Calculated Dose Approach for MP systems with low and high wavelength sensors

Transcription

1 February, 2018 Calculated Dose Approach for MP systems with low and high wavelength sensors logi = 10 A UVA B UVA D F SH S0H Q ASCF UVA G UVA H D 2 C+ D UVA254+ E UVA254 S S0 Q ASCF 2 H+ I UVA220+ J UVA220

2 Fundamentals of MP Disinfection amp Output (W/cm) UVDGM MP amp Modern MP amp Wavelength (nm) MP amp Output (W/cm) amp Output UV Sensor Response Wavelength (nm) UVA (cm-1) Aquifer 1 - No Absorber Aquifer 2 - No Absorber Wavelength (nm) Aquifer 1 -With Absorber Aquifer 2 -With Absorber Quartz Sleeve UVT (%) Type 214 Quartz Type 219 Quartz Synthetic Quartz Wavelength (nm) Dose Action MS-2 Crypto Wavelength (nm) 2

3 Current Guidance UVDGM 2006 UVDGM 2006 considers polychromatic light Describes an approach to account for action spectra differences by calculating the ratio of germicidal output (Pg) for the microbes of interest (Action Spectra Correction Factor) 3 Prominent example: ASCF MS2 / Cryptosporidium: 1.04 However, MP lamps may have a significantly higher output at low wavelengths than the emission spectrum used in the UVDGM ASCF as defined in theuvdgm does not consider quartz sleeve and water UVT and therefore may lead to overly conservative results

4 Current Guidance WRF Project 4376 Guidance for Implementing Action Spectra Correction With Medium Pressure UV Disinfection, 2015 Create accurate action spectra of adenovirus,cryptosporidium, and Giardia and commonly used validation microbes Develop recommendations for calculating action spectra correction factors (ASCFs) by accounting for differences in the action spectra of common validation test microbes and regulated pathogens, UV output from the MP lamp, UV transmittance of the quartz sleeve, UV absorbance spectra of the water, and the reactor s lamp configuration Establish recommendations for applying ASCFs for regulatory credit. 4

5 Current Guidance WRF Project 4376 Final standard action spectra (challenge organisms, crypto, giardia) 5

6 Current Guidance WRF Project 4376 Final standard action spectra (Adenovirus) 6

7 Current Guidance WRF Project 4376 Extensive analysis of ASCF s accounting for action spectra of challengeandtargetorganisms, quartzsleeveandwateruvt s, and target organism log I Based on CFDi models of three commercial reactors, models checked against validation data ASCF valuesthatcanbeusedlikeredbiastablesin theuvdgm Target organism action spectra below240 nmsetto0 ( Nomonitoring nocredit) 7

8 Current Guidance WRF Project 4376 Example: ASCF s for Adenovirus, validation with MS2 Shows theimpactofrestrictingtheactionspectrumbelow240 nm 8

9 Current Guidance WRF Project 4376 Summary of implementation approaches 9

10 Calculated Dose Approach for MP systems with low and high wavelength sensors Rationale ( nm; H nm) log I= logi + logi H ow wavelengthlog I ( nm) logi S S0 = C' Q D ASCF D' ExemplifieddependenceofCV on UVA logi = 10 F UVA G UVA 220 S S Q D ASCF H+ I UVA J UVA

11 Calculated Dose Approach for MP systems with low and high wavelength sensors Complete algorithm has ~ 10 coefficients Two separate sensor models UVA measurementsat254 and220 nm logi = 10 Calculated dose A UVA B UVA D F UVA SH S0H Q ASCF G UVA RED= D logi H D C+ D UVA E UVA S S0 Q ASCF H+ I UVA J UVA

12 Calculated Dose Approach for MP systems with low and high wavelength sensors ow and high wavelength ASCF values calulated acc. WRF 4376 Relative toms2 Table C.1ow and High Wavelength ASCF Values Relative to MS2 Phage Microbe ASCF ASCF H MS B. pumilus Spores * Adenovirus * No general action spectrum available ASCF = 240 λ= 200nm 240 P λ= 200nm ( λ) G ( λ) P MS2 λ ( λ) G ( λ) λ x ASCF H = 320 λ= 240nm 320 P λ= 240nm ( λ) G ( λ) P MS2 λ ( λ) G ( λ) λ x 12

13 ow wavelength sensor and test reactor Sensor 1 Standard DVGW dimensions Standard diffusor Alternative filter Alternative diode material Sensor 2 Shifted peaks Suppression of secondary peak Reletive Sensor Response Sensor 1 Sensor 2 MP Output 1.E E E E E E Wavelength (nm) MP Output Test reactor Q100 One2 kw MP lamp Z-configuration Multiple, adjustable sensor ports 13

14 Calculated Dose Approach for MP systems with low and high wavelength sensors Define sensor equations for low and high wavelength sensors for the full range of operational conditions Measured High Wavelength UV Sensor Intensity (W/m 2 ) Synthetic Type 219 y = 1.008x R² = y = x R² = Measured ow Wavelength UV Sensor Intensity (W/m 2 ) y = x R² = Synthetic Type 219 y = 0.965x R² = Predicted High Wavelength UV Sensor Intensity (W/m 2 ) Predicted ow Wavelength UV Sensor Intensity (W/m 2 ) Define testmatrix over thefullrange of operational conditions for various challenge / target organisms versus synthetic sleeves - Range of UVA sat 220 and 254 nm - MS2, Bacillus pumilus, Adenovirus Table C.6. Summary of Number of Test Conditions Used to Define Equation C.12 Microbe Test Condition Replicates MS GAP EPA CEC EPA B.pumilus B.pumilus Adenov Adenov logi > logi Max Zero Plate Counts ab Error

15 Calculated Dose Approach for MP systems with low and high wavelength sensors Test results Just MS2 Algorithm predicts well for the range of operational conditions vs synthetic - lowvs high UVA 220nm Test results Just MS2 usedfor regression Algorithm predicts B. pumilus and Adenovirus test results More noise due toanalytical methods 15

16 Calculated Dose Approach for MP systems with low and high wavelength sensors Predicting Adenovirus with and without B. Pumilus Algorithm fit to MS2 alone Algorithm fit to MS2 and B. pumilus 16

17 Calculated Dose Approach for MP systems with low and high wavelength sensors Impact of low wavelength inactivation Calculated for test conditions using synthetic quartz sleeves Significant contribution from low wavelengths possible for MS2 Even higher contribution of low wavelengths for Adeno possible ow wavelength sensor monitors themagnitude of log I ow 17

18 Calculated Dose Approach for MP systems with low and high wavelength sensors Example designs Identical flow Identicalaging and fouling(s/s0) Synthetic quartz sleeves UVT 254nm : 98% UVT 220nm : 50%; 90% MS2 UVT log I RED Total RED ASCF Q100 WRF 4376 ow High , ,07 ow ,9 34 High , ,5 2,07 Adenovirus UVT log I RED Total RED ASCF Q100 WRF 4376 ow ,1 High , ,9 1 ow ,1 139 High , ,4 1,7 18

19 Calculated Dose Approach for MP systems with low and high wavelength sensors Summary ow andhigh wavelengthascf s can(and should) be calculated acc. towrf 4376 A test matrix for the presented algorithm should include test conditions that maximize and minimize the contribution of low wavelengths The calculated dose algorithm with low andhigh wavelength sensors for MP systems predicts log inactivation and RED of Adenovirus Using a low wavelength sensor can provide significant advantages for some operational scenarios Without a low wavelength sensorascf s need tobeconsidered (WRF 4376) which may result in significant performance losses 19

20 Thank you! 20