Bioscience, Inc.

Allentown, PA www.bioscienceinc.com

The Biological Process of Wastewater Treatment Jay Hill Product Manager

Typical Wastewater Treatment Steps

• Coarse Physical Treatment • Settling of Suspended Solids/Floatables • Biological Treatment of Dissolved/ Fine Solids • Recovery of Biomass • Removal of Inorganics • Disinfection • Excess Biomass Removal

Primary Treatment

• Bar Screen • Clarifier – Primary sludge • Sand/grit • Coarse organic matter – Floatables • FOG • DAF or API Separator – FOG, petroleum HC, light solids

Activated Sludge Systems

O 2 CO 2

Untreated Discharge Clean Water Aeration Tank Clarifier Recycled Sludge Biomass (Secondary Sludge)

Secondary Clarification

• Clarifier – Secondary sludge • Fine organic matter – Floatables • FOG

Solids Processing

• Sludge Thickening • Aerobic or Anaerobic Digestion • Centrifuge • Belt Press • Incineration, Land Application, Fertilizer, Landfill

Aerobic Microbial Respiration C,H + O

2

*

CO

2

+ H

2

O + protein

* bacteria, N, P, pH, temperature

Composition of Wastewater

 Inorganics   Ammonia Nitrate    Phosphate Carbonate Minerals     Calcium Magnesium Iron Etc.

 Organics   Biodegradable (BOD)    Carbohydrates Proteins (TKN) FOG Non-Biodegradable (COD-BOD)      Large particles Complex polymers (plastics, lignin) Surfactants (some) Pesticides (some) Pharmaceuticals (some)

Requirements for Growth of Microbes

     Temperature pH Water activity Energy source Nutrients   Carbon Nitrogen    Phosphorus Minerals Vitamins/growth factors

Temperature



Thermophiles

 40°C to >100°C  

Mesophiles

 10°C to ~45°C

Psychrophiles

 <5°C to ~35°C

pH



Acidophiles

 pH 0-6  

Alkaliphiles

 pH 8-13

Most bacteria prefer pH 6-8



Most fungi prefer pH 4-7

Water Activity

  Salt content of water  Fresh water <1% NaCl (most bacteria)    Brackish water ~1-3% NaCl (limits some species) Seawater ~3.5% NaCl (salt tolerant only) Saline water up to 30+% (saturated NaCl)- (only few species) Soils (moisture content and salts)  50-100% FMC (most bacteria)  Fungi tolerate lower moisture content

Energy Sources

     Oxygen (aerobes) C 6 H 12 O 6 + 6 O 2  6 CO 2 +6 H 2 O  Autotrophs    NH 4 + + 2 O 2  NO 3 + H 2 O + 2 H + (Nitrifiers) H 2 S + 2 O 2  SO 4 H 2 S + 0.5 O 2  S - 0 + 2 H + H 2 + (sulfur oxidizers) O (sulfur oxidizers) Nitrate (facultative) C 6 H 12 O 6 + 6 H 2 O / 5 H 2 +2 NO 3 + 2 H +  N 2 + 6 H 2  6 CO 2 + 12 H 2 O (denitrifiers) Sulfate (anaerobes) C 2 H 4 O 2  CO 2 / SO 4 (sulfate reducers) -  H 2 S Carbon dioxide (anaerobes) CO 2 + 4 H 2 (methanogens)  Fermentation C 6 H 12 O 6  2 CO 2 +2 C 2 H 5 OH CH 4 +2 H 2 O

Nutrients Required for Growth

       Carbon  Usually from food source or CO 2 Nitrogen  Usually from ammonia, nitrate or simple organics (amino acids) Phosphorus  Inorganic phosphate Sulfur  Inorganic sulfate or simple organics Minerals (Ca, Mg, K, Na, Fe) Trace elements (Ni, Co, Cu, Mo, Zn) Growth factors/vitamins

Operation Limits

 pH 6-9 <4: Most bacteria dead or inactive <6: Bacteria activity drops, fungi may create settling problem <6.5: Nitrification very poor 7.5: optimum for hydrocarbons, fog, nitrification, sulfide >9: Bacteria activity drops  Nutrients BOD:N:P = 100:5:1 Effluent ammonium-N <2 mg/L may limit BOD removal or slow response to slug loading Effluent ammonium-N <0.5 mg/L probably deficient unless nitrifying (nitrate provides N) Effluent ortho-phosphate <1 mg/L may limit BOD removal or slow response to slug loading Effluent ortho-phosphate <0.2 mg/L probably deficient

Operation Limits

 Temperature <5°C Few bacteria are active <15°C Nitrification and most bacteria growth very slow 20-35°C Optimum for most bacteria 39-45°C Bacteria activity drops, death rate increases >45°C Only adapted or thermophilic processes occur  Biomass MLSS normally 1500-6000 mg/L <1500 poor settling, dispersed >6000 oxygen limited?; may overflow clarifier weir MLSS/MLVSS 80-90% <80% low viable percentage, possible accumulation of inert <70% may occur in aerobically digested sludge >90% light (poor settling) floc

Operation Limits

 Sludge Age/MCRT <3 days Poor settling/COD removal/high sludge production <8 days May have poor nitrification >20 days May have filament problems or pin floc; good for exotic chemical degradation and sludge digestion  SOUR Complete mix system 3-15 mg O2/g MLSS per hour <3 Inhibition or severe underload >15 Slug load/ possible overloading Staged aeration –1 st Stage 30-100 mg O2/g MLSS per hour <20 Inhibition <30 Insoluble waste ` >100 Overloading

Operation Limits

 Dissolved Oxygen 2-7 mg/L normal range <0.5 Anaerobic <1 General BOD removal slows <2 Nitrification slows >7 Slow growth (inhibition) or underloaded >9 Bacteria dead or inactive  Sludge Blanket Normal range 3-7 ft below surface <3 feet(1 meter) poor settling or compaction; biomass may washout with flow increase >7 feet (2 meters) Rapid settling may leave dispersed solids in effluent

Typical Upsets

Heavy Organic Load Increased Growth/Respiration Reduced Dissolved Oxygen More Sludge to Clarifier Reduced Growth/Respiration Inadequate Removal Deflocculation of the Biomass Poor Settling Worse Effluent Elevated BOD/COD High Effluent Suspended Solids

Common Wastewater Problems

     

Poor Settling Effluent Violation (TSS or BOD) Filamentous Forms Poor Nitrification Toxicity Odors

Aerobic Microbial Respiration C,H + O

2

*

CO

2

+ H

2

O + protein

* bacteria, N, P, pH, temperature

Chemical Characterization of VISC 25

Parameter Result Comments

pH of 10% solution Alkalinity Ammonium-Nitrogen Nitrite-Nitrogen Nitrate-Nitrogen 10.5

37 meq/100 g 400 mg/L 5 mg/L <5mg/L Titrated to pH 7 w/HCl Color fades rapidly Turns yellow after cadmium addition Phosphate-Phosphorus Chemical Oxygen Demand 30 mg/L 71,000 mg/L

Wastewater Treatment Plant Performance Testing

Process control tests or performance evaluation tests to determine overall treatment process efficiency, identify or investigate problems, or evaluate specific ability to treat target compounds. Process control tests generally must be quick turnaround tests usually performed on-site to allow process adjustment in response to problems. However, some longer time-frame tests may be set up to predict or determine the effect of process changes or identify trends in process efficiency.

Some of the investigations performed by Bioscience have been designed to: 1.

evaluate foam or settling problems 2.

3.

measure nitrification rates or nitrification potential measure FOG degradation rates or potential 4.

5.

measure permissible loading rates for potentially toxic waste streams or septage measure effectiveness of bioaugmentation 6.

measure biomass kinetic constants for process design.

Wastewater Treatment Plant Performance Testing

Available methods include: Standard Methods 5210D Biochemical Oxygen Demand Respirometric Method (Respirometric Oxygen Uptake) Standard Methods 2710B Oxygen-Consumption Rate (Specific Oxygen Uptake Rate; Dissolved Oxygen Probe Method) OECD 209 Activated Sludge, Respiration Inhibition Test ASTM D5120 Standard test Method for Inhibition of Respiration in the Activated Sludge Process Short-Term BOD Test (EZ-BOD instrument test for influent or effluent BOD-5 estimation) Suspended Solids (Photometric Method) CONTRAL Biodegradation Kinetics Microscopic Evaluation of Biomass (Higher Forms and Filaments)

Wastewater Treatment Problems (AS) Problem FOG in collection Odor/H 2 S FOG in aeration basin High temperature/low activity No or partial nitrification Low COD or specific compound removal Excessive filaments Excessive sludge Poor sludge digestion Cause Various Anaerobic condition Slow digestion Hot process water Toxicity/low temp/low SRT/nutrients Low temp /various/industry specific various FOG/cellulose/etc accumulation in sludge Nutrient imbalance/FOG Cure DNT-RF/GEL DNT-RF/ANL DNT-RF/SXM/NPN/TM HT XNC/XNL/TM HX, XR, XP, etc.

XF, SXM, nutrients SR AD, SXM, TM

Wastewater Treatment Problems (Lagoon) Problem Odor/H 2 S Odor/NH 3 FOG in aeration basin High temperature/low activity No or partial nitrification Cause Anaerobic condition High NH 3 /High pH Slow digestion Hot process water Cure ANL/TN and/or aeration ECL DNT-RF/SXM/NPN/TM HT Low COD or specific compound removal Excessive sludge Animal waste consistency Algae Poor denitrification Toxicity/low temp/low SRT/nutrients Low temp /various/industry specific FOG/cellulose/etc accumulation in sludge High solids XNC/XNL/TM LF, HX, XR, XP, etc.

SR DL High nutrients (N,P) AL/ALN Low facultative population DEN

Bioaugmentation

How Does Bioaugmentation Work?

• Numbers – By adding cultures regularly the minor cultures (but important cultures) gain a survival advantage (against the dominant cultures) .

• Natural Genetic Interchange – Recent work indicates the possibility of transfer to the biomass of desirable and needed characteristics (but not permanently), particularly capabilities controlled by the plasmids in the cells and demanded by the conditions in the system.

Activated Sludge Culture Selector

The biomass is comprised of thousands of cultures of bacteria, fungi, protozoans, etc.

The system “selects” cultures with both major/dominant populations and minor counts. Both populations are important in obtaining good effluent quality.

The combination of cultures in the biomass continuously changes and adapts to changes in ambient conditions.

Major Versus Minor Cultures

• Major Cultures Grow rapidly settle well control the general nature of the biomass • Minor Cultures Produce important results Are more difficult to maintain in the biomass

The Transfer of Plasmids

a b d c Scientific American, January 1998, p. 68

Bioaugmentation Benefits

Benefits for Wastewater Treatment:

 Reduce Effluent Peaks (NPDES outages)  Reduce Effects of Toxic Compounds  Improve Settling Thru Filament Control  Enhance Process Stability  Reduce Sludge Production  Minimize Downtime/Reduce Labor

Filamentous Populations

Individual microbes do the work Microbes flocculate and form particles that settle But the filamentous forms inhibit settling

Nitrification

2NH 4 + + 3O 2 2NO 2 + 4H + + 2H 2 O 2NO 2 + O 2 2NO 3 -

Removal of insolubles

NH3 Treatment System

Removal of BOD Clarifier Recycle of Sludge Discharge of Sludge Removal of NOD Clarifier Recycle of Sludge Discharge of Sludge