Pedro J. J. Alvarez

Bio: Pedro J. J. Alvarez is an academic researcher from Rice University. The author has contributed to research in topics: Bioremediation & Medicine. The author has an hindex of 89, co-authored 378 publications receiving 34837 citations. Previous affiliations of Pedro J. J. Alvarez include University of Minnesota & University of Michigan.

Scientists Raise Alarms About Fast Tracking of Transoceanic Canal through Nicaragua.

Abstract: Seeking economic growth and job creation to tackle the nation's extreme poverty, the Nicaraguan government awarded a concession to build an interoceanic canal and associated projects to a recently formed Hong Kong based company with no track record or related expertise. This concession was awarded without a bidding process and in advance of any feasibility, socio-economic or environmental impact assessments; construction has begun without this information. The 278 km long interoceanic canal project may result in significant environmental and social impairments. Of particular concern are damage to Lake Cocibolca, a unique freshwater tropical lake and Central America's main freshwater reservoir; damage to regional biodiversity and ecosystems; and socio-economic impacts. Concerned about the possibly irreparable damage to the environment and to native communities, conservationists and the scientific community at large are urging the Nicaraguan government to devise and reveal an action plan to address and mitigate the possible negative repercussions of this interoceanic canal and associated projects. Critical research needs for preparation of a comprehensive benefit-cost analysis for this megaproject are presented.

Sustained and complete hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) degradation in zero-valent iron simulated barriers under different microbial conditions.

Abstract: Flow-through columns packed with "aged" zero-valent iron (ZVI) between layers of soil and sand were constructed to mimic a one-dimensional permeable reactive iron barrier (PRB). The columns were continuously fed RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine, ca. 18 mg l−1) for over one year. Two columns were bioaugmented with dissimilatory iron reducing bacteria (DIRB) Shewanella algae BrY or Geobacter metallireducens GS-15 to investigate their potential to enhance the reactivity of aged iron by reductive dissolution of passivating iron oxides or via production of biogenic reactive minerals. A third column was not bioaugmented to evaluate colonization by indigenous soil microorganisms. [14C]-RDX was completely removed in all columns at the start of the iron layer, and concentration profiles showed rapid and sustainable RDX removal over one year; however, a phylogenetic profile conducted after one year using DGGE analysis of recovered DNA did not detect S. algae BrY or G. metallireducens in their respective...

Bottom-up biofilm eradication using bacteriophage-loaded magnetic nanocomposites: a computational and experimental study

Abstract: Biofilms cause a variety of pervasive problems in water treatment, distribution and reuse systems that are difficult to mitigate due to their resistance to disinfectants. We used magnetic phage-nanocomposite conjugates (PNCs) to target bacteria in biofilm inner layers for bottom-up eradication. Polyvalent Podoviridae phages PEB1 (54 nm) or PEB2 (86 nm) were covalently conjugated (via amide bonds) with magnetic colloidal nanoparticle clusters (CNCs) of different sizes (150, 250 or 500 nm). Smaller CNCs with higher density of amino groups loaded phages more efficiently than the largest CNCs (e.g., for PEB1, 60 ± 4, 62 ± 5, and 47 ± 4 phages were loaded per μm2). Smaller PNCs dispersed phages more evenly throughout the biofilm bottom, significantly disrupting the biofilm bottom layer and detaching the biofilm within 6 h. The biofilm removal efficiency was 98.3 ± 1.4% for dual species biofilm (i.e., Escherichia coli and Pseudomonas aeruginosa) and 92.2 ± 3.1% for multi-species biofilm (i.e., E. coli, P. aeruginosa, and non-hosts Bacillus subtilis and Shewanella oneidensis). Large PNCs caused higher physical disruption but lower corresponding removal efficiencies (i.e., 80.2 ± 3.4% for dual species biofilm and 67.6 ± 3.8% for multi-species biofilm) due to lower horizontal diffusion at the bottom of the biofilm. A semi-empirical numerical model corroborated the higher biofilm removal efficiency with smaller PNCs and inferred that PNC size influences the mode of phage propagation: Small PNCs facilitate biofilm bottom clearance with significant horizontal dispersion while large PNCs mainly enhance vertical propagation. Overall, this study demonstrates the importance of size control to enhance the biofilm eradication capability of PNCs as an alternative or complementary biofilm control strategy.

Graphitic Carbon Nitride (g-C3N4)-Based Photocatalysts for Artificial Photosynthesis and Environmental Remediation: Are We a Step Closer To Achieving Sustainability?

Abstract: As a fascinating conjugated polymer, graphitic carbon nitride (g-C3N4) has become a new research hotspot and drawn broad interdisciplinary attention as a metal-free and visible-light-responsive photocatalyst in the arena of solar energy conversion and environmental remediation. This is due to its appealing electronic band structure, high physicochemical stability, and “earth-abundant” nature. This critical review summarizes a panorama of the latest progress related to the design and construction of pristine g-C3N4 and g-C3N4-based nanocomposites, including (1) nanoarchitecture design of bare g-C3N4, such as hard and soft templating approaches, supramolecular preorganization assembly, exfoliation, and template-free synthesis routes, (2) functionalization of g-C3N4 at an atomic level (elemental doping) and molecular level (copolymerization), and (3) modification of g-C3N4 with well-matched energy levels of another semiconductor or a metal as a cocatalyst to form heterojunction nanostructures. The constructi...

Advanced Oxidation Processes for Organic Contaminant Destruction Based on the Fenton Reaction and Related Chemistry

Abstract: Fenton chemistry encompasses reactions of hydrogen peroxide in the presence of iron to generate highly reactive species such as the hydroxyl radical and possibly others. In this review, the complex mechanisms of Fenton and Fenton-like reactions and the important factors influencing these reactions, from both a fundamental and practical perspective, in applications to water and soil treatment, are discussed. The review covers modified versions including the photoassisted Fenton reaction, use of chelated iron, electro-Fenton reactions, and Fenton reactions using heterogeneous catalysts. Sections are devoted to nonclassical pathways, by-products, kinetics and process modeling, experimental design methodology, soil and aquifer treatment, use of Fenton in combination with other advanced oxidation processes or biodegradation, economic comparison with other advanced oxidation processes, and case studies.