To remove NO and SO₂ from flue gas simultaneously, a heterogeneous catalytic oxidation system was developed with the nanoscale zero-valent iron (nZVI), vaporized H₂O₂, and sodium humate (HA-Na) acting as the catalyst, oxidant, and absorbent, respectively. The experimental results indicated that the desulfurization was mainly influenced by the absorption, and the denitrification was significantly affected by the catalytic oxidation parameters. Under the optimal conditions, the simultaneous removal efficiencies of SO₂ and NO were 100 and 88.4%, respectively. The presence of ·OH during the removal process was proved by the scavenger tests, and the production of ·OH with and without nZVI was indirectly evaluated by the electron paramagnetic resonance (EPR) and methylene blue experiments. Moreover, the fresh and aged nZVI were characterized by a series of techniques and the results suggested that the redox pair Fe²⁺/Fe³⁺ released by nZVI could react with H₂O₂ to provide the sustainable ·OH, which was important for the oxidation from NO and SO₂ to NO₃⁻ and SO₄²⁻. The removal mechanism was proposed preliminarily based on the correlative experiments, characterizations, and references.

The present study is aimed to analyze the combustion, performance, and emission characteristics of water-emulsified soybean biodiesel fueled diesel engine with alumina nanoadditive and the results compared with conventional diesel fuel (BD). Experiments were conducted in a single-cylinder, four-stroke, variable compression ratio, and natural aspirated diesel engine with an eddy current dynamometer at a constant speed of 1500 rpm. Water-soybean biodiesel emulsion fuel was prepared using a mechanical agitator, in which the water concentration was limited to 10%, whereas soybean biodiesel (SB) and surfactant concentrations were 89% and 1% by volume respectively. Alumina (Al) was chosen as a nanoadditive, and the mass fractions of 50 ppm and 100 ppm were blended with emulsion fuel using ultrasonicator and the physicochemical properties were measured. The physicochemical properties of water-emulsified biodiesel and nanoadditive included emulsified biodiesel are at par with EN14214 limits. The in-cylinder pressure (ICP) and net heat release rate (NHR) values of SB are 5.3% and 7.2% lower than BD respectively, whereas the water inclusion significantly increases the ICP and NHR values by 6.9% and 15.9% compared to SB. Brake-specific fuel consumption (BSFC) of SB is higher than BD, and brake-specific energy consumption (BSEC) is lower than BD. An inclusion of 10% water in SB improves the BSFC and BSEC by 4% and 10.6% respectively compared to SB. The Al nanoparticle inclusion in water-emulsified soybean biodiesel further improves the combustion and performance parameters. The exhaust gas temperature (EGT) of sample fuels seems to be lesser than BD due to efficient combustion. As far as the emission characteristics are concerned, the SB promotes lower level of hydrocarbon (HC), carbon monoxide (CO), and smoke emissions with notable increases in oxides of nitrogen (NOₓ) and carbon dioxide (CO₂) emissions. An inclusion of 10% water in SB reduces the NOₓ, HC, CO, and smoke emission by 21.2%, 16.7%, 16.9%, and 11.8% respectively under peak brake mean effective pressure (BMEP) condition. The addition of Al nanoparticle in biodiesel emulsion fuel further reduce NOₓ, HC, CO, and smoke emissions and marginally increases the CO₂ emission.

Drinking water in the vast Arctic Canadian territory of Nunavut is sourced from surface water lakes or rivers and transferred to man-made or natural reservoirs. The raw water is at a minimum treated by chlorination and distributed to customers either by trucks delivering to a water storage tank inside buildings or through a piped distribution system. The objective of this study was to characterize the chemical and microbial drinking water quality from source to tap in three hamlets (Coral Harbour, Pond Inlet and Pangnirtung—each has a population of <2000) on trucked service, and in Iqaluit (population ~6700), which uses a combination of trucked and piped water conveyance. Generally, the source and drinking water was of satisfactory microbial quality, containing Escherichia coli levels of <1 MPN/100 mL with a few exceptions, and selected pathogenic bacteria and parasites were below detection limits using quantitative polymerase chain reaction (qPCR) methods. Tap water in households receiving trucked water contained less than the recommended 0.2 mg/L of free chlorine, while piped drinking water in Iqaluit complied with Health Canada guidelines for residual chlorine (i.e. >0.2 mg/L free chlorine). Some buildings in the four communities contained manganese (Mn), copper (Cu), iron (Fe) and/or lead (Pb) concentrations above Health Canada guideline values for the aesthetic (Mn, Cu and Fe) and health (Pb) objectives. Corrosion of components of the drinking water distribution system (household storage tanks, premise plumbing) could be contributing to Pb, Cu and Fe levels, as the source water in three of the four communities had low alkalinity. The results point to the need for robust disinfection, which may include secondary disinfection or point-of-use disinfection, to prevent microbial risks in drinking water tanks in buildings and ultimately at the tap.

The Ordos region in the southwestern part of Inner Mongolia experiences frequent PM concentrations in excess of the national PM₂.₅ air quality standards. In order to determine the key sources of PM₂.₅ contributing to these pollution episodes, the main sources of PM₂.₅ OC during elevated PM episodes in the Inner Mongolia were analyzed and compared with non-polluted days. This will provide insight to the main sources of particulate matter pollution during the high-pollution episodes and the effective seasonal strategies to control sources of particulate matter during months and with the highest PM concentrations that need to be controlled. The PMF source contributions to OC demonstrated that the industrial/coal combustion (4762.77 ± 1061.54 versus 2726.49 ± 469.75 ng/m³; p < 0.001) and mobile source factors (4651.14 ± 681.82 versus 2605.55 ± 276.50 ng/m³; p value < 0.001) showed greater contributions to the elevated concentrations during the episode. The spatial analysis of secondary organic carbon (SOC) factors, regional biomass burning, and biogenic sources did not show significant difference in the pollution episodes and the non-polluted months. In addition, the bivariate polar plots and CWT maps of the industrial/coal combustion and mobile illustrated a regional long-range transport patterns from the external sources to the study area, however, adjacent areas were mostly controlling the contributions of these factors during the PM elevated episodes. The SOC sources, regional biomass burning, and biogenic sources illustrated a regional long-range transport with similar locations found during the elevated pollution episodes compared to the normal situations.

Aquatic macrophytes are known to remove trace metals from surrounding water. In the present study, an attempt was made to evaluate the phytofiltration capacity of Hydrocharis morsus-ranae and to show competition between cobalt (Co) and nickel (Ni) for the better understanding of metal bioaccumulation in the species. In a laboratory experiment, H. morsus-ranae was exposed to separate (single) and binary solutions of these metals: Ni 10.7, 18.7, 32.7, 57.1, and 100 (μg L⁻¹); Co 5.33, 9.32, 16.3, 28.6, and 50.0 (μg L⁻¹); and 10.7 Ni + 5.33 Co, 18.7 Ni + 9.32 Co, 32.7 Ni + 16.3 Co, 57.1 Ni + 28.6 Co, 100 Ni + 50.0 Co (μg L⁻¹). The content of Co and Ni in the plant increased with the increasing concentration in the growth medium. Competition between the metals was seen during uptake in binary solutions. Ni interfered with the accumulation of Co, resulting in a lower Co content than in plants cultivated in Co solutions. A particularly high Co content (up to 155 mg kg⁻¹ dry weight [d.w.]) and high efficiency of Ni uptake (Bioaccumulation Factor (BF) 2572–7239) makes the species a very good accumulator of these metals. The high content of both trace metals in plant tissues (up to 511 mg kg⁻¹ d.w. Ni and 155 mg kg⁻¹ d.w. Co) did not affect its growth, indicating tolerance of these toxicants. The plant showed excellent ability in removing Co (up to 98.6% in solution with 5.33 μg L⁻¹ Co) and Ni (up to 91.4% in solution with 57.1 μg L⁻¹ Ni and 28.6 μg L⁻¹ Co) from nutrient solution. The results suggest that H. morsus-ranae may be useful for the phytoremediation of water bodies contaminated with Co and Ni.

In this study, the uptake of hydrophobic bromide-based ionic liquids (ILs) (imidazolium, pyrrolidinium, and pyridinium) from aqueous solutions onto granulated and fabric-based microporous activated carbons (ACs). Surface characterization study shows that both ACs have basic pHpzc, like 8.7 for granulated AC and 8.0 for fabric AC. Granulated AC have ten times higher phenolic groups 0.2 meq g⁻¹ compared to fabric AC which is 0.03 meq g⁻¹. The kinetics of adsorption was remarkably slower for ILs on granulated/fabric AC than milled one. We also studied the effect of AC size on the rate of adsorption in the operating conditions. In order to improve the adsorption kinetics of ILs with ACs, different phenomenological and empirical kinetic models like as pseudo-first order, Boyd model, pseudo-second-order diffusion model and Elovich were applied on the kinetic experimental data. The analysis of kinetic specified that the adsorption mechanism of ILs onto ACs is controlled mainly by the mass transfer through the pores of ACs. So, the selection of appropriate adsorbent particle size of AC plays a main role for the development of viable IL adsorption. Graphical abstract ᅟ

The bioavailability and potential uptake of heavy metals by crops is fundamentally influenced by the forms of metals in soils. Organic matter plays an important role in controlling the transformation of heavy metal fractionations in soils. However, long-term effects of organic matter on heavy metal speciation remains highly uncertain. In this study, rice straw was introduced to a subtropical Pb-contaminated soil for 2-year period so as to clarify the redistribution of Pb fractions and their correlations with soil properties. By combining sequential extraction and X-ray absorption fine structure spectroscopy, we find that lead is predominantly presented in Fe oxide-bound, surface adsorbed, and residual fractions in the soil. The incorporation of rice straw can effectively reduce the labile species of Pb by promoting the binding of Pb to iron oxides. Furthermore, aging leads to the transfer of considerable amounts of Pb to the association with Fe oxides and this transformation is enhanced by the presence of organic matter. Organic matter input and soil aging tend to shift Pb to amorphous Fe oxides than crystalline Fe oxides. The correlation analysis shows that Fe oxide fractions play vital roles in controlling the forms of Pb in soil. This study presents the first result regarding the long-term effect of organic matter on the redistribution of Pb in naturally polluted soil, which is useful for understanding the fate of Pb and developing remediation strategies for Pb-polluted soils.

Fertilizer regime is playing an important role in heavy metal cadmium (Cd) accumulation in paddy soils and crop plant. It is necessary to assess the Cd accumulation in soils and rice (Oryza sativa L.) plants under long-term fertilization managements, and the results which help to assess the environmental and food risk in Southern China. However, the effects of different organic manure and chemical fertilizers on Cd accumulation in soils and rice plant remain unclear under intensively cultivated rice conditions. Therefore, the objective was to explore Cd accumulation in paddy soils and rice plant at mature stage under different long-term fertilization managements in the double-cropping rice system. Cd accumulation in the surface soils (0–20 cm) and rice plant with chemical fertilizer alone (MF), rice straw residue and chemical fertilizer (RF), 30% organic matter and 70% chemical fertilizer (LOM), 60% organic matter and 40% chemical fertilizer (HOM), and without fertilizer input (CK) basis on 32 years long-term fertilization experiment were analyzed. The results showed that the soil total Cd content was increased by 0.296 and 0.351 mg kg⁻¹ and 0.261 and 0.340 mg kg⁻¹ under LOM and HOM treatments at early and late rice mature stages, respectively, compared with the CK treatment. And the soil available Cd content was increased by 0.073 and 0.137 mg kg⁻¹ and 0.102 and 0.160 mg kg⁻¹ under LOM and HOM treatments at early and late rice mature stages, respectively, compared with the CK treatment. The bioconcentration factor of Cd across different parts of rice plant was the highest in root, followed by stem and grain, and the lowest in leaves. At early and late rice mature stages, the root Cd concentration of rice plant was increased by 0.689 and 0.608 mg kg⁻¹ with HOM treatment, the stem Cd concentration of rice plant was increased by 0.666 and 0.758 mg kg⁻¹ with RF treatment, and the leaf and grain Cd concentration of rice plant was increased 0.094 and 0.082 mg kg⁻¹ and 0.086 and 0.083 mg kg⁻¹ with LOM treatment, respectively, compared with the CK treatment. The soil Cd single-factor contaminant index (PCd) under different fertilization treatments was as the following HOM > LOM > RF > MF > CK. Meanwhile, the PCd with LOM and HOM treatments was higher than that of the MF, RF, and CK treatments, but there is no significant difference between that of MF and RF treatments. Therefore, long-term application of rice straw residue and chemical fertilizer had no obvious effect on the accumulation of Cd in paddy soils and grain, and soil Cd accumulation was increased as application of organic fertilizer.

The privatization of water and sewerage services (WSS) has led to the foundation of water economic groups, which integrate several water companies and have gained notable importance at the global level. In the framework of benchmarking studies, there are no prior studies exploring the impact that economic groups have on the efficiency and quality of service provided by water companies. This study investigates, for the first time, whether the membership of water companies in an economic group influences their performance. Quantity- and quality-adjusted efficiency scores were computed using data envelopment analysis models. An empirical application was developed for the Chilean water industry since most of their water companies are private and belong to an economic group. The results show that independent water companies provide WSS with better quality than do water companies that belong to an economic group. From a statistical point of view, it was evident that membership in an economic group impacts both the quantity- and quality-adjusted efficiency scores of water companies. The results of this study illustrate that applying the model-firm regulation to the Chilean water industry has significant drawbacks that should be addressed by the water regulator to promote the long-term sustainability of the water industry.

The energy sector has become the largest contributor to greenhouse gas (GHG) emissions. Among these GHG emissions, most threatening is CO₂ emission which comes from the consumption of fossil fuels. This empirical work analyzes the roles of renewable energy consumption and non-renewable energy consumption in CO₂ emissions in Pakistan. The empirical evidence is based on an auto-regressive distributive lag (ARDL) model of data from 1970 to 2016. The disaggregate analysis reveals that renewable energy consumption has an insignificant impact on CO₂ emission in Pakistan and that, in the non-renewable energy model, natural gas and coal are the main contributors to the level of pollution in Pakistan. Economic growth positively contributes to CO₂ emission in the renewable energy model but not in the non-renewable energy model. Policies that emphasize the contribution of renewable energy to economic growth and that add more clean energy into the energy mix are suggested.