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Nitrogen Reduction: Process & Application
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Presentation Outline Environmental effects of Nitrogen Health Effects of Nitrogen The Nitrogen Cycle What interrupts the cycle? Applications Environmental effects of Nitrogen Health Effects of Nitrogen The Nitrogen Cycle What interrupts the cycle? Applications
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Environmental Effects: Excess Nitrogen Increased Nitrogen in Rivers and Oceans Causes eutrophication of coastal waters Causes algal blooms Causes a decrease in oxygen in waters Killed significant numbers of fin fish and shellfish Increased Nitrogen in Rivers and Oceans Causes eutrophication of coastal waters Causes algal blooms Causes a decrease in oxygen in waters Killed significant numbers of fin fish and shellfish
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Health Effects of Nitrates Methemoglobinemia (Blue Baby Syndrome) Hyperthyroidism CNS malformations in newborns Diabetes Methemoglobinemia (Blue Baby Syndrome) Hyperthyroidism CNS malformations in newborns Diabetes
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The Nitrogen Cycle Forms of Nitrogen NITROGEN GAS (N 2 ) ORGANIC NITROGEN AMMONIA (NH 3 ) NITRITE (NO 2 ) NITRATE (NO 3 ) NITROGEN GAS (N 2 ) ORGANIC NITROGEN AMMONIA (NH 3 ) NITRITE (NO 2 ) NITRATE (NO 3 )
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The Nitrogen Cycle N 2 – 78% of earth’s atmosphere Lightning – High-energy fixation Nitrates NO 3 - BiologicalFixation Ammonia NH 3
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How does nitrogen get into our bodies? Plants produce organic molecules - Amino Acids - Proteins - Nucleic Acids Animals eat plants or other animals Plants produce organic molecules - Amino Acids - Proteins - Nucleic Acids Animals eat plants or other animals
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The Nitrogen Cycle N 2 – 78% of earth’s atmosphere BiologicalFixation Lightning – High-energy fixation Nitrates NO 3 - Ammonia NH 3 Plants and microorganisms create proteins Food Chain
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How does Nitrogen leave our bodies? Breakdown of proteins, etc. into organic forms of Nitrogen Returned to the environment as excretions Breakdown of proteins, etc. into organic forms of Nitrogen Returned to the environment as excretions
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The Nitrogen Cycle N 2 – 78% of earth’s atmosphere BiologicalFixation Lightning – High-energy fixation Nitrates NO 3 - Ammonia NH 3 Plants and microorganisms create proteins Food Chain Decay
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The Nitrogen Cycle In a denitrification wastewater treatment system N 2 – 78% of earth’s atmosphere Nitrates NO 3 - Ammonia NH 3 Nitrites NO 2 - Nitrifying bacteria Denitrifying Bacteria
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Concentration Limits and Water Conservation Example: The Jar of Marbles 1 Liter of Water, 40 marbles1 Liter of Water, 40 marbles Concentration = 40 Mb/LiterConcentration = 40 Mb/Liter What happens if you take out half of the water? Concentration = 80 mb/literConcentration = 80 mb/liter
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What does that mean? When it comes to treatment…. –A percent reduction removes the same number of marbles. –The receiving environment is accepting the same number of marbles. When it comes to treatment…. –A percent reduction removes the same number of marbles. –The receiving environment is accepting the same number of marbles.
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Septic Tank Effluent – Nitrogen Breakdown Example (2004) Total N - 80 mg/L Org. Nitrogen10 mg/L NH 3 (Ammonia)70 mg/L NO 3 (Nitrate)0 mg/L NO 2 (Nitrite)0 mg/L
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After Treatment – Total N - 24 mg/L Org. Nitrogen5 mg/L NH 3 (Ammonia)9 mg/L NO 3 (Nitrate)10 mg/L NO 2 (Nitrite)0 mg/L
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Basic Steps in Nitrogen Removal Systems Anoxic Zone Conversion of nitrate to nitrogen gas (denitrification) BOD removal Aerobic Zone BOD removal and nitrification Anoxic Zone Conversion of nitrate to nitrogen gas (denitrification) BOD removal Aerobic Zone BOD removal and nitrification
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NITRIFICATION Conversion of Ammonia–Nitrogen to Nitrate–Nitrogen Conversion of Ammonia–Nitrogen to Nitrate–Nitrogen
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Nitrification Process Step 1: NH + 4 + 1.5 O 2 Nitrosomonas NO 2 + 2H + + H 2 O Step 2: NO 2 + 0.5 O 2 Nirtrobacter NO 3 Overall Reaction: NH + 4 + 2 O 2 NO 3 + 2H + + H 2 O 4.6 lbs O2/lb NH3-N 7.14 lbs alkalinity destroyed/lb NH3-N
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Basic Design Considerations for Nitrogen Removal Systems Aerobic Zone Optimum Oxygen and Mixing Aerobic SRT for Nitrification Alkalinity & pH HRT Liquid Temperature Toxicity
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Toxic Chemicals (for wastewater treatment) Homes: liquid fabric softeners, pine oil, and drain cleaners Commercial Facilities: Strong sanitizers or Quats, floor stripping waste (Zinc) Pesticides Acid and Caustic Materials Homes: liquid fabric softeners, pine oil, and drain cleaners Commercial Facilities: Strong sanitizers or Quats, floor stripping waste (Zinc) Pesticides Acid and Caustic Materials
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QUATERNARY AMMONIUM COMPOUNDS QUATs OR QAC BENZALKONIUM CHLORIDE CH 3 | Cl-Benz Ring-CH 2 -N-C 18 H 37 | CH 3 QUATs OR QAC BENZALKONIUM CHLORIDE CH 3 | Cl-Benz Ring-CH 2 -N-C 18 H 37 | CH 3
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Problems with QUATs in Wastewater Treatment Toxic/Inhibitory to Nitrifying Bacteria - in concentrations <2 mg/l Non-biodegradable Organic Nitrogen Exponential Increase in Use Toxic/Inhibitory to Nitrifying Bacteria - in concentrations <2 mg/l Non-biodegradable Organic Nitrogen Exponential Increase in Use
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Quaternary Ammonium Compounds - Disinfectant Ammonium Ion with 4 Radicals Attached Not oxidizers - Surface-active agents Breakdown bacterial cell walls Internal contents of bacteria leak out Commonly used at 200 ppm Effective at High Temperatures Ammonium Ion with 4 Radicals Attached Not oxidizers - Surface-active agents Breakdown bacterial cell walls Internal contents of bacteria leak out Commonly used at 200 ppm Effective at High Temperatures
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DENITIRIFICATION Denitrification is the conversion of Nitrate–Nitrogen to Nitrogen gas through a biological process.
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Denitrification Process NO 3 + organic carbon carb. bacteria N 2 + CO 2 + OH + H 2 0 CO 2 + OH HCO 3 NO 3 NO 2 NO N 2 O N 2 2.86 lbs oxygen recovered / lb NO3-N 3.57 lbs alkalinity recovered / lb NO3-N
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Basic Design Considerations for Nitrogen Removal Systems Anoxic Zone D.O. <0.5 mg/L BOD:NO3-N Ratio HRT Mixing pH (6.5-7.5 ideally) Anoxic Zone D.O. <0.5 mg/L BOD:NO3-N Ratio HRT Mixing pH (6.5-7.5 ideally)
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Carbon Source for Denitrification Influent BOD Endogenous Respiration External Source Methanol Ethanol Acetic Acid Sugar, etc. External carbon source should be: Easy to use Low cost Available Favorable Microbial Growth Influent BOD Endogenous Respiration External Source Methanol Ethanol Acetic Acid Sugar, etc. External carbon source should be: Easy to use Low cost Available Favorable Microbial Growth
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Denitrification Rate It varies with the source of carbon Methanol provides the highest rate Endogenous respiration provides the lowest rate It varies with temperature It varies with the source of carbon Methanol provides the highest rate Endogenous respiration provides the lowest rate It varies with temperature
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How Does One Size a System? How Does One Size a System? Influent Laboratory Analysis Experience Common Sense Influent Laboratory Analysis Experience Common Sense
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Why Should I Worry About It? “Thou Shalt Not Live By Flow Alone” Biological Vs. Hydraulic Loading “Thou Shalt Not Live By Flow Alone” Biological Vs. Hydraulic Loading
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Design Source of the waste Facility Practices Flow Patterns (e.g. churches) Effluent Requirements Operational/Management Resources Source of the waste Facility Practices Flow Patterns (e.g. churches) Effluent Requirements Operational/Management Resources
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System Loading w/ N Reduce treatment expectations by 20% Why? Nitrifying bacteria are easily crowded out when high levels of BOD 5 are present.Nitrifying bacteria are easily crowded out when high levels of BOD 5 are present. The bugs that reduce BOD 5 are stronger than those that nitrify.The bugs that reduce BOD 5 are stronger than those that nitrify. Therefore physical space must be made available for nitrifiers.Therefore physical space must be made available for nitrifiers.
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Real World Examples Restaurant Subdivision School Restaurant Subdivision School
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BOD 5 & TKN Calculations Must convert BOD5 and TKN influent from mg/L to lbs. /day. = flow (gpd) x 8.34 x BOD (mg/L) = BOD5 (lbs/day) 1,000,000 = flow (gpd) x 8.34 x TKN (mg/L) = TKN (lbs/day) 1,000,000
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Restaurant Lbs/day<200mg/L<30 mg/L NH3 Reduction Total Nitrogen Reduction Flow1500 BOD 5 1000 FOG150 TKN60
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BOD 5 Calculation Restaurant. Flow 1500 gpd, BOD = 1000 mg/L. Calculation: = flow (gpd) x 8.34 x BOD5 (mg/L) = BOD5 (lbs/day) 1,000,000 = 1500 gpd x 8.34 x 1000 mg/L = ~12.5 (lbs/day) 1,000,000
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TKN Calculation Restaurant. Flow 1500 gpd, TKN = 50 mg/L. Calculation: = flow (gpd) x 8.34 x TKN (mg/L) = TKN (lbs/day) 1,000,000 = 1500 gpd x 8.34 x 60 mg/L = 0.75 (lbs/day) 1,000,000
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Restaurant Lbs/day<200mg/L<30 mg/L NH3 Reduction Total Nitrogen Reduction Flow1500 BOD 5 1000 ~12.5 FOG150 TKN60 0.75
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Restaurant Lbs/day<200mg/L<30 mg/L NH3 Reduction Total Nitrogen Reduction Flow1500 BOD 5 1000 ~12.5 FOG150 TKN60 0.75
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Subdivision Lbs/day<200mg/L<30 mg/L NH3 Reduction Total Nitrogen Reduction Flow1500 BOD 5 220 FOG30 TKN70
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BOD 5 & TKN Calculations Subdivision: Flow 1500 gpd, BOD = 220 mg/L, TKN = 70 Calculation: BOD= 1500 gpd x 8.34 x 220 mg/L = ~2.7 (lbs/day) 1,000,000 TKN= 1500 gpd x 8.34 x 70 mg/L = ~0.9 (lbs/day) 1,000,000
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Subdivision Lbs/day<200mg/L<30 mg/L NH3 Reduction Total Nitrogen Reduction Flow1500 BOD 5 220 ~2.7 FOG30 TKN70 ~0.9
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Subdivision Lbs/day<200mg/L<30 mg/L NH3 Reduction Total Nitrogen Reduction Flow1500 BOD 5 220 ~2.7 FOG30 TKN70 ~0.9
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School Lbs/day<200mg/L<30 mg/L NH3 Reduction Total Nitrogen Reduction Flow1500 BOD 5 450 FOG50 TKN200
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BOD 5 & TKN Calculations School: Flow 1500 gpd, BOD = 220 mg/L, TKN = 200 Calculation: BOD= 1500 gpd x 8.34 x 450 mg/L = ~5.6 (lbs/day) 1,000,000 TKN= 1500 gpd x 8.34 x 200 mg/L = ~2.5 (lbs/day) 1,000,000
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School Lbs/day<200mg/L<30 mg/L NH3 Reduction Total Nitrogen Reduction Flow1500 BOD 5 450 ~5.6 FOG50 TKN200 ~2.5
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School Lbs/day<200mg/L<30 mg/L NH3 Reduction Total Nitrogen Reduction Flow1500 BOD 5 450 ~5.6 FOG50 TKN200 ~2.5
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Effluent Influent (Q) Final Clarifier Nitrified Recycle (100-400% Q) RAS (10-100% Q) WAS Alternative Denitrification Systems: Single-Stage Anoxic Zone (MLE) Anoxic Basin Aeration Basin BODr & Nitrification
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Alternative Denitrification Systems: Single-Stage Anoxic Zone Effluent nitrate of 8-12 mg/L without external carbon source Alkalinity and oxygen recovery Influent WW should have adequate BOD to satisfy the denitrification needs Sensitive to the aeration tank DO and the nitrate recirculation flow rate Suitable for large plants Effluent nitrate of 8-12 mg/L without external carbon source Alkalinity and oxygen recovery Influent WW should have adequate BOD to satisfy the denitrification needs Sensitive to the aeration tank DO and the nitrate recirculation flow rate Suitable for large plants
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Alternative Denitrification Systems: Post Anoxic Influent Aeration Basin BODr & Nitrification Anoxic Basin Aeration Basin Final Clarifier Carbon Feed
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Alternative Denitrification Systems: Post Anoxic Simple to Operate Can tolerate variations in the influent nitrate Monitoring of carbon addition is not very critical No internal recirculation flows Can be designed to remove high influent nitrate Requires external carbon source (cost & complexity) Alkalinity and oxygen recoveries benefits from denitrification process are not used within the system Simple to Operate Can tolerate variations in the influent nitrate Monitoring of carbon addition is not very critical No internal recirculation flows Can be designed to remove high influent nitrate Requires external carbon source (cost & complexity) Alkalinity and oxygen recoveries benefits from denitrification process are not used within the system
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Challenges of Nitrogen Removal for On-Site Applications Periodic and Non-uniform Influent Flow Adverse Impact of High and Low Loading Rates on Nitrogen Removal Typically Non-Optimum Influent BOD:TKN for Denitrification Process Potential for unexpected toxicity in the Influent Periodic and Non-uniform Influent Flow Adverse Impact of High and Low Loading Rates on Nitrogen Removal Typically Non-Optimum Influent BOD:TKN for Denitrification Process Potential for unexpected toxicity in the Influent
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Questions?
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For More Information... Phone: (800) 753-FAST Fax: (913) 422-0808 E-mail: onsite@biomicrobics.com Web site: www.biomicrobics.com Phone: (800) 753-FAST Fax: (913) 422-0808 E-mail: onsite@biomicrobics.com Web site: www.biomicrobics.com
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