ammonia analyzer provides real time process control capability pwo operator seminar – february 22,...
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Ammonia Analyzer Ammonia Analyzer Provides Real Time Provides Real Time
Process Control CapabilityProcess Control CapabilityPWO Operator Seminar – February 22, 2002PWO Operator Seminar – February 22, 2002
Greg Farmer - Littleton / Englewood WWTPGreg Farmer - Littleton / Englewood WWTPGary Girolimon - Ted Miller and AssociatesGary Girolimon - Ted Miller and Associates
Littleton / Englewood WWTPLittleton / Englewood WWTPProcess SchematicProcess Schematic
Before Automating Process ControlBefore Automating Process Control
Diurnal ammonia variations led to:Diurnal ammonia variations led to:
Breakpoint chlorinationBreakpoint chlorination Inconsistent fecal coliform counts Inconsistent fecal coliform counts
BenefitsBenefits
Dial in Final Effluent Ammonia ConcentrationDial in Final Effluent Ammonia Concentration Centrate Return Timing FeedbackCentrate Return Timing Feedback Maximize Nitrifying Trickling Filter (NTF) Maximize Nitrifying Trickling Filter (NTF)
EfficiencyEfficiency More Consistent Fecal Coliform Counts Through More Consistent Fecal Coliform Counts Through
Control of Ammonia to Chlorine RatioControl of Ammonia to Chlorine Ratio Only 2-3 hours/month MaintenanceOnly 2-3 hours/month Maintenance
Ammonia ControlAmmonia Control
Nitrifying Trickle Filters Nitrifying Trickle Filters
NTF Effluent Ammonia NTF Effluent Ammonia Control ModesControl Modes
By-Pass Valve ControlBy-Pass Valve Control 24 / 7 Effluent ammonia goal 24 / 7 Effluent ammonia goal
is 2.0 mg/lis 2.0 mg/l Valve opens incrementally Valve opens incrementally
when ammonia is below 2.0 when ammonia is below 2.0 mg/l mg/l
Valve closes incrementally Valve closes incrementally when ammonia above 2.0 when ammonia above 2.0 mg/lmg/l
Pump ControlPump Control If ammonia level increases If ammonia level increases
above 7.0 mg/l, NTF pump above 7.0 mg/l, NTF pump speeds increasespeeds increase
When ammonia falls below 5.0 When ammonia falls below 5.0 mg/l pump speeds decrease.mg/l pump speeds decrease.
Pumps cannot go below a Pumps cannot go below a preset speed so that the preset speed so that the minimum hydraulic loading is minimum hydraulic loading is maintained.maintained.
By-Pass Valve ControlBy-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.
By-Pass Valve OperationBy-Pass Valve Operation
Ammonia >
Valve closes when ammonia level increases above set point of 2 mg/l.
Valve opens when ammonia level decreases below set point of 2 mg/l.
< Valve position
Nitrate >
Pump Speed ControlPump Speed Control
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.
If the analyzer detects ammonia levels above a set point the NTF pump speeds increase.
Pump Speed Control OperationPump Speed Control Operation
By-pass valve
Position >
< NTF Pump Output
Nitrate >
< Ammonia
ChlorinationChlorination
Controlled Chlorine to Ammonia Controlled Chlorine to Ammonia RatioRatio
Fecal Coliform CountsFecal Coliform Counts
Analyzer AccuracyAnalyzer Accuracy
Instrument AccuracyInstrument AccuracyAnalyzer vs. LabAnalyzer 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.
Final Effluent AmmoniaFinal Effluent Ammoniavs.vs.
STIP Daily AverageSTIP Daily Average
Nitrate BuoyNitrate Buoy
<---- Calibrated Properly ----->
Recalibrated During Regular Maintenance - Suspect Poor
Quality 3rd party Reagent
ISCO/STIP ISCO/STIP Process BuoyProcess Buoy
STIP Process BuoySTIP Process Buoy
Operates by being Operates by being placed directly in placed directly in wastewater (even wastewater (even activated sludge)activated sludge)
Separate buoys for Separate buoys for ammonium and ammonium and nitratenitrate
STIP Process BuoySTIP Process Buoy
Follows EPA approved Follows EPA approved methods of analysismethods of analysis
Operates in a batch Operates in a batch analysis mode with typical analysis mode with typical analysis times of 3 to 5 analysis times of 3 to 5 minutesminutes
Measuring range of 0.1 - 50 Measuring range of 0.1 - 50 mg/l as N for both nitrate mg/l as N for both nitrate and ammoniumand ammonium
Method of Analysis - GeneralMethod of Analysis - General
Solenoid valve opens permitting Solenoid valve opens permitting sample to fill settling chamber via sample to fill settling chamber via hydrostatic pressurehydrostatic pressure
Sludge settles for pre Sludge settles for pre programmed time periodprogrammed time period
Ammonium and nitrate measured Ammonium and nitrate measured with ion selective electrodes (ISE)with ion selective electrodes (ISE)
Solenoid valve reopens permitting Solenoid valve reopens permitting supernatant to fill measurement supernatant to fill measurement chamberchamber
Method of Analysis - NHMethod of Analysis - NH44NN
Caustic (NaOH) added till Caustic (NaOH) added till pH>11.5pH>11.5
Ammonium is converted Ammonium is converted to Ammonia (gas)to Ammonia (gas)
Ammonia measurement Ammonia measurement taken with gas selective taken with gas selective electrodeelectrode
Method of Analysis - NOMethod of Analysis - NO33NN
Conductivity sensor used Conductivity sensor used to add reagent (ion to add reagent (ion suppression) to adjust suppression) to adjust ionic strength of solutionionic strength of solution
Concentration measured Concentration measured with nitrate selective with nitrate selective electrodeelectrode
Method of Analysis - SchematicMethod of Analysis - Schematic
CalibrationCalibration
Buoy calibration is Buoy calibration is done using three done using three step standard step standard addition methodaddition method
Calibrated Calibrated automatically automatically once per dayonce per day
Buoy Bulkhead LayoutBuoy Bulkhead Layout
Process Buoy In Open PositionProcess Buoy In Open Position
ShowsShows Settling ChamberSettling Chamber Measuring ChamberMeasuring Chamber ElectrodesElectrodes ValvesValves AmplifiersAmplifiers
Process Buoy Without Stainless Process Buoy Without Stainless Steel HousingSteel Housing
ControllerController
One controller can operate One controller can operate two buoystwo buoys
LCD screen displays current LCD screen displays current reading and graph of last 6-reading and graph of last 6-hours of operationhours of operation
Outputs:Outputs: 4-20 mA4-20 mA Bi-directional RS 232 Bi-directional RS 232
The EndThe End