About

Kelvin B. Gregory is a professor in the Department of Civil and Environmental Engineering at Carnegie Mellon University in Pittsburgh, Pennsylvania. His research explores the microbiology, ecology, and fundamental interactions between bacteria and their physical and chemical environment. Gregory has a B.S. degree in biological systems and agricultural engineering from the University of Nebraska and a Ph.D. in civil and environmental engineering from the University of Iowa. He studied microbial diversity and ecology at Woods Hole Marine Biological Laboratory and completed postdoctoral studies at the University of Massachusetts Environmental Biotechnology Center. His current research interests include produced water management, environmental nanotechnology, geologic carbon sequestration, and microfluidic cell sorting.

Research topics

• Computer Science
• Acoustics
• Nanotechnology
• Engineering
• Optics
• Mechanical engineering
• Automotive engineering
• Materials science
• Physics
• Environmental science

Selected publications

• Rebates and grid decarbonization from the Inflation Reduction Act promote equitable adoption of energy efficiency retrofits

  Environmental Research Letters · 2025-02-18 · 6 citations

  articleOpen access

  Abstract Residential and commercial buildings account for 75% of electricity and 40% of the total energy consumption in the United States, costing over $400 billion annually. Electrification and energy efficiency retrofits offer a viable decarbonization pathway, especially since half of US homes were built before modern building codes. These older homes are often occupied by low-to-moderate-income (LMI) families. Equitable electrification provides a unique opportunity to considerably reduce emissions in communities where energy bill savings have the most impact on household finances. This study evaluates how the Inflation Reduction Act (IRA) impacts the adoption potential of air-source heat pumps (ASHPs), heat pump water heaters and clothes dryers, and electric cooking ranges across income groups in the United States. Using a database that statistically represents the US housing stock, we estimate the indicative adoption potential of these technologies under scenarios that represent Pre-IRA conditions and a reference case with IRA provisions. After IRA rebates were introduced, adoption potential for LMI households more than doubled for ASHPs, heat pump water heaters, and electric cooking ranges and more than tripled for heat pump clothes dryers relative to Pre-IRA adoption potential. Cooking retrofits had the lowest adoption potential, and homes that electrified space heating without weatherization had greater adoption potential than those that underwent basic or enhanced enclosure upgrades. Our results show that the introduction of IRA rebates and a gradually decarbonizing grid substantially improves adoption potential for LMI households and even surpasses the adoption potential of middle and upper-income households.

  PublisherDOI

• Corrigendum to “Review: Mitigation measures to reduce tire and road wear particles” [Sci. Total Environ. Volume 904, 15 December 2023, 166537]

  The Science of The Total Environment · 2023-10-16 · 1 citations

  erratumSenior author
  PublisherDOI

• Review: Mitigation measures to reduce tire and road wear particles

  The Science of The Total Environment · 2023 · 48 citations

  Senior authorCorresponding
  • Environmental science
  • Engineering
  • Automotive engineering
  PublisherDOI

• Microparticle sorting with a microfluidic system and ultrasonic standing waves

  2020

  • Computer Science
  • Materials science
  • Acoustics

  In earlier work, our research group developed a technology to sort microparticles in a microfluidic system fabricated within a rigid polymethyl methacrylate (PMMA, acrylic) prism, sandwiched by lead-zirconium-titanate (PZT) wafers that operate in through-thickness mode (with inertial backing) to produce standing bulk waves. The overall configuration is compact, solid, and mechanically robust. The “tilted angle” geometry (orienting the microfluidic channel skew with respect to the standing wave node lines) enables robust separation, whereby particles of different sizes can separate by multiples of the node line spacing; the microparticles display undulating trajectories, where deviation from the straight path increases with particle diameter and excitation voltage. Our earlier work involved particles with large size differences, exemplified by separating 2 μm particles from 15 μm particles, or by separating red blood cells from white blood cells. In this paper we describe our recent results separating 2 μm particles (polystyrene spheres) from 6 μm particles. We describe challenges faced by researchers working with these experimental systems, including the following examples: internal reflections can produce standing wave nodes additional to those predicted by a simple model; particles are observed through a microscope, but the limited depth-of-field places some particles in focus and others out of focus; the conditions in the microfluidic channel vary over relatively short time intervals, including thermal variations produced by the excitation process; and, there exist tradeoffs in choosing an acoustic couplant between the PZT wafers and the PMMA prism. Nonetheless, we show effective separation of microparticles of different sizes.

  PublisherDOI

• Oxidative damage of antibiotic resistant E. coli and gene in a novel sulfidated micron zero-valent activated persulfate system

  Chemical Engineering Journal · 2019-09-10 · 76 citations

  article
  PublisherDOI

• Ultrasonic microparticle alignment and direct ink writing using glass capillaries

  2019-03-29 · 2 citations

  article

  We envision implementing direct ink writing for 3-D printing while aligning microfibers in the resin using standing wave ultrasonics; the aligned fibers would control desired mechanical properties such as strength and ductility, and 3-D printing would match the mechanical properties to the particular part geometry. At this time we work with highviscosity fluids as a physical simulant of representative resins, and spherical polystyrene microparticles or glass microrods instead of microfibers. In this paper we show experimental results using square glass capillaries (with interior dimensions ranging from 0.4 to 1.0 mm) as our microfluidic systems, which are inherently well-suited by their geometry to act as print nozzles, sandwiched between two piezoceramic plates that generate the ultrasonic standing waves. We report experimental data for particle alignment as we change from our initial test fluid, water, to high-viscosity fluids. Similarly, we report experimental data of the fluid behavior pertinent to direct ink writing; we enforce controlled volumetric flow rates (which correspond to print speeds) for high-viscosity fluids under pressurized flow through glass capillaries of varying cross-sectional areas and varying lengths, observing and measuring the approximate ink line width and height. Our use of commercially available square glass capillaries (sandwiched between piezoceramic transducers that are driven at frequencies away from transducer resonance) is novel and distinguishes our approach from that of other research groups; the underlying physics of our devices differs from that of Lund-type acoustic resonators.

  PublisherDOI

• Reduction in sulfate inhibition of microbial dechlorination of polychlorinated biphenyls in Hudson and Grasse River sediments through fatty acid supplementation

  Chemosphere · 2019-05-28 · 22 citations

  article
  PublisherDOI

• Effects of Ferric Oxyhydroxide on Anaerobic Microbial Dechlorination of Polychlorinated Biphenyls in Hudson and Grasse River Sediment Microcosms: Dechlorination Extent, Preferences, Ortho Removal, and Its Enhancement

  Frontiers in Microbiology · 2018-07-20 · 10 citations

  articleOpen access

  Microbial reductive dechlorination of polychlorinated biphenyls (PCBs) has been observed in many PCB-impacted sediments. However, this biodegradation is relatively site-specific and can be affected by PCB compositions and sediment geochemical conditions. To better understand the influence of a common competing electron acceptor, ferric oxyhyroxide (FeOOH), on dechlorination, two sediments (Hudson River and Grasse River sediments), and two PCB mixtures (PCB 5/12, 64/71, 105/114 and 149/153/170 in Mixture 1 and PCB 5/12, 64/71, 82/97/99, 144/170 in Mixture 2) were used for this microcosm study. The addition of 40 mmole/kg FeOOH completely inhibited PCB dechlorination in the Hudson sediment, but only moderately inhibited PCB dechlorination in the Grasse sediment with a 3-week longer lag time. The inhibitory effect in the Grasse sediment was mainly due to the loss of unflanked para dechlorination activity. Fe(II) analysis showed that dechlorination started prior to the consumption of Fe(III), which indicates PCB reduction and Fe(III) reduction were able to take place concurrently. Dehalococcoides 16S rRNA genes increased with the commencement of dechlorination in the Grasse sediment, but not in the completely inhibited Hudson sediment. Rare ortho dechlorination pathways were identified in FeOOH-amended Grasse sediment microcosms, dominated by transformations of PCB 25(24-3-CB) to PCB 13(3-4-CB) and PCB 28(24-4-CB) to PCB 15(4-4-CB). The addition of carbon sources (acetate or a fatty acid mixture with acetate, propionate and butyrate) after 27 weeks of incubation reinitiated dechlorination in FeOOH-amended Hudson sediment microcosms. Also, the addition of carbon sources greatly enhanced ortho dechlorination in FeOOH-amended Grasse microcosms, indicating the utilization of acetate and/or the fatty acid mixture for ortho dechlorination related microorganisms. A dechlorination pathway analysis approach revealed that para-flanked meta dechlorination was primarily preferred followed by ortho-/double-flanked meta dechlorination and single-/double-flanked para dechlorination in the Grasse sediment.

  PublisherOA PDFDOI

• Comparative metagenomics of coalbed methane microbial communities reveals biogenic methane potential in the Appalachian Basin

  bioRxiv (Cold Spring Harbor Laboratory) · 2018-05-10 · 1 citations

  preprintOpen access

  Natural gas is a major source of global energy, and a large fraction is generated in subsurface coalbed deposits. Microbial communities within coalbed deposits impact methane production, and as a result contribute to global carbon cycling. The process of biogenic coal-to-methane conversion is not well understood. Here we demonstrate the first read- and assembly-based metagenome profiling of coal-associated formation waters, resulting in the recovery of over 40 metagenome-assembled genomes (MAGs) from eight individual coalbed methane wells in the Appalachian Basin. The majority of samples contained hydrogenotrophic methanogens, which were present in higher relative abundances than was previously reported for other coalbed basins. The abundance of Archaea and salinity were positively correlated, suggesting that salinity may be a controlling factor for biogenic coalbed methane. Low-abundance coalbed microbial populations were functionally diverse, while the most dominant organisms exhibit a high degree of genomic and functional similarities. Basin-specific pan-metagenome clustering suggests lower abundant and diverse bacterial communities are shaped by local basin parameters. Our analyses show Appalachian Basin coalbed microbial communities encode for the potential to convert coal into methane, which may be used as an indicator of potential biogenic methane production for future well performance and increased well longevity.

  PublisherOA PDFDOI

• Quorum Sensing Signals Form Complexes with Ag⁺ and Cu²⁺ Cations

  ACS Chemical Biology · 2018-03-06 · 13 citations

  articleSenior authorCorresponding

  Quorum sensing (QS) regulates important bacterial behaviors such as virulent protein production and biofilm formation. QS requires that molecular signals are exchanged between cells, extracellularly, where environmental conditions influence signal stability. In this work, we present a novel complexation between metal cations (Ag+ and Cu2+) and a QS autoinducer signal, N-hexanoyl-L-homoserine lactone (HHL). The molecular interactions were investigated using mass spectrometery, attenuated total reflectance—Fourier transform infrared spectroscopy, and computational simulations. Results show that HHL forms predominantly 1:1 complexes with Ag+ (Kd = 3.41 × 10–4 M) or Cu2+ (Kd = 1.40 × 10–5 M), with the coordination chemistry occurring on the oxygen moieties. In vivo experiments with Chromobacterium violaceum CV026 show that sublethal concentrations of Ag+ and Cu2+ decreased HHL-regulated QS activity. Furthermore, when Ag+ was preincubated with HHL, Ag+ toxicity to CV026 decreased by an order of magnitude, suggesting HHL:metal complexes alter the bioavailability of the individual constituents.

  PublisherDOI

Frequent coauthors

• Gregory V. Lowry

  42 shared

• Pedro J. J. Alvarez

  Systems Engineering Research Center

  15 shared

• Radisav D. Vidić

  University of Pittsburgh

  13 shared

• Djuna Gulliver

  12 shared

• Irving J. Oppenheim

  Carnegie Mellon University

  11 shared

• Arvind Murali Mohan

  Dow Chemical (United States)

  11 shared

• Zongming Xiu

  9 shared

• Erin R. Dauson

  Los Alamos National Laboratory

  9 shared

Labs

• Steinbrenner Institute for Environmental Education and ResearchPI

  The Steinbrenner Institute works to enhance and accelerate environmental education and research efforts at CMU.

Education

• B.S., Biological Systems and Agricultural Engineering

  University of Nebraska

  1995

• M.S., Civil and Environmental Engineering

  University of Iowa

  1999

• Ph.D., Civil and Environmental Engineering

  University of Iowa

  2002

Awards & honors

• Ruth Furman Miller and David H. Miller Presidential Fellowsh…
• GEM Consortium Fellow
• Marshall Scholarship
• Cohon Graduate Fellowship