Low Carbon Conditions Research Articles

Zero-Valent Iron Enhances Nutrient Removal and Long-Term Stability of Algal–Bacterial Granular Sludge under Low Carbon Conditions

Zero-Valent Iron Enhances Nutrient Removal and Long-Term Stability of Algal–Bacterial Granular Sludge under Low Carbon Conditions

Low-Carbon-Oriented Capacity Optimization Method for Electric–Thermal Integrated Energy System Considering Construction Time Sequence and Uncertainty

The interdependence of various energy forms and flexible cooperative operation between different units in an integrated energy system (IES) are essential for carbon emission reduction. To address the planning problem of an electric–thermal integrated energy system under low-carbon conditions and to fully consider the low carbon and construction sequence of the integrated energy system, a low-carbon-oriented capacity optimization method for the electric–thermal integrated energy system that considers construction time sequence (CTS) and uncertainty is proposed. A calculation model for the carbon transaction cost under the ladder carbon trading mechanism was constructed, and a multi-stage planning model of the integrated energy system was established with the minimum life cycle cost, considering carbon transaction cost as the objective function, to make the optimal decision on equipment configuration in each planning stage. Finally, a case study was considered to verify the advantages of the proposed capacity optimization method in terms of economy and environmental friendliness through a comparative analysis of different planning cases. Simulation results show that, compared with the scenario of completing planning at the beginning of the life cycle at one time, the proposed low-carbon-oriented capacity optimization method that considers construction time sequence and uncertainty can not only reduce the cost of the integrated energy system, but also help to enhance renewable energy utilization and reduce the system’s carbon emissions; the total cost of phased planning is reduced by 11.91% compared to the total cost of one-time planning at the beginning of the year.

Protein NirP1 regulates nitrite reductase and nitrite excretion in cyanobacteria

When the supply of inorganic carbon is limiting, photosynthetic cyanobacteria excrete nitrite, a toxic intermediate in the ammonia assimilation pathway from nitrate. It has been hypothesized that the excreted nitrite represents excess nitrogen that cannot be further assimilated due to the missing carbon, but the underlying molecular mechanisms are unclear. Here, we identified a protein that interacts with nitrite reductase, regulates nitrogen metabolism and promotes nitrite excretion. The protein, which we named NirP1, is encoded by an unannotated gene that is upregulated under low carbon conditions and controlled by transcription factor NtcA, a central regulator of nitrogen homeostasis. Ectopic overexpression of nirP1 in Synechocystis sp. PCC 6803 resulted in a chlorotic phenotype, delayed growth, severe changes in amino acid pools, and nitrite excretion. Coimmunoprecipitation experiments indicated that NirP1 interacts with nitrite reductase, a central enzyme in the assimilation of ammonia from nitrate/nitrite. Our results reveal that NirP1 is widely conserved in cyanobacteria and plays a crucial role in the coordination of C/N primary metabolism by targeting nitrite reductase.

Ephemeral microbial responses to pulses of bioavailable carbon in oxic and anoxic salt marsh soils

Roots of salt marsh grasses contribute to soil building but also affect decomposition by releasing bioavailable carbon exudates and oxygen. Disentangling exudate and oxygen effects on decomposition is difficult in the field but essential for marsh carbon models and predicting the impacts of global change disturbances. We tested how pulsed, simulated exudates affect soil metabolism under oxic and anoxic conditions, and whether carbon and oxygen availability facilitate mineralization of existing organic matter (i.e., priming). We conducted a laboratory experiment in flow-through reactors, adding carbon pulses weekly for 84 days and then following starvation under low carbon conditions. Oxygen consumption and sulfide production were inhibited under anoxic and oxic conditions and slowed by 21 ± 10% and 55 ± 8%, respectively, between 1- and 5- days following exudate pulses. Respiration rates immediately following and between pulses increased over time, suggesting that microbes capitalize on and may acclimate to patchy resources. Starvation caused oxygen consumption and sulfide production to fall 28% and 78% in oxic and anoxic treatments. Smaller decreases in oxygen consumption following pulses could suggest greater access to secondary carbon sources and that sulfate reducers were more reliant on exudates. Soil organic carbon was not the likely secondary source because porewater dissolved inorganic carbon δ13C values did not change during transit through the reactors, despite a ∼26‰ difference between the supplied seawater and marsh soil. Interpretation of oxygen consumption rates is complicated by non-respiratory oxidation of reduced inorganic compounds and possibly significant lithoautotrophy. Exudate pulses elicited rapid and ephemeral respiratory responses, particularly under anoxia, but non-respiratory oxidation of reduced compounds obscured the impact of oxygen availability in our experimental system. Despite this, greater aerobic respiration rates suggest that oxygen availability has more potential to regulate carbon mineralization in coastal wetlands than root exudates.

Heat distribution model under hydrogen-rich low-carbon conditions in blast furnace

Heat distribution model under hydrogen-rich low-carbon conditions in blast furnace

Path analysis of energy economic management standardization in the context of carbon neutralization and carbon peak

Carbon neutrality and carbon peak are two important measures to control climate change. They have a huge impact on many companies in the fields of energy, industry, construction, transportation, etc. They can change the development pattern of related industries and increase many new investment and development opportunities. This paper proposes a path analysis of the standardization of energy economic management under the background of carbon neutrality and carbon peak, aiming to study the development forecast of energy economic management under low-carbon conditions. The algorithm proposed in this paper is an energy consumption analysis algorithm based on the IPAT model, which can be combined with the IPAT model to analyze and process energy consumption data. In addition, by analyzing and evaluating the contribution of various factors, people can better understand the impact of energy consumption on the environment and formulate corresponding solutions. The experimental analysis results of energy economic management based on carbon neutrality and carbon peak show that, from 2013 to 2017, under the baseline scenario, carbon emissions increased year by year, from 9.25 billion tons to 10.48 billion tons. Under the carbon neutral scenario, its carbon emissions are 9.22 billion tons, 9.24 billion tons, 9.22 billion tons, 9.19 billion tons and 9.21 billion tons respectively. Obviously, under the carbon neutral scenario, carbon emissions can be better controlled through carbon neutral and carbon peak strategies. Through these experimental prediction results, it can be proved that carbon neutrality and carbon peaking have excellent effects on promoting energy economic management. At the same time, this study also provides valuable reference information for further research on carbon neutrality and carbon peaks.

Scenario prediction of energy consumption and carbon emissions in Lingang New Area based on LEAP model

Based on the statistical data of Lingang New Area in 2021, the LEAP-Lingang model was constructed, and the energy consumption and carbon emissions of Lingang New Area from 2022 to 2035 were predicted and studied by setting three scenarios: benchmark, policy and low carbon. The results show that under the policy scenario, the new area can maintain low energy consumption and carbon emission development, but fails to peak carbon emissions before 2035, and can basically peak carbon emissions around 2030 under low-carbon conditions. On the basis of existing policies, the new area can further promote clean energy development, accelerate regional industry and energy efficiency upgrading, and actively promote green power and green certificate trading to accelerate the process of carbon peaking.

New Insights Into Microbial Induced Calcium Carbonate Precipitation Using Saccharomyces cerevisiae.

Saccharomyces cerevisiae plays an important role in the mineralization of many metal ions, but it is unclear whether this fungus is involved in the mineralization of calcium carbonate. In this study, S. cerevisiae was cultured under various conditions to explore its ability to perform microbially induced calcium carbonate precipitation (MICP). Organic acids, yeast extract, and low-carbon conditions were the factors influencing the biomineralization of calcium carbonate caused by S. cerevisiae, and biomolecules secreted by the fungus under different conditions could change the morphology, size, and crystal form of the biosynthesized mineral. In addition, transcriptome analysis showed that the oxidation of organic acids enhanced the respiration process of yeast. This implied that S. cerevisiae played a role in the formation of calcium carbonate through the mechanism of creating an alkaline environment by the respiratory metabolism of organic acids, which could provide sufficient dissolved inorganic carbon for calcium carbonate formation. These results provide new insights into the role of S. cerevisiae in biomineralization and extend the potential applications of this fungus in the future.

Nitrate removal under low carbon to nitrogen ratio by modified corn straw bioreactor: Optimization and possible mechanism

ABSTRACT The removal of nitrate (NO3 −−N) from water bodies under the conditions of poor nutrition and low carbon to nitrogen (C/N) ratio is a widespread problem. In this study, modified corn stalk (CS) was used to immobilize Burkholderia sp. CF6 with cellulose-degrading and denitrifying abilities. The optimal operating parameters of the bioreactor were explored. The results showed that under the hydraulic retention time (HRT) of 3 h and the C/N ratio of 2.0, the maximum nitrate removal efficiency was 96.75%. In addition, the organic substances in the bioreactor under different C/N ratios and HRT were analyzed by three−dimensional fluorescence excitation–emission mass spectrometry (3D−EEM), and it was found that the microorganisms have high metabolic activity. Scanning electron microscope (SEM) showed that the new material has excellent immobilization effects. Fourier transform infrared spectrometer (FTIR) showed that it has potential as a solid carbon source. Through high−throughput sequencing analysis, Burkholderia sp. CF6 was observed as the main bacteria present in the bioreactor. These research results showed that the use of waste corn stalks waste provides a theoretical basis for the advanced treatment of low C/N ratio wastewater.

Denitrification and DNRA in Urban Accidental Wetlands in Phoenix, Arizona.

Denitrification and dissimilatory nitrate reduction to ammonium (DNRA) both require low oxygen and high organic carbon conditions common in wetland ecosystems. Denitrification permanently removes nitrogen from the ecosystem as a gas while DNRA recycles nitrogen within the ecosystem via production of ammonium. The relative prevalence of denitrification versus DNRA has implications for the fate of nitrate in ecosystems. Unplanned and unmanaged urban accidental wetlands in the Salt River channel near downtown Phoenix, Arizona, USA receive high nitrate relative to non-urban wetlands and have a high capacity for denitrification, but unknown capacity for DNRA. We conducted in-situ push-pull tests with isotopically labelled nitrate to measure denitrification and DNRA rates in three of the dominant vegetative patch types in these urban accidental wetlands. DNRA accounted for between 2 and 40% of nitrate reduction (DNRA plus denitrification) with the highest rates measured in patches of Ludwigia peploides compared to Typha spp. and non-vegetated patches. The wetland patches were similar with respect to dissolved organic carbon concentration but may have differed in carbon lability or strength of reducing conditions due to a combination of litter decomposition and oxygen supply via diffusion and aerenchyma. The ratio of DNRA to denitrification was negatively correlated with nitrate concentration, indicating that DNRA may become a more important pathway for nitrate attenuation at low nitrate concentration. Although DNRA was generally lower than denitrification, this pathway was an important component of nitrate attenuation within certain patches in these unmanaged urban accidental wetlands.

Enhanced corrosion resistance to molten iron of carbon bricks through nano-scale micropores and alumina addition

The composition and micropores characteristics of carbon bricks have significant influence on their corrosion resistance to molten iron. In this study, the corrosion of an ultra-microporous carbon brick (MG carbon brick) in molten iron was studied by the rotating cylinder method. The results indicated that the corrosion resistance to molten iron of the MG carbon brick was better than that of the NMA carbon brick, especially under the conditions of low carbon, high sulfur and low titanium molten iron. The nano-scale micropores and the addition of Al2O3 were the main factors which made the MG carbon brick more resistant to corrosion by molten iron than the NMA carbon brick. In terms of chemical composition, the MG carbon brick contained 8.74 wt.% Al2O3 and 6.91 wt.% SiC, while their content in the NMA carbon brick was very little. The corrosion resistance to molten iron of carbon bricks can be enhanced by adding Al2O3. But it cannot be ignored that the thermal stability of the carbon brick would deteriorate due to the addition of Al2O3. Moreover, because of the better properties of the MG carbon brick in terms of average pore size and ≤1 μm pore volume, the MG carbon brick had better permeation resistance to molten iron than the NMA carbon brick.

Microbiome response to foam fractionation and ozonation in RAS

Efficient water treatment is required to maintain high water quality and control microbial growth in recirculating aquaculture systems (RAS). Here, we examined the effects of two treatment methods, ozonation and foam fractionation, separately and combined, on the microbiology in twelve identical experimental RAS with rainbow trout (Oncorhyncus mykiss) during 8 weeks. Microbes suspended in water and growing in biofilter biofilms were examined using flow cytometry analysis and high throughput sequencing of the 16S rRNA gene. The results showed that foam fractionation did not cause large changes in abundance or overall community composition of free-living microbes. Instead, through decreasing the organic matter availability in water, it targeted specific microbial taxa, leading to e.g. decreased potential for off-flavor production. In contrast, ozonation was found to have a profound impact on the system microbiology, by reducing the overall cell abundance, increasing microbial dead/live ratio, and changing the community composition of both free-living and biofilm microbes. Ozonation increased the abundance of certain key microbial taxa adapted to low carbon conditions, which might form a stable and more abundant community under a prolonged ozone dosing. Combining the two treatment methods did not provide any additional benefits as compared to ozonation solely, corroborating the high disinfection potential of ozone. However, ozone had only a minor impact on biofilter microbial communities, which were, in general, more resistant to water treatment than water communities. Water treatment had no effect on the overall genetic nitrification potential in the biofilter biofilms. However, foam fractionation led to changes in the nitrifying microbial community in biofilter, increasing the abundance of Nitrospira conducting complete ammonia oxidation to nitrate (comammox). Altogether, the results obtained indicate that although these two water treatment methods have similar outcomes on physico-chemical water quality and microbial activity, their underlying mechanisms are different, potentially leading to different outcomes under the long-term application.

Effect of organic concentration on biological activity and nitrogen removal performance in an anammox biofilm system.

The effects of different concentrations of organic matter on the biological activity and nitrogen removal performance of the anaerobic ammonium oxidation (anammox) system was studied. The results showed that under the conditions of low influent total organic carbon (TOC ≤ 100 mg/L), the activity rate of anammox bacteria was basically unaffected, the anammox bacteria and denitrifying bacteria formed a good synergistic effect, and the maximum total nitrogen (TN) removal efficiency reached 95.77%. However, when the influent TOC concentration was up to 200 mg/L, the activity of anammox bacteria was seriously inhibited. At this time, denitrification becomes the main pathway of nitrogen removal, the effluent ammonia nitrogen content increases, and the TN removal efficiency decreases to 64.17%. High-throughput sequencing analysis showed that with the increase in organic matter concentration, the relative abundance of Proteobacteria and Planctomycetes changed significantly. In particular, the relative abundance proportion of Proteobacteria increased from 21.06% to 25.57%, the Planctomycetes dropped from 10.01% to 3.03% and the Candidatus Brocadia genus had the largest decrease. In conclusion, the concentration range of organic matter for collaborative denitrification was proposed in this study, which provided theoretical reference for the practical application of anammox biofilm process.

Diel Variations of Extracellular Microcystin Influence the Subcellular Dynamics of RubisCO in Microcystis aeruginosa PCC 7806.

The ubiquitous freshwater cyanobacterium Microcystis is remarkably successful, showing a high tolerance against fluctuations in environmental conditions. It frequently forms dense blooms which can accumulate significant amounts of the hepatotoxin microcystin, which plays an extracellular role as an infochemical but also acts intracellularly by interacting with proteins of the carbon metabolism, notably with the CO2 fixing enzyme RubisCO. Here we demonstrate a direct link between external microcystin and its intracellular targets. Monitoring liquid cultures of Microcystis in a diel experiment revealed fluctuations in the extracellular microcystin content that correlate with an increase in the binding of microcystin to intracellular proteins. Concomitantly, reversible relocation of RubisCO from the cytoplasm to the cell’s periphery was observed. These variations in RubisCO localization were especially pronounced with cultures grown at higher cell densities. We replicated these effects by adding microcystin externally to cultures grown under continuous light. Thus, we propose that microcystin may be part of a fast response to conditions of high light and low carbon that contribute to the metabolic flexibility and the success of Microcystis in the field.

Condensation of Rubisco into a proto-pyrenoid in higher plant chloroplasts

Photosynthetic CO2 fixation in plants is limited by the inefficiency of the CO2-assimilating enzyme Rubisco. In most eukaryotic algae, Rubisco aggregates within a microcompartment known as the pyrenoid, in association with a CO2-concentrating mechanism that improves photosynthetic operating efficiency under conditions of low inorganic carbon. Recent work has shown that the pyrenoid matrix is a phase-separated, liquid-like condensate. In the alga Chlamydomonas reinhardtii, condensation is mediated by two components: Rubisco and the linker protein EPYC1 (Essential Pyrenoid Component 1). Here, we show that expression of mature EPYC1 and a plant-algal hybrid Rubisco leads to spontaneous condensation of Rubisco into a single phase-separated compartment in Arabidopsis chloroplasts, with liquid-like properties similar to a pyrenoid matrix. This work represents a significant initial step towards enhancing photosynthesis in higher plants by introducing an algal CO2-concentrating mechanism, which is predicted to significantly increase the efficiency of photosynthetic CO2 uptake.

Thermodynamic and Dynamic Study on the Carbon Deposition on an Iron Surface in a C–H–O System

The C–H–O ternary phase diagrams in equilibrium with graphite were developed to determine the gas compositions and boundaries for graphite formation in 500–900 °C. Thermogravimetric calculation results showed that carbon deposition was favored under the conditions of low temperature, high carbon, and low oxygen potential. The carbon deposition with reduced iron was carried out in a syngas of H2 and CO by thermal gravimetric experiments. The results showed that carbon deposition started at 400 °C, accelerated at 600–800 °C, and stopped at 1000 °C. Carbon deposition was accelerated by the presence of H2, which was increased with the CO ratio in the gas mixture, and depressed by the addition of CO2. The reduced iron with large surface area fabricated the carbon deposition. Cementite (Fe3C) was formed as intermediate that accelerated the carbon deposition rate. The C–H–O ternary phase diagrams in equilibrium with Fe3C were also provided.

Rhizosphere Microbial Community Structure Is Selected by Habitat but Not Plant Species in Two Tropical Seagrass Beds.

Rhizosphere bacterial community structures and their determining drivers have been studied in a variety of marine and freshwater ecosystems for a range of plant species. However, there is still limited information about the influence of habitat on microbial communities in seagrass beds. This study aimed to determine which factors (habitat and plant species) have crucial roles on the rhizospheric bacteria associated with two tropical seagrass species (Thalassia hemprichii and Enhalus acoroides) that are dominant at Xincun Bay and Tanmen Harbor in Hainan Island, South China. Using Illumina HiSeq sequencing, we observed substantial differences in the bacterial richness, diversity, and relative abundances of taxa between the two habitats, which were characterized differently in sediment type and nutrient status. Rhizospheric bacteria from sandy sediment at the eutrophic Xincun Bay were dominated by Desulfobacteraceae and Helicobacteraceae, which are primarily involved in sulfate cycling, whereas rhizosphere microbes from the reef flat at oligotrophic Tanmen Harbor were dominated by Vibrionaceae and Woeseiaceae, which may play important roles in nitrogen and carbon fixing. Additionally, we speculated that host-specific effects of these two seagrass species may be covered under nutrient-rich conditions and in mixed community patches, emphasizing the importance of the nutrient status of the sediment and vegetation composition of the patches. In addition, our study confirmed that Proteobacteria was more adapted to the rhizosphere environment than to low-carbon conditions that occurred in bulk sediment, which was primarily dominated by well-known fermentative bacteria in the phylum Firmicutes.

Efficiency of vanillin in impeding metabolic adaptability and virulence of Candida albicans by inhibiting glyoxylate cycle, morphogenesis, and biofilm formation.

Background and Purpose: Candida albicans is the fourth most common cause of nosocomial fungal infections across the world. The current drug regimens are suffering from such drawbacks as drug resistance, toxicity, and costliness; accordingly, they highlight the need for the discovery of novel drug agents. The metabolic adaptability under low-carbon conditions and expression of functional virulence traits mark the success of pathogens to cause infection. The metabolic pathways, such as glyoxylate cycle (GC), enable C. albicans to survive under glucose-deficient conditions prevalent in the hostile niche. Therefore, the key enzymes, namely isocitrate lyase (ICL) and malate synthase (MLS), represent attractive agents against C. albicans. Similarly, virulence traits, such as morphogenesis and biofilm formation, are the crucial determinants of C. albicans pathogenicity. Regarding this, the present study was conducted to uncover the role of vanillin (Van), a natural food flavoring agent, in inhibiting GC, yeast-to-hyphal transition, and biofilm formation in human fungal pathogen C. albicans.Materials and Methods:For the determination of hypersensitivity under low-glucose conditions, phenotypic susceptibility assay was utilized. In addition, enzyme activities were estimated based on crude extracts while in-silico binding was confirmed by molecular docking. The assessment of morphogenesis was accomplished using hyphal-inducing media, and biofilm formation was estimated using calcofluor staining, MTT assay, and biomass measurement. Additionally, the in vivo efficacy of Van was demonstrated using Caenorhabditis elegans nematode model.Results:Based on the results, Van was found to be a potent GC inhibitor that phenocopied ICL1 deletion mutant and displayed hypersensitivity under low-carbon conditions. Accordingly, Van facilitated the inhibition of ICL and MLS activities in vitro. Molecular docking analyses revealed the in-silico binding affinity of Van with Icl1p and Mls1p. Those analyses were also confirmative of the binding of Van to the active sites of both proteins with better binding energy in comparison to their known inhibitors. Furthermore, Van led to the attenuation of such virulence traits as morphogenesis, biofilm formation, and cell adherence. Finally, the antifungal efficacy of Van was demonstrated by the enhanced survival of C. elegans with Candida infection. The results also confirmed negligible hemolytic activity on erythrocytes.Conclusion:As the findings of the present study indicated, Van is a persuasive natural compound that warrants further attention to exploit its anticandidal potential.

低碳条件下的配送中心路径优化研究

低碳条件下的配送中心路径优化研究

The profit model design and development strategy of Industry 4.0 under the concept of green and low-carbon

In order to overcome the environmental degradation and energy crisis caused by the rapid industrialisation process, the profit model design and development strategy of Industry 4.0 under the concept of green and low-carbon are proposed. Through the macro, meso and micro levels of green and low-carbon concept, this paper analyses the low-carbon operating conditions of Industry 4.0, determines the development process of low-carbon elements in the performance evaluation of industrial system; introduces carbon management and development of carbon industry, respectively designs relevant profit models; on the premise of ensuring the performance of industrial products, it advocates energy-saving behaviour, attaches importance to guiding behaviour design, and gives full play to it. The function of high technology prolongs the service life of products. We should implement the green and low-carbon principle, and formulate comprehensive development strategies for promoting the construction of ecological civilisation and industrial progress.