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Abstract In this paper, a 600 MWe Babcock & Wilcox boiler is selected as the research object. Numerical simulation and field experiments have been applied to this study under original and new combustion systems. The new approach mainly involves changing the operation mode of swirl burner, rearranging secondary air, and employing separated over-fire air. Numerical results showed that NO x emissions and the unburned combustible in flue dust decrease with the arrangement of the swirl burner changing from co-rotating mode to counter-rotating one. Consequently, counter-rotating mode of adjacent burners was chosen as the optimized arrangement. The introduction of separated over-fire air resulted in a remarkably reduction of the NO x emissions, which reduced from 1085 mg/m3 to 547 mg/m3. With increase of the distance between separated over-fire air and arch from 0.5 m to 3.0 m, NO x emissions changed slightly and the unburned combustible in flue dust were not greatly affected. When the distance continued increase to 6.0 m, NOx generation was suppressed and boiler efficiency declined. Considering the economic efficiency and NOx emissions reduction, the optimal sofa position is 3.0 m above the arch. In situ measurement results are consistent with the modelling predictions This work provides a feasible and economic approach for Babcock & Wilcox down-fired boilers to achieve high efficiency and low pollutant emissions. Highlights • Study the effects of burner rearrangement on low-nitrogen combustion. • Accurate calculate carbon content in fly ash by using CBK model. • Optimize the combustion system based on numerical simulations. • NOx at furnace exit decrease from 1085 mg/m3 to 547 mg/m3 by introduce SOFA. [ABSTRACT FROM AUTHOR]

Pyrolysis has proven an effective method of recycling waste printed circuit boards (WPCBs) for high-value product generation. The kinetics and debromination studies on the pyrolysis of WPCBs with copper species was performed using a thermogravimetric-mass spectroscopy analyzer and a vertical quartz-tube reactor. A multiple distributed activation energy model (M-DAEM) was applied to illustrate the potential multiple reactions over the thermal decomposition process. The introduction of copper species into WPCBs reduced the initial activation energies, resulting in lower decomposition temperatures. Meanwhile, several distinct subprocesses were observed and resolved by three-reaction models. The addition of CuO obtained the lowest liquid yield (53.9 wt %) and the maximum gas yield (8.9 wt %), and the introduction of Cu 2 O resulted in the highest solid yield (40.4 wt %). Copper particles preserved 57 % of bromine in residual solid, while CuO and Cu 2 O particles resulted in approximately 65 % and 74 % retention of bromine in the residues, respectively. Particularly, less than 3.7 % of bromine was transferred into the liquid when Cu 2 O was added. The optimal debromination performance of Cu 2 O was attributed to its effective capture capacity of HBr/Br 2 , fairly high catalytic efficiency on dissociating C–Br bond, and multipath conversion of organobromine to cross-linked carbonaceous compounds. [Display omitted] • The introduction of Cu species altered the pyrolysis kinetics of WPCBs. • Higher gas yield and residue yield were obtained by the addition of Cu Species. • Cu 2 O exhibited the optimal debromination performance. • Possible debromination mechanisms of copper and copper oxides were proposed. [ABSTRACT FROM AUTHOR]

Diverse Fe 3 O 4 @TiO 2 catalysts, featuring a range of core-shell ratios, were employed within an H 2 O 2 catalytic activation system to facilitate the oxidation of NO. These catalysts underwent comprehensive structural characterization, including XRD, TEM, BET, XPS, VSM and TPR analysis. Experimental investigations were conducted with the specific goal of assessing the catalytic efficiency of Fe 3 O 4 @TiO 2 core-shell catalysts and Fe 3 O 4 /TiO 2 supported catalysts in the contexts of desulfurization and denitrification. The results demonstrated that catalysts featuring a core-shell ratio of 1:2 exhibited the highest catalytic efficiency. Moreover, the core-shell catalysts outperformed their supported counterparts with the same molar ratio in terms of physicochemical properties, removal efficiency, and stability. Notably, the core-shell catalysts possessed exceptionally favorable pore structures and substantial specific surface areas, facilitating enhanced H 2 O 2 activation for NO oxidation through synergistic interactions between the core and shell components. This research holds the potential to guide future endeavors in the development of catalysts aimed at achieving superior H 2 O 2 catalytic efficiency. • Core-shell catalyst is applied to catalyze H 2 O 2 for NO oxidation. • The stability of core-shell catalyst is enhanced by reducing contact between active components and SO 2 /H 2 O. • More active Fe2+ sites formed through the electron transformation from TiO 2 shell to Fe 3 O 4 core. [ABSTRACT FROM AUTHOR]

Heavy metals (HMs) are frequently detected in wastewaters, especially in industrial discharges. Phytoremediation is one of the promising low cost, environmental friendly and efficient technique to remove HMs from industrial wastewater. The current research was carried out to investigate the ability of constructed wetland (CW) for the removal of HMs including copper (Cu), cadmium (Cd), lead (Pb), nickel (Ni) and chromium (Cr) from local wastewater of industries by using two local common hydrophytes species Pistia stratiotes and Lemna Gibba. After 45 days cultivation, the concentration of HMs reduced to 0.25–0.90 mg/L and 0.78–1.4 mg/L from 5 mg/L for Lemna gibba and Pistia stratiotes , respectively. The HMs removal efficiency ranged from 82% to 95% for Lemna gibba and 72%–84.4% for Pistia stratiotes. The accumulation of HMs in roots are always higher than that in aerial part including stems and leaves for both plants. The accumulation of HMs in roots of Lemna gibba ranged from 4.3 to 4.7 mg/kg and, 1.85–3.9 mg/kg in aerial part. The corresponding values were 3.9–4.7 mg/kg and, 1.75–3.3 mg/kg for Pistia stratiotes. Results of health risk models including the average daily intake (ADI), hazard quotient (HQ) and cancer risk (CR) models indicated lower health risk of water after treatment than before treatment water. Result indicated the selected hydrophytes could be applied for HMs treatment from contaminated water. [ABSTRACT FROM AUTHOR]

The rapid expansion of marine aquaculture poses a big challenge for sustainable development. More efficient production strategies are necessary to ensure a sustainable mariculture sector, yet the potential of feasible production gains without further environmental impacts is largely unknown. This work took one of the biggest mariculture centers in China to analyze the spatiotemporal dynamics of mariculture products in 2003, 2010, and 2016, explore potential factors associated with resource use efficiency, and quantify the potential of these factors to increase regional production. The mariculture sector had a rapid expansion in 2003–2010 and accelerated product diversification in 2010–2016, with overall annual growth rates of 4.6%, 24.9%, 14.6%, 20.4%, 24.7%, and 8.7% in finfish (Larimichthys crocea and others), sea cucumber (Apostichopus japonicus), abalone (Haliotis spp.), laminaria (Laminaria japonica), gracilaria (Gracilaria spp.), and porphyra (Porphyra spp.) production, respectively. Resource use impacts were dominated by finfish production (over 90% of the total), but recent increases were mostly due to the farming of other products. Our study also identified several demographic (household size), socioeconomic (income per capita), technical (farming density, feed usage, and energy usage), and environmental (distance between farms and total nitrogen concentration) variables that were correlated with resource use efficiency. Simulations based on regression models suggested that changes in these factors could increase fish and seaweed production by at least 3%–18% and 2%–23%, respectively, without increasing resource use levels. Sustainable intensification of local mariculture systems could be achieved by enhancing the access to more efficient technology and financial capital, increasing the willingness of engagement in the sector, facilitating the transaction of sea use rights, reducing the amount of nutrient released in coastal areas, and including the heterogeneous effects of farm distances and water quality in marine spatial planning. Our results highlight the existing opportunities in policymaking for more sustainable food production systems and the management of coastal ecosystems in mariculture-dominated seascapes. • Mariculture production has increased annually by over 15% in the study area. • Production trends suggest a transition towards resource-intensive products. • Several human- and nature-related factors were linked with mariculture efficiency. • These factors constitute pathways for achieving sustainable intensification. [ABSTRACT FROM AUTHOR]

Since the beginning of 2020, the weak domestic power demand caused by the COVID-19 pandemic and the large-scale advancement of coal power construction projects may have further aggravated the coal power overcapacity in China. Given the new situation, this study collected the data on China's installed electricity capacity and electricity demand during the 13th Five-Year Plan period. Moreover, a reasonable capacity evaluation model of coal power was established based on the energy and electric power balance to analyze China's coal power overcapacity in 2019 and determine the reasonable capacity for 2025. The internal reasons of unreasonable energy structure and regional difference of energy structure are systematically discussed. Results show that the overcapacity in 2019 was approximately 170 GW, and the overcapacity situation in North, Northwest, and South China was particularly serious. The reasonable coal power capacity for 2025 under the basic situation is 950 GW, indicating that if all the coal power units under construction and planning are operated, the overcapacity in 2025 will be 300 GW. Sensitivity and comprehensive scenario analyses show that under different scenarios, the upper and lower limits of the reasonable coal power capacity in 2025 are 1083 and 794 GW, respectively. Finally, this paper proposes relevant policy recommendations to cope with China's serious coal power overcapacity problem. [Display omitted] • Capacity evaluation model of coal power is established. • Quantitative analysis is provided for each regional power grid of China. • The coal power overcapacity of China exceeds 170 GW in 2019. • The overcapacity situation may further deteriorate during the 14th FYP period. • A reasonable scale of coal power is 950–1000 GW at 2025. [ABSTRACT FROM AUTHOR]

The rapid socio-economic development and various ecological conservation policies in China have significantly affected sediment yield in the large basin. However, how these two aspects of influencing factors jointly drive the dynamics of sediment retention service is still poorly understood, although it is critical to evaluate ecosystem service dynamics and realize the balanced relationships between human activities and aquatic ecosystem health. Integrating the revised universal soil loss equation (RUSLE) model and sediment delivery ratio (SDR) model, this study evaluated dynamics of sediment retention service driven by combined factors of socio-economic development and ecological conservation policies. Furthermore, the relative contribution analysis identified contributions of these drivers to sediment dynamics. Results indicated that (1) sediment retention service improved from 2000 to 2015 in the Qiantang River Basin, with a 39.89% reduction in sediment export. (2) Ecological conservation policies played a more critical role in this improvement than socio-economic development. (3) In particular, the Green Project made the major contribution to controlling sediment export among all the drivers, additionally, increasing grain yield (per unit area) benefited sediment retention service because it mitigated the substantial demand for farmland and the excessive deprivation of ecological lands. (4) The emerging Ecological Conservation Red Line (ECRL) policy could reduce sediment export inside the redline regions by 84.13% through future scenario analysis, providing practical guidance for exploring more ecological benefits. Finally, suggestions for formulating targeted ecological protection policies and sustainable socio-economic plans were proposed to promote aquatic ecosystem services and strengthen ecological security in the large basin. Image 1 • From 2000 to 2015, sediment retention service improved in the Qiantang River Basin. • Ecological conservation policies had more benefits than socio-economic development. • Green Project was a primary contributor to enhancing sediment retention service. • Growing grain yield, as a socio-economic factor, was beneficial to sediment control. • The ECRL would have significant advantages in improving sediment retention service. [ABSTRACT FROM AUTHOR]

Low-NO X combustion is the main technology for reducing NO X emission in coal-fired plants. In this work, numerical simulation was conducted on a 600-MWe down-fired lean coal boiler to study the effects of important factors on NO X reduction, namely, the arrangements of tertiary air (TA), the jet angle of secondary air (SA), the separated over-fire air (SOFA) ratio, and the SOFA jet angle. The optimal arrangement was obtained with the original TA moved down; the jet angle of SA (A layer) at 20° (downdip); the SA (F layer) and the TA at 20° and 30° (downdip), respectively; and the SOFA set in the upper furnace, with a 20% ratio and a 30° jet angle. The NO X emissions were reduced from 1527 mg/m3 to 773 mg/m3 in the optimized system. Meanwhile, the exhaust gas temperature decreased from 1387 K to 1369 K, and the unburned carbon content increased slightly by 0.24%, with the overall boiler efficiency kept nearly constant. The in situ measurement results are consistent with the simulation predictions. • Combustion system modification and operating parameters optimization were adopted. • The arrangement of different air jets was optimized. • The NO X at the furnace was reduced from 1527 mg/m3 to 773 mg/m3. • The overall boiler efficiency remained nearly constant after optimization. [ABSTRACT FROM AUTHOR]

Numerous organic contaminants existing in the municipal secondary effluent (SE) have gained considerable attention because of their persistent nature and adverse environmental effects. In this study, micro-nano bubbles (MNB) and UV/Titanium dioxide (TiO 2) system, both individual and in combination, were investigated for advanced treatment of the SE. The integrated MNB and photocatalysis system significantly improved the removal of chemical oxygen demand (COD) and persistent organic pollutants by 27.52 and 14.38%, respectively. The hybrid system efficiently decreased all five categories of organic contaminants according to excitation-emission matrix (EEM) spectrum, while the molecular weight (MW) fractions were decreased and the UV-absorbance at wavelength 254 nm (UV 254) of MW (<3 kDa) increased by 16%. The enhanced removal was induced by the elevated production of reactive oxygen species (ROSs) in a two-stage model. Further experiments were conducted to identify the mechanism involved, and the results showed that the MNB treatment mainly generated ·OH species and the UV/TiO 2 process produced most of the other ROSs (H 2 O 2 , HO 2 − and O 2 −). The results showed that the photocatalytic degradation could be readily enhanced by the green MNB technique for SE treatment without any modifying, micrifying or doping of the photocatalyst. • An integrated micro-nano bubbles and photocatalysis system was developed. • The hybrid system significantly improved the treatment of organic contaminants. • Enhanced removal was induced by the elevated ROSs production in a two-stage model. [ABSTRACT FROM AUTHOR]