1 / 31

Ammonia Analyzer Provides Real Time Process Control Capability

Ammonia Analyzer Provides Real Time Process Control Capability. PWO Operator Seminar – February 22, 2002 Greg Farmer - Littleton / Englewood WWTP Gary Girolimon - Ted Miller and Associates. Littleton / Englewood WWTP Process Schematic. Before Automating Process Control.

arissa
Download Presentation

Ammonia Analyzer Provides Real Time Process Control Capability

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Ammonia Analyzer Provides Real Time Process Control Capability PWO Operator Seminar – February 22, 2002 Greg Farmer - Littleton / Englewood WWTP Gary Girolimon - Ted Miller and Associates

  2. Littleton / Englewood WWTPProcess Schematic

  3. Before Automating Process Control Diurnal ammonia variations led to: • Breakpoint chlorination • Inconsistent fecal coliform counts

  4. Benefits • Dial in Final Effluent Ammonia Concentration • Centrate Return Timing Feedback • Maximize Nitrifying Trickling Filter (NTF) Efficiency • More Consistent Fecal Coliform Counts Through Control of Ammonia to Chlorine Ratio • Only 2-3 hours/month Maintenance

  5. Ammonia Control

  6. Nitrifying Trickle Filters

  7. NTF Effluent Ammonia Control Modes By-Pass Valve Control • 24 / 7 Effluent ammonia goal is 2.0 mg/l • Valve opens incrementally when ammonia is below 2.0 mg/l • Valve closes incrementally when ammonia above 2.0 mg/l Pump Control • If ammonia level increases above 7.0 mg/l, NTF pump speeds increase • When ammonia falls below 5.0 mg/l pump speeds decrease. • Pumps cannot go below a preset speed so that the minimum hydraulic loading is maintained.

  8. By-Pass Valve Control If the analyzer detects ammonia level below the set point, the by-pass valve opens incrementally. If the analyzer detects ammonia levels above the set point, the by-pass valve closes incrementally.

  9. By-Pass Valve Operation Ammonia > Nitrate> < Valve position Valve opens when ammonia level decreases below set point of 2 mg/l. Valve closes when ammonia level increases above set point of 2 mg/l.

  10. Pump Speed Control If the analyzer detects ammonia levels above a set point the NTF pump speeds increase. If the analyzer detects ammonia levels below a set point the NTF pumps speeds decrease. Pump speed cannot go below a selected value so that the minimum hydraulic loading is maintained.

  11. Pump Speed Control Operation Nitrate > < Ammonia < NTF Pump Output By-pass valve Position >

  12. Chlorination

  13. Controlled Chlorine to Ammonia Ratio

  14. Fecal Coliform Counts

  15. Analyzer Accuracy

  16. Instrument AccuracyAnalyzer vs. Lab Instrument values are extracted daily at 8:00 am and logged to the historical data server. Operators collect a sample near the analyzer at ~8:00 am for analysis by the lab.

  17. Final Effluent Ammoniavs.STIP Daily Average

  18. Nitrate Buoy <---- Calibrated Properly -----> Recalibrated During Regular Maintenance - Suspect Poor Quality 3rd party Reagent

  19. ISCO/STIP Process Buoy

  20. STIP Process Buoy • Operates by being placed directly in wastewater (even activated sludge) • Separate buoys for ammonium and nitrate

  21. STIP Process Buoy • Follows EPA approved methods of analysis • Operates in a batch analysis mode with typical analysis times of 3 to 5 minutes • Measuring range of 0.1 - 50 mg/l as N for both nitrate and ammonium

  22. Method of Analysis - General • Solenoid valve opens permitting sample to fill settling chamber via hydrostatic pressure • Sludge settles for pre programmed time period • Ammonium and nitrate measured with ion selective electrodes (ISE) • Solenoid valve reopens permitting supernatant to fill measurement chamber

  23. Method of Analysis - NH4N • Caustic (NaOH) added till pH>11.5 • Ammonium is converted to Ammonia (gas) • Ammonia measurement taken with gas selective electrode

  24. Method of Analysis - NO3N • Conductivity sensor used to add reagent (ion suppression) to adjust ionic strength of solution • Concentration measured with nitrate selective electrode

  25. Method of Analysis - Schematic

  26. Calibration • Buoy calibration is done using three step standard addition method • Calibrated automatically once per day

  27. Buoy Bulkhead Layout

  28. Process Buoy In Open Position • Shows • Settling Chamber • Measuring Chamber • Electrodes • Valves • Amplifiers

  29. Process Buoy Without Stainless Steel Housing

  30. Controller • One controller can operate two buoys • LCD screen displays current reading and graph of last 6-hours of operation • Outputs: • 4-20 mA • Bi-directional RS 232

  31. The End

More Related