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Bioscience, Inc.

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

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Bioscience, Inc.

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  1. Bioscience, Inc. Allentown, PA www.bioscienceinc.com

  2. The Biological Process of Wastewater Treatment Jay Hill Product Manager

  3. 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

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

  5. Activated Sludge Systems O2 CO2 Untreated Discharge Clean Water Aeration Tank Clarifier Recycled Sludge Biomass (Secondary Sludge)

  6. Secondary Clarification • Clarifier • Secondary sludge • Fine organic matter • Floatables • FOG

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

  8. Aerobic Microbial Respiration * C,H + O2 CO2 + H2O + protein * bacteria, N, P, pH, temperature

  9. 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)

  10. Requirements for Growth of Microbes • Temperature • pH • Water activity • Energy source • Nutrients • Carbon • Nitrogen • Phosphorus • Minerals • Vitamins/growth factors

  11. Temperature • Thermophiles • 40°C to >100°C • Mesophiles • 10°C to ~45°C • Psychrophiles • <5°C to ~35°C

  12. pH • Acidophiles • pH 0-6 • Alkaliphiles • pH 8-13 • Most bacteria prefer pH 6-8 • Most fungi prefer pH 4-7

  13. 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

  14. Energy Sources • Oxygen (aerobes) C6H12O6+ 6 O26 CO2+6 H2O • Autotrophs • NH4++ 2 O2 NO3-+ H2O + 2 H+ (Nitrifiers) • H2S + 2 O2 SO4- - + 2 H+ (sulfur oxidizers) • H2S + 0.5 O2 S0 + H2O (sulfur oxidizers) • Nitrate (facultative) C6H12O6 + 6 H2O6 CO2+ 12 H2/ 5 H2 +2 NO3- + 2 H+  N2 + 6 H2O (denitrifiers) • Sulfate (anaerobes) C2H4O2CO2 / SO4-- H2S (sulfate reducers) • Carbon dioxide (anaerobes) CO2+ 4 H2 CH4 +2 H2O (methanogens) • Fermentation C6H12O62 CO2+2 C2H5OH

  15. Nutrients Required for Growth • Carbon • Usually from food source or CO2 • 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

  16. 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

  17. 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

  18. 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 –1st Stage 30-100 mg O2/g MLSS per hour <20 Inhibition <30 Insoluble waste ` >100 Overloading Operation Limits

  19. 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 Operation Limits

  20. 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 Elevated BOD/COD Worse Effluent High Effluent Suspended Solids

  21. Common Wastewater Problems • Poor Settling • Effluent Violation (TSS or BOD) • Filamentous Forms • Poor Nitrification • Toxicity • Odors

  22. Aerobic Microbial Respiration * C,H + O2 CO2 + H2O + protein * bacteria, N, P, pH, temperature

  23. Parameter Result Comments pH of 10% solution 10.5 Alkalinity 37 meq/100 g Titrated to pH 7 w/HCl Ammonium-Nitrogen 400 mg/L Nitrite-Nitrogen 5 mg/L Color fades rapidly Nitrate-Nitrogen <5mg/L Turns yellow after cadmium addition Phosphate-Phosphorus 30 mg/L Chemical Oxygen Demand 71,000 mg/L Chemical Characterization of VISC 25

  24. 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: • evaluate foam or settling problems • measure nitrification rates or nitrification potential • measure FOG degradation rates or potential • measure permissible loading rates for potentially toxic waste streams or septage • measure effectiveness of bioaugmentation • measure biomass kinetic constants for process design.

  25. 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)

  26. Wastewater Treatment Problems (AS)

  27. Wastewater Treatment Problems (Lagoon)

  28. Bioaugmentation

  29. How Does Bioaugmentation Work? • Numbers – By adding cultures regularlythe minor cultures (but important cultures) gaina survival advantage (against the dominant cultures) . • Natural Genetic Interchange – Recent workindicates the possibility of transfer to the biomassof desirable and needed characteristics (but not permanently), particularly capabilitiescontrolled by the plasmids in the cells and demanded by the conditions in the system.

  30. Activated Sludge- Culture Selector The biomass is comprised of thousands of culturesof bacteria, fungi, protozoans, etc. The system “selects”cultures with both major/dominant populations andminor counts. Both populations are importantin obtaining good effluent quality. The combination of cultures in the biomasscontinuously changes and adapts to changes in ambient conditions.

  31. 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

  32. The Transfer of Plasmids a b d c Scientific American, January 1998, p. 68

  33. 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

  34. Filamentous Populations Individual microbesdo the work Microbes flocculate andform particles thatsettle But the filamentous formsinhibit settling

  35. Nitrification 2NH4+ + 3O2 2NO2- + 4H+ + 2H2O 2NO2- + O2 2NO3-

  36. NH3 Treatment System Removal ofinsolubles Removal ofBOD Clarifier Recycle of Sludge Removal of NOD Discharge of Sludge Clarifier Recycle of Sludge Discharge of Sludge

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