Application and Discussion of Ion Exchange Resin and PFAS Removal. Thomas Baker, PMP Sales & Applications Specialist

Transcription

1 Application and Discussion of Ion Exchange Resin and PFAS Removal Thomas Baker, PMP Sales & Applications Specialist

2 Presentation outline Intro to ECT Construction of target synthetic medias, properties, and how they function Mechanisms of ion exchange resin to remove PFAS Water chemistry background and implications on process efficacy and application success Design Options and Requirements Comparing resin vs. GAC: Bench to pilot studies Full scale applications Other technologies & applications

3 Introduction to ECT Treatment technology solutions provider focused on emerging contaminants Initial focus was on 1,4-dioxane: partnership with Dow Chemical Interest by DOD to find alternate solution for PFAS Synthetic Media Synthetic adsorbents and Ion Exchange resins Regenerable, sustainable, cost-effective technologies

4 What are the emerging contaminants? Primary focus today... PFAS (formerly PFCs) Per- and Polyfluoroalkyl Substances (PFOA, PFOS, GenX) 1,4-Dioxane...but there are others 1,2,3-Trichloropropane (TCP) N-Nitrosodimethylamine suspected human carcinogen (NDMA or DMN) Pharmaceuticals and personal care products Tungsten - Linked with leukemia Tributyltin - wood preservative, biocide in certain paints Ethylene dibromide - pesticide, fumigant Hex chrome carcinogen, taking another look and dropping levels

5 Focus on the top two PFAS (PFOA is pictured) By Manuel Almagro Rivas - Own work using: Avogadro, Discovery Studio, GIMP, CC BY-SA 4.0, 1,4-dioxane

6 Leader in testing and applying IX resins for emerging contaminants

7 Standardized design components SORBIX VESSEL SKID PUMP SKID FOR REGEN SYSTEM

8 PFAS: The emerging contaminant in the headlines

9 Synthetic Medias: Types, Construction, and Functionality Structure Co-polymer matrix of DVB and styrene typically Functional groups are added to the chemical makeup to interact with ions of interest based on electrochemical charge Cationic removes positively charged ions Anionic removes negatively charged ions Functional groups also determine strength of attraction and bond Spherically shaped bead Crosslinking chemistry is added to matrix to impart porosity

10 Synthetic Medias: Types, Construction, and Functionality Typical resin is therefore a complex 3 dimensional structure, consisting of the Polystyrene chains crosslinked together to form a backbone or bead structure, Attached functional groups fixed to the polymer chains that determine the type of ion it can hold and exchange, Pores located in the structure that are determined by the level of crosslinking used in the manufacture Exchangable counterions attached to the functional groups

11 Porosity in synthetic medias Porosity essentially determines the size of a molecule or ion that can enter the resin bead structure, and its rate of diffusion. This is very similar to LGAC medias, which are graded on performance by the porosity and their ability to uptake (adsorb) organics from aqueous mediums. Porosity also determines a resins resistance to chemical attack, osmotic shock, and expansion/contraction if regenerated. This is an important aspect in the use of resin for PFAS, as we will see.

12 Resin Capacity Expressed as Total Capacity Operating Capacity Total capacity is basically the equivalent value of the total number of fixed sites assumed on the unit of resin that can functionally exchange ions. Operating capacity is the measure of useful performance of resin unit under loading conditions. These are influenced by (not a complete list) Flow Temperature Vessel design Bed depth Feed concentration Background water matrix Selectivity or competition Foulants

13 Common Technology Parameters of Consideration Terminology that is important to understand Bed Volume (BV) the amount volume of a vessel has that is usable and typically filled with media. Generally expressed as cubic feet CROSS SECTION BED BED DEPTH

14 Common Technology Parameters of Consideration Empty Bed Contact Time (EBCT) the amount of time, expressed in minutes, that a volume of water is in contact with the media bed. Initial contact BED Time Final contact

15 PFOS & PFOA Common Features Important for Treatment PFOS Sulfonated end, C8 (8 carbons) Highly ionized PFOA Acid end, C8 (8 carbons) Highly ionized PFOA & PFOS most common form Very stable compound, carbon fluorine bond is strongest in nature, and considered inert Exhibits strong negative charge C-F Tail is hydrophobic (non-water soluble) and oleophobic (non-fat soluble) Each molecule has a functional group Head that is hydrophilic extremely soluble in water. Compounds that have >6 carbons (as shown) are considered to be Long Chain, and are known to be more stable and more difficult to breakdown Compounds that have <6 carbon atoms are considered short chained compounds, and can be either degraded long chain materials, or individual compounds themselves.

16 How does IEX resin remove PFAS? Dual mechanism of removal: IEX and adsorption PFOS Molecule Simplified Resin Bead

17 Feed Water Quality & Resin Design needs to take into consideration the selectivity that s exhibited by ion exchange resin, and in some cases, that competition for exchange sites

18 Operating Capacity Impacts from Competition and Fouling Normally, resin has an excellent capacity for PFAS removal in normal waters, however the following ions can cause some complications for applications: Sulfate Chloride Excessive alkalinity Iron ph Iron in reduced form should pass through resin, however can oxidize, fouling the bed Any sediment or TSS needs to be removed before water is introduced into the bed, or it could cause plugging or channeling of the flow, thus reducing bed throughput.

19 Types of Applications for PFAS Removal Outside of water quality, primary determining factor is feed concentrations of the specific PFAs compounds, relative to their ability to be adsorbed or exchanged in the resin. By order of magnitude, a balance is incorporated into a design relative to feed concentration, expected operating capacity of the resin based on all factors, and the calculated replacement interval and cost of the resin. A determination is made to either use: Single Use resin 1 time and disposed of, typically where low foulant, low feed concentrations are present, with longer term bed volumes processed to breakthrough. Generally DWS applications and barrier wells Regenerable resin typically fed with higher feed concentrations where replacement would be cost or OPEX prohibitive, such as extraction/recovery wells

20 SORBIX PURE Single Use Process Flow EBCT: min per vessel 36 min bed depth Space Velocity: 6-12 gpm/ft 2 SORBIX PURE IEX Resin INFLUENT WATER Bag Filter 10 micron Resin Resin SORBIX PURE LEAD SORBIX PURE LAG Backwash at startup only Classify the bed TREATED WATER

21 SORBIX A3F Regenerable Process Flow NH Installation Regenerable IEX Resin SORBIX A3F

22 Applications Pilot through Full Scale Evaluating Real World Applications against GAC

23 Case study: What happened at New England Air Base? Community of roughly 21,000 PFOA and PFOS detected in public drinking water supply PFAS tied to health impacts; citizens become concerned Contamination originated from firefighting foam use at the AFB

24 Pilot test Process Flow Diagram 24 Amec Foster Wheeler 2016.

25 Proof of Performance Testing IEX vs LGAC

26 PFOA breakthrough at 5-min EBCT GAC Resin

27 PFOS breakthrough at 5-min EBCT GAC Resin

28 Pilot test: IEX resin vs. GAC Process pumps GAC (front) and resin (rear) vessels 28 Amec Foster Wheeler Cartridge filters for solids removal

29 Removal Comparison PFOA + PFOS 2.50 GAC - PFOS + PFOA First sample at 574 gals Treated 2860 BVs 2.5 IX - PFOS + PFOA Concentration (ppb) GAC 10.0 min GAC 5.0 min GAC 2.5 min INFLUENT Concentration (ppb) ppt IX 10.0 min IX 5.0 min IX 2.5 min INFLUENT 0.00 HAL 70 ppt PFOS+PFOA 0 Date GAC Breaks 50ppt at 13,000 BV s or 10,400 gals Treated (10 min EBCT) Date IX Resin is ND after 171,000 BV s or 34,300 gals Treated (2.5 min EBCT)

30 Removal Comparison PFAS 5.0 GAC - TOTAL PFAS First sample at 574 gals Treated 2860 BVs 5.0 IX - TOTAL PFAS Concentration (ppb) GAC 10.0 min GAC 5.0 min GAC 2.5 min INFLUENT Concentration (ppb) All PFBA 48,000 BVs IX 10.0 min IX 5.0 min IX 2.5 min INFLUENT Date GAC Treated 10,400 Gals or 13,000 BVs through 10 min EBCT Date IX Resin Treated 34,400 Gals or 171,000 BVs through 2.5 min EBCT

31 Removal Comparison PFBA GAC - PFBA First sample at 574 gals Treated 2860 BVs IX - PFBA Concentration (ppb) min EBCT 3,800 gals 4,740 BVs GAC 10.0 min GAC 5.0 min GAC 2.5 min INFLUENT Concentration (ppb) IX 10.0 min IX 5.0 min IX 2.5 min INFLUENT min EBCT 18,950 gals 23,600 BVs Date Date GAC Treated 10,400 Gals or 13,000 BVs through 10 min EBCT IX Resin Treated 34,400 Gals or 171,000 BVs through 2.5 min EBCT

32 Removal Comparison PFNA 0.03 GAC - PFNA First sample at 574 gals Treated 2860 BVs 0.03 IX - PFNA Concentration (ppb) GAC 10.0 min GAC 5.0 min GAC 2.5 min INFLUENT Concentration (ppb) IX 10.0 min IX 5.0 min IX 2.5 min INFLUENT Date GAC Treated 10,400 Gals or 13,000 BVs through 10 min EBCT Date IX Resin Treated 34,400 Gals or 171,000 BVs through 2.5 min EBCT

33 Removal Comparison PFBS 0.07 GAC - PFBS First sample at 574 gals Treated 2860 BVs 0.07 IX - PFBS Concentration (ppb) GAC 10.0 min GAC 5.0 min GAC 2.5 min INFLUENT Concentration (ppb) IX 10.0 min IX 5.0 min IX 2.5 min INFLUENT Date Date GAC Treated 10,400 Gals or 13,000 BVs through 10 min EBCT IX Resin Treated 34,400 Gals or 171,000 BVs through 2.5 min EBCT

34 Removal Comparison PFHxA GAC - PFHxA First sample at 574 gals Treated 2860 BVs IX - PFHxA Concentration (ppb) GAC 10.0 min GAC 5.0 min GAC 2.5 min INFLUENT Concentration (ppb) IX 10.0 min IX 5.0 min IX 2.5 min INFLUENT Date GAC Treated 10,400 Gals or 13,000 BVs through 10 min EBCT Date IX Resin Treated 34,400 Gals or 171,000 BVs through 2.5 min EBCT

35 Removal Comparison PFHxS GAC - PFHxS First sample at 574 gals Treated 2860 BVs IX - PFHxS Concentration (ppb) GAC 10.0 min GAC 5.0 min GAC 2.5 min INFLUENT Concentration (ppb) IX 10.0 min IX 5.0 min IX 2.5 min INFLUENT Date Date GAC Treated 10,400 Gals or 13,000 BVs through 10 min EBCT IX Resin Treated 34,400 Gals or 171,000 BVs through 2.5 min EBCT

36 Full Scale Process Life Cycle Cost and Design

37 Activated Carbon and Resin Piloting Haven Well Haven Well PFOS+PFOA Results HA Limit 70 ppt PFOS+PFOA (ppt) ½ HA Limit 35 ppt Trigger for GAC Change out GAC - 10 Min EBCT Resin - 5 Min EBCT ,000 10,000 15,000 20,000 25,000 30,000 Gallons Treated (Pilot Scale)

38 (3) Lead/Lag IX Resin Trains In Parallel (3) GAC Vessels In Parallel

39 Full Scale Rendering DWS LGAC Vessels Resin Vessels Influent Well Manifold

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41 Summary and Lessons Learned Single Use Compared IX Resin vs GAC on a gallons treated basis. GAC: 50 ppt PFOS+PFOA break through in 10 min EBCT effluent after 13,000 BVs or 10,400 gallons treated IX resin: Non-Detect PFOS+PFOA in 2.5 min EBCT effluent after 171,000 BVs or 34,300 gallons treated IX Resin provides dual mechanism for PFAS removal: Adsorption & Ion Exchange Higher Capacity and Faster Kinetics Full Scale Life Cycle Cost Comparison revealed IX Resin Hybrid System provided: 1/2 Capital cost 1/3 O&M Media cost 1/2 Total Present Worth Cost

42 Regenerable System Development Pease Site 8

43 Goals for Regenerable System Development Address remediation of localized area around firefighting zone (Site 8) to extract water, treat, and return water to aquifer free of PFAS. Because of high concentrations in remediation wells vs DWS wells, treatment needed to be designed to be regenerable, and not single use, which would be cost prohibitive to operate. Water quality should not be altered on returned water to aquifer such that it could cause prevention of use for public water supply. No adverse characteristics.

44 Influent Data PFAS Compound Average Influent Concentration (µg/l) PFOA 11.5 PFOS 27.4 Other PFAS 55.6 Total PFAS 94.5

45 Successful Regeneration 6.0 Total PFAS Concentration from Lead IX Media Bed Total PFAS Concentration (ppb) Virgin Media Post Regen 0.0-2,000 4,000 6,000 8,000 Volume Treated (Bed Volumes)

46 Full-scale Site 8 resin system

47 In-vessel resin regeneration system

48 Distillation for recovery of regen solution

49 Influent / Effluent from Full Scale System

50 Regeneration process and applications The regeneration process results in a smaller volume of waste, currently processed through super loaders (GAC with very low flow) that requires disposal or further treatment. Not determined to be hazardous at this point, but landfilling is not considered an option, incineration is preferred method. Regenerable systems are not, at this time, acceptable to be used in the US for drinking water applications, due to the use of the regenerant chemistry. While these resins do carry NSF certification, this is a long term driver to get the process certified for drinking water. Two promising technologies are on the forefront for regenerant destruction Plasma destruction Electrochemical treatment. Both are bench scale development stage, and scale up and cost design analysis needs to be completed

51 Current Status of Site 8 System has processed more than 10 million gallons of water as of mid-november, 2018 System has undergone 5 regeneration sequences since commissioning with less than 2% difference in throughput volumes until breakthrough. System has consistently returned ND PFAS water back to aquifer for re-injection.

52 Thank you! Thomas Baker (614)