Evaluation of Anaerobic digestion by Influent of Ammonia Nitrogen Concentration and Nitrogen Loading
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Transcript of Evaluation of Anaerobic digestion by Influent of Ammonia Nitrogen Concentration and Nitrogen Loading
Evaluation of Anaerobic digestion by Influent of Ammonia Nitrogen
Concentration and Nitrogen Loading Rate
Park Hyun Chul • Kim Sung Jin • Oh Yong Keol • Park Chul Hwi
University of Seoul
Background
2
3
Food Waste Water(Leachate) ?
Water(wash water, settling water) that is produced by course of the
treatment and recycling of food waste or part of food waste.
separate discharge
Food waste water
HOME Food
Waste tank
Particle
Dumping / Incineration
Breaking food
waste
Settling water
Food waste water
Steam condensate
water
Dewatering Dryer
Composting
Ocean Dumping
Prohibit London Dumping
Convention
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Food Waste Water(Leachate) ?
Anaerobic digestion
Dumping of food waste water is prohibited by London Dumping
Convention , anaerobic digestion is in the limelight for land treatment.
Anaerobic digestion produce sludge smaller than aerobic treatment, also
it can produce methane from organic matter.
It produced approximately 9,000 ton per day, concentration of BOD is
about 74,000 mg/L.
The cost of food waste water treatment is high because concentration of
organic matter is too high.
Thus, an average of approximately 5,000 tons per day or more was
dumping at sea.
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Anaerobic digestion using food waste water
For efficient and reliable operation of anaerobic digestion, it is
important that operater maintain the operating conditions.
Operating factors are pH, temperature, alkalinity, ammonia
nitrogen, etc., and each has a deep relevance.
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Anaerobic digestion using food waste water
For efficient and reliable operation of anaerobic digestion,
anaerobic digestion need to maintain the appropriate
concentration of ammonia nitrogen.
NH4+-N Concentration Effects
50~200 mg/L Beneficial
200~1,000 mg/L No adverse effect
1,500~3,000 mg/L Inhibitory at high pH value
Above 3,000 mg/L Toxic
• Anaerobic digestion is reduction process that convert organic nitrogen to
ammonia nitrogen.
• In anaerobic digestion, the accumulation of ammonia nitrogen is inevitable.
• In anaerobic digestion, food waste water which containing high concentrations of
organic matter and nitrogen much more convert organic matter and nitrogen to
ammonia nitrogen than sludge
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Anaerobic digestion using food waste water
Optimal concentration of ammonia nitrogen can lead to maintain
alkalinity and pH
• When concentration of ammonia nitrogen is high in digester, ammonia
combines with carbon dioxide to generate HCO3- and NH4
+. Accordingly, pH
increase due to alkalinity supplement.
NH3 + H2O + CO2 -> NH4+ + HCO3
-
In anaerobic digestion, the accumulation of ammonia
nitrogen is inevitable.
In order to maintain the concentration of ammonia nitrogen,
process is required which means removal and maintaince of
ammonia nitrogen.
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Anaerobic digestion using food waste water
In this study, for stable operation of the anaerobic digestion
using food waste water, operational characteristics were
investigated by nitrogen loading rate.
• In order to investigate the behavior of the ammonia
nitrogen, anaerobic digestion is studied without feed.
• Investigation of behavior of ammonia nitrogen by
nitrogen loading rate.
• To maintain the appropriate concentration of ammonia
nitrogen, the experiment of anaerobic digestion using
watering and sludge recirculation process was conducted.
Materials & Method
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Characteristics of food wastewater (S landfill food wastewater) Items Unit Value
pH - 3.9
TS % 11.5
VS % 9.1
TCODcr mg/L 182,642
SCODcr mg/L 99,119
T-N mg/L 3,583
NH4+-N mg/L 528
Items Unit Value
pH - 7.44
TS % 2.1
VS % 1.34
SCODcr mg/L 886.1
T-N mg/L 1,505
NH4+-N mg/L 451
VFAs mg/L 138.2
Alkalinity mg/L as CaCO3
2,404
Characteristics of seed sludge (N sewage treatment plat digestion sludge)
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Schematic diagram of anaerobic digestion process
System Single anaerobic digestion
Total volume Anaerobic digestion(35L), Gas storage(50L)
Temperature 35◦C , mesophilic
Substrate S landfill food wastewater
Seeding sludge N sewage treatment plant digestion sludge
System of experiment
Gas collector
Gas collector
Gas collector
Food waste water tank
R2 R3 R4 R1
Gas collector
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The experiments were carried out with two different operating conditions. 1. Test of no loading
• Without feed, it is conducted test to investigate about change concentration of ammonia nitrogen during 30 days
2. Test of loading
• The investigation of behavior of ammonia nitrogen by nitrogen loading
rate.
• To maintain the appropriate concentration of ammonia nitrogen, the
experiment of anaerobic digestion using watering and sludge recirculation
process was conducted.
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Watering and sludge recirculation process(R1)
Condition Purpose Solution
Case 1 ․ NH4
+-N 700mg/L ≤ R1
․ TS 2.2% ≤ R1
․ TS and NH4+-N
control
· effluent digested sludge
(3L) and replace DW (3L).
Case 2 ․ NH4
+-N 700mg/L ≤ R1
․ TS 1.9~2.2%
․ NH4+-N
control
Centrifuge 1L digested sludge for
5min.
Pour off supernatant and replace DW.
Case 3 ․ NH4
+-N 700mg/L
․ TS 2.2% ≤ R1
․ TS
control
· Stop mixing and concentrating
digester.
Effluent concentrated digester.
Items R1(control) R2 R3 R4
Nitrogen Loading rate
(NLR, kg N/m3•d)
0.075 0.075 0.15 0.3
SRT (d) HRT
70 70 35 17.5
Internal TS control (%) 1.9~2.2 - - -
NH4+-N control (mg/L) 500 - - -
VFAs control (mg/L) 300 - - -
Condition of experiment
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Gas collector
Sedimentation and
stabilization
Treated water
WWTP
River
Q : 500 mL
Qe : 1,500 mL
Qe’ : 1,200 mL Qw : 300 mL
Qr : 1,000 mL (300+700)
Qx : 700 mL
Results & Discussion
15
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Time (Day)
0 5 10 15 20 25 30 35
Concentr
ation (
mg
/L)
200
400
600
800
1000
1200
1400
1600
T-N
NH4+-N
NH
4+
-N/T
-N (
%)
0
20
40
60
80
100
NH4+-N/T-N
Nitrogen was decreased slightly
Ammonia nitrogen was increased from 451 mg/L to 1,060 mg/L
Alkalinity and pH was increased 4,800 mg/L and 7.9 respectively.
Time (Day)
0 5 10 15 20 25 30 35
Alk
alinity(m
g/L
as C
aC
O3)
2000
2500
3000
3500
4000
4500
5000
Alkalinity
pH
7.0
7.5
8.0
8.5
9.0
pH
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Time(Day)
0 5 10 15 20 25 30 35
Co
nce
ntr
atio
n (
%)
1.0
1.2
1.4
1.6
1.8
2.0
2.2
TS
VS
VS
/TS
(%
)
40
50
60
70
80
VS/TS
Time (Day)
0 5 10 15 20 25 30 35
VF
A c
on
ce
ntr
atio
n (
mg/L
)
0
20
40
60
80
100
120
140
160
180
VFA
Accu
mu
lative
bio
ga
s p
rod
uctio
n(L
)
2
3
4
5
6
7
Biogas production
Concentration of TS and VS was decreased from 2.1 ~ 1.8 and 1.4 ~ 1.1
respectively
VS/TS ratio was decreased from 65% to 50%
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Time(Day)
0 50 100 150 200 250
Concentr
ation o
f N
H4+
-N (
mg/L
)
0
500
1000
1500
2000
2500
R1
R2
R3
R4
NLR
(kg N
/m3/d
)
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
NLR(R4)NLR(R3)NLR(R1 R2)
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Time(Day)
0 50 100 150 200 250
pH
5.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
R1
R2
R3
R4
NLR
(kg N
/m3
/d)
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
NLR(R3)NLR(R2)
NLR(R1)
NLR
(kg N
/m3
/d)
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
NLR(R3)NLR(R2)NLR(R1)
Time(DAY)
0 50 100 150 200 250
HC
O3- ,
Alk
alinity (
mg/L
as C
aC
O3)
0
2000
4000
6000
8000
10000
12000
14000
R1
R2
R3
R4
pH was increased consequently during experiment due to increasing of
ammonia nitrogen and it leads to increase of alkalinity
Bicarbonate alkalinity and pH was increased in proportion to nitrogen loading
rate.
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Time(Day)
0 50 100 150 200 250
VF
As (
mg/L
)
0
500
1000
1500
2000
2500
3000
3500
4000
6000
8000
R1
R2
R3
R4
NLR
(kg N
/m3/d
)
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
NLR(R4)NLR(R3)
NLR(R1 R2)
Time(Day)
0 50 100 150 200 250
SC
OD
cr
0
500
1000
1500
2000
4000
6000
8000
10000
12000
R1
R2
R3
R4 NLR
(kg N
/m3
/d)
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
NLR(R4)NLR(R3)NLR(R1 R2)
The difference in speed between acidogenesis and methanogenesis occurred
and then VFA was accumulated.
The tendency of SCODCr is similar to VFAs
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Time(Day)
0 50 100 150 200 250
VS
(%
)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
8.0
10.0
R1
R2
R3
R4
Feedstock
NL
R (
kg N
/m3
/d)
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
NLR(R4)
NLR(R3)
NLR(R1 R2)
NLR
(kg
N/m
3/d
)
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
NLR(R4)NLR(R3)
NLR(R1, R2)
Time(Day)
0 50 100 150 200 250
TS
(%
)
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
8.0
10.0
12.0
R1
R2
R3
R4
Feedstock
TS and VS increased gradually except R1
Excessive increasing of TS and VS inhibits microorganism activity
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Time(Day)
0 50 100 150 200 250
Bio
gas y
ield
(m
3/k
g V
Sre
mo
ve
d)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
R1
R2
R3
R4
NLR
(kg N
/m3/d
)
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
NLR(R4)NLR(R3)NLR(R1 R2)
Time(Day)
0 50 100 150 200 250
VS
re
du
ctio
n (
%)
0.75
0.80
0.85
0.90
0.95
R1
R2
R3
R4
NL
R (
kg N
/m3/d
)
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
NLR(R3)NLR(R2)NLR(R1)
R1,R2 biogas yield was 1.0~1.2 and 0.9~1.1 respectively.
Biogas yield of R2 was not decreased in spite of accumulated VFAs.
VS reduction in R1 is higher than R2
Thank you
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