1st innovations in nitrogen and phosphorus removal · polishing pilot plant is located in hampton...
TRANSCRIPT
1st Annual Innovative Wastewater Technologies Seminar
Innovations in Nitrogen and Phosphorus Removal
Jose A. Jimenez, Ph.D., P.E.
Director of Technology and Innovation
Brown and Caldwell
July 15th, 2015
Recovery of key resources
Energy neutral or positive treatment
Public and private sector partnerships
Optimal integration of sources
AND: Always ensure protection of public health
Vision of WRRF
2
Innovation
3
Fundamentals of Nutrient Removal
4
• Nitrogen Removal
• Nitrification requires oxygen = energy for blowers/aerators
• Denitrification requires carbon = organics needed; organics that could have been used for energy production
• Phosphorus Removal
• Phosphorus Accumulating Organisms (PAO) require soluble carbon = competition with denitrification for organics; organics could have been used for energy production
Nutrient Removal Basics
5
• Energy required for secondary wastewater treatment
• 1,200 to 2,400 MJ/1000 m3
• Energy available in wastewater for treatment
• 5,850 MJ/1000 m3 (@ COD = 500 mg/L)
• Energy available in wastewater is 2 to 4 times the amount required for treatment
Required and Available Energy for Wastewater Treatment, Exclusive of Heat Energy
6
• 1.3 MJ/person per day ($0.01/person/day)
• Can be readily recovered as energy
• Can also be recovered as value added carbon ($0.05-$0.5/person/day)
• methane generated from anaerobic digestion
• bioplastics (i.e., PHA) via activated sludge
• alginate/biogels via granular sludge
• soluble organics via fermentation
Organic Carbon vs. Energy
7
Estimated Capital and Operating Costs for Each Treatment Level
0
200
400
600
800
1,000
1,200
1,400
1,600
Op
era
tio
ns
cost
s ($
/MG
tre
ate
d)
Levels of treatment
No N/P removal
8 to 10 mg/l N
8 to 10 mg/l N; 1 mg/l P
6 mg/l N; 0.5 mg/l P
3 mg/l N; 0.1 mg/l P
3 mg/l N; 0.05 mg/l P
2 mg/l N; 0.05 mg/l P
1 mg/l N; 0.05 mg/l P)
5Example greenfield Level 2 plant (24 mgd design flow) with NO solids handling (sludge discharged to sewer) was $2.45/gpd
0
5
10
15
20
25
30
Cap
ital
co
sts
($/g
pd
)Levels of treatment
No N/P removal
8 to 10 mg/l N
8 to 10 mg/l N; 1 mg/l P
6 mg/l N; 0.5 mg/l P
3 mg/l N; 0.1 mg/l P
3 mg/l N; 0.05 mg/l P
2 mg/l N; 0.05 mg/l P
1 mg/l N; 0.05 mg/l P)1 2 3 4 5 6 7 8
Levels of Treatment
0
5
10
15
20
25
30
Ca
pit
al c
ost
s ($
/gp
d)
Levels of treatment
No N/P removal
8 to 10 mg/l N
8 to 10 mg/l N; 1 mg/l P
6 mg/l N; 0.5 mg/l P
3 mg/l N; 0.1 mg/l P
3 mg/l N; 0.05 mg/l P
2 mg/l N; 0.05 mg/l P
1 mg/l N; 0.05 mg/l P)
5Example greenfield Level 2 plant (24 mgd design flow) with NO solids handling (sludge discharged to sewer) was $2.45/gpd
0
5
10
15
20
25
30
Cap
ital
co
sts
($/g
pd
)
Levels of treatment
No N/P removal
8 to 10 mg/l N
8 to 10 mg/l N; 1 mg/l P
6 mg/l N; 0.5 mg/l P
3 mg/l N; 0.1 mg/l P
3 mg/l N; 0.05 mg/l P
2 mg/l N; 0.05 mg/l P
1 mg/l N; 0.05 mg/l P)1 2 3 4 5 6 7 8
Levels of Treatment
0
5
10
15
20
25
30
Cap
ital
co
sts
($/g
pd
)
Levels of treatment
No N/P removal
8 to 10 mg/l N
8 to 10 mg/l N; 1 mg/l P
6 mg/l N; 0.5 mg/l P
3 mg/l N; 0.1 mg/l P
3 mg/l N; 0.05 mg/l P
2 mg/l N; 0.05 mg/l P
1 mg/l N; 0.05 mg/l P)
1:
2:
3:
4:
5:
6:
7:
8:
Nitrogen Removal Processes
9
Carbon Requirements for Mainstream Biological Nitrogen Removal Processes
10
Constituent Nitrification
denitrification
Nitritation-
denitritation
Partial nitritation-
deammonification
Carbon required for nitrogen
removal (mg COD /mg N) 6.0 – 10.0 3.0 – 5.0 1.0 – 3.0
Net Process Oxygen Requirement
(mg O2/mg N Converted to N2) 1.71
• Influent COD:N Ratio often 10 – 13 mgCOD/ mgN
• Opportunities available to divert COD out of the plant and use it for energy generation
• The conundrum of aerobic treatment is that electrical energy is needed to destroy chemical energy (COD)
• Process units available to redirect Carbon for energy generation
Conventional Nitrogen Removal Processes
11
Electricity ( e.g., aeration, pumping)
Infrastructure (facility footprint)
Chemicals (e.g., external carbon, alkalinity, polymers)
TN 8 -10 mg/L
TN 3 - 5 mg/L
Conventional Nitrification-Denitrification
12
1 mole Ammonia
(NH3 / NH4 +)
½ mol Nitrogen Gas
(N2 )
1 mole Nitrite
(NO2-)
1 mole Nitrite
(NO2-)
1 mole Nitrate
(NO3-)
Autotrophic Bacteria
Aerobic Environment
Heterotrophic Bacteria
Anoxic Environment
75% O2 (energy)
~100% Alkalinity
25% O2 (energy)
40% Carbon (BOD)
60% Carbon (BOD)
Ammonia Oxidizing Bacteria (AOB)
Nitrite Oxidizing . Bacteria (NOB)
Advances in Nitrogen Removal
13
Recent Advances in N Removal started with Sidestream Treatment
14
Anammox Bacteria
• Very Slow Growth • 10 day doubling time at 20C
• SRT (30 - 50 days)
• Sensitive to:
• Nitrite
• causes irreversible loss of activity
• toxicity based on concentration & exposure time
• NH4+ : NO2
- ratio 1 : 1.3
1 Gallon 80 Gallons 635 Gallons 132,000 Gallons
– DO - reversible inhibition
– Free ammonia (<10 mg/l)
– Temperature >30C preferred
– pH (neutral range)
Bernhard Wett, 2005
• Couples nitritation (NH3 conversion to NO2) followed be incomplete denitrification (NO2 conversion to N2O)
• N2O is captured and can be used for combustion (e.g., biogas engine or boiler)
• Increase power output making the net energy recovery much more favorable
Coupled Aerobic-Anoxic Nitrous Decomposition Operation (CANDO)
16 Gao, Scherson and Wells 2014
17
NO2-
NO3-
NH2OH NH3
AOB
CARBON RECOVERY? CH4 CH3OH
ANAEROBIC DIGESTION
BNR Process
NITRIFICATION
Su et. al., 2015
From Green House Gas to Green Biofuel
• C:N ratio into the bioreactor may be a key control factor in defining predominant pathway for TN removal
• Control denitrification by heterotrophic organisms
• If C/N ratio is sufficient for conventional nitrification/denitrification, opportunity to: • Reduce C:N ratio by CEPT and HRAS and reduce Energy needed for nitrogen
removed
• Divert carbon to anaerobic digestion to both recover energy (CHP system)
Wastewater C:N Ratio
19
Higher C:N ratio
6 - 10 :1 range?
Heterotrophs Outcompete
Medium C:N
3 - 5 :1 range?
Lower C:N ratio
1 - 3 :1 range ?
Anammox Outcompete
Conventional Nitrification / Denitrification
Nitrite Shunt Deammonification
Resource Efficient Recycling Options
20
Stage 1
Carbon Removal
and Recovery
Stage 2
Nitrogen
Removal
Stage 3
P Removal/
Recovery
Water Reuse
Biosolids
Energy Generation
Fertilizer
By-Products
Carbon Removal Processes
21
Anaerobic - UASB Physical - Primary Settling
Activated Sludge / A-Stage Physical - Micro-Sieves and
Micro-Filters
Nitrite Shunt/ Mainstream Deammonification
22
Low DO Operation Nitrite-Shunt Process
Jimenez et al. (2014) 23
0
2
4
6
8
10
7/28/13 8/4/13 8/11/13 8/18/13 8/25/13 9/1/13
Nit
roge
n S
pe
cie
s, m
g/L
Ammonia Nitrite Nitrate
Ammonia vs NOx control
Regmi et al., 2014 24
Aer
ob
ic F
ract
ion
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Nit
rog
en (
mg
/L)
0
2
4
6
8
10
Aerobic Fraction
NH4-N
NOx-N
24-hour
Dis
solv
ed O
xyg
en (
mg
/L)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
DO
1-hour
Dis
soved
Ox
ygen
(m
g/L
)
0.0
0.5
1.0
1.5
2.0
D.O.NO2-NNO3-N
NH4-N
Aerobic Duration
Controller/PLC
DOController/
PLC
DO = set point
NH4-N - NOx-N = setpoint
MAirS
N Species
SecEff Ammonia N SecEff Nitrite + NitrateSecEff Total inorganic N
9/02/20132/02/201326/01/201319/01/201312/01/20135/01/2013
CO
NC
. (m
gN
/L)
6
5
4
3
2
1
0
Nitrite Shunt through FNA Production
Zhiguo Yuan, The University of Queensland
Approaches to Mainstream Deammonification
26
Influent Preliminary
Treatment
Anaerobic
Process
Biogas
Effluent N
Removal
Waste sludge Disintegration
of Sewage
Sludge
Dewatering
Sludge
Disposal
Integrated Anaerobic/Aerobic Treatment
Energy neutrality or self sufficiency
C-redirectionMainstream
Deammonification
AnaerobicDigester
Sidestream Deammonification
• Harness energy content of wastewater (14 MJ/kg COD)
• While performing nitrogen removal
Strass WWTP, Austria
HRSD’s Approach
RAS
WAS
AER PCL
A-stage
HRAS
SCL
RAS
AER AER AER
IMLR
ANX
B-stage(AvN+)
AER
WAS
AvN Anammox MBBR
AER AER
Regmi et al. (2014)
Carbon redirection Nitrite-shunt Nitrogen
Polishing
Pilot Plant is Located in Hampton Roads Sanitation District’s
Chesapeake Elizabeth Treatment Plant, Virginia Beach.
Enhanced Mainstream Nitrogen Removal
Zhiguo Yuan, The University of Queensland
What about P Removal?
31
Some Traditional Flow Diagrams for Bio-P
Barnard (2011) 32
• Bio-P becomes less stable when applied in conjunction with N removal processes due: • competition with GAOs
• introduction of nitrate/nitrite to anaerobic zone
• competition for carbon
• N removal via denitrification becomes carbon limited due to bio-P
• Supplemental carbon is added to enhance denitrification and/or bio-P
• PAOs that can use nitrate/nitrite as an electron acceptor instead of O2 to be highly desirable pathway for both N and P removal
Issues with Bio-P and N Removal
33
Biological Advances
Denitrifying Phosphorus Removal
34 Y. Ma et al, 2009
Biological Advances
Nitrite Shunt and Bio-P (DPAO?)
35
0
1
2
3
4
5
6
7
8
9
Effl
ue
nt
Qu
alit
y, m
g/L
TN TP
Ballasted-Flocculation with Magnetite
36
Bionanotechnological phosphate removal system with thermostable ferritin
BiAqua Technology: Biobased adsorbents
37
Struvite Crystallization Processes for Bio-P Plants
• Liquid technologies:
• Crystalactor®
• Ostara Pearl®
• PHOSPAQTM
• Multiform Harvest
• Solids technologies:
• AirPrex®
Recovery of key resources
Energy neutral or positive treatment
Public and private sector partnerships
Optimal integration of sources
AND: Always ensure protection of public health
Vision of WRRF
39
• Nitrogen removal in nitrite-shunt
HRSD Mainstream Nitrite-Shunt + Anammox Polishing
• Anammox Polishing
41
Energy Balance of WRRF
42 Wett et al. (2007)
ET - thermal energy ES - syntheses energy EE - electricity
43 Jurg Keller, The University of Queensland
• Anoxic P removal possible by denitrifying PAOs (DPAOs)
• Carbon and oxygen requirements are curbed
• PHA stored by PAOs in anaerobic conditions can be used for denitrification and P uptake in anoxic conditions
• DPAOs activity over nitrite is of interest when integrating bio-P in a shortcut N removal system.
• Bio-P and denitrifying dephosphatation with advanced biological nitrogen removal processes.
Biological Advances
Denitrifying PAOs
44