Emerging Opportunities of Nanotechnology to Address Groundwater - PowerPoint PPT Presentation

Emerging Opportunities of Nanotechnology to Address Groundwater Remediation Challenges and Enhance Bioremediation Pedro J.J. Alvarez Rice University NIEHS Webinar 11 October 2019

Nano = Dwarf (Greek) = 10 -9 “Nanotechnology is the understanding and control of matter at dimensions of roughly 1 to 100 nanometers, where unique phenomena enable novel applications.” -National Nanotechnology Initiative

Opportunities for Engineered Nanomaterials (ENMs) in Hazardous Waste Treatment (mainly above-ground applications) ENM Properties Examples of Enabled Technologies Large surface area to Superior sorbents (e.g., nanomagnetite or graphene oxides volume ratio to remove heavy metals and radionuclides) Enhanced catalytic Hypercatalysts for advanced oxidation & reduction processes properties Antimicrobial properties Disinfection and biofouling/biocorrosion control without harmful byproducts Multi-functionality Fouling-resistant (self-cleaning & self-repairing) membranes (antibiotic, catalytic) that operate with less energy; trap & zap sorbents High conductivity Novel electrodes for selective electro-sorption and energy- efficient electrocatalytic treatment

When Does Nano Make Sense? • Where current technologies do not meet current or upcoming regulations ; • When it enhances cost-effectiveness (e.g., faster, less energy, and less materials) • When one needs easy-to-deploy modular systems with small footprint (remote locations?)

Opportunities in Remediation • Degradation of recalcitrant compounds (when biodegradation alone is ineffective) • Higher selectivity towards target contaminants to efficiently utilize the available treatment capacity • Multifunctionality to address mixed contamination. • Lower energy requirements for thermal treatment • Improve source zone remediation (AOPs, ARPs) • Improve monitoring of remediation progress.

Example 1. Nano-Scale Zerovalent Iron (NZVI) First used in 2000 70 full scale or pilot tests by 2013

Synergistic Biogeochemical Interactions H 2 produced by iron corrosion stimulates RDX mineralization: Fe 0 + 2H 2 O • Fe +2 + H 2 + 2OH - Bacteria RDX Fe 0 Fe 2+ H + H 2 2 e - H + CO 2 , CH 4 RDX MNX, DNX, TNX, others

RDX Mineralization ( 14 CO 2 ) is mediated by bacteria, and Fe 0 has a stimulatory effect Cumulative 14 RDX Mineralization (%) 100 Sterile Fe 0 80 Soil + sludge Soil + Fe(0) + sludge 60 40 20 0 0 15 30 45 60 75 Time (days) Oh, Just, and Alvarez (2001). Environ. Sci. Technol. 35(21):4341-4346

Polymer Coatings Mitigate NZVI Aggregation and Toxicity to Bacteria Li Z., K. Greden, P.J.J. Alvarez, K.Gregory, and G.V. Lowry. Environ. Sci. Technol. 44 (9):3462–3467

Dose response of E. coli exposed to nZVI 10 10 10 10 Uncoated nZVI Poly-peptide Coated nZVI 8 10 9 10 6 10 CFU/ml CFU/ml 8 10 4 10 7 10 2 10 0 6 10 10 0 2 4 6 8 10 0 2 4 6 8 10 RNIP (Fresh) concentrations (g/L) MRNIP (fresh) concentrations (g/L) Xiu Z-M, Z-H Jin, T-L Li, S. Mahendra, G.V. Lowry, and P.J.J Alvarez. Bioresource Technology 101: 1141–1146

Coating the NZVI Enables Expression of Dehalogenase Genes as it Mitigates Toxicity (Enables Microbial Reductive Dechlorination) Uncoated nZVI: Poly-peptide Coated nZVI: downregulated upregulated (a) (b) Log (gene expression fold changes) Log (gene expression fold changes) 1.0 Time (h) tceA 1 vcrA tceA 0 24 48 72 96 120 144 vcrA 0.5 0 -1 0.0 0 24 48 72 96 120 144 168 Time (h) -2 10 -0.5 10 Xiu Z-M, K.B. Gregory, G.V. Lowry, and P.J.J. Alvarez. Environ. Sci. Technol. 44: 7647–7651

Sulfidation overcomes preferential reaction of nZVI with Water Gu. Wang and Tratnyek, ES&T 2017; DOI:10.1021/acs.est.7b03604

Example 2: Photocatalysis with nTiO 2

Photocatalytic Hydroxylation of Weathered Oil to Enhance Bioavailability and Bioremediation OH OH ROS OH CO 2 Weathered Hydroxylated or Oil Fragmented (Recalcitrant) Residue Photocatalyst (Bioavailable)

Photocatalysis Increased Solubilization and Biodegradation of Weathered Oil Dark * 90 * With UV 60 TOC (mg/L) * 30 0 No PC P25 FG * statistically significant ( p <0.05) after 1-day exposure Brame J., S.W. Hong, J. Lee and P.J.J. Alvarez . Chemosphere 90: 2315–2319.

Looking Forward: ENMs with multifunctionality could target complex contaminant mixtures

ENMs with high selectivity for contaminants could improve performance and reactive lifetime

Nano-tracers to delineate distribution of contaminants in the subsurface

ENMs to enhance thermal treatment and decrease energy requirements?

In situ generation of NMs to provide NMs in low-conductivity regions to sequester or degrade contaminants?

Stimuli-responsive ENM that release reactants/biostimulants only when needed

ENMs to enhance rates and performance of bioremediation

CONCLUSIONS • Some ENMs offer high-performance remediation opportunities as hypercatalysts, oxidants, reductants, and improved separation processes. • Mainly for above-ground treatment (higher selectivity, lower EEO) but also as pretreatment or biostimulants for enhanced in situ bioremediation • Need pilot studies to delineate practical applicability and limitations

Backup Slides

Groundwater circulating wells to emplace ENMs over larger areas?

Feasibility of ENMs to improve specific remediation niches

In Situ Chemical Oxidation Using NZVI (Fenton’s Reaction) Fe 0 + O 2 + 2H + → Fe 2+ + H 2 O 2 Fe 0 + H 2 O 2 → Fe 2+ + 2 OH - Fe(II) + H 2 O 2 → Fe 3+ + OH• + OH -

NZVI (1g/L) Preferentially Biostimulated Methanogens, also Dechlorinators after Inhibitory Period 16 300 14 Methane ( µ mol/bottle) 250 Control TCE ( µ mol/bottle) 12 NZVI 200 10 Bacteria Bacteria Bacteria + NZVI 8 150 Bacteria + NZVI 6 100 4 50 2 00 0 100 200 300 400 500 0 50 100 150 200 Time (h) Time(h) NZVI NZVI 16 12 Bacteria Bacteria 14 Bacteria + NZVI NZVI + Bacteria 10 Ethene ( µ mol/bottle ) 12 VC ( µ mol/bottle) 8 10 8 6 6 4 4 2 2 0 0 0 100 200 300 400 500 0 100 200 300 400 500 Time (h) Time (h) Xiu Z-M, Z-H Jin, T-L Li, S. Mahendra, G.V. Lowry, and P.J.J Alvarez (2010). Bioresource Technology 101: 1141–1146

Enhancing Land Farming ? • Contaminated soil is spread as a thin layer (< 0.3 m) on a Spray dissolved TiO 2 photocatalyst 1 prepared surface • Indigenous microorganisms (bacteria and fungi) remove hydrocarbons • Bioremediation is stimulated by aeration and addition of Bioremediation (Landfarming) 2 nutrients and moisture. • Can be slow (6-month cycles) • TiO 2 pre-treatment could increases number of cycles per year per pit

Other Potential Applications (TRL 1-4) • Nanoparticles that enhance in situ (microwave) heating to enable thermal desorption/smoldering • Nano-sorbents that selectively bind priority pollutants (higher capacity, faster kinetics) • Nano-catalysts for faster (pump and treat) advanced oxidation or reductive dehalogenation • Porous nanocarriers with antimicrobial agents that minimize membrane biofouling

Oxidized GW Pollutants Degraded by NZVI • The Dirty Dozen: • Organics: • Dioxins • Chlorinated solvents • Furans (PCE, TCE) • PCBs • Munitions Wastes • HCB (TNT, HMX, RDX) • DDT • PFCs • Chlordane • Toxaphene • Inorganics: • Dieldrin • Aldrin • Nitrate • Endrin • U(VI) • Heptachlor • Cr(VI) • Mirex