Increases in phosphate availability in drinking water distribution systems (DWDSs) from the use of phosphate-based corrosion control strategies may result in nutrient and microbial community ...composition shifts in the DWDS. This study assessed the year-long impacts of full-scale DWDS orthophosphate addition on both the microbial ecology and density of drinking-water-associated pathogens that infect the immunocompromised (DWPIs). Using 16S rRNA gene amplicon sequencing and droplet digital PCR, drinking water microbial community composition and DWPI density were examined. Microbial community composition analysis suggested significant compositional changes after the orthophosphate addition. Significant increases in total bacterial density were observed after orthophosphate addition, likely driven by a 2 log 10 increase in nontuberculous mycobacteria (NTM). Linear effect models confirmed the importance of phosphate addition with phosphorus concentration explaining 17% and 12% of the variance in NTM and
density, respectively. To elucidate the impact of phosphate on NTM aggregation, a comparison of planktonic and aggregate fractions of NTM cultures grown at varying phosphate concentrations was conducted. Aggregation assay results suggested that higher phosphate concentrations cause more disaggregation, and the interaction between phosphate and NTM is species specific. This work reveals new insight into the consequences of orthophosphate application on the DWDS microbiome and highlights the importance of proactively monitoring the DWDS for DWPIs.
In April 2014, the drinking water source in Flint, Michigan was switched from Lake Huron water with phosphate inhibitors to Flint River water without corrosion inhibitors. The absence of corrosion ...control and use of a more corrosive source increased lead leaching from plumbing. Our city-wide citizen science water lead results contradicted official claims that there was no problem– our 90th percentile was 26.8 μg/L, which was almost double the Lead and Copper Rule action level of 15 μg/L. Back calculations of a LCR sampling pool with 50% lead pipes indicated an estimated 90th percentile lead value of 31.7 μg/L (±4.3 μg/L). Four subsequent sampling efforts were conducted to track reductions in water lead after the switch back to Lake Huron water and enhanced corrosion control. The incidence of water lead varied by service line material. Between August 2015 and November 2016, median water lead reduced from 3.0 to <1 μg/L for homes with copper service lines, 7.2–1.9 μg/L with galvanized service lines, and 9.9–2.3 μg/L with lead service lines. As of summer 2017, our 90th percentile of 7.9 μg/L no longer differed from official results, which indicated Flint’s water lead levels were below the action level.
Although the Flint, Michigan, water crisis renewed concerns about lead (Pb) in city drinking water, little attention has been paid to Pb in private wells, which provide drinking water for 13% of the ...US population. This study evaluates the risk of Pb exposure in children in households relying on private wells. It is based on a curated dataset of blood Pb records from 59,483 North Carolina children matched with household water source information. We analyze the dataset for statistical associations between children’s blood Pb and household drinking water source. The analysis shows that children in homes relying on private wells have 25% increased odds (95% CI 6.2 to 48%, P < 0.01) of elevated blood Pb, compared with children in houses served by a community water system that is regulated under the Safe Drinking Water Act. This increased Pb exposure is likely a result of corrosion of household plumbing and well components, because homes relying on private wells rarely treat their water to prevent corrosion. In contrast, corrosion control is required in regulated community water systems. These findings highlight the need for targeted outreach to prevent Pb exposure for the 42.5 million Americans depending on private wells for their drinking water.
Concentrated solar power (CSP) plants with thermal energy storage (TES) system are emerging as one kind of the most promising power plants in the future renewable energy system, since they can supply ...dispatchable and low-cost electricity with abundant but intermittent solar energy. In order to significantly reduce the levelized cost of electricity (LCOE) of the present commercial CSP plants, the next generation CSP technology with higher process temperature and energy efficiency is being developed. The TES system in the next generation CSP plants works with new TES materials at higher temperatures (> 565 °C) compared to that with the commercial nitrate salt mixtures. This paper reviews recent progress in research and development of the next generation CSP and TES technology. Emphasis is given on the advanced TES technology based on molten chloride salt mixtures such as MgCl2/NaCl/KCl which has similar thermo-physical properties as the commercial nitrate salt mixtures, higher thermal stability (> 800 °C), and lower costs (< 0.35 USD∙kg−1). Recent progress in the selection/optimization of chloride salts, determination of molten chloride salt properties, and corrosion control of construction materials (e.g., alloys) in molten chlorides is reviewed.
In this work, electrolysis with a Mg anode is presented to purify the molten chloride salt (MgCl2/KCl/NaCl 60/20/20 mol.%) for reducing its corrosivity. Using a Mg anode, the production of toxic ...gases like Cl2 on an inert anode (e.g., tungsten) can be avoided. Moreover, compared to an inert anode, a lower over-potential is required to remove the corrosive impurity MgOH+ in the molten salt due to the high reactivity of Mg. In order to evaluate the effect of the salt purification, the cyclic voltammetry (CV) method developed in our previous work is used to in-situ measure the concentration of the corrosive MgOH+ impurity in the molten salt. The CV measurements indicate that the corrosive impurity is efficiently removed by electrolysis. For decreasing the cathode inactivation due to produced MgO on the surface, a pulsed potential applied on the tungsten cathode during electrolysis shows to be promising. This electrochemical salt purification method has shown to be promising by efficiently controlling the corrosivity of the molten chloride salt. The potentiodynamic polarization (PDP) measurements on a commercial high-temperature alloy (Incoloy 800 H) immersed in the molten salt indicate that the corrosion rate of the alloy is significantly reduced due to the salt purification. It could also lead to a reduction of the cost of the conventional salt purification step, structural container materials, and piping in next generation concentrated solar power (Gen3 CSP) plants.
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•Electrolysis with a Mg anode purifies a molten chloride salt to reduce its corrosivity.•Cathode passivation due to produced MgO at the surface is significantly reduced by applying pulsed potential.•CV shows that concentration of corrosive impurity in purified salt has a reduction of ~93% compared to unpurified salt.•PDP of Incoloy 800 H in purified salt shows ~80% corrosion rate reduction compared to that in unpurified salt.
This study explored the ability of orthophosphate addition to limit lead release from lead service lines delivering high pH, low alkalinity water. We built pipe loop reactors with lead pipes ...harvested from Providence, RI, and we operated them with high pH and low alkalinity water of a composition similar to that in Providence. Orthophosphate addition decreased the release of both dissolved and particulate lead to the water. The most substantial decreases in total lead concentrations occurred after 15 weeks of orthophosphate addition, which was associated with the formation of calcium-lead-phosphorus (Ca–Pb–P) solids as part of the pipe scale. Pre-existing hydrocerussite (Pb3(CO3)2(OH)2(s)) in the scale of the lead pipe appeared to promote the formation of a Ca–Pb–P solid similar to phosphohedyphane (Ca2Pb3(PO4)3(Cl,F,OH)(s)). Continuous orthophosphate addition was also associated with the formation of a calcium phosphate solid with features like those of fluorapatite (Ca5(PO4)3F(s)) on the outermost layer of the scale. Through promoting the formation of these new solids within and on top of the scales, orthophosphate addition limited release of dissolved and particulate lead. These results demonstrate the ability of orthophosphate to control lead release at higher pH conditions than those for which it has typically been used. In addition to the formation of phosphate solids, PbO2(s), which was not present on the as-received pipes, was formed due to the constant supply of free chlorine in the laboratory-scale experiment.
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•Orthophosphate addition can decrease lead concentrations even at pH > 10.•Total lead concentrations decreased after 15 weeks of orthophosphate addition.•A Ca–Pb-phosphate solid formed as part of the lead-rich scale.•A coarser Ca-phosphate solid formed on top of the existing scale.•PbO2(s) was formed during experiments due to the constant free chlorine supply.
We present a study on the electrochemical behavior of magnesium hydroxide (MgOH
+
) reduction on a tungsten (W) cathode in molten chloride salt (MgCl
2
-KCl-NaCl) across the temperature range of 475 ...°C–525 °C. MgOH
+
, which forms within the salt upon exposure to moisture, is a leading cause of corrosion. Corrosion is a major barrier to deployment of chloride salts across a number of applications, including concentrating solar power plants and nuclear power plants. While pre-purification protocols have been developed to ensure MgOH
+
is removed from molten chloride salts prior to deployment, MgOH
+
forms in situ during operation of chloride-salt based plants. Thus, methods for continuous purification during plant operation are needed. Continuous electrochemical purification via electrolysis using a Mg anode and W cathode has been proposed, but little has been done to assess scalability. Here, we assess fundamental properties of electrochemical removal of MgOH
+
to enable future scale up of this method.
This study directly compared the data obtained from coupon studies and flow‐through pipe rack studies from two sources in the Denver Water system. The pipe rack study was completed over multiple ...years using harvested lead service lines. The coupon studies were completed in about 2 months using pure lead coupons. Orthophosphate at 2 mg/L was found to reduce lead concentrations by about 81% in the pipe racks, whereas 74%–81% was observed in the coupons. At an orthophosphate dose of 1 mg/L lead concentrations were reduced by 62%–65% in the pipe loop and by 55%–75% in the coupons, pH at 8.8 reduced lead by 45%–60% in the pipe racks and by 27%–48% in the coupons. The pipe racks were able to give insights into the transition from one condition to another, which is time‐based and dependent on existing pipe scales. Both types of demonstration studies produced similar conclusions about treatment options. The pipe rack was more representative of conditions in the distribution system while the coupon studies were performed in a fraction of the time.
Bacteriophage particles are the most abundant biological entities on our planet, infecting specific bacterial hosts in every known environment and being major drivers of bacterial adaptive evolution. ...The study of bacteriophage particles potentially sheds light on the development of new biotechnology products. Bacteriophage therapy, although not new, makes use of strictly lytic phage particles as an alternative in the antimicrobial treatment of resistant bacterial infections and is being rediscovered as a safe method due to the fact that these biological entities devoid of any metabolic machinery do not have affinity to eukaryotic cells. Furthermore, bacteriophage-based vaccination is emerging as one of the most promising preventive strategies. This review paper discusses the biological nature of bacteriophage particles, their mode(s) of action and potential exploitation in modern biotechnology. Topics covered in detail include the potential of bacteriophage particles in human infections (bacteriophage therapy), nanocages for gene delivery, food biopreservation and safety, biocontrol of plant pathogens, phage display, bacterial biosensing devices, vaccines and vaccine carriers, biofilm and bacterial growth control, surface disinfection, corrosion control, together with structural and functional stabilization issues.
In this study, we present a facile strategy to construct a smart PN-Zn-MOF-74 nanocontainer-based coating with outstanding triple functions including the barrier effect, as well as self-healing and ...self-reporting features. Flattened 2D PN-Zn-MOF-74 nanocontainers were synthesized by decorating the hexagonal boron nitride (h-BN) sheets with a polydopamine (PDA) layer, which was employed to interlink the Zn-MOF-74 nanodevices. The composite nanocontainers were then uniformly dispersed in a waterborne epoxy coating (WEC) and coated onto Q235 mild steel surfaces. Thus, as the Fe3+ and H+ ions were gradually released from the localized corrosion sites, the encapsulated active inhibitors (Zn2+ and PDA) in PN-Zn-MOF-74 were exchanged and released promptly to form a robust protective film, coating the micro-damaged sites. The EIS results indicated that PN-Zn-MOF-74 with two inhibitors demonstrated a remarkable active corrosion protection performance, with the |Z|0.01Hz value increasing from 381 Ω cm2 (blank) to 1389 Ω cm2 (PN-Zn-MOF-74). However, the cation exchange between Fe3+ and Zn2+ can collapse the fluorescent Zn-MOF-74 and form a weak fluorescent compound at the damage sites, achieving the self-reporting ability of the coating. In addition, the coating adhesion test and cross-sectional images showed that the presence of PN-Zn-MOF-74 can effectively strengthen the impermeability of the composite coating, guaranteeing its long-lasting barrier properties. The coating demonstrated a higher |Z|0.01Hz value (4.91 × 109 Ω cm2) despite following 504-h immersion tests, which was over 2 orders of magnitude higher than that of the blank WEC coating. This study provides a simplified and feasible method for augmenting the dependability, practicality, and versatility of anti-corrosion polymer coatings.
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•Nanocontainers with multiple corrosion inhibitors are beneficial for enhancing the anti-corrosion protection effect.•The incorporation of the organic-modified boron nitride can enhance the compatibility of the additive-coating interface.•Fluorescent PN-Zn-MOF-74 endows the coating with corrosion-sensing functions.•PN-Zn-MOF-74 increases active corrosion protection of the coatings.
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