Optimizing Nutrient RemovalPNCWA - Southeast Idaho Operators Section Pocatello, ID | February 11, 2016| Jim Goodley, P.E.
Types of Optimization
Outline
• Wastewater Characterization
• BNR Optimization
– N Removal
– P Removal
• Physical-Chemical
Types of Optimization
• Pollutant Removal- Nutrients
• Capacity- Flow/Loading
• Energy Use-Efficiency
• Operating Costs
• Effluent Stability
• Etc., Etc.
Total COD
Biodegradable
COD
Colloidal COD
Slowly
Biodegradable COD
Non-Biodegradable
COD
Particulate
COD
Soluble COD
VFA COD
Complex
Soluble COD
Particulate COD
Readily-
Biodegradable COD
Important
for BNR
Wastewater Characterization
• COD• Readily Biodegradable
rbCOD (soluble)• Soluble Complex COD
• e.g. Fermentable
• Volatile Fatty Acids (VFA’s)• aka SCFA- short chain fatty
acids
– Carbon source for:• EBPR- Phosphorus Release• Pre-denitrification
Filter (0.45um ) to determine ‘soluble’ (includes colloids) vs. particulate components
Total TKN
Organic
Nitrogen
Soluble
Organic N
Biodegradable
Organic N
Free Ammonia
(NH4-N)
Soluble Organic
N (rDON)
Particulate
Organic N
Particulate
Organic N
Non-Biodegradable
Organic N
Typically
1-2 mg/L
Total NitrogenNitrate/Nitrite
NO3-N/NO
2-N
Total
Phosphorus
Organically Bound
Phosphorus
Soluble
Organic P
Non-Biodegradable
Organic P
Orthophosphate
(soluble)
Soluble
Organic P
Particulate
Organic P
Particulate
Organic P
Biodegradable
Organic P
Typically
Largest
Fraction
(60-80%of TP)
BNR Process Fundamentals
• Predominant Conditions
• P Removal : Anaerobic – Aerobic• EBPR- Enhanced Biological Phosphorus Removal
• N Removal: Anoxic –Aerobic
• N&P Removal: Anaerobic-Anoxic-Aerobic
– BNR Process Challenge: Conflicting Environments
Optimizing Nitrogen Removal
• Nitrogen Removal Requirements
– Series Anoxic & Aerobic Conditions
– Carbon Source
– Internal (Nitrate) Recycle
TKN
NH3-N
NO3-N
NO2-N
Org-N
Optimizing Nitrogen Removal
• True Anoxic- No/Very Low Dissolved Oxygen– Internal Recycle- Make Sure D.O. is low, < 0.5 mg/L
– Influent (Aerated Grit Removal)
– Mindful of Aeration Design- Low Loading Periods• Provide Turndown
• Consider ‘jockey’ Blower
– Do not entrain air• Vortexing
• Cascades
Optimizing Nitrogen Removal
• Substrate (Carbon) Sources– Internal Sources:
• Influent, Fermenter
• rbCOD/SCFA/VFA’s
• Analyze Your Influent (WW Characterization)
– ‘External’ Sources• Methanol
• ‘Micro-C’, glycerine
• Other Sources- Beverage/Food Processing Wastes
Affects/Impacts Denitrification Rate
Optimizing Nitrogen Removal
• Internal Recycle– Make sure the rate is optimal
– Put VFD’s on Pumps
HRT Too Low
Nitrate
Concentration
Too High
Optimized
Optimizing Nitrogen Removal Source: USEPA Nitrogen Control Manual
Control based on NO3-N Concentration at end of pre-anoxic zoneUse on-line NO3-N analyzer
IF NO3-N = 0 mg/L THEN increase IRQ flow rateIF NO3-N ~ 0-0.5 mg/L THEN no change IF NO3-N >0.5 mg/L THEN decrease IRQ flow rate
Influent
Return activated sludge
AnoxicEffluent
Sludge
Anaerobic
Secondaryclarifier
Aerobic
Internal/Nitrate Recycle
Anoxic
Ae
rob
ic
N03
Optimizing Nitrogen Removal
Optimizing Nitrogen Removal
• Swing Zone- Flexibility to Adapt Volume
1 2 3A 4A 5 6
Return Sludge
Internal RecycleInf.
3B 3C 4B
Swing Zone
•Winter – Aerobic, need volume for nitrification
•Summer- Anoxic, enhance denitrification
Optimizing Phosphorous Removal
• Enhanced Biological Phosphorous Removal (EBPR) – EBPR Requirements
• Series Anaerobic-Aerobic Conditions (Luxury Uptake)
• Carbon Source
• Solids Removal
• Chemical Removal– Metal Salts- Ferric or Alum Typ.
– Mixing is Key
Optimizing Phosphorous Removal
• Anaerobic Conditions
– NO Dissolved Oxygen
– NO Nitrate
– Check P Release
Optimizing Phosphorous Removal
• Carbon (Readily Biodegradable)
– Volatile Fatty Acids
– COD:P Ratio (>45:1)
– Fermentation
– External Sources• Methanol
• Glucose
Optimizing Phosphorous Removal
• Process Sidestreams– Solids Handling
• Phosphorus ‘Recycling’
• Anaerobic Conditions (Unwanted P Release)
• Solids Dewatering- High P Load
– Sidestream Treatment
Once it’s out, keep it out
Optimizing Phosphorous Removal
Physical-Chemical Methods
• Physical –Filtration
– Remove TSS that contain phosphorus
and
– Remove chemical solids, bound phosphorus
Optimizing Phosphorous Removal
Physical-Chemical Methods
• Chemical
– Metal Salts• Alum
• Ferric
Questions?
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