ENHANCED ACTIVATED CARBON AND PERFORMANCE PREDICTION USING A NOVEL TEST METHOD

Transcription

1 ENHANCED ACTIVATED CARBON AND PERFORMANCE PREDICTION USING A NOVEL TEST METHOD Presented by Adam Redding Thursday, October 23 rd, 2014 CA-NV Section AWWA Fall Conference 2014 Evoqua Water Technologies LLC

2 Presentation Overview Activated Carbon Background What does enhanced actually mean? Where can we apply this enhancement? The Dye Test Performance prediction Identifying carbon age Conclusions 2014 Evoqua Water Technologies LLC PAGE 2

3 Preview: Part I: Predicting 1,2-dichloroethane breakthrough. Breakthrough = ( * Iodine) + ( * Dye) Evoqua Water Technologies LLC PAGE 3

4 Preview: Part II: Quantifying organic fouling Evoqua Water Technologies LLC PAGE 4

5 Activated Carbon In a Nutshell Common Sources Coal Bituminous Anthracite Lignite Coconut Shell Wood Properties Strong affinity for organic contaminants. Performance determined by porosity and surface chemistry. Porosity varies with source material and activation method. Surface chemistry varies with activation method Evoqua Water Technologies LLC PAGE 5

6 Activated Carbon: Porosity Pore volume distribution shows internal structure of carbon. Capacity is determined by micropores. Adsorption Rate is determined by mesopores. Enhanced carbon benefits from faster adsorption and greater capacity Evoqua Water Technologies LLC PAGE 6

7 Enhanced Coconut-Based Carbon: Porosity 2014 Evoqua Water Technologies LLC PAGE 7

8 What is the result of enhancement? 2014 Evoqua Water Technologies LLC PAGE 8

9 What is the result of enhancement? 2014 Evoqua Water Technologies LLC PAGE 9

10 How can enhancement be applied? Enhanced coconut is designed to perform well in the presence of natural organic mattter (NOM) and offers faster adsorption for treatment of groundwater. Carbon Surface Water Treatment Enhanced Coconut DBP precursors, Taste and Odor Compounds. Standard Coconut Limited applicability. Ground Water Treatment Improved removal of halogenated organics, BTEX and MTBE. Halogenated organics, BTEX and MTBE Evoqua Water Technologies LLC PAGE 10

11 Enhanced Coconut Performance: Rapid Small-Scale Column Tests (RSSCTs) 2014 Evoqua Water Technologies LLC PAGE 11

12 Enhanced Coconut Performance: RSSCTs with Background Chlorinated Contaminants Other Influent Organics PCE = 5 ppb TCE = 1.5 ppb CTC = 3 ppb CHCl 3 = 0.7 ppb 2014 Evoqua Water Technologies LLC PAGE 12

13 and the competing organics Carbon Tetrachloride Chloroform 2014 Evoqua Water Technologies LLC PAGE 13

14 Full-Scale Results: 1,2,3-TCP from Southern California Groundwater 2014 Evoqua Water Technologies LLC PAGE 14

15 Full-Scale Results: Trichloroethylene Removal v. Bituminous GAC in Groundwater 2014 Evoqua Water Technologies LLC PAGE 15

16 The Dye Method A sample of ground carbon is mixed with a known concentration of dye. The dye and carbon are allowed to mix for 90 minutes. The amount of dye that adsorbs in 1 hour is calculated by measuring the remaining amount of dye at set intervals Evoqua Water Technologies LLC PAGE 16

17 The Dye Method: Rationale Desires for Method Simple minimal requirement for equipment. Quick yields a result within several hours. Reproducible multiple tests yield comparable results. Why use a dye? Concentration can be determined photometrically by measuring absorption at a specific wavelength. Multiple types and molecular sizes available to probe carbon structure Evoqua Water Technologies LLC PAGE 17

18 The Dye Method: Details GAC ground and wet sieved to US Mesh. Phosphate buffer used to maintain ph % weight carbon solution Stir plate used to maintain uniform mixture. Carbon allowed to wet for at least 20 minutes prior to start. Dye dosed at time zero and samples pulled at intervals thereafter. Concentration determined via spectrophotometer Evoqua Water Technologies LLC PAGE 18

19 The Dye Method: Results v. Time (hr) 2014 Evoqua Water Technologies LLC PAGE 19

20 The Dye Method: Results v. Square Root Time (hr 1/2 ) 2014 Evoqua Water Technologies LLC PAGE 20

21 The Dye Method: Interpretation Intraparticle Diffusion Model Loading ( mg / g) IDC Time( hr) IDC = Intraparticle Diffusion Rate Constant = Dye Number Important Test Conditions Dye concentration in solution must remain relatively constant during test period. Loading of dye on carbon surface must not be so high as to be approaching a maximum Evoqua Water Technologies LLC PAGE 21

22 Putting the Dye Method to Use: Groundwater treatment for 1,2-Dichloroethane Carbon A B C D E Source Material Coconut Virgin Reagg. Bituminous Virgin Non- Reagg. Bituminous React. Non- Reagg. Bituminous Lignite Apparent Density (g/ml) Iodine Number (mg/g) Dye Number (mg/g) 1,2-DCA Breakthrough (BV) Normalized Breakthrough (BV/AD) Evoqua Water Technologies LLC PAGE 22

23 Groundwater treatment for 1,2-Dichloroethane: Using Either Iodine or Dye Number to Predict Performance Iodine Number Dye Number 2014 Evoqua Water Technologies LLC PAGE 23

24 Groundwater treatment for 1,2-Dichloroethane: Using Iodine and Dye Number to Predict Performance Norm. Breakthrough = ( * Iodine) + ( * Dye) Evoqua Water Technologies LLC PAGE 24

25 The Dye Test: a one trick pony? Many utilities using carbon to treat taste & odor and/or disinfection byproduct precursors. No readily available method for determining degree of fouling from organic matter. Needs to use full-scale (unground) grains as to not change influence of fouling. Longer contact time needed since grains are larger: sieve out 20x30 fraction to speed up the process Measures Diffusion Rate Organic fouling slows diffusion Fouling increases with carbon age Dye adsorption should slow with age 2014 Evoqua Water Technologies LLC PAGE 25

26 Hypothesis supported? 2014 Evoqua Water Technologies LLC PAGE 26

27 Hypothesis supported? Maybe 2014 Evoqua Water Technologies LLC PAGE 27

28 Hypothesis supported? Yes! 2014 Evoqua Water Technologies LLC PAGE 28

29 How does the virgin carbon fit the trend? More data is needed for younger carbons! 2014 Evoqua Water Technologies LLC PAGE 29

30 Is there another way to see carbon age? Confirms fouling observed with Dye Test Evoqua Water Technologies LLC PAGE 30

31 Did column tests confirm Dye Numbers? Grinding to 325x400 likely changed the impact of fouling Evoqua Water Technologies LLC PAGE 31

32 The Dye Number: Recap Dye Number indicates level of enhancement. Acts as a predictor of performance. Offers an advanced specification method for the water utility. Provides additional value beyond the Iodine Number. Can quantify level of fouling as a function of carbon age Evoqua Water Technologies LLC PAGE 32

33 Enhanced Coconut: Recap Enhanced coconut Combines capacity of coconut-based GAC with the adsorption kinetics of coal-based GAC; Offers a 30%-70% improvement in performance over standard coconut-based GAC for 1,2,3-TCP treatment; Also offers performance improvement for other halogenated contaminants; Can be readily identified by the Dye Number test Evoqua Water Technologies LLC PAGE 33

34 Thank you for your attention. Questions? Adam M Redding, PhD Scientist, Activated Carbon Products Evoqua Water Technologies LLC 181 Thorn Hill Road Warrendale, PA adam.redding@evoqua.com or adam.redding@siemens.com 2014 Evoqua Water Technologies LLC

35 Additional Supporting Data 2014 Evoqua Water Technologies LLC PAGE 35

36 Enhanced Coconut Performance: RSSCTs N2 Gas ~ 2 psi H 2 O + TCP + etc Pump Pump Balance Balance Refrigeration (4 C) 2014 Evoqua Water Technologies LLC PAGE 36

37 Enhanced Coconut Performance: RSSCTs 2014 Evoqua Water Technologies LLC PAGE 37