state
conditions,
was 2j.l
The aerobic
using
50
to
be
System
removal
treatment
liquor
in
KLSS concentration
a 14 1 fermentogfor
The mixed
out
at
experimental
for
2.
to
of
PlL-‘S
the
:-
The feed
was 0.32
equilibruim in
combined 8 -
respectively,
an attached
the
was carried
commenced
Attached
100 $ efficiency
Tuo Step
85 ‘$,
urea.
treatment
conditions.
urea
System
( Fig.8_1).
12-19
an dverage
denirrification
in
for
Growth
YES
. g -’
in
g/l
nitrogen
denirrification
NOj - ?j
Using iias
system average
of
Denitrification
of
average
and ammonia)
Attached
The results
treatment
$ during rate
(urea
identical
0.36
total
efficiency
85-88
d,,yc.
the
experiment,
be achieved for
step
the
denitrification
with
30 days.
Suepended
treatment and
that
(Fig.8_1)
105 mg/l
h -I.
in
nitrate
and
100 ?L and
in
preceeding
could
The bio-oxidation
of
were
was run under
compared
mg N . g -’ ?ILSS
This
show
nitrogen
Biodegradation
the
than
efficiency
Denitrification
total
System
an R 1 fermentor
ammonia
12)
Growth
!&SS-h-l.
The YRT was more removal
for
and Urea
VLSS was 0.31
of
and ammonia
rate
Suspended
employed
( Fig.
121
of Wastewater
in
100 mg/l
a 19 day run
bio-oxidation
14.56
Treatment
- N
growth
O.j4@
g/l.
al-erage . g -l
Nitrification
rrite
i: Denitrification
with
the
step
urea
biodegradation
involved
ratio
to
feed
process
configuration and
a 4 1 fermentor rate
17
of
-1 . . 11
MISS
was attempted
denitrification,
system Fig.
was
2
:
1.
kas
M. S. Khalafawi
122
I . I
.
/
I I.
/J \ ) /
??
et a/.
1lWl’ =
!!,I
t1 I
tllt’l’
-
t’o
Ii
= = = =
MISS
t ttrr ‘I’emp. t1.0.
%.
0967
30
24.20
0.31
w/l
11
K/l
124
M. S. Khalafawi
ef al
i t
I
/ 4’ / I
Biological
Treatment
of Wastewater
12.5
126
M. S. Khalafawi
The that
results
of
the
efficiency
although
and
denitrification
the
high
the
of
ammonia
III an attached in
this
case
of
were
however,
contained
( Fig.
70 mg/l
not
17 ).
the
where
the
was
two
steady
thereby
16)
indicate
as may be
seen
by
effluent. times
state
100 74 ( 13th
nitrate-11
( Fig.
YBS 100 %, nitrification
satisfactory,
in
system,
and nitrification
treatment
bio-oxidation
and nitrate
growth
was used
growth
urea
efficiencies
levels
bio-oxidation
suspended
ef al.
more
biomass
efficiency
to
22nd
indicating
of
day).
than urea
The effluent,
ineffi&nt
denitrification. Three Step Treatment Denitrification. This the
process
for
treatment
the
ratio
treatment, of
eighth
:
2
\ILSS
tiring rate
. h -l.
dnd the
15 days for
the
is
Shotin
of
18)
2
ratio
denitrification
ammonia,
urrd
unlikel?
in
Table
dnd TS3. a biological
that
steady
the
( davs and
1.
during
Remora1 treatment
the
show of
q-24),
lhis
ereddy
a 99 -
TDS was not system.
at
and
the
seven
On the
the
methanol
step in
lasting
till
irate
period
100 Ci removal efficient,
in
22.47
resulted
days
a recycle
overall
) vas
post-denitrification 4 :
initial
efficiency
ammonia
a situation
results
treatment:
post-denitri-
satisfactory.
was introduced
(urea
to
data
during
state
the
of
(N)
was operated was not
step
day,
The
by employing
system
The sequence
100 5: denitrifitation
efficiency,
3.
gro*_th 3.
treatment
\tas raised
The performance in
and
biodegradation
efficiency
nitrogen
24th
Nitrification
: 1 was used.
indicate
trso step
in
of
total
On the
recpcle
in
( Fig.
resulted
8 -
and ammonia
denitrification
which
attached
Fig.
a post-denitrification
day,
oxidation
in
ratio
when the
1,
was doubled, system.
urea
A recycle
The results of
the
shown
(DN)
(DN).
Biodegradation.
involved
configuration
pre-denitrification fication
Urea
dose
the bio-
mg N . g *ds
the the
deleted treakdobn
i9rh
(days
day. 9 -
rffirienc?which
-1
is
24) for
not
Biological
Treatment
of Wastewater
. ,
0
1
M. S. Khal;ifaw
<‘Itrl.
Biological
Treatment
129
of Wastewater
5
88
m -
130
M. S. Khalafawi
Pcrform,;nce
Data
For
Integrated
( mg/l
\x
Biological
3
rrea SO
so:
)
Y.D.
S‘.D.
0.4
S.-n.
0.23 3.1
Turbidity
(SrC)
Eic?2
1.1
87
5.2
1.;
by.3
1.52
-12.1,
I.35
222
24.6
=
Y.D.
I’ot
detectable
of
Pollutant
Comparison
5.5 100
8.5
222
Cl
75.4
V.D.
@.Ol
Oil
;00
451
477
TSS
( ci )
19.7
0.3
160.3
12.6
TDS
Remora1 Efficiency
!mg/l)
100
ROD5
C>-stem
Effluent Concentration
Feed Concentration
parxneter
cl ui
Cl -31.3
32.3
Biodegradation
Rates
With
Data
Reported
In Literature. The in
the
rates
range
of
of
7 -
denitrification
in
The bio-oxidation ammonia 22.47 of
in
mg
these
Table
the
mg
the
range
rates
for
wastewater
N.
g -I
results
total
were
MISS
with
observed
during
NH - N. g -’ 3 of 3 - 7.3 mg nitrogen
from
. h -1
the
data
may be pointed
out
9 -
in
NO3 -
14 in
in
study
h -I
N.
for
MLSS
studies
studies.
h-l.
.
by urea
batch
the
were
and
g -I
contributed
continuous
reported
this
.
MLSS
and
and
17.9
-
A comparison
literature
is
shown
in
4. It
expressed and
nitrification
10.6
in
terms
of
denitrification
fication which
would
rates is
could
totally
the
fication nitrification
become
even to
of
the
rates
are rates
‘C.
observed
results the
higher. the
urea,
used
by the at
of
which
in
The
by other van’t
30 ‘C
of
any
nitrifying was set
investigators.
Hoff-Arrhenius are
not
unexpected.
of
nitrithe
other
generates
study
were
high
nature or
itself
study
nitrification
observed
specific this
this
rates
nitrogenous
with
temperature
normally
governed
the MLSS)
carbohydrates
was enriched
incubation
20-25
proteins,
except
biomass
the
if
attributed
substrates active
Furthermore, and not
be
devoid
biodegradable Thus,
that
MLVSS ( and not
ammonia. bacteria. at Since
law,
feed
easily
the
30 ‘C. nitrihigh
Biological
Quality
of
Treated
Effluent
The quality
of
biological
treatment
stantial the
effluent,
This
data
7.14
mg of
mgofT0 had
to
treated
( Table
reduction
in
there
alkalinity
is
3 be neutralized It
rates.
is
for
be required
for
acid
minimize
the
With
Bio-Oxidation
mg of 3.75
if
by
toial
three
there
pollution
nitrite
was a sub-
the
is
produced
boiler
OR -
biological
reclaimed
per
ions
oxidation
water
is
treatment
feed
(IDS).
produced,
The excess
a tertiary
in
solids
nitrogen
oprimum
step
pardmeters
dissolved
1980).
to
the
mg all-alinit>-
al.,
TDS level
to
be
step
bould
quality.
4
Of Pollutant Data
the
water,
131
although
maintain
that
feed
TABLE Comparison
et to
evident
as boiler
in
and
(Mivaji
therefore
that
and other
each
utilized
with
reuse to
urea
ltas no reduction
- X denitrified
produced
3 ) shows
since
of Wastewater
effluent
ammonia,
was expected
employed
Treatment
Reported
Biodegradation
Rates
In Literature.
Rate Source
(mg N . g -’ MLVSS . h-l unless otherwise stated)
vitrification 0.85
h’ong-Chong
1.07
Bridle
1.5
-
0.83 7.0
3.0 -
al
Bungaard
7.7
-
and Caruso
et
et
(1980) al.
(1980)
EPA (19i5)
8.8
(batch
16.6
(Pure
17.9
-
22.47
-
1.6
studies)
This
NH40H) *
Study
Rridle
(continuous
studies)
This
et
* al.
study
(1979)
*
Denitrification 1.22
Panzer
4 4.04 3 -
*
Rate
**
Total
et
al.
(1981)
EPA (1975) Yonteith 7.3
(batch
expressed l’Bj
studies)
as mg
and Urea-N
This
N . g -I oxidation
?ILSS rate
.
et
al.
study
h-l.
expressed
as *
(1980)
(1977)
132
M. S. Khalafawi et ul.
CONCLUSION
1.
The urea
effluent
of
from
significant
color,
oil
or
sustain
biological levels
plant
sludge
under
stages Kuwaiti
be more
identical
conditions.
Despite
than
ammonia
too
be
the
free turbidity,
and urea.
nutritionally of
unbalanced
this
essential
to
wastewarer
trace
metals
a prerequisite
from
inoculum
involving
for
the
local
with and
urea
for
the
municipal
-
treatment.
of
efficiencies biological
conventional
wastekater
biological
a combination
treatment
An attached than
in growth
suspended
aerobic
excess system
grokth
and of
99 9r
prored
s?-stem
under
conditions.
high
accomplish
solids,
denitrification.
obtained
accomplish
efficient
dissolved
to
and
treatment
could
experimental
5. cannot
appears
hydrolyzer
or
Supplementation
was a suitable
A biological
4.
to
donor)
the
relatively
is
it
of is
phosphate,
nitrification
Activated
anoxic
effluent
inorganic
(electron
treatment
other
out
as
suspended
activity. of
biodegradation,
3.
of
hydrolyzer
coming
wastewater,
compounds
toxic
optimum methanol
wastewater
a unique
amounts
This
2.
plants
PIC is
treatment
d reduction
efficiencies, in
the
the
dissolved
biological
solids
of
system file
II>-drol?-rrr
effluent.
It
h.
is
technically
of
PIC by resorting
of
Kuwait
for
and to
irrigation
or
to
feasible a total
produce a second
reno~afo
biological
a qualit>grade
to
of
the
hydro1!.7c’r
tretitment reclaimed
industrial
wdrer
water.
in
tile rh,~t
ef’fluc:nt
en\-ironment could
be used
REFERENCES
1ddms , (‘.E.
and W.W. Eckenfelder,
for
high
strength
Control Bridle,
T.R.,
Federation
D.C.
scale
W.K.
of
coke
12
:
Rungadrd,
Climenhage
Journal
T.R.,
D.
of
design
Journal
of
approach
Water
Pollution
413-21.
and A.
Stelzig.
Water
1979.
Operation
industrial
Pollution
and B.E.
Control
dank.
wastewaters.
Bangsbo
wastewater
and 0. from
International f‘nvironmental
1980.
Progress
Nitrogen
Hoybye.
rendering
Congress
Protection
for
Nitrification
of
waste
a full-
treatment
Federation
51:127-119
Biological
nitrogen
Water
Technology(Toronto)
in
control
667-80
E., of
1977.
denitrification
Bedford
plant
:
49
nitrification
plant, Bridle,
Jr.
ammonia wastewaters,
1980.
Adranced
plants.
Paper
on Wastewater,
Agency
Stockholm,
( FPA, VS.\). Office
Control,
biological
presented
1975.
treaiment at
3rd
February
Process
G-R
Design
%nual
of
Technology
Transfer,
hashington
coking
and coal
gasification
waste-
D.C. Luthy,
1981.
Treatment
waters.
Journal
R.
‘ii:-a j i , Y.,
M. Ivasaki
by step Yonteith,
M.D.,
Pi,n/er,
M.
in
combined
hong-(‘hong,
Komao*s~
wastewater stage
S.(‘. for
of
Pollution (‘aruso.
the
1980.
Senske.
rechnology
removal
12:195-202.
Industrial
baste
Progress
1977.
control
of
Industrial
Canada.
hastes
of
Improved
1981.
of
(‘control
Proceedings
reactor.
Services,
Sutton.
53:325-19.
nitrogen
denitrification.
,lnd G.E.
Water
and
fication
Water
nirrification,‘denitrificaTion
of
G.Y.
Biological
in
biological
Federation
in
Water
12:12:-141.
(‘.P.,
Journal
and P.M.
for
rontrol
1980.
Progress
Bridle
sources
Pollution
Sekigawa.
process.
T.R.
Technology
coal Water
and Y.
feed
carbon
of of
Federation
Biological nitrogen Biological horkshops,
performance
rannery
wste.
ii:lii4-39. oxidation
compounds
in
of
coke
pl,~nl
a single
Vitrification/llenitriI‘nrironmental
Protection