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?