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Despite the high abundance and potential toxicity of ferrocyanide in the environment, data on the bioremediation of these complexes in contaminated soils are missing. In this study we isolated forty bacterial species presented in soil highly contaminated with ferrocyanide complexes, originating from a Manufactured Gas Plant (MGP). All bacterial strains were resistant to ferrocyanide (500 mg L−1). Six isolates showed better growth in the presence of ferrocyanide and were able to use it as a sole nitrogen source. One of them was able to assimilate ferrocyanide‐derived nitrogen and carbon. The strains varied in their tolerance to the ferrocyanide. The Minimum Inhibitory Concentration (MIC) values determined in the rich medium ranged from 1400 mg L−1 to 2000 mg L−1 and in all cases were greater than those set on the minimal medium. Molecular analysis revealed that the investigated isolates had the highest similarity to the Bacillus and Rummeliibacillus lineages. Rummeliibacillus was recognized for the first time for its ferrocyanide-degrading potential. Soil samples collected from MGP sites indicated that the overall indigenous population of microorganisms was low. Total cyanide content ranged from 220 mg kg−1 to 346 mg kg−1. Additionally, elevated Pb concentrations and an imbalanced C:N:P ratio were observed. Our study provides new information about the presence of a well-acclimated bacterial community associated with long-term ferrocyanide-contaminated soil. This bacterial community could play an important role in MGP site bioremediation processes and has the potential for application for other bioremediation purposes; however, it is likely limited due to unfavorable environmental conditions.

After long time operation of the manufactured gas pipeline, the naphthalene in the gas will jam the pipeline and threaten the safety of the pipeline seriously. To study the naphthalene particle deposition law in the manufactured gas pipeline, a horizontal straight pipe of Kunming manufactured gas pipeline is taken as an example; based on Reynolds stress model and discrete phase model, ANSYS Fluent software is used to carry out the numerical simulation in different pipe diameters, particle size, inlet velocity, temperature, and pressure conditions. The main conclusion can be obtained as follows (1) in the horizontal straight pipe section, particle diameter and temperature are positively correlated with the deposition rate and the deposition velocity of naphthalene particle and the inlet velocity and pressure are negatively correlated with them; (2) the naphthalene particle deposition rate is mainly affected by the particle size and the inlet velocity; (3) the larger the pipeline diameters, the greater the particle mass flow rate under the same particle inlet concentration, the lower the carrying capacity of the fluid to particles, the greater the naphthalene particle deposition rate; (4) the naphthalene particle deposition can be suppressed by increasing the gas transmission velocity and pressure and reducing the temperature, thus ensuring the safe operation of manufactured gas pipeline.

The toxicity and uptake of polycyclic aromatic hydrocarbons (PAHs) by earthworms were measured in soil samples collected from manufactured‐gas plant sites having a wide range in PAH concentrations (170–42,000 mg/kg) and soil characteristics. Samples varied from vegetated soils to pure lampblack soot and had total organic carbon contents ranging from 3 to 87%. The biota‐soil accumulation factors (BSAFs) observed for individual PAHs in field‐collected earthworms (Aporrectodea caliginosa) were up to 50‐fold lower than the BSAFs predicted using equilibrium‐partitioning theory. Acute toxicity to the earthworm Eisenia fetida was unrelated to total PAH concentration: Mortality was not observed in some soils having high concentrations of total PAHs (>42,000 mg/kg), whereas 100% mortality was observed in other soils having much lower concentrations of total PAHs (1,520 mg/kg). Instead, toxicity appeared to be related to the rapidly released fraction of PAHs determined by mild supercritical CO2 extraction (SFE). The results demonstrate that soils having approximately 16,000 mg rapidly released total PAH/kg organic carbon can be acutely toxic to earthworms and that the concentration of PAHs in soil that is rapidly released by SFE can estimate toxicity to soil invertebrates.

The toxicity of polycyclic aromatic hydrocarbons (PAHs) to Hyalella azteca, was measured in 34 sediment samples collected from four manufactured‐gas plant (MGP) sites ranging in total PAH16 (sum of 16 U.S. Environmental Protection Agency priority pollutant PAHs) concentrations from 4 to 5,700 mg/kg, total organic carbon content from 0.6 to 11%, and soot carbon from 0.2 to 5.1%. The survival and growth of H. azteca in 28‐d bioassays were unrelated to total PAH concentration, with 100% survival in one sediment having 1,730 mg/kg total PAH16, whereas no survival was observed in sediment samples with concentrations as low as 54 mg/kg total PAH16. Twenty‐five of the 34 sediment samples exceeded the probable effects concentration screening value of 22.8 mg/kg total PAH13 (sum of 13 PAHs) and equilibrium partitioning sediment benchmarks for PAH mixtures (on the basis of the measurement of 18 parent PAHs and 16 groups of alkylated PAHs, [PAH34]); yet, 19 (76%) of the 25 samples predicted to be toxic were not toxic to H. azteca. However, the toxicity of PAHs to H. azteca was accurately predicted when either the rapidly released concentrations as determined by mild supercritical fluid extraction (SFE) or the pore‐water concentrations were used to establish the bioavailability of PAHs. These results demonstrate that the PAHs present in many sediments collected from MGP sites have low bioavailability and that both the measurement of the rapidly released PAH concentrations with mild SFE and the dissolved pore‐water concentrations of PAHs are useful tools for estimating chronic toxicity to H. azteca.

U.S. cities contain unknown numbers of undocumented “manufactured gas” sites, legacies of an industry that dominated energy production during the late-19th and early-20th centuries. While many of these unidentified sites likely contain significant levels of highly toxic and biologically persistent contamination, locating them remains a significant challenge. We propose a new method to identify manufactured gas production, storage, and distribution infrastructure in bulk by applying feature extraction and machine learning techniques to digitized historic Sanborn fire insurance maps. Our approach, which relies on a two-part neural network to classify candidate map regions, increases the rate of site identification 20-fold compared to unaided visual coding.

Estimating leaks in urban gas distribution systems is crucial for reducing greenhouse gas emissions from fugitive losses and mitigating costly waste. This study aimed to use a simplified methodology to estimate pipeline leakage in gas distribution systems and validate these estimations against established benchmarks or other gases globally. The estimation encompassed sources including third-party damage, long-term permeation, flaring, and purging during pipeline commissioning and decommissioning, as well as fugitive leakage, each requiring respective evaluation. Results showed that the total town gas leakage volume was around 695,044 m3 to 2,009,991 m3, accounting for 0.045% to 0.13% of the total town gas sales in 2022. Among the five leakage sources, fugitive leakage was the major contributor with the leakage volume of 1,938,914 m3. To comprehensively benchmark all emission factors (EFs), those from previously reported studies were adapted to the town gas scenario and combined with the current activity factors (AFs) in Hong Kong to calculate the leakage amounts. Comparing our results with different models, we observed variations in estimated leakage amounts based on years, regions, and sampling methods. Upgrades in pipeline materials led to reduced EFs and subsequently lower total gas leakage. Our findings support efforts to reduce greenhouse gas emissions by providing actionable data for policymakers and utility companies to address gas leakage issues.

Bioaugmentation effectively enhances microbial bioremediation of hazardous polycyclic aromatic hydrocarbons (PAHs) from contaminated environments. While screening for pyrene-degrading bacteria from a former manufactured gas plant soil (MGPS), the mixed enrichment culture was found to be more efficient in PAHs biodegradation than the culturable pure strains. Interestingly, analysis of 16S rRNA sequences revealed that the culture was dominated by a previously uncultured member of the family Rhizobiaceae. The culture utilized C1 and other methylotrophic substrates, including dimethylformamide (DMF), which was used as a solvent for supplementing the culture medium with PAHs. In the liquid medium, the culture rapidly degraded phenanthrene, pyrene, and the carcinogenic benzo(a)pyrene (BaP), when provided as the sole carbon source or with DMF as a co-substrate. The efficiency of the culture in the bioremediation of PAHs from the MGPS and a laboratory waste soil (LWS) was evaluated in bench-scale slurry systems. After 28 days, 80% of Σ16 PAHs were efficiently removed from the inoculated MGPS. Notably, the bioaugmentation achieved 90% removal of four-ringed and 60% of highly recalcitrant five- and six-ringed PAHs from the MGPS. Likewise, almost all phenanthrene, pyrene, and 65% BaP were removed from the bioaugmented LWS. This study highlights the application of the methylotrophic enrichment culture dominated by an uncultured bacterium for the efficient bioremediation of PAHs.

Biodegradation of polycyclic aromatic hydrocarbons (PAHs) under completely anaerobic sulfate-reducing conditions is an energetically challenging process. To date, anaerobic degradations of only two-ringed naphthalene and three-ringed phenanthrene by sediment-free and enriched sulfate-reducing bacteria have been reported. In this study, sulfate-reducing enrichment cultures capable of degrading naphthalene and four-ringed PAH, pyrene, were enriched from a contaminated former gas plant site soil. Bacterial community composition analysis revealed that a naphthalene-degrading enrichment culture, MMNap, was dominated (84.90%) by a Gram-positive endospore-forming member of the genus Desulfotomaculum with minor contribution (8.60%) from a member of Clostridium . The pyrene-degrading enrichment, MMPyr, was dominated (97.40%) by a species of Desulfotomaculum . The sequences representing the Desulfotomaculum phylotypes shared 98.80% similarity to each other. After 150 days of incubation, MMNap degraded 195 µM naphthalene with simultaneous reduction of sulfate and accumulation of sulfide. Similarly, MMPyr degraded 114 µM pyrene during 180 days of incubation with nearly stochiometric sulfate consumption and sulfide accumulation. In both cases, the addition of sulfate reduction inhibitor, molybdate (20 mM), resulted in complete cessation of the substrate utilization and sulfate reduction that clearly indicated the major role of the sulfate-reducing Desulfotomaculum in biodegradation of the two PAHs. This study is the first report on anaerobic pyrene degradation by a matrix-free, strictly anaerobic, and sulfate-reducing enrichment culture.

Power-to-Gas is gaining interest in the energy industry to support broad decarbonization goals by storing excess renewable electricity as hydrogen in the existing gas grid, which can then be consumed in blends with natural gas by existing combustion systems. Hydrogen offers a significant means of seasonal energy storage at energy densities not matched by electric batteries and could create additional value for renewable electricity projects, which may otherwise curtail generation during periods of excess capacity. While multiple pilots are already underway in Europe and North America, these studies are in their infancy. More work is still needed to develop the underlying technologies and to demonstrate safety, reliability, and economic benefits of the approach. Multiple studies have identified that end use appliances (residential, commercial, and industrial combustion systems) are likely to pose the lowest limits of hydrogen compatibility when no changes are made to the burners and controls. Limits of compatibility of 15% to 30% of hydrogen by volume have been cited. The wide range of blending limits is in large part due to the variety of gas combustion systems used throughout the world. In North American residential and commercial applications, the vast majority of the natural gas burners are low-cost, atmospheric partial premix burners, found in appliances such as gas furnaces, boilers, water heaters, as well as non-HVAC equipment such as cooking ranges and gas dryers. Partial premix burners are characterized by low-pressure injection of fuel into the burner which entrains 50-70% of the total air required for combustion, with the balance made up as secondary air at the flame. These types of burners have been extensively used since the 19th century for their stability, efficiency, and high turn-down. For this reason, the design approaches used in the product development of partial premix gas-fired appliances have not substantially changed since the mid-20th Century when a broad transition from the use of town gas (up to 50% hydrogen) to natural gas occurred. This paper summarizes the results of a theoretical investigation into fundamentals of gas burner designs, identifying important characteristics that may permit or restrict their compatibility with hydrogen-blended gas, as well as the interrelated effects of hydrogen blending on burners designed for natural gas.

The distribution and delivery of fuels to the built environment is a mega-scale form of seasonal energy storage in the United States, delivering greater than 600 GW of energy during the winter, often in the form of heating, and with storage built up over periods of 6-8 months. Combined with Canada, this distribution system serves 85 million homes and businesses with a network spanning 5.4 million km. With increasing efforts to reduce the impact of buildings on the environment, the greater than 1,000 Mt CO2e/year emitted from this fuel consumption must be mitigated. In addition to energy efficiency and conservation, which remain the pillars of any climate mitigation scheme, one pathway to reduce CO2e emissions from buildings is displacing delivered fossilfuels (e.g. naturalgas) with low or zero carbon fuels, which can include methane-based fuels and hydrogen, generated from renewable energies/feedstocks or employing integrated carbon capture. Seeking to scale-up the generation and distribution of these low or zero carbon fuels in many regions throughout the U.S. and Canada, utilities are demonstrating the injection, blending, and delivery of these fuels. Of particular note are the hydrogen-focused demonstrations, which seek to quantify the risks and benefits of distributing hydrogen using legacy and purpose-built infrastructure, and its impacts on the downstream homes and businesses, with activity in numerous large metropolitan areas and in cold and hot climate zones alike. This paper provides an overview of these North American utility projects, which displace delivered fossil fuels with low or zero carbon fuels, from th e end user perspective and with a focus on the hydrogen-based fuels, both blended and 100%. The authors compare and contrast these projects with similar projects abroad, where in the U.K., Germany, and Japan, for instance, significant fractions of homes and businesses already enjoy access to these non-fossil fuels. Finally, using the historical transition from manufactured gases to widespread distribution of natural gas, a ~30 year transition that occurred from the 1920s to the 1950s, the authors draw comparisons between this significant historical energy transition to the modern context, considering safety implications, regionality, impacts on HV AC equipment, and the role of codes and standards.