Generation Of Pollutants Research Articles

Constructing high-resolution fingerprints and analyzing complex pollution source of electronic waste recycling base

Disposal of e-waste is an issue of great concern to society due to its resource value and environmental pollution. Previous studies on the pollution generation and release during e-waste recycling process are piecemeal, and pollution source analysis in e-waste bases is still a challenge. In this study, we synthetically analyzed pollution generation from a typical e-waste recycling base, containing e-waste dismantling process and e-waste glass recycling process. Heavy metals are widely distributed in the whole base, and 22 pollution fingerprints were constructed based on processing characteristics. Based on these fingerprints, an accurate pollution source apportionment model was innovatively built together with logistic regression analysis. Intelligent full-component recycling system for e-waste can improve recycling efficiency and decrease pollution release. This study will provide a novel way of analyzing various factors and complex pollutions in secondary resource recycling scenarios.

A Process‐Based Model to Track Water Pollutant Generation at High Resolution and Its Pathway to Discharge

AbstractThe estimation of water pollutant loads is of crucial importance as it decides data inputs for both subsequent water quality models and watershed pollutant mitigation strategy. However, the generation of water pollutant loads at high resolution and the life‐cycle pathway of them from sources, through pipelines and wastewater treatment plants, finally to recipient water bodies remain unclear. This study aims to establish a process‐based Water Pollutant Loads Tracking model and applies it to a rapidly urbanizing watershed in Taihu Lake Basin, China at the resolution of 5 m × 5 m in 2017, whose terrain is flat, slowly lowing from west to east. Results show that, of 261.55 tons of the total phosphorus (TP) generation, 71.28% is collected, and 64.32% is treated, with only 26.46% discharged to the water bodies and 1.25% to the target ones. The spatial hotspots of TP generation are mainly concentrated in residential and industrial areas. Direct discharges from point sources and nonpoint runoffs, especially in rainy seasons, are recognized as the main challenges for local water pollution control. The main innovation of this study is to quantify the generation of water pollutant loads at high resolution and to trace the subsequent pathway to collection and discharge, and then to identify the potential substantial gap between generation and discharge, demonstrating the efficacy and broader applicability of this model.

Mesoporous γ-Al2 O3 Supported Mn–Ce–Co Ternary Oxides for the Efficient Plasma-Catalytic Oxidation of Formaldehyde

Coupling low-temperature plasma technology with catalysts can significantly enhance air purification efficiency and mitigate the generation of secondary pollutants. In this study, mesoporous [Formula: see text]-Al2O3 supported Mn–Ce–Co ternary oxides were introduced into a widely employed tubular dielectric barrier discharges (DBD) reactor for indoor air purification. The plasma-catalytic degradation of HCHO exhibited the following degradation efficiency order: Mn–Ce–Co/[Formula: see text]-Al2O3 [Formula: see text] Mn/[Formula: see text]-Al2O3 [Formula: see text] Mn–Ce/[Formula: see text]-Al2O3 [Formula: see text] Co/[Formula: see text]-Al2O3 [Formula: see text] [Formula: see text]-Al2O3 [Formula: see text] Ce/[Formula: see text]-Al2O3 [Formula: see text] Plasma. When compared to plasma treatment alone, the catalyst resulted in a remarkable 1.8-fold enhancement under conditions of 3.0[Formula: see text]kV, [Formula: see text]C, 60% RH. Additionally, the concentrations of the by-products O3 and NO[Formula: see text] were significantly reduced by 88.2% and 93.3%, respectively. The synergistic interaction between Mn, Ce and Co oxides facilitated the formation and transportation of surface-reactive oxygen species, thereby contributing to the thorough oxidation of HCHO and organic intermediates during the plasma-catalytic process. Moreover, the high specific surface area offered by mesoporous materials enhanced the adsorption and catalytic activity towards HCHO.

Harmonizing Biological and Chemical Strategies for Hazardous Chemical Detoxification: An Integrative Review

The management and mitigation of hazardous chemicals pose significant challenges to environmental and human health. This comprehensive review critically examines the efficacy of biological and chemical methods for the detoxification of hazardous chemicals. Hazardous chemicals, ranging from organic pollutants to heavy metals, often contaminate soil, water, and air, leading to adverse ecological and health impacts. Traditional chemical-based approaches have limitations, such as secondary pollutant generation and high operational costs. In contrast, biological methods harness the metabolic activities of microorganisms, plants, and enzymes to transform or degrade hazardous compounds. This review evaluates the performance of biological systems, including bioremediation, phytoremediation, and enzyme-based approaches, in detoxifying various classes of hazardous chemicals. Additionally, chemical methods, such as advanced oxidation processes, redox reactions, and adsorption, are scrutinized for their efficiency in chemical degradation and transformation. The comparative analysis considers factors like effectiveness, cost, environmental impact, and applicability to different chemical classes. Understanding the strengths and weaknesses of these detoxification approaches is essential for informed decision-making in environmental remediation and industrial processes. This review offers valuable insights into the selection of appropriate detoxification methods, based on the nature of the hazardous chemicals and the desired environmental and economic outcomes.

Study on Noise Pollution Generated from Vehicles in Gazipur City Corporation, Dhaka, Bangladesh

Gazipur city corporation has established on 16th January, 2013. It has a total 329.53 sq.km with a population of 6500000. About 75% of the garments of the country are located in this city corporation [1]. For this huge number of population and garment factories a huge number of vehicles moves in the city every day. This huge number of vehicles not only moves in the city they are responsible for the generation of noise pollution. The study shows the variation of noise level with traffic volume. To conduct the research noise level was measured along with traffic count. From the research, it has established that the level of noise pollution is not dependent on the traffic volume. Even the noise level has found maximum, when the traffic volume is minimum compare to the maximum traffic volume. Even it has also found that in off pick hour when the traffic volume is minimum, the noise level has no influence. That has happened due to reckless driving of the drivers and unawareness of the noise pollution.

Latin America towards Sustainability through Renewable Energies: A Systematic Review

Nowadays, the increase in global energy demand is notorious, a situation that, in turn, impacts the environment through the generation of pollutants that are harmful to the planet. In this sense, an energy transition towards clean energy sources, also known as renewable sources, is essential, as well as better energy management and a responsible use of available natural resources. In this context, the objective of this systematic review was to analyze the use of renewable energy sources in Latin America, in addition to the guidelines established for their use, and the consequences of the use of non-renewable sources. Therefore, the PRISMA method was applied, and 60 publications were selected, from which the existing interest in this region in combatting the increase in energy demand and the use of fossil fuels through renewable energies is evidenced. Finally, it is concluded that there is still a need for greater dissemination in the region regarding this problem, as well as greater actions on the part of industries and governments to make proper use of this type of energy source.

The Blue Flag Award in South Africa: Raising Consciences and Influencing Beach Goers’ Decisions

In recent years, the tourism sector has experienced significant expansion, with the beach ecosystem emerging as the most popular destination for recreational and leisure pursuits. The proliferation of marine tourism activities has resulted in undeniable ecological consequences, including but not limited to the generation of solid waste, noise and air pollution, unattractive landscapes, and degradation of the coastal biome. The Blue Flag certification has been widely embraced by several coastal municipalities as a means of addressing the adverse environmental consequences that arise from tourism and recreational activities. The objective of this research is to evaluate the perceptions and level of awareness of beach visitors regarding the Blue Flag award, as well as determine if their selection of a beach destination is influenced by the Blue Flag standards. The study employed a quantitative methodology and gathered data, using convenience sampling, from beach visitors at nine Blue Flag beaches located in KwaZulu-Natal. The data were collected through a structured, self-administered questionnaire. The findings suggest that there is a dearth of awareness among beach visitors regarding the Blue Flag certification and that certain criteria associated with the award have an impact on their selection of beaches. The study is expected to yield significant advantages in enhancing and strengthening the Blue Flag certification program within the country at large. Additionally, it will promote the necessity of public environmental education and awareness regarding the award.

Rational construction of hollow ZnO@SnS2 core-shell nanorods: A way to boost catalytic removal of Cr (VI) ions, antibiotic and industrial dyes

Herein, the novel hollow ZnO@SnS2 core-shell nanorods with variable shell thickness have been synthesized by a chemical synthesis approach. The transmission electron microscopy (TEM) images signified the creation of a hollow core-shell nanostructure. The SnS2 layer coating on ZnO nanorods broadens visible light absorption and suppresses near-band edge emission of ZnO nanorods. Interestingly, the band gap (optical) of the developed ZnO nanorods decreased from 3.3 eV to 2.1 eV after the coating of SnS2 shell. Consequently, the coated hollow ZnO@SnS2 core-shell nanorods displayed a significant enhancement in catalytic activity for the decomposition of toxic industrial dyes, pharmaceutical pollutant tetracycline, and Cr(VI) ion in comparison to hollow ZnO NRs. The photon-induced charge carrier generation and separation were confirmed by the three-electrode electrochemical amperometric analysis and impedance analysis under illumination of simulated solar light (AM 1.5, One Sun). Moreover, an exceptionally higher photocurrent generation (∼10 times higher than ZnO nanorod). The improved ZnO@SnS2 core shell NRs catalytic activity was attributed to its core-shell structure, proper band structure, and effective charge carrier transfer across the core shell interface. This work offers new insights for the design and growth of visible light-active core shell nanorods for resolving environmental pollution and photocurrent generation.

Sponge-like biodegradable polypyrrole-modified biopolymers for selective adsorption of basic red 46 and crystal violet dyes from single and binary component systems

Recently, several researchers have been trying to reduce the ecological effects of water pollution by considering the use of biodegradable materials that prevent the generation of secondary pollution in our environment and enable water reuse. Here, new biodegradable hydrogels based on alginate (Alg), gelatin (Gel) and polypyrrole (PPy) were successfully implemented to remove two known highly toxic cationic dyes from wastewater. The design process was performed in two steps: in-situ polymerization of polypyrrole within the Alg/Gel mixture, followed by hydrogel formation. Biocomposites showed promising efficacy for the removal of both basic red 46 (BR46) and crystal violet (CV) dyes from real and demineralized water samples. However, Alg-Gel-PPy hydrogel showed better selectivity for BR46 than for CV as compared to the pristine Alg-Gel hydrogel. Adsorption of both pollutants on biocomposite hydrogel beads followed the Langmuir isotherm and pseudo-second order kinetic models. Besides, the highest adsorption capacities (125 mg g−1 for BR46 and 88.5 mg g−1 for CV) were obtained for the Alg-Gel-PPy hydrogel, compared with those determined for PPy-free hydrogel (103.09 mg g−1 for BR46 and 86.96 mg g−1 for CV) and remained at a satisfactory level for five adsorption-desorption cycles. Finally, the obtained hydrogels showed excellent biodegradability by natural soil microorganisms, with 91 % decomposition.

Optimal Allocation of Battery Energy Storage Systems to Enhance System Performance and Reliability in Unbalanced Distribution Networks

The continuously increasing renewable distributed generation (DG) penetration rate significantly reduces environmental pollution and power generation cost and satisfies society’s rapid growth in electricity demand. Nevertheless, high penetration of renewable DGs, such as wind power and photovoltaics (PV), might deteriorate the system’s efficiency and reliability due to its intermittent and stochastic natures. Introducing battery energy storage systems (BESSs) to the distribution system provides a practical method to compensate for the above deficiency since it can deliver and absorb power when needed. Hence, it is important to determine the optimal allocation of BESS to achieve maximum assistance in the grid. This study proposes an optimal BESS allocation methodology to improve reliability and economics in unbalanced distribution systems. The optimal BESS allocation problem is solved by simultaneously minimizing the cost of energy interruption, expected energy not supplied, power loss, line loading, voltage deviation, and BESS cost. The proposed technique is implemented and analyzed on a high renewable DG penetrated unbalanced IEEE-33 bus network using DIgSILENT PowerFactory software (version 2020 SP2A). An enhanced grey wolf optimization (EGWO) algorithm is developed to optimize BESS location and size according to the selected objective function. The simulation results show that the proposed optimal BESS optimization technique significantly improves the economics and reliability in unbalanced distribution systems and the EGWO outperforms the gray wolf optimization (GWO) and particle swarm optimization (PSO) algorithms.

Analysis of the effect of COVID-19 lockdown on air pollutants using multi-source pollution data and meteorological variables for the state of Uttar Pradesh, India

The present study, conducted in the most populous state of India, i.e., Uttar Pradesh, estimates the variation of air quality for the period between 2019 and 2021, taking into account the extraordinary situation of COVID-19. The Government of India imposed the four-phased complete lockdown on 25th March, 2020, which lasted until 31st May, 2020. The study deals with pollution data during these phases with the help of ground station-based pollution data as well as available satellite data. Since ground data is available at limited stations, an Inverse Distance Weighted (IDW) interpolation technique is used for the generation of phase-wise pollution maps for the whole state during the timeline of 2020. The generated maps show a sharp decline in pollution levels for PM2.5, PM10, NO2, NOx and NO, and an increase in the level of SO2 and Ozone in Phase-I (P1), justifying the effectiveness of the lockdown. Further, for station-wise analysis, a six-phase timeline for the years 2019, 2020 and 2021 has been devised to calculate mean pollution levels as well as pollution level changes. In comparison to 2019 and 2021, the mean and standard deviation in the year 2020 through P1-P4 is the least, emphasising the least spread of pollution level in 2020 due to the lockdown. The analysis is also accompanied by Sentinel-5P TROPOMI satellite data, giving similar observations for NO2. Regarding correlation, data from ground stations and satellites correlate most for NO2 and least for SO2. In addition, empirical relations between pollution data (dependent) and meteorological data (independent) are generated, which reveal that the power to explain the pollution level variability has further increased by using binary lockdown variables along with meteorological data.

Circularity in Materials: A Review on Polymer Composites Made from Agriculture and Textile Waste

Agriculture and textiles have the highest production yields among all sectors to meet mankind’s basic needs, i.e., feeding and clothing; however, they are top contributors to environmental pollution and global waste generation. Their wastes and byproducts are precious organic materials, they have great potential as raw materials for the manufacturing of valuable products. This review sheds light on various textile and agricultural wastes, waste management issues, and their existing utilization. Current waste processing methods are mostly based on waste-to-energy routes or material reclamation; however, both methods are hazardous for the environment and are inefficient. During the past decade, many researchers have utilized agriculture and textile wastes in the fabrication of composites. Textile and agricultural wastes and byproducts can be efficiently used for composite fabrication and can be suitable alternatives to existing raw materials. Using textiles and agricultural wastes for composite manufacturing can not only address waste management issues and replace non-eco-friendly materials in the composite industry but also significantly improve composite properties.

Modeling the effects of speed limit cameras (SLCs) on air quality and traffic flow on access-controlled highways

The impact of speed limit cameras (SLCs) on speed limit enforcement and traffic safety has long been studied. However, the effects of SLCs on air quality have not been thoroughly investigated due to the lack of data at sites where both air quality and traffic flow measurements (such as speed and volume) are monitored in close proximity to SLCs. This study aims to quantify the effect of SLCs on air quality and traffic flow parameters on access-controlled highways using linear regression models (LRM) and generalized additive models (GAM). The latter allows the modeling of nonlinear functional relationships between the predictor and outcome variables. We collected experimental data, including traffic flow parameters, weather conditions, and air pollutants (CO, CO2, NO2, SO2, and VOC), on high-volume, high-speed access-controlled highways in the wider metropolitan area of Dammam, Saudi Arabia. Key parameters related to traffic, such as volume, speed, percentage of heavy-duty vehicles (HDV), and percentage of traffic exceeding the speed limit, were used to estimate air pollutant generation from vehicular exhaust emissions near highway locations. Our analysis of the collected data revealed that locations with SLCs showed higher adherence to the speed limit of 120 km/h. The 85th percentile speed at these sites was approximately 114 km/h, which was 11 percent lower than that at the no-camera sites. Additionally, field data demonstrated a significant reduction in CO and SO2 emissions at the camera locations by approximately 23.7 and 20.3 percent, respectively. However, at these locations, the CO2, NO2, and VOC gas concentrations increased slightly, ranging from 1.5 to 4.9 percent. The predictive capabilities of the GAMs for gas emissions were higher than those of the LRMs, except for CO2 emissions. The GAM results identified optimal speed values between 110 km/h and 130 km/h to minimize vehicle emissions. Furthermore, the GAM results indicated that SLC locations had significantly lower concentrations of exhaust gas emissions for CO, SO2, and VOC, but higher levels of CO2 and NO2 gases. Thus, the field data and GAM results were in agreement for all gases except VOC. These findings have implications for shaping environmental transportation policies and guidelines, highlighting the multifaceted impact of SLCs on both traffic behavior and air quality.

Mitigating the barriers of industrial symbiosis for waste management: An integrated decision-making framework for the textile and clothing industry.

Waste management in the textile and clothing (TAC) industry is a challenging issue due to high resource consumption and pollution generation. Therefore, the adoption of industrial symbiosis (IS) is the need of the hour for the TAC industry. However, the adoption of IS in emerging economies like India, Brazil, Bangladesh, etc. is limited due to various impediments. The present work aims to identify and analyse these barriers and develop mitigation strategies in the context of Indian TAC industry. Eighteen IS barriers have been identified and validated; and the interrelationships among them are studied by applying the 'weighted influence non-linear gauge system (WINGS)' method, which not only estimates the intensity of influence but also takes the self-strength of barriers into account. The results show that lack of trust amongst supply chain partners, lack of financial incentives from the government, lack of guidance from regularity bodies and industry associations and lack of consumer awareness are the most significant barriers. Additionally, the strategies to mitigate these barriers are developed based on a quadruple helix framework considering academia--government-industry-society as the main actors. The findings of the study will be helpful for the TAC industry, policymakers and other concerned stakeholders in framing suitable strategies to improve the long-term waste management practices of the industry and to achieve sustainable development goals (SDGs).

Advancing sustainable solutions: Harnessing polyaniline/BiOCl/GO ternary nanocomposites for solar-powered degradation of organic pollutant and photocatalytic hydrogen generation

Recently, polyaniline-based photocatalysts have gained great attention due to their narrow band gap (E = 1.77 eV), which enables them to absorb a significant amount of visible light (∼43%) in the solar spectrum. In this study, we have synthesized a ternary nanocomposite (PANI/BiOCl/GO) through an oxidative polymerization approach, incorporating polyaniline (PANI), graphene oxide (GO), and bismuth oxychloride (BiOCl). Different weight percentages of composites (GO/BiOCl: 0.5%, 1%, 2.5%, and PANI: 99.5%, 99%, 97.5%) were prepared and named as 0.5PBG, 1PBG, and 2.5PBG, respectively. The ternary nanocomposite's successful development, crystallinity, purity, porosity, and optical properties were evaluated through several spectroscopic and surface analysis techniques, including UV–Vis-DRS, PL, XRD, XPS, BET, and EDS analysis. FESEM and HRTEM images unveiled the porous characteristics of PANI, the morphology of exfoliated GO layers, and the nanoplate-like structure of BiOCl. The ternary nanocomposite was finally tested for its ability to degrade an organic dye, rhodamine-b (Rhb), and in the process also generate solar-light-driven green hydrogen by water half-splitting. The composite achieved about 90% detoxification (assigned from GC-TCD by analyzing the evolved CO2 gas after degradation) and 96% color removal of Rhb dye within 120 min. The degradation of Rhb by 1PBG displayed a first-order reaction, featuring a rate constant 7.25 times higher than that observed for pure PANI, 3.8 times higher than for pure GO, and 3.9 times higher than for pure BiOCl. Thus, the ternary composites achieve a good amount of synergy. Significantly, this reaction rate constant is 4.7 times greater than the rate observed with commercially used TiO2–P25 photocatalyst. Various reaction parameters including solution pH, different illumination areas, catalyst dosage, and the study of scavengers were investigated to understand their effects on the degradation reaction. The photocatalyst's reusability effectiveness was evaluated over 6 cycles, and its stability was subsequently confirmed through XRD and ICP-OES analysis. The LC-MS study revealed the identification of various intermediates and end products following the degradation reaction. The nanocomposite also produced 1000 ppm of hydrogen gas with an apparent quantum efficiency (AQE) of 17.97% when CH3OH was used as a sacrificial agent, 500 ppm (AQE of 9.69%) in the acidic conditions, and 600 ppm (AQE of 11.63%) in the basic conditions. In a broader perspective, this endeavor paves the way for exploring fresh opportunities in the utilization of this ternary nanocomposite. Its potential extends beyond accelerating dye degradation to encompass diverse solar-driven applications as well.

Emission characteristics of typical gas pollutants during oxygen-enriched waste incineration process

Oxygen-enriched waste incineration can improve incineration efficiency and reduce pollutant generation, while greenhouse gases and pollutant emission characteristics of different wastes are still unclear. In this study, pollutant emission characteristics of actual municipal solid waste (MSW) and typical components at different oxygen concentrations and moisture content were investigated to reveal the pollutant generation mechanism. The results illustrated that when oxygen concentrations increased from 21% to 30%, CO, CH4 and HCN emissions decreased by 95%, 95.5% and 96.5%, respectively. NO emissions increased by 75% due to the promotion of oxygen on fuel NO and rapid NO. The slight increase in SO2 (from 25.8% to 26.87%) was due to the promotion of oxygen on organic S and the reaction between SO42− and HCl. The decrease in HCl emissions (from 78.42% to 76.85%) was caused by the increasing deacon reaction. Besides, with increasing moisture content, CO, CH4 and HCN generation decreased first because of the CO oxidation and CH4 reforming reaction, and then increased due to the water–gas reaction between fixed carbon and water. Furthermore, the moisture content contained (66%) would promote NO and HCl generation by 35.7% and 9.1% through fuel N oxidation by OH radicals and hydrolysis of chlorine salt at high temperatures. The increased oxygen concentration would inhibit the moisture influence and improve applicability for different MSW. In addition, 25% oxygen-enriched incineration was selected as the most suitable parameter for improving combustion efficiency and reducing pollutant emissions of MSW with high moisture content.

Bimetallic nickel iron sulfide directly grown on defect-rich Ti3C2 MXene as an efficient bifunctional electrocatalyst for water electrolysis

Water electrolysis has been regarded as ideal method for producing high-purity hydrogen without the generation of environmental pollutants. Accordingly, the development of precious metal-free electrocatalysts that demonstrate high activity for both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) is essential for practical water electrolysis. Herein, porosity-engineered Ti3C2 MXene is employed as an efficient substrate for a bimetallic Ni-Fe-S electrocatalyst. The porous and defect-rich Ti3C2 (D-Ti3C2) flakes provide metal-like electrical conductivity and large surface area for direct growth of active species. Simultaneously, the Ni-Fe-S nanoparticles, constructed through a strong coupling between NiS2 and (Ni,Fe)S2 solid solution, not only serve as active sites with rich redox properties, but also generate charge transfer channels for electrochemical reactions. Leveraging these advantageous properties, the resulting Ni-Fe-S/D-Ti3C2 electrocatalyst exhibits excellent bifunctional electrocatalytic performance toward both OER and HER. As a result, the symmetric water electrolysis cell using the Ni-Fe-S/D-Ti3C2 requires a low cell voltage of 1.621 V to deliver current density of 10 mA cm−2, and shows stable electrocatalytic performance over 100 h of continuous operation.

Can the Federal Reserve save the environment?

This study examines the environmental effect of monetary policy, particularly within the framework of global value chains (GVCs). Given the escalating climate concerns and the urgent need for sustainable solutions, it is crucial to investigate the environmental consequences of monetary policy decisions which directly influence domestic production and international input-sourcing activities. As the monetary policy is likely to be associated with a variety of economic factors influencing environmental outcomes, it is critical to introduce an exogenous shock that reflects variations in monetary policies to derive unbiased causal estimates. We thus adopt a proxy-vector autoregression (VAR) approach with U.S. monetary policy surprise as an exogenous instrument. We uncover compelling evidence that one standard deviation of contractionary monetary policy surprise leads to a reduction in overall emissions by approximately 0.5 percent. However, the more significant and concerning result is the observed rise in emission intensities by 0.2 percent. We highlight the key mechanism underlying this outcome: higher domestic credit costs discourage firms from effectively outsourcing production tasks abroad, thereby increasing the generation of air pollutants per unit of output arising from reduced production efficiency. The identification of a previously unrecognized environmental externality calls for a reevaluation of policy approaches and underscores the importance of integrating environmental considerations into monetary policy frameworks.

Competition, Chromium, and Contracts: The Interaction Between Bidding Intensity and Toxic Waste Releases

The public procurement sector has a high impact on the environment including pollution from manufacturing. Competition is the primary way that the United States government ensures that the most efficient facilities receive contracts, but whether this competition leads to more, or less, pollution is unknown. We explore the impact of competition for contracts on contractor pollution in sectors that handle chromium, a toxic, yet necessary, component in many goods. We find that competition alone has negligible impact on overall chromium releases among contractors; however, the way chromium is used in the manufacturing process does. Contractors that use chromium as a component report higher releases of chromium waste than contractors that only use chromium in non-incorporative ways. However, when contractors face higher competition for contracts, pollution levels significantly decrease. This suggests that both competition and the use of the metal are important. Findings support a complex association between competition and pollution generation.

Comparative Analysis of Combustion Characteristics of a CFB Boiler during the Changes Process between High-Rated Loads and Low-Rated Loads

In order to alleviate problems such as large fluctuations in grid load caused by the high proportion of renewable energy, circulating fluidized bed (CFB) power plants undertake the task of rated load regulation. This study discussed the combustion characteristics of a 100 KW CFB boiler during the operation process of varying loads and analyzes the combustion characteristics, load regulation rate and emissions variation law during the operation process of high- and low-rated load intervals. The experimental results showed that under the condition of a high-rated load, the average temperature of each area in the furnace was proportional to the size of the load. Under low-rated load conditions, the temperature change increased first and then decreased with the reduction in load. In the 30% load stage, the lowest temperature in the riser was 740 °C, while the temperature in the loop seal was even as low as 650 °C. The concentrations of O2, CO and unburned carbon mainly depended on the combustion reaction intensity under each load condition, which showed a higher trend at low load (30%). In terms of NOx emission, it was proportional to the load in the high-rated load range. However, the NOx generation at the 30% load was about 30 mg/Nm3(@6%O2) higher than the 50% load. In addition, the regulation load rate (2.5%/min) between high-load conditions exhibited significantly greater than that between low-load conditions (0.78%/min). Therefore, the low-load operation will face problems such as low furnace temperature, uneven gas–solid fluidization, and difficult control of pollutant generation, which need to be paid attention to during operation.