Upload
vuongxuyen
View
219
Download
0
Embed Size (px)
Citation preview
1
Superior Wastewater Treatment Utilizing SBR Technology
GRWA SBR Training
November 6, 2008
Stuart Humphries, Crocker & Associates, Inc.770-855-8090, [email protected]
www.crocker-associates.com, www.stuarthumphries.com
AQUA-AEROBIC
SYSTEMS, INC.
Crocker & Associates, Inc.
Presentation Topics
• SBR Introduction
• Nutrient Removal – Nitrogen
• AquaSBR® Operating Cycles & Phases
• AquaSBR® System Components
• AquaSBR® Process Control
• AquaSBR® Biological Process Control Example
• Nutrient Removal – Phosphorus
• Enhanced Biological Phosphorus Removal (EBPR)
• AquaSBR® EBPR Example
• Chemical Phosphorus Removal
• AquaSBR® Chemical Phosphorus Removal Example
• Wrap Up
Your Wastewater Specialists
AquaSBR®
Sequencing Batch Reactor
Aqua-Aerobic Systems, Inc.
2
Main
AquaSBR - Activated Sludge
Aqua-Aerobic Systems, Inc.
AquaSBR - Activated Sludge Types
Aqua-Aerobic Systems, Inc.
AquaSBR® - Activated SludgeAquaSBR vs. Flow-Through Activated Sludge
• Equalization
• Anaerobic Mix
• Staged Aeration
• Oxidation
• Nitrification
• Anoxic Mix
• Denitrification
• Clarification
• Sludge Wasting
Aqua-Aerobic Systems, Inc.
3
Typical Flow Through System Layout:
Aqua-Aerobic Systems, Inc.
SBR Comparison to Flow Through:SBR: Reduced Space Requirements
Aqua-Aerobic Systems, Inc.
AquaSBR
Aqua-Aerobic Systems, Inc.
4
AquaSBR
Aqua-Aerobic Systems, Inc.
AquaSBR
Aqua-Aerobic Systems, Inc.
AquaSBR
Aqua-Aerobic Systems, Inc.
5
AquaSBR - Process Capabilities
Tolerates Hydraulic Fluctuations
Tolerates Organic Fluctuations
Excellent Solids-Retention Capabilities
Process Flexibility
Aqua-Aerobic Systems, Inc.
AquaSBR - Applications
Organic Reduction
Total Nitrogen Reduction
Phosphorous Reduction
Municipal
Aqua-Aerobic Systems, Inc.
Why Remove Nutrients in
Wastewater?
• Ammonia is toxic to aquatic organisms
• Ammonia exerts oxygen demand on receiving waters
• Nitrates pose health hazard if consumed by infants
• P and N contribute to Eutrophication
• High NO2- (i.e., partial denitrification) interferes
with Cl- disinfection (Nitrite Lock)
Aqua-Aerobic Systems, Inc.Crocker & Associates, Inc.
6
• Contributes to eutrophication, which leads to deterioration of water quality in lakes
• Eutrophication is a condition in an aquatic ecosystem where high nutrient concentrations stimulate blooms of algae (e.g., phytoplankton).
• Creates conditions that interfere with the recreational use of lakes and estuaries, and the health and diversity of indigenous fish, plant, and animal populations.
Why Remove Nutrients in
Wastewater?
Aqua-Aerobic Systems, Inc.Crocker & Associates, Inc.
Algal blooms hurt the ecosystem in two ways:
1. Cloud the water and block sunlight, causing underwater grasses to die.
- Because these grasses provide food and shelter for aquatic creatures, spawning and nursery habitat is destroyed and waterfowl have less to eat when grasses die off.
2. When algae die and decompose, oxygen is consumed
- Dissolved oxygen in the water is essential to most organisms living in the water
- For coastal waters such as the Gulf of Mexico, hypoxia is especially severe due to the shallow waters of the coastal shelf and differences in water salinity.
Aqua-Aerobic Systems, Inc.Crocker & Associates, Inc.
• Nitrogen and phosphorus loading concerns on receiving waters
• Both point source and non-point sources are a concern
• Trend is towards lower discharge levels due to TMDLsand Waste Load Allocation
• Nutrient removal can play a role in reuse applications
Nutrient Removal Trends
Crocker & Associates, Inc.
7
• GA 0.5 NH3-N, 1.5 Org N (discussed), 0.13 Total P “Metro Atlanta Limits”
• FL 3.0 Total N, 1.0 Total P
• Chesapeake Initiative: State specific, 4.0-8.0 Total N, 0.3-2.0 Total P
• Michigan 5 TIN (NH3 + NO2- + NO3
-), 1 TP
NOTE: EPA-Region 4 is encouraging GAEPD to develop nutrient standards for all waters. Currently, GAEPD is requiring 1.0 mg/L TP for
new and expanding facilities >1.0 MGD (or 8.34 lbs/day for <1.0 MGD);
and for existing facilities renewing their permit, monitor TP only. This is being done because of nutrient criteria coming soon.
Regional Target Levels
Crocker & Associates, Inc.
Nitrogen
Crocker & Associates, Inc.
Crocker & Associates, Inc.
Nitrogen Basics
• Domestic wastewater contains Organic (40%),
Ammonium (60%), and Nitrates (<1%)
• Ammonium + Organic N = TKN
8
Crocker & Associates, Inc.
Nitrogen Basics
• From protein metabolism in human body
• 16 grams/cap/day
• 21 to 42 mg/L TKN typical
• Watch out for WWTP recycle streams
– Digester Supernatant
– Belt Press Filtrate
O2
O2
Nitrate (NO3-N)
Nitrite (NO2-N)
Ammonia Nitrogen
Nitrification
Crocker & Associates, Inc.
Carbon
Carbon
Aqua-Aerobic Systems, Inc.
Your Wastewater Specialists
Nitrification
2NH4HCO3 + 3O2 Nitrosomonas 2HNO2 + 4 H2O + CO2
2HNO2 + O2 + 2 HCO3 Nitrobacter 2NO3 + 2H2O + 2CO2
Lose alkalinity
Crocker & Associates, Inc.
9
Organic
CompoundsNH3
NO2-NO3
-
N2O
N2
Nitrification
Denitrification
NO
Fixation
Nitr
ate
Assim
ilatio
n
Ammonification by Microorganisms
Ammonia Assimilation
Nitr
ific
atio
n
Assim
ilative
Nitr
ate
R
ed
uctio
n (
Ind
ustr
ial)
Nitrogen Cycle
Crocker & Associates, Inc.
Aqua-Aerobic Systems, Inc.
Generally, SRT > 5 days for stable nitrification
– Nitrifiers work very slowly
– Cannot control very well (either fully nitrifying or NO nitrification)
– Best at SRT = 12-15 days
Crocker & Associates, Inc.
Best to be here!
Aqua-Aerobic Systems, Inc.
Characteristics
– Optimum pH 7.0 - 8.0, stops below 6.0
– Maximum temp 40oC
– Consumes 4.6 lbs O2/lbs NH3-N converted
– D.O. > 1.0, preferably 2.0 mg/L, distributed throughout basin (If Low D.O., must have higher SRT)
– Consumes 7.2 Gm alkalinity (ability of the water to neutralize acid) /Gm ammonia oxidized
– 0.15 Gm new cells Formed/Gm ammonia oxidized
Nitrification
Crocker & Associates, Inc.
10
pH Control/Alkalinity Addition
3.6NO3-N denitrified
0.9Na2CO3 (Sodium Carbonate)
1.2NaOH (Sodium Hydroxide)
1.4Mg(OH)2
(Magnesium Hydroxide)
1.8CaO (Calcium Oxide)
Mg Alkalinity as CaCO3 per mg of Source Mat’l
Source Material
Crocker & Associates, Inc.
Aqua-Aerobic Systems, Inc.
Organic Carbon Absence of O2
Nitrogen Gas (N2)
Nitrate (NO3-N)
Denitrification
Absence of O2Carbon
Note: Must Nitrify first to be able to Denitrify!
Crocker & Associates, Inc.
Aqua-Aerobic Systems, Inc.
Denitrification
NO3- + (5/6)CH3OH (5/6)CO2 + ½ N2 + (7/6)H2O + OH-
Methanol
(or other
carbon source) Increase alkalinity
Crocker & Associates, Inc.
11
Aqua-Aerobic Systems, Inc.
Characteristics
– Optimum pH 7.0 - 8.5
– Produces 2.86 lbs O2/lb NO3-N converted (“Denitrification O2 Credit”)
– D.O. < 0.5 mg/l
– Recovers 3.6 Gm alkalinity /Gm NO3-N denitrified
– 0.45 Gm new cells formed
– Consumes 1.9 Gm Methanol/Gm NO3-N reduced
Denitrification
Crocker & Associates, Inc.
Aqua-Aerobic Systems, Inc.
Benefits prior to clarification
– Returns 63% of nitrification O2
– Returns 50% of nitrification alkalinity
– Eliminates discharge of algal nutrient
– Eliminates discharge of toxic NO2-
– Eliminates drinking water issues
– Controls nitrite chlorine demand
Denitrification
Crocker & Associates, Inc.
Aqua-Aerobic Systems, Inc.Crocker & Associates, Inc.
Typical Nitrification WWTP Processes Include:
Activated Sludge
• Conventional
• Pure Oxygen
• Contact Stabilization
• Extended Aeration
• Oxidation Ditch
• Sequencing Batch Reactor
Trickling Filters
Rotating Biological Contactors
In my opinion, most
flexible and easily enables denitrification
12
Your Wastewater Specialists
AquaSBR®
Operating Phases
Aqua-Aerobic Systems, Inc.
Aqua-Aerobic Systems, Inc.
AquaSBR - Operating Phases
Aqua-Aerobic Systems, Inc.
13
Time Based Operation
Increased Operator Control
Mix Fill React Fill React Settle
React Settle Decant Mix Fill React Fill
SBR 1
SBR 2
Decant
SBR 1 SBR 2
AquaSBR - Operating Phases
Aqua-Aerobic Systems, Inc.
Aqua-Aerobic Systems, Inc.
AquaSBR - Operating PhasesProposed Peurifoy WPCP Phase Structure
AquaSBR - Mixed Fill
Aqua-Aerobic Systems, Inc.
14
Mixer: AquaDDM
Aqua-Aerobic Systems, Inc.
AquaSBR - Mixed Fill
Mixed Fill
Anaerobic/Anoxic
Environment
OrganicLoading
CompletelyMixed
ConditionsBiomass
Alkalinity recovery through denitrification can occur
Aqua-Aerobic Systems, Inc.
AquaSBR - React Fill
Aqua-Aerobic Systems, Inc.
15
AquaSBR - React Fill
React Fill
Aerobic/Anoxic
Environment
OrganicLoading
CompletelyMixed
Aerobic/Anoxic Metabolism
Nitrification consumes alkalinity
Aqua-Aerobic Systems, Inc.
Aqua-Aerobic Systems, Inc.
AquaSBR - React
Aqua-Aerobic Systems, Inc.
16
AquaSBR - React
React
Aerobic/Anoxic
Environment
Termination of Organic Loading
CompletelyMixed
Polishing ofEffluent
Nitrification and metal salt addition consumes alkalinity
Aqua-Aerobic Systems, Inc.
AquaSBR - Settle
Aqua-Aerobic Systems, Inc.
AquaSBR - Decant/Waste Sludge
Aqua-Aerobic Systems, Inc.
17
AquaSBR - Decant/Waste Sludge
Aqua-Aerobic Systems, Inc.
AquaSBR - Decant
Maintains Design MLSS
1-1.5% Concentration (Fluidized)
Subsurface Withdrawal
Follows Liquid Level
Absolute Seal
AquaSBR – Sludge Waste
Aqua-Aerobic Systems, Inc.
AquaSBR®
System Components• Aeration System• Mixer • Decanter • Controls
Aqua-Aerobic Systems, Inc.
18
Aeration
•Retrievable/fixed fine-bubble diffusers•Retrievable/fixed coarse-bubble diffusers
•Mechanical surface aerators
Aqua-Aerobic Systems, Inc.
SURFACE AERATOR: Aqua-Jet®
Aqua-Aerobic Systems, Inc.
RETRIEVABLE
COURSE-BUBBLE
Crocker & Associates, Inc.
19
RETRIEVABLE
FINE-BUBBLE
Aqua-Aerobic Systems, Inc.
0
1
2
3
4
5
6
7
8
9
10
0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0
Air Flow - SCFM/Diffuser
SAE - lb. O2/Hr/HP
MixAir® - Aeration ComparisonSAE – lbs. O2 delivered/hour/bHP
Fine Bubble Diffused Air
5-7 lbs. O2/bhp-hr
Surface Low-Speed: 2.0-4.0 lbs. O2/bhp-hr
Aqua-Aerobic Systems, Inc.
0
1
2
3
4
5
6
7
8
9
10
0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0
Air Flow - SCFM/Diffuser
SAE - lb. O2/Hr/HP
MixAir® - Aeration ComparisonSAE – lbs. O2 delivered/hour/bHP
Fine Bubble Diffused Air
5-7 lbs. O2/bhp-hr
Savings of 2 lbs. O2/hp-hour = saves $15,000 annually per 1.0 MGD treated
Aqua-Aerobic Systems, Inc.
20
Mixing
Direct drive Mixer-blender
Aqua-Aerobic Systems, Inc.
AquaDDMProven Mixing Efficiency
The AquaDDM establishes
a powerful downflow
mixing pattern that
transports surface liquid downward and increases
mass transfer. Flow
entrainment and regenerative flow create
high reactor turnover rates
for efficient mixing.
Crocker & Associates, Inc.
AquaMixAir®
Independent Mixing — Improved aeration efficiency
The MixAir System utilizes
fine/coarse-bubble diffusers or
floating aerators along with
the AquaDDM mixer. The MixAir System provides full
range aeration control without
compromising mixing, by enabling the operator to
operate the aeration system
only when oxygen is required.
Click to animate
Aqua-Aerobic Systems, Inc.
21
Decanting
Floating Decanter
Aqua-Aerobic Systems, Inc.
DECANTER: AquaDecanter®
Crocker & Associates, Inc.
DECANTER
Aqua-Aerobic Systems, Inc.
22
SLUDGE PUMP
Aqua-Aerobic Systems, Inc.
Controls
Aqua-Aerobic Systems, Inc.
Aqua-Aerobic Systems, Inc.
CONTROL SYSTEM
23
AAS SCADA: Plant Overview
Crocker & Associates, Inc.
AAS SCADA: SBR Overview
Crocker & Associates, Inc.
AAS SCADA: Equipment Detail
Crocker & Associates, Inc.
24
SBR Biological Process Control
Crocker & Associates, Inc.
What Can You Change with an AquaSBR?
• Number of Basins online
• Number of Cycles
– e.g., 4/day/basin, 5/day/basin
• Phase length times within Cycle
– Mix Fill, React Fill, React, Settle, Decant
• Aeration cycling and duration (D.O. control)
• Sludge Waste duration
• Chemical Feed set points
Process Control
Aqua-Aerobic Systems, Inc.
Dissolved Oxygen (D.O.) Control
SBR PLC controls max/min D.O. concentration using probe signals during aeration “on” time
Crocker & Associates, Inc.
0.0
1.0
2.0
3.0
4.0
5.0
0 50 100 150 200 250 300 350
Time (min)
D.O
. SBR #1
SBR #2
25
What can be done to stay on top of
process conditions?
• Keep good eye on control parameters– Flow
– MLSS
– Settleability
– Microscope observation
– D.O.
– SRT
• Trend it! Make a Chart—
Crocker & Associates, Inc.
Which is easier to evaluate?
MLSS
8/1/2005 2502
8/3/2005 2490
8/5/2005 2530
8/7/2005 2480
8/9/2005 2470
8/11/2005 2450
8/13/2005 2455
8/15/2005 2420
8/17/2005 2425
8/19/2005 2410
8/21/2005 2440
8/23/2005 2390
8/25/2005 2410
8/27/2005 2380
8/29/2005 2400
8/31/2005 2360
MLSS
2250
2300
2350
2400
2450
2500
2550
8/1/2
005
8/3/2
005
8/5/2
005
8/7/
2005
8/9/
2005
8/11/
2005
8/13/
2005
8/15
/200
5
8/17
/2005
8/19/
2005
8/21/
2005
8/23/
2005
8/25/2
005
8/27
/200
5
8/29
/200
5
8/31/
2005
MLSS
(A)
(B)-OR-
Crocker & Associates, Inc.
How to make changes
• Slowly—No more than 10% per data
collection point period unless “emergency”
• Consider what might happen in reaction to
your changes—Good AND Bad
• Don’t be scared! You’re the professional—You know the plant better than anyone
Crocker & Associates, Inc.
26
SBR Biological Process Control
Example
Crocker & Associates, Inc.
Two SBRs
Two ABFs
Stephen D. Peurifoy WPCP, Stockbridge GA
Control Room
Post-EQ
Aqua-Aerobic Systems, Inc.
Changes in Conditions at Peurifoy WPCPAugust 2005
• Increased flow: 0.6 MGD to 0.8 MGD
• Loading still about 250 mg/L BOD5
• Max D.O. during React Fill & React from
0.6 mg/L to 0.8 mg/L
• Settling not quite as good but still OK
• What do you do?
Crocker & Associates, Inc.
Process Control Example
27
Summary of Control Changes at
Peurifoy WPCPJuly Aug
MF 100 80
RF 80 100
R 75 80
S 60 60
D 45 40
MLSS 2400 2600
Blowers
Cycle 1 45/30 50/30
Cycle 2 45/25 50/30
Cycle 3 30/15 30/15
Cycle 4 20/20 20/10
Cycle 5 15/15 30/30
Crocker & Associates, Inc.
Phosphorus
Crocker & Associates, Inc.
Crocker & Associates, Inc.
What is Phosphorus?
• Essential part of the nutrient cycle in nature,
along with others such as sodium, potassium,
calcium, iron, copper, etc.
• Atomic Number = 15
• Word derives from Greek phosphoros: light
bearing; ancient name for the planet Venus
when appearing before sunrise)
• Brand discovered phosphorus in 1669 by
preparing it from urine.
28
Sources of Phosphorus
• Fecal and waste materials
• Paint strippers, soft drinks, toothpaste, and baking powder
• Industrial and commercial uses
• Synthetic detergents and cleaning products
Crocker & Associates, Inc.
Crocker & Associates, Inc.
Phosphorus Limits in GA Lakes:
Lake Lanier
36,900 pounds / year
West Point Lake (from Chattahoochee River)
1,400,000 pounds / year
Lake Allatoona
16,200 pounds / year to each of:
Bartow County
Cobb County
City of Canton
Cherokee Co. WSA
Lake Jackson
Discharge specific basis
Division of the Influent P Into Constituent
Fractions
TOTAL INFLUENT P
ORTHOPHOSPHATEReactive P
PO4-3 Predominant
ORGANICALLY-BOUNDPHOSPHATES
POLY-PHOSPHATES(Hydrolyzable)
Crocker & Associates, Inc.
29
Poly-Phosphates:
• Poly-phosphates include molecules with two or more
phosphorus atoms, oxygen atoms, and hydrogen atoms,
combined in a complex molecule
• Not removable by metal salt addition
• Reduced over time through hydrolysis to orthophosphate
• De-polymerized in anaerobic step of biological
phosphorus removal
Crocker & Associates, Inc.
Orthophosphates:
• Available for biological metabolism without further
breakdown
• This is the reactive form of phosphorus
It is the ONLY form of phosphorus whose removal
can be enhanced by metal salt addition.
Crocker & Associates, Inc.
• Goal: Incorporate Phosphorus into TSS
• Conventional: 1-2% P in WAS(typical 10-30% removal using secondary
treatment)
• Augmented: 3-6% P in Waste Sludge
– Biological
– Chemical
Available Phosphorus Removal Options
Crocker & Associates, Inc.
30
Biological Solids are Typically
3 - 5% Phosphorus(No Chemical Involved)
Effluent TSS P in Effluent TSS
2
5
10
15
0.06 - 0.10
0.15 - 0.25
0.3 - 0.5
0.45 - 0.75
Crocker & Associates, Inc.
• Should NOT be thought of as cure-all for
phosphorus removal
• Membranes are just a type of filter
(A relatively expensive one, too)
• Should phosphorus be in soluble form,
membranes will not take it out
• Other options available
Membranes
Crocker & Associates, Inc.
Enhanced Biological Phosphorus Removal
Aqua-Aerobic Systems, Inc.
31
• Incorporate P into sludge
Earliest research performed by Levine and Shapiro in 1965
• Reduce metal salt costs
• Reduce polymer costs
• Reduce alkalinity adjustment costs
• Denitrification benefit
Enhanced Biological Phosphorus Removal
(EBPR)
Aqua-Aerobic Systems, Inc.
Schematic of EBPR
Aqua-Aerobic Systems, Inc.
EBPR: Basic Features
• Anaerobic Conditions: Release Phosphorus
• Aerobic Conditions: Store Phosphorus
• Selects microorganisms that accumulate
higher levels of intracellular phosphorus than
other microorganisms
– Phosphorus accumulating organisms (PAOs)
exhibit “luxury uptake”
Aqua-Aerobic Systems, Inc.
32
EBPR Issues
• Low BOD/TP ratios result in BPR failure because PHA storage becomes too
low to produce the reducing equivalents for ATP production in the aerobic stage
• Excessive BOD/TP ratios have been found to act as an inhibitor to PAOs
• Appropriate BOD/TP ratios ~ 20-30:1 (Peurifoy WPCP~31:1)
• Only readily biodegradable COD can be converted to VFAs, which are taken up
by PAOs in anaerobic stage
• Phosphorus release in anaerobic conditions is faster in higher concentration
sludge than lower
• If TKN/COD ratio > 0.14, insufficient denitrification occurs— Complete
denitrification occurs at < 0.08
• Recycles must be accounted for (P and N)
• Too long of an anaerobic contact time allows phosphorus release to occur
without the uptake of VFAs. When this occurs, there is not enough energy to
force the full uptake of the released phosphorus in the aerobic contact period
Aqua-Aerobic Systems, Inc.
EBPR Systems
• BardenPho (Phoredox)
• Oxidation Ditch
4Q
Q
Q
Aqua-Aerobic Systems, Inc.
SBR EBPR Example
Aqua-Aerobic Systems, Inc.
33
• 4 cycles/day/Basin– MF = 100 min.
– RF = 80 min.
– R = 75 min.
– S = 60 min.
– D = 45 min.
360 min. Total
• MLSS = 2,400 mg/l
• Aeration Timers:
Total/On
– 45/30
– 45/25
– 30/15
– 20/20
– 15/15
Stephen D. Peurifoy WPCP Operation:
July, 2005
Aqua-Aerobic Systems, Inc.
0.0
1.0
2.0
3.0
4.0
5.0
0 50 100 150 200 250 300 350
Time (min)
D.O
. SBR #1
SBR #2
Aeration
–45/30
–45/25
–30/15
–20/20
–15/15
Mix Fill React Fill React Settle Decant
Stephen D. Peurifoy WPCP
Anerobic, Aerobic, and Anoxic Periods within SBR Cycle
05/13/05, 05/18/05
Aqua-Aerobic Systems, Inc.
AquaSBR® - Total Phosphorus (typical)
Aqua-Aerobic Systems, Inc.
34
Design Data
Peurifoy AquaSBR®
Influent Effluent
ADF (MGD) 1.5 - -
MDF (MGD) 1.9 - -
BOD5 (mg/L) 250 6.0
TSS 250 20
TKN 40 - -
NH3-N - - 1.3
Total P 5.0 0.3
0.15 mg/L Total P without chemical addition
Aqua-Aerobic Systems, Inc.
Actual (June 2008)Influent Effluent
ADF (MGD) 0.534 0.461
MDF (MGD) - - - -
BOD5 (mg/L) 245 2.0
TSS 305 1.4
TKN - - - -
NH3-N 22.3 0.09
Total P 7.9 0.15
Total Phosphorus in EffluentJan – Dec 2004
Stephen D. Peurifoy WPCP
0
0.2
0.4
0.6
0.8
1
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
TP
(m
g/L
)
Note: Sampling indicates TP ~0.2 mg/L prior to filters
– Phosphorus being removed overwhelmingly through EBPR –
Aqua-Aerobic Systems, Inc.
Chemical Phosphorus Removal
Aqua-Aerobic Systems, Inc.
35
• Goal: Create insoluble forms of P
• Basic Elements to Precipitate P
– Ferrous Iron — Fe(II)
– Ferric Iron — Fe(III)
– Aluminum
– Lime — Ca(OH)2
Chemical Phosphorus Removal
Crocker & Associates, Inc.
• Alum (Aluminum Sulfate) — Al2(SO4)3.14H2O
Al+3 + HnPO4n-3 AlPO4 + nH+
• Ferric Chloride — FeCl3
Fe+3 + HnPO4n-3 FePO4 + nH+
• Poly Aluminum Chloride (PAC)
Common Chemicals Used
Crocker & Associates, Inc.
• Ideal pH for AlPO4(s) is 6.3
• Ideal pH for FePO4(s) is 5.3
Metal Salt Addition Considerations
Crocker & Associates, Inc.
36
• Ideal pH for AlPO4(s) is 6.3
• Ideal pH for FePO4(s) is 5.3
• Actual Requirements > Stoichiometry
– Typically 1-3 metal ions per one Phosphorus ion
• Proper location(s) for chemical addition
– Headworks, Mixed Liquor, Secondary Effluent, Digester
• Chemical Cost
• Dry or liquid
Metal Salt Addition Considerations
Crocker & Associates, Inc.
• Storage Issues
• Increased removals increase sludge production
• Sludge handling issues
• Disposal issues
• Corrosion and Staining
• Alkalinity supplementation
– In low alkalinity waters, addition of base may be
needed to keep pH in appropriate range
Metal Salt Addition Considerations (cont.)
Crocker & Associates, Inc.
% P Reduction Mg Al per mg P
75
85
95
1.2 – 1.5
1.6 – 1.9
2.1 – 2.6
Typical Aluminum Dosage as a Function of
Ortho-Phosphate Removal
Crocker & Associates, Inc.
37
AquaSBR®: Chemical Feed
Metal Salt Addition, Alkalinity Addition
Alkalinity Addition
Aqua-Aerobic Systems, Inc.
SBR Chemical Phosphorus Removal
Example
Aqua-Aerobic Systems, Inc.
AquaSBR
Aqua-Aerobic Systems, Inc.
38
• 5.33 cycles/day/Basin– MF = 50 min.
– RF = 85 min.
– R = 50 min.
– S = 55 min.
– D = 30 min.
270 min. Total
• MLSS = 3,210 mg/L
• MLVSS = 2,735 mg/L
• DO Control Program
Blower Always ON
Set 3.5-4 mg/L
• pH Control Program
Setpoint – 6.58
Gain – 5 (0-10)
• Alum Addition Program
Dosage - 105 mg/L
Dick Creek WRF Operation:
Crocker & Associates, Inc.Aqua-Aerobic Systems, Inc.
pH Control System
• pH meter/controller for each SBR
• Caustic Feed pump skids with motorized valves
• Caustic added to SBRs during React-Fill and React cycles
• Flow rate of caustic is in response to SBR tank pH in
comparison to setpoint input through SBR control panel
interface
• Flow rate is adjusted according to a proportional-integral loop
• Caustic pump will shut off when the process variable reaches
an adjustable threshold of the desired setpoint
• Gain input value determines output reaction – high gain,
quicker response
Crocker & Associates, Inc.
Alum (or Polymer) Feed System
• Alum feed pump skid with motorized valves
• Volume of each batch calculated by pressure transducer level
indication at the end of React-Fill
• Quantity of alum fed is directly proportional to batch volume
• Alum dosage (mg/L) is input by Operator through SBR
control panel interface
• Calculated gallons of alum are paced into SBR through the
length of the React cycle minus an “end” Offset Time
• This Offset Time allows for React cycle mixing without alum
feed to ensure sufficient alum dispersion and phosphorus
precipitation prior to Settle phase
Crocker & Associates, Inc.
39
Dick Creek WRF – Sampling Data
Dick Creek WRF Direct Discharge Effluent Permit (Nov-Apr, 83.0 MG total):5 mg/L BOD, 5 mg/L TSS, 3 NTU, 1 mg/L NH3-N, 0.13 mg/L Total P
Aqua-Aerobic Systems, Inc.
Influent
Pump
Station Screening AquaSBR®
PAC
Filtration
BOD5 < 4 mg/LNH3-N < 0.5 mg/LTotal P < 0.13 mg/L
High-Level SBR Treatment Process Flow
Aqua-Aerobic Systems, Inc.
Grit Removal
Mag Meter
PAC
Inline Mixer Post-EQMag Meter Flow Control
Valve
UV
Effluent
Questions?
Aqua-Aerobic Systems, Inc.
40
Superior Wastewater Treatment Utilizing SBR Technology
GRWA SBR Training
November 6, 2008
Stuart Humphries, Crocker & Associates, Inc.770-855-8090, [email protected]
www.crocker-associates.com, www.stuarthumphries.com
AQUA-AEROBIC
SYSTEMS, INC.