Resource Recovery at Blue Plains

Resource Recovery
VWEA Annual
Education Conference
May 1st, 2014
Chris Peot, P.E., BCEE
Director of Resource Recovery,
DC Water
DC Water Service Area
• Wastewater treatment for over
2.2 million population
• District of Columbia + portions of
Maryland and Virginia
• CSO flows
• Excellent history of treatment
performance
2
370 MGD plant capacity
Largest AWTP in the world
3
CIP Projects Currently Underway
BP Tunnel Dewatering Pump Station &
Enhanced Clarification Facility
$300 million
New Biosolids
Management Program
$450 million
Dual Purpose Sed Basins
Upgrade
$18 million-
New Centrate
Treatment Process
$84 million
Enhanced Nutrient Removal
Facilities
$340 million
Upgrade & expansion of
the Nit/ Denit system
Upgrade of the Secondary High
Rate System
$26 million
5
DC Water and Sewer Authority Biosolids
Reuse Program
1200 wtpd lime stabilized Class B biosolids
Agriculture: 39 counties in 2 states
Silviculture: 40,000 acres permitted in 8 Virginia counties
Poplar plantation on gravel mine
Reclamation projects: 3 sites to date
National Biosolids Partnership EMS certified agency
6
Biosolids Land Applied from Plant and Storage
County, tons to storage
(if applicable), tons
applied, agriculture $
7
Agriculture
8
Storage Facility – 32,500 tons capacity,
Cumberland County, VA
9
10
Spotsylvania County Composting Facility –
Covered, Biofilter Odor Control
11
Blue Plains Garden & Compost Giveaway
Connecting with the DC Gardening Community
Urban gardening community outreach
Nutrient Rebate Research Projects –
$2/wt rebated through biosolids contracts. DC Water is obligated to spend it on research
Virginia Tech
• Drought resistance study
• Greenhouse gas balance
• Wintertime N uptake
• P land base analysis
• Blended soil products
development
University of Maryland
• Wye poplar plantation surface application
• Odor modeling and prevention
• Mine reclamation w/poplars
USDA + University of Maryland
• Triclosan, triclorocarbon
• PBDEs
+
16
Biosolids Enhance Drought Stress
Tolerance in Corn
Biosolids
1.0x Ag N rate
Microbial Production of Auxin
in Biosolids
Microbial action
Organic
matter
Tryptophan
Auxin
Auxin (ng g-1 FW)
Corn Earleaf Auxin Content at Silking Stage
80
a
70
40
Control
a
b
60
50
a
c
c
0.5x Ag N rate
1.0x Ag N rate
1.5x Ag N rate
BluePlains
Alexandria
30
20
10
0
Treatment
Values marked with same letters are not significantly
different at P≤0.05
Corn Photosynthetic Efficiency (PE)
0.8
Control
b
b
PE
0.7
a
a
0.5x Ag N rate
1.0x Ag N rate
1.5x Ag N rate
0.6
c
c
BluePlains
Alexandria
0.5
0.4
Treatment
Values marked with same letters are not significantly different at P≤0.05
Corn Grain Yield
a
Yield (Mg ha-1)
6
b
a
ab ab
Control
0.5x Ag N rate
1.0x Ag N rate
4
1.5x Ag N rate
c
BluePlains
2
Alexandria
0
Treatment
Mean corn productivity = 7.54 Mg/ha; a severe drought year
Values marked with same letters are not significantly different at P≤0.05
Economics of Current DC Water Biosolids
Recycling Program
• Pay a third party ~$43/wt for full service contract
(transport, land app, reporting)
• $19M/yr program cost =21% of the Blue Plains operating
budget
• Delivered free to farmers
• Farmers value product at $300/acre (nutrients, lime,
etc.), approximately $15/wt
• Nutrient rebate back to DC Water ($2/wt), $500K/yr
designated for research and outreach.
• Value to farmers @ $15/wt, 1200 wtpd = $6,570,000/yr
• We do not extract this value
Digestion and Thermal Hydrolysis Project
Thermal Hydrolysis Digested Dewatered
Products from the UK
30% solids
Very stable
Class A
No debris
Low odor
24
4 Anaerobic Digesters
Pressurized
412
Cambi
Trains Solids
Screens
10 Pre-Dewatering
Centrifuges
16 Belt Filter Presses
Gas Handling and CHP
Process Schematic of DC Water’s
New Biosolids Program
Gravity
Thickeners
R
DAFTs
Power
Emissions
Biogas Treatment and
CHP
R
Steam
Blend
Tank
Screening and
Pre-Dewatering
Cambi™ THP
Biogas
Mesophilic
Anaerobic
Digestion
Final
Dewatering
Loadout
R
Recycle
Processing
Lime
Dewatering
Mix
Store &
Loadout
R
Class A
R
Class B
26
Process Flow of THP Before Anaerobic
Digestion – Cambi™ Batch Class A
Sludge cake
(P+WAS)
~15 to 18% DS
Process gases
(to digester)
REACTOR(s) –
Batch pressure cooking
Recycled steam
for energy
recovery
Homogenized
and preheated
sludge
PULPER
Pre-heat tank
Hydrolyzed
sludge
Steam 150 psi
Hydrolyzed sludge
to digestion at
8-12% DS.
Dilution and
cooling required.
FLASH TANK
disintegration
27
Pulper
• Influent solids
15 to 18.5 %TS
• Preheated to
140-210°F with
recycle steam
• Mixing pumps
Reactors
• Batch process
• Heated to 302356°F
• 54-138 psi
• 22-30 minute
detention time
Flash Tank
• Depressurization
• Cools down to
158-239°F
• 8-12 %TS to
digesters
Why Thermal Hydrolysis?
Reinventing Biosolids
1. Easier to pump and
mix
2. Smaller digester
space
3. Class A Biosolids
29
Effects of Thermal Hydrolysis
Program Benefits
Resource Recovery
Reduce biosolids quantities by more than 50%
Improve product quality (Class A and more)
Generate 13 MW of clean, renewable power
Cut GHG emissions dramatically
Save millions of dollars annually when the
facility begins operating in 2014
31
Construction is Well Underway
Thermal Hydrolysis Reactors
Future Plans for Class A Biosolids
• Continue land application
of remaining Class A
dewatered biosolids
• Produce a blended soil
product (similar to
compost)
• Use product in service
area for tree planting,
restoration, green
infrastructure, etc.
34
Clean Rivers Project Synergies
• Clean Rivers Project ($2.5B) will capture rainwater
and sewage in our combined sewers and prevent CSO
events
• Soil production for green infrastructure will reduce
runoff
• Working with local blenders and Va Tech to develop
these mixes
•
•
•
•
Use within the service area
Save hauling cost
Eventually may generate revenue
Potential partner (DPW) for greenwaste reuse
Clean Rivers Project – Phase I
DC Water is modeling carbon balance for
base year, current year, and future projects
Table 1. Summary of Annual Emission Estimates, Calendar Year: 2008
Annual Emissions Estimate
Metric Tons CO2e
Scope 1 and 2
Percent Contribution
Scope 2
Electricity
DSS
146,920
11,053
88%
DWS
DWT
9,163
126,704
5%
76%
2,967
197
371
441
1,924
34
2,586
0.064
1041
1545
142
2%
0.1%
0.2%
0.3%
1%
0.02%
2%
0.00004%
0.6%
0.9%
0.08%
12,007
443
2,009
167,074
7%
0.3%
1%
Emission Source
7%
Scope 1
Natural Gas
CS
DSS
DWS
DWT
FLEET
Vehicle (fuel usage)
Compressed Natural Gas (CNG)
Diesel Fuel No. 1 and 2
Motor Gasoline
Refrigerants
Nitrification/Denitrification (process emissions)
CO2 from Addition of Methanol
N2O from Dentrification
Effluent Discharge (process emissions)
Total with Scope 1 and 2
Scope 3
Biosolids Hauling (fuel usage/distance travelled)
Chemical Hauling (distance travelled)
Lime Production
Methanol Production
N2O Emissions from Land Application of Biosolids
Methane Emissions from Landfilling Biosolids
Total with Scope 3
Carbon Credits
Carbon Sequestration Land Application
4,107
1,450
14,883
6,747
52,548
7
246,815
26,844
Carbon Sequestration Land Application with Composting
13,576
Carbon Sequestration Landfill
Avoided N2O Emissions from Replacement of Inorganic Fertilizers
Fertilizer Credits Direct Applied Biosolids (N and P)
2
52,548
9,006
Fertilizer Credits Composted Biosolids (N and P)
Total
GRAND TOTAL
1,692
103,668
143,147
37
Discretionary Projects that Could Reduce
Carbon Footprint
• Main stream anammox nutrient removal
• Co-digestion of foodwaste, fats/oils/grease, and other high
strength wastes
• Solar power at Blue Plains
• Offsite solar potential
Biological Nitrogen Removal Technologies
•Traditional – Requires use of blowers (to aerate) and use of additional chemicals (methanol) –
Both are energy intensive, have large carbon footprints, and are expensive
•Innovative - (Anammox) – Reduces aeration and methanol addition – Results in
significant reductions in energy use and carbon footprint
•63% reduction in Oxygen demand
•Almost 100% reduction in Carbon demand
•Reduced biomass production
•Reduced CO2 emissions
25% O2
40% Carbon
25% O2
75% O2
1 mol Ammonia
(NH3 / NH4 +)
½ mol Nitrogen Gas
(N2 )
Nitrification /
Denitrification
1 mol Nitrite
(NO2- )
60% Carbon
---- 75% O
2
37%
Am
(e. mo
g. ni
Ni a O
tr o x
so idi
mo zer
na s
s)
1 mol Nitrite
(NO2- )
1 mol Nitrite
(NO2- )
1 mol Nitrate
(NO3- )
N
(e itrit
.g e
. N Ox
i tr i d
ob ize
ac rs
te
r)
1 mol Nitrate
(NO3- )
Autotrophic
Aerobic Environment
1 mol Ammonia
(NH3/ NH4 +)
Heterotrophic
Anoxic Environment
40% Carbon
1 mol Nitrite
(NO2- )
60% Carbon
Autotrophic
Anaerobic
Environment
½ mol Nitrogen Gas
(N2 )
39
Benefits of Innovative Nitrogen Removal
Technology
7
6
Conventional Nitrification / Denitrification
Deammonification
5
4
3
2
1
0
Energy Demand (kWhr/kg Ammonia-Nitrogen
Removed)
Carbon Demand (kg
COD/kg Total Nitrogen
Removed)
40
Co-Digestion and energy production has led
utilities toward energy neutrality
East Bay MUD (Calif) announced April 3rd that with its new 4.6 MW ga turbine
on-line, it is the 1st water/ww utility in the US to produce more power than it
uses (EBMUD now sells power to the grid).
Having excess digester capacity available,
EBMUD has operated like a business to allow fats,
greases, and various food and beverage wastes
to be trucked in and co-digested at the plant.
Other WWTPs use a similar approach:
1. Reduce plant power use (conservation)
2. Greatly expand renewable power production, normally via co-digestion.
41
Camden County (NJ) Solar Center
Potential array locations for Blue Plains
43
Offsite Solar Potential
Year
2025
2024
2023
2022
2021
alternative nitrogen removal
co-digestion
5
2020
2019
2018
off-site solar
10
2017
15
Blue Plains solar array
20
2016
digestion
25
2015
ENR
30
2014
2013
2012
2011
2010
2009
2008
35
2007
2006
Power Draw (MW)
Potential Grid Power Draw Reductions
Blue Plains Grid Power Draw During Sunlight Hours
total power draw (MW)
0
46
There is no such thing as waste,
only wasted resources.
Chris Peot
[email protected]

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