Swine wastewater treatment technology to reduce nitrous ... - T. Yamashita.pdf · Swine wastewater...
Transcript of Swine wastewater treatment technology to reduce nitrous ... - T. Yamashita.pdf · Swine wastewater...
National Agriculture
and Food Research Organization
Food and Agriculture for the Future
Swine wastewater treatment technology to reduce
nitrous oxide emission by using an aerobic
bioreactor packed with carbon fibres
NARO Institute of Livestock and Grassland Science
Animal Waste Management and Environment Division
Senior Researcher
Takahiro Yamashita
Outline
Current state of manure management in Japan・Amount of livestock waste
・Effluent regulations
・Amount of greenhouse gas emissions
・N2O generation from wastewater treatment processes
Objective
Development of technology that can reduce N2O
generated from wastewater treatment processes
「Swine wastewater treatment technology using an aerobic bioreactor packed with carbon fibers to reduce nitrous oxide emissions」-new technology for reducing N2O emissions-
Livestock (pig, cattle, chicken)
Reference:Guidelines for the treatment and use of livestock manure
(Livestock Industry’s Environmental Improvement Organization)
Urine
Feces
13.4 L/head/day
0.13 kg/head/day
45.5 kg/head/day
Feces
Urine
3.8 L/head/day
2.1 kg/head/day
Feces
Urine purified in
treatment
Manure compost
Feces
Urine
Total manure: over
80,000,000 t / year
Soil as fertilizer
Purified water is discharged into rivers and other water bodies
The discharge of such water is
governed by several regulations
Water Quality Pollution Control Act
The wastewater from livestock farms negatively affects surrounding areas directly; it is therefore very important to adopt effective pollution-control measures. Effluents are regulated by the Water Quality Pollution Control Act in Japan.
Standards for the livestock industry
‘Living environment’ itemsEffluent standards
ItemsPermissible
limits
The general effluent standard
pH 5.8-8.6
Biochemical oxygen demand (BOD) (mg/L) 160
Chemical oxygen demand (COD) (mg/L) 160
SS (mg/L) 200
Coliform count (organisms/cm3) 3,000
Nitrogen (N) content (mg/L) 170 120
Phosphorus (P) content (mg/L) 25 16
The Act and its Regulations are applicable to barns on livestock farms with a total floor space of 50 m2 or
larger (pigs), 200 m2 or larger (cattle), and 500 m2 or larger (horses), and with an average effluent volume of
50 m3 or more per day.
the provisional standards are
expected to be tightened further to
match these general standards.
The effluent standard items above
are classified as ‘living
environment’ items, which are
regulated for effluent volumes of
50 m3 or more per day.
0
300
600
900
1200
1500硝酸性窒素規制濃度
(mg
N/L
)暫定基準
一律排水基準
Re
gu
late
d c
on
ce
ntr
ati
on
of
nit
rate
nit
rog
en
Prov. standard
Uniform effluent std. Prediction
If regulations on nitrogen
are tightened further
Background: Nitrogen effluent Control
low-cost nitrogen-removal technology
must be promptly developed.
Livestock farmers
Quickly
Because the general effluent standard for nitrate nitrogen is 100 mg/L, the
provisional standard will be strengthened further at the next
revision in 2016.
The current nitrate nitrogen regulation for livestock wastewater is the provisional standard of
700 mg/L (Fiscal Year 2013).
The cost of wastewater treatment will
increase, leading to lower earnings,
which may become a make-or-break
issue for livestock farmers.
Background: Climate Change
N2O emissions totaled
22,700,000 t, accounting for 1.6%
of the total GHG emissions.
N2O emissions in Japan (FY 2013)
The global warming potential of N2O is 298-times larger than that of CO2
(The IPCC Fourth Assessment Report)
Improved wastewater treatment
technology for greenhouse gas
emission reduction is needed.
Activated sludge treatment
N2O
Agriculture accounts for almost
half of the total emissions, and
40% of this (or 20% of the total)
are emissions from livestock
waste management, which
includes wastewater treatment.
Agriculture
Fuel combustion
Waste
Industrial process
Biological Nitrogen Removal
NH4+
N2O
NO
NO2-
NO3-
N2
Nit
rifi
cati
on
Den
itrification
[Anaerobic]If oxygen is not present
CO2N2↑
NO3-
Organic
matter
Denitrifying
bacteria
NH4+O2
NO3-
Nitrifying
bacteria
[Aerobic]If oxygen is present
Time
Concentr
ation
NH4+
NO3-
Time
Concentr
ation
NH4+
NO3-
NH4+
N2O
NO
NO2-
NO3-
N2
Most of the nitrogen in barn
wastewater, particularly soluble nitrogen, exists as NH4
+.Barn
When both reactions proceed efficiently, N2O is not emitted into the air. However, in
the conventional activated sludge method, N2O is emitted due to various factors.
How to Treat Livestock Wastewater?
Return sludge
wa
ste
wate
r
Wa
ter
treatm
ent
Sludge from the
initial sedimentation
tank (used as
fertilizer)
Initial
sedimentation
tank
Final
sedimentation
tank
Aeration tank
Organic matter removal by
microorganisms
wastewater is separated into solid and liquid fractions by physical treatment such as gravitational
sedimentation.
In the next tank, containing floc-like activated sludge, the pollution
materials, or organic matters, are decomposed by microorganisms.
the wastewater is again separated into solid and liquid
fractions, and the resulting liquid is discharged as treated
water.
Excess sludge (used as
fertilizer)
Return sludge
wa
ste
wate
r
Wa
ter
treatm
ent
Sludge from the
initial sedimentation
tank (used as
fertilizer)
Initial
sedimentation
tank
Final
sedimentation
tank
Aeration tank(activated sludge tank)
Organic matter removal by
microorganisms
Excess sludge (used as
fertilizer)
N2O Generation During Wastewater Purification
N2O generation
NH4+ NO2
-
NO3-
Nitrifying bacteria
NO2- and NO3
- accumulation
Aerobic conditions
Formation of Aerobic & Anaerobic Conditions Using Biofilms
Activated sludge (microorganisms) adhere to
carbon fibers to form aerobic superficial layers
and anaerobic deep layers.
Interior of the
activated sludge tank Carbon fibers
NH4+ NO3
- N2
Nitrification
(aerobic)
Denitrification
(anaerobic)
Activated sludge
Microorganisms adhere
to carbon fibersN2O
Microorganisms adhere to the carriers
installed in the activated sludge tank, to
form biofilms consisting of aerobic
superficial layers and anaerobic deep layers.
This allows the microorganisms to grow,
and simultaneously accelerates both the
(aerobic) nitrification and (anaerobic)
denitrification reactions. Such a smooth
oxidation-reduction reaction is considered
to inhibit the production of N2O.
Deep
anaerobic
layers
Superficial aerobic
layers
Carrier
Approx. 400 mL of wastewater supplied through
the reactor bottom every 6 hours
Overview of Experimental Device
Activated sludge reactor(control)
Carbon fiber reactor (fixed bed type)
Fiber size:
Φ7 μm
(6 m3/m3.h)
P
Water treatment
Carbon fibersAir
Swine wastewater P B
Water treatment
Air
Swine wastewater P B
Activated sludge(MLSS: Avg. 5000)
55cm
5 cm5-cm interval
5 cm
Mesh cylinder (flat)Mesh cylinder
11 layers of carbon fibers in 4 directions
Water treatment
Reactor water volume: 10 L(Diameter: 15 cm)
Swine wastewater
Ventilation flow
(aeration strength)
Reduced N2O generation
Average BOD load:0.3 kg/m3/day
Thermostatic
chamber (20 °C) operation
Experimental Results (Water Quality)
0
500
1000
1500
2000
2500
流入水 炭素繊維
リアクター
処理水
活性汚泥
リアクター
処理水
BO
D (
mg/
L)BOD
0
50
100
150
200
250
300
流入水 炭素繊維
リアクター
処理水
活性汚泥
リアクター
処理水
溶解性窒素
(mg
/L)
NO3-N NO2-N NH4-N
Water quality data for Days 73 – 176 of operation
The carbon fiber reactor was found to inhibit the accumulation of nitrate
nitrogen more than the activated sludge reactor.
So
lub
le n
itro
ge
n
Influent Influent Water
treated in
carbon
fiber
reactor
Water
treated in
activated
sludge
reactor
Water
treated in
carbon
fiber
reactor
Water
treated in
activated
sludge
reactor
Experimental Results (Gas Generation)
0
200
400
600
800
1000
1200
温室効果ガス発生量
(g-
CO
2e
q/m
3/d
ay)
N2O
CH4
活性汚泥法 炭素繊維法
N2O
CH4
Carbon fiber method was therefore
found to be capable of significantly
reducing N2O emissions.
Activated
sludge method
Carbon fiber
method
Am
ou
nt
of
gre
en
ho
use
gas g
en
era
ted
Amount of greenhouse gas generated by
wastewater purification treatment
The carbon fiber reactor successfully reduced N2O generation by 98% or
more, compared to the activated sludge reactor (with continuous aeration)
0
100
200
300
400
500
600
700
800
0 24 48 72 96 120 144 168
NH
3, N
2O
an
d C
H4
(mg/
m3)
経過時間(hrs)
ASリアクター(130~136日)
NH3
N2O
CH4
Time
0.03 gN2O-N/gTN-load
7180.5 mg-CO2
equivalent/day
Activated sludge reactor
0
100
200
300
400
500
600
700
800
0 24 48 72 96 120 144 168
NH
3, N
2O
an
d C
H4
(mg/
m3)
経過時間(hrs)
CFリアクター(130~136日)
NH3
N2O
CH4
Time
339.4 mg-CO2
equivalent/day
0.0003 gN2O-N/gTN-load
Carbon fiber reactor (fixed bed type)
*Measurement every 15 minutes
Amount of gas generated in reactors (Days 130 – 136 of operation)
Reactions Inside the Treatment Tank
Activated sludge method
(conventional method)
In activated sludge
NH4+ NO3
- accumulated
N2O
Aeration tank
Nitrifying
bacteria
Carbon fiber
method
Aeration
tank
Biofilms
Carb
on
fiberNH4
+
Superficial
layer Deep layer
N2
NO3-
Carbon fiber
Biofilms
Activated
sludge
Activated
sludge Activated
sludge
Activated
sludge
Activated
sludgeActivated
sludge
Activated
sludge
Denitrifying
bacteria
Nitrifying
bacteria
Denitrifying
bacteria
Application of this technology will lead to …
Global warming reduction
N2O generation
Nitrogen reduction
Eutrophication reduction
Lakes and inner bays
Livestock farmers
Wastewater treatment Increasing the safety of
drinking water
Thank you for your attention
Causes of Nitrous Oxide (N2O) Generation in Wastewater Treatment
NH4+ NO3
- N2
N2O
Low DO
condition
Nitrification Denitrification
High
NO2-
concent
-ration
- Insufficient aeration
- Organic matter high-
load operation
- Insufficient aeration
- Low SRT
- Low water temperature
- High ammonia concentration
High DO
conditionLow
COD/N
High
NO2-
concent-
ration
- Influence of excess
aeration by nitrification- COD restriction
- NO2- inflow from
the nitrification
process
- Properties of influent
- Influence of excess
sedimentation in the
up-stream process
When the COD/N ratio is 3.5 or less, 20 – 30%
of N load is discharged as N2O.
(Itokawa et al., 2001)
When the DO concentration is 1 mg/L or less,
10% of N load is discharged as N2O.
(Goreau et al., 1980)
- Decrease in pH due to
accumulated NO2
Reaction Path of Biological Nitrogen Removal in Purification
N2
N2O
NO
NO2-
NO3-
Anammox
bacteria
NH4+
N2ONO
Aerobic
reaction
Anaerobic
reaction
Nitrification process
Denitrification
process
Denitrifying
bacteria
Ammonium
oxidizing
archaebacteria
Nitrite
oxidizing
bacteria
Ammonium
oxidizing
bacteria
In either process, of denitrification or nitrification,
N2O may be discharged.
Denitrifying
bacteria
Denitrifying
bacteria
Denitrifying
bacteria
Ammonium
oxidizing
bacteria
Ammonium
oxidizing
bacteria
- FY 2013Lab scale
Carbon fiber reactorActivated sludge reactor
FY 2014Bench scale
Carbon fiber reactorActivated sludge reactor
Size 10 L 1 m3 (125 cm deep)
Amount of carbon fiber to supply; or Amount of activated sludge (mg/L)
55 cm (11-layer, 4 directions, 5 cm);
or 5000
6 pieces (90 cm);or
5000
Sewage to supply Swine wastewater Swine wastewater
BOD load (kg/m3/day) 0.3 0.3
BOD/N ratio Average 6 Approximately 2.5
Aeration amount 1 L/min (6 m3/m3・h) 50 L/min (3 m3/m3・h)
Water temperature (°C) 20 Vary by season
GHG gas measurement 15-minute cycle 15-minute cycle
Carbon Fiber Supply Experiment at the Actual Facility
Partially supply
water by bypass
operation
Treated
water
Area for testing with
carbon fiber
Volume:
Approx. 1 m3
P
P
A
Wastewater draw-up
Pump
Aeration
Partially supply
water by bypass
operation
Treated
water
Area for comparison
(no carbon fiber)
Volume:
Approx. 1 m3
P
P
A
Wastewater draw-up
Pump
Aeration4.8 m3/h
BOD load: 0.3 kg/m3/day
6 pieces (90 cm)
Activated sludge amount
MLSS: 5000 mg/L
Barn wastewater pit
0
200
400
600
800
1000
1200
0 10 20 30 40 50 60 70
NH
4-N
, N
O3-N
an
d N
O2-N
(m
g/L
)
Period(days)
Influent NH₄-N Effluent NH₄-N Influent NO₃-N
Effluent NO₃-N Influent NO₂-N Effluent NO₂-N
In the activated sludge (AS) reactor
0
200
400
600
800
1000
1200
0 10 20 30 40 50 60 70
NH
4-N
, N
O3-N
an
d N
O2-N
(m
g/L
)
Period(days)
Influent NH₄-N Effluent NH₄-N Influent NO₃-N
Effluent NO₃-N Influent NO₂-N Efflent NO₂-N
In the carbon fiber (CF) reactor
0
100
200
300
400
500
0 10 20 30 40 50 60 70
NH
3, N
2O
an
d C
H4
(mg
/m3)
Period (days)
CFリアクター
NH₃
N₂O
CH₄
0
100
200
300
400
500
0 10 20 30 40 50 60 70
NH
3, N
2O
an
d C
H4
(mg
/m3)
Period (days)
ASリアクター
NH₃
N₂O
CH₄
Generated Gas and Water quality
0.008 g N2O-N/g TN-load 0.021 gN2O-N/g TN-load
Aeration tank 10L Carbon fiber
Biofilms
Carbon fiber
Biofilms
Aeration tank 700L
Non- contact aeration in the indoor
experiment with small-scale equipment Direct contact aeration in the scaled-up experiment
Microorganism Carriers: Carbon Fibers
When microorganisms adhere to non-carbon fibers, there is an energy barrier which
impedes and retards adhesion. However, it was found that this barrier is not present in
the case of adhesion to carbon fibers, which means that microorganisms can adhere
to such fibers more quickly and easily.
[Comparative rate test of microorganism
adhesion to various fibers]
- Carbon fiber (CF)
- Polyacrylonitrile (PAN)
- Aromatic polyamide (AP)
- Polyethylene (PE)
It was found that the rate of microorganism adhesion was 1.5 – 10 times
faster in the case of carbon fiber than other fiber types. (The carbon fiber
adhesion rate for Escherichia coli was 5 times that of polyamide fiber.)
Between any substances, there is mutual attraction caused by intermolecular forces.
In the case of microorganisms in water, there is greater attraction to carbon fiber
than to other fibers.
Under water, both
microorganism
cells and fibers
have a negative
electric charge.
It was found that the
negative electric charge on
carbon fiber is less than that
on other fibers.
Micro-organism
cells
--
-
- --
CF--
PAN----
AP----
PE----
Reference:Matsumoto S, Ohtaki A, Hori K. 2012. Carbon fiber as an excellent
support material for wastewater treatment biofilms. Environmental Science &
Technology 46, 10175–10181.
Carbon fiber method
Aeration tank
BiofilmsC
arbo
n fib
er
NH4+
Superficial
layerDeep layer
N2
NO3-
Carbon fiber
Biofilms
Intermittent aeration method in activated sludge treatment plants
. Osada et al. (1995) reported that less than 1% of influent nitrogen was emitted as N2O gas during the
intermittent aeration process. However, the intermittent aeration method produces lower degradation of organic
matter than standard activated sludge processes.
Activated
sludge
Activated
sludge Activated
sludge Activated
sludge
Activated
sludgeActivated
sludge
Activated
sludge
Activated
sludgeActivated
sludgeActivated
sludge
Activated
sludgeActivated
sludge Activated
sludgeActivated
sludge
Cycle
Aeration No aeration
Sedimentation
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