ORP Improves Operational Efficiency - ORP Presentation.pdfREDUCTION (CHEMICAL) ORP Definition Bing...
Transcript of ORP Improves Operational Efficiency - ORP Presentation.pdfREDUCTION (CHEMICAL) ORP Definition Bing...
OXIDATION
(CHEMICAL)
ORP Definition
Bing says 8,650,000 definitions 1. A chemical reaction in which oxygen is
added to an element or compound
2. The process of losing electrons from a chemical element or compound
Example: Nitrification 2NH4
+ + 3O2 -> 2H+ + 2H2O + 2NO2-
2NO2- + O2 -> 2NO3
-
REDUCTION
(CHEMICAL)
ORP Definition
Bing says 50,300,000 definitions Any chemical reaction in which the atoms in a material take on electrons. Note: Reduction is the opposite of oxidation. Example: Denitrification 2NO3
- + organic matter -> N2(Gas) + CO2 + H2O
POTENTIAL
ORP Definition
Bing says 204,000,000 definitions 1.Possible but as yet not actual: having a latent possibility or likelihood of occurring, or of doing or becoming something
2.Capacity for development: a capacity to develop, succeed, or become something
How steep is the hill you are standing on?
ORP Definition
In wastewater treatment, ORP is:
A measure of the ability or potential of a wastewater to permit specific biological reactions (oxidation and or reduction).
YSI Environmental
–Application Note
ORP Biological Values
Biochemical Reactions and Corresponding ORP Values
Biochemical Reaction ORP, mV
Nitrification +100 to +350
cBOD degradation with free molecular oxygen +50 to +250
Biological phosphorus removal +25 to +250
Denitrification +50 to -50
Sulfide (H2S) formation -50 to -250
Biological phosphorus release -100 to -250
Acid formation (fermentation) -100 to -225
Methane production -175 to -400
Where Might You Use ORP
• Collection System
• Lift Stations
• Sewers
• Treatment Plant
• Activated Sludge
• Anaerobic
• Anoxic
• Aerobic
• Digesters
• Fermenters
• Final Clarifiers
How Use ORP
• Collection System
• Hydrogen Sulfide Control
• Treatment Plant
• CBOD removal
• Nitrification
• Denitrification
• Biological Phosphorous Removal
• Fermentation
• Methane production
YSI Environmental
–Application Note
ORP Biological Values
Biochemical Reactions and Corresponding ORP Values
Biochemical Reaction ORP, mV
Nitrification +100 to +350
cBOD degradation with free molecular oxygen +50 to +250
Biological phosphorus removal +25 to +250
Denitrification +50 to -50
Sulfide (H2S) formation -50 to -250
Biological phosphorus release -100 to -250
Acid formation (fermentation) -100 to -225
Methane production -175 to -400
Placement ORP Probe
• Understand the process
• Location is Critical
• Avoid influence of process equipment
• Be aware of process phases
• Maintenance required
Large Community
Random Odor complaints
• Could not be tied to operational changes
• Could not be tied to wet/dry weather events
Sewer Collapse in Area
Have high H2S levels but why?
Collection System
Sample
Event
Results
Collection System
Units 8/28/2010 8/29/2010 8/30/2010
Lab
BOD5 mg/l 380 89 285
Sulfate mg/l 4.21 21.7 10.6
Total Sulfide mg/l 5.4 3 3.9
TSS mg/l 568 46 307
Field
pH s.u. 7.75 7.63 7.99
Temp °C 21 22.95 25.02
D.O. mg/l 3.93 2.62 3.01
Dis Sulfide mg/l 4.55 5.35 3.25
H2S, Air ppm 37 66 27
% O2 % 20.9 20.9 20.9
LEL s.u. 0 0 0
The
Rest
Of
The Story
Collection System
Units 8/28/2010 8/29/2010 8/30/2010
Lab
BOD5 mg/l 380 89 285
Sulfate mg/l 4.21 21.7 10.6
Total Sulfide mg/l 5.4 3 3.9
TSS mg/l 568 46 307
Field
pH s.u. 7.75 7.63 7.99
Temp °C 21 22.95 25.02
D.O. mg/l 3.93 2.62 3.01
Dis Sulfide mg/l 4.55 5.35 3.25
H2S, Air ppm 37 66 27
% O2 % 20.9 20.9 20.9
LEL s.u. 0 0 0
ORP mv -68.6 -89.3 -61.4
WWTP Upset Background
• Plant 1. Aerated Lagoon System 2. Settling Ponds 3. Storage Ponds
• Operations 1. Monitor Influent and Effluent
for standard parameters 2. DO measured at effluent 3. As Effluent DO varies, adjust air
feeds • Event
1. Over very short period went anaerobic
2. With all aeration on, could not meet demand
hjg
WWTP Upset - Investigation
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Effluent Dissolved Oxygen vs. Aerators
Aerators
WWTP Upset - Investigation
• Mixers turned off to save energy when DO demand low
• When mixers turned on: 1. Re-suspend solids
2. Initial increase in DO demand
3. Some Odor
• During spring warm-up 1. Increasing biological activity
2. Influent Loading
3. Stored Loading • Mixer selection based on effluent
DO, which indicated wastewater carrying a positive DO
WWTP Upset Background
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Aerators vs. Temperture
Temperature
Aerators
hjg
WWTP Upset Background
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DO vs. ORP Results
WWTP Upset - Findings
• Operator placed in a no win situation by positive DO probe results
• Actual events 1. Spring with warm
temperatures 2. Entire volume went
anaerobic 3. Turned on mixers for more
air, which in turn added more demand
• DO probe under influence of point of re-aeration
• Mixers must be turned on before demand
Aerobic Digestion/Holding
• Holds Activated Sludge
• Fully Automated Controls
1. Level Sensor
2. DO Sensor
3. ORP Sensor
• Process Operations
• Fill – Selected Tank
• Mix/Aerate
• Settle/Decant
• Feed ISPs