Water Quality Challenges: Treatment Technologies for Emerging Contaminants

Transcription

1 NYSAWWA 2017 Tifft Symposium Water Quality Challenges: Treatment Technologies for Emerging Contaminants Bill Becker, PhD, PE Erik Rosenfeldt, PhD, PE Jim DeWolfe, PE

2 Outline Drivers for advanced technology Defining emerging contaminants Advanced technologies Removal/Separation Transformation Summary 2

3 Turbidity (NTU) Filtered Water Turbidity Standards Standards have lowered, but designs are basically the same

4 And now for something completely different.. DEET Chlorpyrifos Diazepam Pesticides Galaxolide Anthracene Trifluralin Personal Care Products Oxybenzone Diuron Hexachloro- Estrone cyclo- hexane Nonyl- Gemfibrozil Fluorene phenol Pharmaceuticals Ethion Napthalene Dilantin Musk Chrysene ketone Estriol Polycyclic Aromatic Pyrene Hydrocarbons 4

5 Drivers Stressed water resources Utilities often forced to consider less pristine sources Polluted sources Wastewater reuse Public Pressure and Concerns Senate to Hold Hearing in Hoosick Falls on PFOA Water Contamination By TWC News Web Staff Friday, August 12, 2016 at 07:33 AM EDT 5

6 De Facto Reuse 6

7 Regulated compounds Future Regs?: DBPs Chromium VI Chlorate & Perchlorate PFCs Strontium Perception Emerging Contaminants Aesthetics Potable Reuse 7

8 What is an emerging contaminant A chemical or material that is characterized by a perceived, potential, or real threat to human health or the environment or a lack of published health standards, or A new source or a new pathway to humans has been discovered or a new detection method or treatment technology has been developed USEPA Fact Sheet referencing DoD,

9 Current Emerging Contaminants Pharmaceuticals Antibiotics, Pain killers, Antidepressants, Antiepileptic drugs, Statins, Chemotherapy drugs Personal Care Products Fragrances, Sunscreen, Insect repellents Endocrine Disrupting Compounds Natural (e.g., estrone*, estradiol*, estriol*) Synthetic (e.g., ethinyl estradiol*, bisphenol A) Algal Toxins Microcystin, Saxitoxin, Cylindrospermopsin * CCL3 Compound 9

10 Health Advisory Level De Facto Regulation As described, Health Advisory Level Exceedances have potential Public Notification Consequences 10

11 Emerging, emerging contaminants Flame retardents Polybrominated diphenyl ethers (PBDEs) Organophosphates ( Tris flame retardants) Perfluorinated compounds (PFOA, PFOS) Perfluorooctanoic acid (PFOA)* Perfluorooctanesulfonic acid (PFOS)* * CCL3 Compound 11

12 How Much Effort to Assess Toxicity and Treatment Per Compound? Over 100,000,000 Registered Chemical Substances It would take one person working 40 hours per week, 52 weeks per year, 385,000 years to evaluate this list at 8 hours per compound At one hour per compound it would take 48,000 years. To do this in a reasonable time frame, you would need a staff of 4800 highly trained people working full time for 10 years (not including new compounds) 12

13 The Universe of Chemicals Elements and their aqueous forms 91 elements with t 1/2 >100 years Each may have as many as 10 isotopes, 11 oxidation states, and many oxo-hydroxyl complexes Chemical compounds and ions most are organic 18.4 M in NIH s PubChem database (9.8 M in Beilstein) ~100,000 new ones each year 800,000 are in active use today 85,000 are or have been readily available in commerce 8,000 currently in high production At 20 min/compound, lecture ends at 3:50 AM on January 19, 2715 Courtesy of Professor Dave Reckhow 13

14 EDCs and PPCPs aren t new November 1965; J.WPCF Professor Stumm Elizabeth Stumm-Zollinger 14

15 The Good News Advanced technologies (and traditional in some cases) can take care of many emerging contaminants in water. 15

16 The Bad News $$$$, and 16

17 Technology Alternatives Removal / Separation Technologies Removes contaminants from water, but leaves a concentrated waste stream Membranes Activated Carbon Ion Exchange Transformation Technologies Changes contaminants, but leaves byproducts UV Ozone Advanced Oxidation 17

18 Activated carbon Specific Surface Area: surface area per mass Pores Large for activated carbon Most of the area is within internal pores These are spaces between the graphite-carbon platelets Pores are classified between Micropores: < 2 nm width (adsorption of small molecules; micropollutants) Mesapores: 2-50 nm width (adsorption of larger molecules and NOM) Macropores: > 50 nm width (adsorption of larger molecules and NOM ) 18

19 Activated Carbon Adsorption Hydrophobic compounds like hydrophobic solids Leverage to remove many organic contaminants H 2 O Carbon 19

20 Activated Carbon Adsorption Performance Bed Volumes to 10% Breakthrough >50,000 BVs 20,000 50,000 BVs <20,000 BVs Androstenedione Estradiol Estrone Ethinylestradiol Fluoxetine Oxybenzone Progesterone Testosterone Triclosan Acetaminophen Atrazine Caffeine Carbamazepine DEET Diazepam Erythromycin Estriol Hydrocodone Pentoxifylline Trimethoprim Dicolfenac Dilantin Gemfibrozil Ibuprofen Iopromide Meprobamate Naproxen Sulfamethoxazole TCEP 20

21 Activated Carbon Adsorption Benefits: Effective removal of many organic compounds GAC can be regenerated for repeated use Several methods of treatment GAC filter adsorber GAC contactors (separate from filtration) Powdered activated carbon (PAC) Drawbacks and Limitations: Regeneration - expensive, energy intensive process Competition with NOM decreases adsorption efficiency 21

22 Impact of TOC on Removal of MIB by GAC Influent MIB of 0.10 µg/l, 12x40 mesh GAC, EBCT 10 min (Figure 14-26, WQ&T, (2011) 22

23 Membrane Processes Microporous Micro/Ultrafiltration Semi Permeable Reverse Osmosis & Nanofiltration Membrane Bioreactors 23

24 Membrane Separations Thin barrier to constituents in water What gets through depends on size Microfiltration (MF) Ultrafiltration (UF) Nanofiltration (NF) Reverse Osmosis (RO) Particle Removal Molecule Removal Feed Side Reject H 2 O Permeate 24

25 Membranes Process Microfiltration 5-80 psi Ultrafiltration < 150 psi Nanofiltration < 600 psi Reverse Osmosis > psi Ideal Removal Efficiency Suspended particles Macromolecules Sugar, Divalent salts Monovalent salts Pore Size MF 100 nm 0.1 mm UF 2-50 nm NF 2-5 nm RO < 1 nm Water But not absolute some compounds pass thru RO

26 Membrane Separations Units MBR Influent MBR Filtrate RO Permeate (no oxidation treatment) Atenolol ng/l 3, < 25 Atrazine ng/l < 10 < 10 < 10 Carbamazepine ng/l DEET ng/l < 25 Meprobamate ng/l 2, < 10 Dilantin ng/l < 10 Primidone ng/l < 10 Sulfamethoxazole ng/l 2,800 1,400 < 25 Trimethoprim ng/l 1, < 10 TCEP ng/l < 200 Bisphenol A ng/l 250 < 50 < 50 Diclofenac ng/l < 25 Gemfibrozil ng/l 5, < 10 Ibuprofen ng/l 30, < 25 Musk Ketone ng/l < 100 < 100 < 100 Naproxen ng/l 29, < 25 Triclosan ng/l < 25 MBR is a low-pressure membrane (with biological activity). Capable of removing 16 99%. RO is a high-pressure membrane. Capable of removing to detection limit. 26

27 Membrane Separations Benefits Separates contaminants from water Low pressure - remove particle contaminants High pressure - very effective for many (almost all) contaminants Drawbacks High pressure membranes require lots of energy Concentrated (very concentrated) waste stream Toxicity? Disposal? Need pretreatment to deal with fouling concerns 27

28 UV Photochemistry UV is high energy and can provide effective contaminant transformation if: UV energy is absorbed by contaminant Bonds are amenable to breaking Two types of UV for photochemistry Low Pressure (one emitted UV wavelength 254nm) Medium Pressure (many UVC wavelengths emitted) Disinfection Photolysis 28

29 % Degradation Log reduction/ unit power Chemical Log Reduction per Unit of Power Draw UV Photochemistry Performance UV works for NDMA TCE UV-Oxidation UV-Photolysis NDMA 1,4-Dioxane Not as well for others Peroxide helps ppm H2O2 14 ppm H2O2 7 ppm H2O2 14 ppm H2O2 7 ppm H2O2 14 ppm H2O mj/cm 2 60 LP, 0 mg/l H 2 O 2 40 MP, 0 mg/l H 2 O 2 20 LP, 15 mg/l H 2 O 2 0 Bisphenol A 17-a-Ethinyl Estradiol 17-b-Estradiol MP, 15 mg/l H 2 O 2 29

30 UV Photochemistry Benefits Transforms contaminants (no concentrate) No chemical addition At photochemistry doses, very effective disinfection is achieved Drawbacks and limitations Limited effectiveness for many chemicals Don t know what photoproducts are being made Eg NDMA photoproducts can reform NDMA High energy requirements for photolysis (compared to disinfection) Impacted by particles, other UV absorbing substances 30

31 Ozone Oxidation O 3 is a very strong chemical oxidant When O 3 decays naturally, OH are formed Always some AOP formed when you ozonate O 3 produces more OH at higher ph ( > 8.5) O 3 produces OH in presence of peroxide Highly effective at oxidizing EDCs and PPCPs especially: Alkene Amine Phenol 31

32 % Removal % Removal % Removal % Removal Ozone Oxidation Removal of Sulfamethoxazole Ozone Ozone/Hydrogen Applied Ozone Dose (mg/l) Removal of TCEP Ozone Ozone/Hydrogen Peroxide Applied Ozone Dose (mg/l) Removal of DEET Ozone Ozone/Hydrogen Peroxide Applied Ozone Dose (mg/l) Removal of Dilantin Ozone Ozone/Hydrogen Applied Ozone Dose (mg/l) 32

33 Ozone Oxidation Benefits Transforms chemicals (no concentrate) Rapid kinetics Relatively selective oxidation Drawbacks Ozone formation requires high energy No residual Bromate formation if bromide is present Formation of unknown byproducts NOM impacts ozone demand 33

34 Advanced Oxidation Effective disinfection and chemical oxidation o o o Barriers for protecting public health and improving public perception Pharmaceuticals, Personal Care Products, EDCs Crypto, Viruses, E. coli, etc. AOPs work by creating hydroxyl radicals ( OH) o OH then blast away at organic chemicals UV Based AOPs o UV/H 2 O 2, UV/O 3, UV/HOCl, etc. Ozone Based AOPs o Ozone/H 2 O 2, Ozone/NOM, Ozone/pH Usually expensive Complex chemistry 34

35 % Degradation [MIB]/[MIB]o Advanced Oxidation mg/l H2O2 Taste and Odor 5 mg/l H2O Dose (mj/cm2) mj/cm 2 LP, 0 mg/l H 2 O 2 MP, 0 mg/l H 2 O 2 LP, 15 mg/l H 2 O 2 MP, 15 mg/l H 2 O 2 0 Bisphenol A 17-a-Ethinyl 17-b-Estradiol Estradiol Rosenfeldt and Linden, Environmental Science and Technology,

36 Advanced Oxidation Not all AOPs are effective for all contaminants 36

37 Advanced Oxidation Benefits Very rapid kinetics with many organic compounds Limited bromate formation Many ways to make AOPs Usually see high levels of disinfection Drawbacks / Limitations High Energy processes Unselective = Inefficient Formation of unknown byproducts No residual NOM can interfere 37

38 Ion exchange Specialty resins for PFCs (PFOS/PFOA) 38

39 What about Biological Treatment? As much chemistry as necessary, as much biology as possible ASR Stream bank filtration Biological filtration (BAF) 39

40 Effectiveness of advanced treatment technologies Technology Removes T&O Effective for Algal Toxins Emerging Contaminants Effective Disinfection As Needed Capability Ozone Warm water GAC PAC Nano/RO UV AOP Ozone AOP 40

41 Capital Cost Considerations Technology Cost: $/gallon GAC $1.00 Ozone $0.50 UV/AOPs $0.30 NF/RO $5.00 Costs vary widely and are a function of: Specific contaminant Raw water quality Site conditions Other treatment objectives 41

42 Summary Advanced Treatment Processes for emerging contaminants are powerful, high energy options Decisions - analyze how the technology will work down the road for new contaminants Specific to your water Specific to your contaminants of concern Specific to you site conditions Source Contaminants Site Specifics 42

43 Summary Two classifications for advanced treatment processes Oxidation processes destroy contaminants, but leave you with unknown byproducts Ozone, AOPs Removal processes separate contaminants from water, but leave you with a concentrated waste stream NF/RO GAC must be regenerated 43

44 Final thoughts As analytical detection continues to improve, we will find new emerging contaminants in drinking water. Advanced treatment processes will effectively treat emerging contaminants. When should advanced treatment processes be implemented as we aim to ensure protection of protect health? 44

45 Questions? Cell: