An evaluation of properly operated NSF/ANSI-53 Pb certified drinking water filters in Benton Harbor, MI.

Communities across the United States and particularly in the Midwest continue to grapple with the complications associated with aging infrastructure. This includes the presence of lead (Pb)-bearing plumbing components such as lead service lines, downstream galvanized iron pipes, and Pb/tin solder. The community of Benton Harbor, MI, experienced six Pb action level exceedances between 2018 and 2021, leading to increasing community concern and a request from the state of Michigan for the US Environmental Protection Agency involvement. Between 9 November and 17 December 2021, US EPA Region 5 and Office of Research and Development, along with the state of Michigan, conducted a water filter efficacy and Pb-nanoparticulate (<100 nm) study to evaluate the performance of NSF/ANSI-53 Pb-certified drinking water filters and the presence of nanoparticulate. In this study, a total of 199 properly installed and operated drinking water filters (combination of faucet mounted and pitcher) were tested in their residential locations. One hundred percent of the water filters were found to perform to the standard to which they were certified, with filtered drinking water Pb concentrations below 5 ppb (maximum observed was 2.5 ppb). In addition, Pb particulate was identified; however, discrete Pb-containing nanoparticles were not widely found or identified.

Orthophosphate Interactions with Destabilized PbO2 Scales.

This research presents two case studies in which a change in the disinfectant from free chlorine to chloramine caused an increase in lead corrosion. In both systems, the predominantly tetravalent lead (PbO2) scales destabilized as a result of disinfectant change. Orthophosphate corrosion control was used in both systems, and the effect of this treatment chemical on the destabilized PbO2 scales was examined. The absence of chemical reactivity between PbO2 and phosphorus is well known, and this research confirms that phosphorus does not interact with the legacy PbO2 scales. Instead, phosphorus and calcium were found to permeate through the destabilized PbO2 material and react with divalent lead [Pb(II)] at the surface of a basal litharge (PbO) layer. This reaction precipitated a crystalline lead phosphate in both systems, which could not be specifically identified by any known powder diffraction files. Further analysis suggested that the compound formed was not the typically modeled hydroxypyromorphite but rather a calcium-substituted hydroxypyromorphite. During scale formation, calcium is frequently bound to the Pb(II) phosphate crystal lattice structure, causing measurable crystal lattice distortion in powder X-ray diffraction patterns. The results of this study illustrate the longevity of legacy scales and how disequilibrium compounds persist long after treatment changes have been made.

Lead Particle Size Fractionation and Identification in Newark, New Jersey's Drinking Water.

Following a pH reduction in their drinking water over a span of more than 20 years, the City of Newark, New Jersey, has struggled with elevated lead (Pb) release from Pb service lines and domestic plumbing in the zone fed by the Pequannock Water Treatment Plant. In response, Newark initiated orthophosphate addition and provided faucet-mounted point-of-use (POU) filters and pitcher filters certified for Pb and particulate reduction under NSF/ANSI Standards 53 and 42 to residential homes in that zone. Water chemistry analysis and size fractionation sampling were performed at four of these houses. Analysis of the particulate material retained by the fractionation filters revealed that Pb was dominantly present in the water as fine Pb(II) orthophosphate particles. A considerable amount of the particulates occurred as a nanoscale fraction that sometimes passed through the POU faucet or pitcher filtration units. Scanning electron microscopy, transmission electron microscopy, and energy-dispersive spectroscopy analyses showed that the nanoparticles (<100 nm) and their aggregates were composed of Pb, phosphorus, and chlorine, which are consistent with pyromorphite, Pb5(PO4)3Cl. Electron diffraction and X-ray analyses supported the presence of hydroxypyromorphite and chloropyromorphite nanoparticles and the size range estimates from the imaging. This research confirmed that nonadherent Pb(II)-orthophosphate nanoparticles were an important form of Pb in drinking water in the Pequannock water quality zone of Newark.

Copper Nanoparticle Induced Cytotoxicity to Nitrifying Bacteria in Wastewater Treatment: A Mechanistic Copper Speciation Study by X-ray Absorption Spectroscopy.

With the inclusion of engineered nanomaterials in industrial processes and consumer products, wastewater treatment plants (WWTPs) could serve as a major sink for these emerging contaminants. Previous research has demonstrated that nanomaterials are potentially toxic to microbial communities utilized in biological wastewater treatment (BWT). Copper-based nanoparticles (CuNPs) are of particular interest based on their increasing use in wood treatment, paints, household products, coatings, and byproducts of semiconductor manufacturing. A critical step in BWT is nutrient removal through nitrification. This study examined the potential toxicity of uncoated and polyvinylpyrrolidone (PVP)-coated CuO, and Cu2O nanoparticles, as well as Cu ions to microbial communities responsible for nitrification in BWT. Inhibition was inferred from changes to the specific oxygen uptake rate (sOUR) in the absence and presence of Cu ions and CuNPs. X-ray absorption fine structure spectroscopy, with linear combination fitting (LCF), was utilized to track changes to Cu speciation throughout exposure. Results indicate that the dissolution of Cu ions from CuNPs drive microbial inhibition. The presence of a PVP coating on CuNPs has little effect on inhibition. LCF analysis of the biomass combined with metal partitioning analysis supports the current hypothesis that Cu-induced cytotoxicity is primarily caused by reactive oxygen species formed from ionic Cu in solution via catalytic reaction intermediated by reduced Cu(I) species.

Comprehensive characterization of aerobic groundwater biotreatment media.

Aerobic biotreatment systems can treat multiple reduced inorganic contaminants in groundwater, including ammonia (NH3), arsenic (As), iron (Fe), and manganese (Mn). While individual systems treating multiple contaminants simultaneously have been characterized and several systems treating one contaminant have been compared, a comparison of systems treating co-occurring contaminants is lacking. This study assessed the treatment performance and microbial communities within 7 pilot- and full-scale groundwater biotreatment systems in the United States that treated waters with pH 5.6-7.8, 0.1-2.0 mg/L dissolved oxygen, 75-376 mg CaCO3/L alkalinity, < 0.03-3.79 mg NH3-N/L, < 4-31 µg As/L, < 0.01-9.37 mg Fe/L, 2-1220 µg Mn/L, and 0.1-5.6 mg/L total organic carbon (TOC). Different reactor configurations and media types were represented, allowing for a broad assessment of linkages between water quality and microbial communities via microscopy, biofilm quantification, and molecular methods. Influent NH3, TOC, and pH contributed to differences in the microbial communities. Mn oxidase gene copy numbers were slightly negatively correlated with the influent Mn concentration, but no significant relationships between gene copy number and influent concentration were observed for the other contaminants. Extracellular enzyme activities, community composition, and carbon transformation pathways suggested heterotrophic bacteria may be important in nitrifying biofilters. Aerobic groundwater biofilters are complex, and improved understanding could lead to engineering enhancements.

Design and evaluation of degassed anaerobic membrane biofilm reactors for improved methane recovery.

Anaerobic treatment of domestic wastewater (DWW) produces dissolved methane that needs to be recovered for use as an energy product. Membrane-based recovery systems have been reported in the literature but are often limited by fouling. The objective of this study was to develop a methane producing biofilm on the shell side surface a membrane to allow for immediate recovery of methane as it was produced, negating mass transfer resistance caused by fouling. Between 89 and 96% of total methane produced was recovered via in-situ degassing without the need for fouling control or cleaning throughout 72 weeks of operation. High methane recovery efficiencies led to predictions of net positive energy yield in one reactor and a 32-61% reduction in energy demand in the others compared to the control. This research demonstrates the feasibility and usefulness of combining attached growth anaerobic wastewater treatment processes with hollow fiber membrane methane recovery systems for improved operation.

Dermal transfer and environmental release of CeO2 nanoparticles used as UV inhibitors on outdoor surfaces: Implications for human and environmental health.

A major area of growth for "nano-enabled" consumer products have been surface coatings, including paints stains and sealants. Ceria (CeO2) nanoparticles (NPs) are of interest as they have been used as additives in these these products to increase UV resistance. Currently, there is a lack of detailed information on the potential release, and speciation (i.e., ion vs. particle) of CeO2 NPs used in consumer-available surface coatings during intended use scenarios. In this study, both Micronized-Copper Azole pressure-treated lumber (MCA), and a commercially available composite decking were coated with CeO2 NPs dispersed in Milli-Q water or wood stain. Coated surfaces were divided into two groups. The first was placed outdoors to undergo environmental weathering, while the second was placed indoors to act as experimental controls. Both weathered surfaces and controls were sampled over a period of 6months via simulated dermal contact using methods developed by the Consumer Product Safety Commission (CPSC). The size and speciation of material released was determined through sequential filtration, total metals analysis, X-Ray Absorption Fine Structure Spectroscopy, and electron microscopy. The total ceria release from MCA coated surfaces was found to be dependent on dispersion matrix with aqueous applications releasing greater quantities of CeO2 than stain based applications, 66±12mg/m2 and 36±7mg/m2, respectively. Additionally, a substantial quantity of CeO2 was reduced to Ce(III), present as Ce(III)-organic complexes, over the 6-month experimental period in aqueous based applications.

Evidence for endothermic ancestors of crocodiles at the stem of archosaur evolution.

Physiological, anatomical, and developmental features of the crocodilian heart support the paleontological evidence that the ancestors of living crocodilians were active and endothermic, but the lineage reverted to ectothermy when it invaded the aquatic, ambush predator niche. In endotherms, there is a functional nexus between high metabolic rates, high blood flow rates, and complete separation of high systemic blood pressure from low pulmonary blood pressure in a four-chambered heart. Ectotherms generally lack all of these characteristics, but crocodilians retain a four-chambered heart. However, crocodilians have a neurally controlled, pulmonary bypass shunt that is functional in diving. Shunting occurs outside of the heart and involves the left aortic arch that originates from the right ventricle, the foramen of Panizza between the left and right aortic arches, and the cog-tooth valve at the base of the pulmonary artery. Developmental studies show that all of these uniquely crocodilian features are secondarily derived, indicating a shift from the complete separation of blood flow of endotherms to the controlled shunting of ectotherms. We present other evidence for endothermy in stem archosaurs and suggest that some dinosaurs may have inherited the trait.

Experimental and modeling studies of sorption of ceria nanoparticle on microbial biofilms.

This study focuses on the interaction of ceria nanoparticles (CeO2-NPs) with Pseudomonas fluorescens and Mycobacterium smegmatis biofilms. Confocal laser microscopy and transmission electron microscopy determined the distribution of NPs in the complex structures of biofilm at molecular levels. Visual data showed that most of the adsorption takes place on the bacterial cell walls and spores. The interaction of nanoparticles (NPs) with biofilms reached equilibrium after the initial high adsorption rate regardless of biofilm heterogeneity and different nanoparticle concentrations in the bulk liquid. Physical processes may dominate this sorption phenomenon. Pseudo first order sorption kinetics was used to estimate adsorption and desorption rate of CeO2-NPs onto biofilms. When biofilms got exposed to CeO2-NPs, a self-protecting mechanism was observed. Cells moved away from the bulk solution in the biofilm matrix, and portions of biofilm outer layer were detached, hence releasing some CeO2-NPs back to the bulk phase.

A new in vitro model using small intestinal epithelial cells to enhance infection of Cryptosporidium parvum.

To better understand and study the infection of the protozoan parasite Cryptosporidium parvum, a more sensitive in vitro assay is required. In vivo, this parasite infects the epithelial cells of the microvilli layer in the small intestine. While cell infection models using colon, kidney, and stomach cells have been studied to understand the infectivity potential of the oocysts, an ideal in vitro model would be readily-available, human-derived, and originating from the small intestine. In this study, we developed a reproducible, quantitative infection model using a non-carcinoma, human small intestinal epithelial cell type, named FHs 74 Int. Our results show that FHs 74 Int cells are productively infected by viable oocysts, and exhibit higher levels of infection susceptibility compared to other cell types. Moreover, infection rate of the sporozoites on the monolayer was found to be comparable or better than other cell types. We furthermore demonstrate that infection can be improved by 65% when pre-treated oocysts are directly inoculated on cells, compared to inoculation of excysted sporozoites on cells. Identification of a better infection model, which captures the preferred site of infection in humans, will facilitate studies on the host pathogenesis mechanisms of this important parasitic human pathogen.

Inside-out core-shell architecture: controllable fabrication of Cu2O@Cu with high activity for the Sonogashira coupling reaction.

Inside-out core-shell architectures (Cu(2)O@Cu) with a Cu(2)O core and a Cu shell, which are in contrast to the normally reported Cu(2)O-outside structure (Cu@Cu(2)O), were fabricated. This strategy can also be applied to construct square and hexapod Cu(2)O@Cu. The obtained Cu(2)O@Cu composite exhibits excellent catalytic activity for the Sonogashira coupling reactions.