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ANAEROBIC SLUDGE DIGESTION PROCESS
The document discusses the process of anaerobic sludge digestion, which involves microorganisms breaking down organic matter in sludge into biogas consisting of methane and carbon dioxide. It describes the two-stage anaerobic digestion process, where acid-forming bacteria first convert organic material into organic acids in stage one, and methane-forming bacteria then use the organic acids to produce methane and carbon dioxide in stage two. Key factors that must be controlled for effective anaerobic digestion include temperature, pH, volatile acids levels, bacteria quantities, loading amounts, and mixing to ensure contact between bacteria and food sources.
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ANAEROBIC SLUDGE DIGESTION PROCESS
- 1. Welcome to MyPresentation ANAEROBIC SLUDGE DIGESTION PROCESS GREEN UNIVERSITY OF BANGLADESH
- 2. Name & IDNo: MD.GOLAM SARWAR 120103019 Course Code : TEX-403 An Assignment Alternating of Class Test
- 3. WHAT IS ANAEROBICSLUDGE DIGESTION ? WASTEWATER And Sources of Wastewater SLUDGE And SLUDGE CHARACTERISTICS Types of Digestion AEROBIC DIGESTION AND ANAEROBIC DIGESTION Anaerobic Digestion Process Digestion Factors And OPERATION AND CONTROL SUMMARY Question & Ans. session PRESENTATION CONTENTS
- 4. WASTEWATER Water usedto carry waste products away from homes, schools, commercial establishments, and industrial enterprises.
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- 6. GOAL – PURPOSE– RESPONSIBILITY Of “Treating” or Stabilizing Wastewater PROTECTION OF NATURAL RESOURCES PROTECTION OF PUBLIC HEALTH
- 7. The SETTLEABLE solids separatedfrom liquids during processing.
- 8. SLUDGE CHARACTERISTICS •Organic /Inorganic •OxygenDemand •Odors •Nutrients •Pathogens •Mostly Water
- 9. Types of Digestion Biological Bacteria Aerobic Anaerobic Use“Free” Oxygen No “Free” Oxygen
- 10. AEROBIC DIGESTION Advantages: Effective for“secondary” sludge Simple operation No hazardous gas production Disadvantages: Higher operating costs High energy demands No burnable gas Higher organic content
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- 12. Anaerobic digestion processoverview In the anaerobic digestion process, micro-organisms convert complex organic matter to biogas, which consists of methane (CH4) and carbon dioxide (CO2) Some organic matter remains even after the digestion step, and this is called digestate or digester residue or digested organic matter Anaerobic digestion is used to treat high-strength wastewater, organic solid waste, sewage sludges, blackwater, faecal sludge, agricultural waste, food industry waste (e.g. breweries, slaughter houses, dairy).
- 13. ANAEROBIC DIGESTION Advantages Low operatingcosts Proven effectiveness Burnable gas produced Disadvantages Long start-up time Affected by changes in loading and conditions Explosive gas produced
- 14. Anaerobic Digestion Process “TWO-STAGE”Process OR “Two Phase” Process
- 15. Anaerobic Digestion Process “TWO-STAGE”Process This Does Not Mean Two Tanks
- 16. Anaerobic Digestion Process “TWO-STAGE”Process OR “Two Phase” Process Two Types of Bacteria Each Relying On The Other First Stage Second Stage
- 17. Anaerobic Digestion Process FirstOrganic Material Changed By Acid Forming Bacteria To Simple Organic Material Organic Matter Bacteria Organic Acids First Stage +
- 18. Anaerobic Digestion Process Second Methane-FormingBacteria Use Organic Acids Produce Carbon Dioxide and Methane Organic Acids + Bacteria CH4 + CO2 Second Stage
- 19. Anaerobic Digestion Process ContinuousProcess “TWO-STAGE” Process Stabilization Organic Matter Bacteria Organic Acids First Stage Acid Forming CH4 + CO2 Methane Forming Second Stage
- 20. Type of Food OrganicInorganic Soluble Insoluble Anaerobic Digestion Process
- 21. Soluble Organics Cell Membrane Acids Adsorbed Particle Enzymes (Absorption) Typical AcidForming Bacteria Liquid
- 22. Not All OrganicMaterial Broken Down Type of Food Poor Food Inert Solids -Not Readily Degradable -Plastics, etc. 40 to 60 % of Organics are Reduced
- 23. Anaerobic Digestion Process “TWO-STAGE”Process OR “Two Phase” Process Two Types of Bacteria Each Relying On The Other Must Be In Balance !
- 24. Organic Matter Bacteria Organic Acids First Stage Acid Forming CH4 + CO2 MethaneForming Second Stage Anaerobic Digestion Process Volatile AcidsAcid Phase Acids Used at Rate Produced
- 25. Anaerobic Digestion Process Productsof Digestion 1. Gases Methane (CH4) Carbon Dioxide (CO2) 65 to 70 % 30 to 35 % 7 to 12 cubic feet per pound of volatile destroyed 500 to 600 BTU per cubic foot Can Be Utilized: Heating Digester Heating Buildings Running Engines Electrical Power
- 26. Anaerobic Digestion Process Productsof Digestion 2. Scum Lighter Solids Floating from Gas Entrapment Builds Up If MIXING Is Inadequate Not Digested ( Separated from Bacteria) Reduces Digester Capacity Plugs Piping Plugs Vents and Flame Traps
- 27. Anaerobic Digestion Process Productsof Digestion 3. Supernatant Liquid That Leaves Digester Two Sources of Water In Digester: Water Pumped In Water Formed During Digestion Recycled Through Treatment Plant High In: Solids BOD Ammonia
- 28. Anaerobic Digestion Process Productsof Digestion 3. Supernatant Liquid That Leaves Digester Should Be Removed Frequently in Small Quantities
- 29. Anaerobic Digestion Process Productsof Digestion 4. Digested Sludge “Stabilized” Final Product Inorganic Solids Volatile (Organic) Solids - Not Easily Digested
- 30. TYPICAL “Two-Stage” ANAEROBIC DIGESTERSYSTEM Transfer Pump Heat Exchanger Hot Water Gas Gas Recirculation Pump Note: Two-Stage System here refers to two separate tanks (One for the treatment process and one for water-solids separation)
- 31. Digestion Factors 1. ANAEROBIC 2.TEMPERTURE 3. pH 4. VOLATILE ACIDS Mesophilic - Constant Best - 6.8 to 7.2 ENVIRONMENT 5. BUFFERS (Alkalinity) Incoming Sludge and Created No Oxygen Not Excessive
- 32. Digestion Factors 1. BACTERIA 2.FOOD 3. LOADING 4. CONTACT 5. ENVIRONMENT
- 33. OPERATION AND CONTROL 1.BACTERIA Maintain Adequate Quantity Don’t Remove Too Much Don’t Displace Too Much Plan For Re-Start
- 34. 2. FOOD Minimize Amountof Inorganics Entering Eliminate Toxic Material Industrial Discharges Grit Systems OPERATION AND CONTROL
- 35. 3. LOADING AMOUNT Applied tothe Treatment Process Related to the SIZE of the System For An Anaerobic Digestion System – The SIZE Is The VOLUME Available for Digestion (Volume - Cubic Feet OR Gallons)
- 36. 1. CONTACT Bacteria andFood 2. HEAT DISTRIBUTION 3. MINIMIZE SETTLING 4. MINIMIZE SCUM Even Throughout Reduces Available Volume Operational Problems CONTACT (MIXING)
- 37. Temperature controls activityof bacteria. Psychrophilic 50 F to 68 F Mesophilic 68 F to 113 F Best 85 F to 100 F Thermophilic Above 113 F Best 120 F to 135 F TEMPERATURE
- 38. OPERATION AND CONTROL ENVIRONMENT TemperatureControl 90 to 950 F Methane Formers Very Sensitive to Changes Good Mixing Essential
- 39. SUMMARY First Stage SecondStage Balance Poor Mixing Over Loading Excess Water Temperature
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