Selective catalytic reduction (SCR) of NO by urea loaded on activated carbon fibre (ACF) and CeO2/ACF at 30 degrees C: the SCR mechanism.

Selective catalytic reduction (SCR) of NO by urea loaded on rayon-based activated carbon fibre (ACF) and CeO2/ACF (CA) was studied at ambient temperature (30 degrees C) to establish a basic scheme for its reduction. Nitric oxide was found to be reduced to N2 with urea deposited on the ACF and CA. When oxygen was present, the greater the amount of loaded urea (20-60%), the greater the NO(x) conversions, which were between 72.03% and 77.30%, whereas the NO(x) conversions were about 50% when oxygen was absent. Moreover, when the urea was loaded on CA, a catalyst containing 40% urea/ACF loaded with 10% CeO2 (UCA4) could yield a NO(x) conversion of about 80% for 24.5 h. Based on the experimental results, the catalytic mechanisms of SCR with and without oxygen are discussed. The enhancing effect of oxygen resulted from the oxidation of NO to NO2, and urea was the main reducing agent in the SCR of loaded catalysts. ACF-C was the catalytic centre in the SCR of NO of ACF, while CeO2 of urea-loaded CA was the catalytic centre.

Are biodegradable plastics a promising solution to solve the global plastic pollution?

A large amount of plastic waste has been discharged into the environment worldwide, which causes the current white pollution problem. The accumulated waste plastics in the environment can be furtherly degraded into small pieces such microplastics and nanoplastics through weathering, which will do more harm to the environment and humans than large plastics. Therefore, plastic production and disposal are needed to be considered. Biodegradable plastics (BPs) have become the focus of recent research due to their potential biodegradability and harmlessness, which would be the most effective approach to manage the issue of plastic waste environmental accumulation. However, in the long run, it is uncertain whether BPs can be a promising solution to waste disposal and global plastic pollution. Consequently, both sides of the dispute are discussed in this paper. At present, most conventional plastics can not be replaced by theses BPs. Biodegradation of BPs needs certain environmental conditions, which are not always reliable in the environment. Additionally, changes in human behavioral awareness will also affect the development and application of BPs. BPs should not be considered as a technical solution, thus excusing our environmental responsibility, because littering does not change with the promotion of an effective technology. As such, the conclusion is that BPs may be a part of the solution. The effectiveness in providing environmentally solutions for plastic waste management depends on the combination of affordable waste classification technologies and investment in organic waste treatment facilities. Therefore, there is still a long way to go to solve the global plastic pollution through BPs.

Public health benefits of optimizing urban industrial land layout - The case of Changsha, China.

In China, ambient fine particulate matter (PM2.5) causes a large health burden and raises specific concerns for policymakers. However, assessments of the health effects associated with air pollution from industrial land layouts remain inadequate. This study established a comprehensive assessment framework to quantify the health and economic impacts of PM2.5 exposure at different industrial geographical locations. This framework aims to optimize the spatial distribution of industrial emissions to achieve the lowest public health costs in Changsha, a representative industrial city in China. Health effects were estimated by applying the integrated exposure-response model and a long-range pollution dispersion model (CALPUFF). The value of statistical life (VSL) was used to monetize health outcomes. It was found that implementing an optimal industrial land layout can yield considerable social and financial benefits. Compared with the current industrial space layout, in 2030, the averted contribution by Changsha's industrial sector to PM2.5-related mortality and corresponding economic losses will be 60.8% and 0.69 billion US dollars (USD), respectively. The results of optimization analyses highlighted that population density and emission location are significant factors affecting the health burden. This method can identify the optimal geographical allocation of industrial land with minimal expected health and economic burden. These results will also provide policymakers with a measurable assessment of health risks related to industrial spatial planning and the associated health costs to enhance the effectiveness of efforts to improve air quality.

Characterization of Cr(VI) removal from aqueous solutions by a surplus agricultural waste--rice straw.

The removal of Cr(VI) from aqueous solution by rice straw, a surplus agricultural byproduct was investigated. The optimal pH was 2.0 and Cr(VI) removal rate increased with decreased Cr(VI) concentration and with increased temperature. Decrease in straw particle size led to an increase in Cr(VI) removal. Equilibrium was achieved in about 48 h under standard conditions, and Cr(III), which appeared in the solution and remained stable thereafter, indicating that both reduction and adsorption played a part in the Cr(VI) removal. The increase of the solution pH suggested that protons were needed for the Cr(VI) removal. A relatively high level of NO(3)(-) notably restrained the reduction of Cr(VI) to Cr(III), while high level of SO(4)(2-) supported it. The promotion of the tartaric acid modified rice straw (TARS) and the slight inhibition of the esterified rice straw (ERS) on Cr(VI) removal indicated that carboxyl groups present on the biomass played an important role in chromium remediation even though were not fully responsible for it. Isotherm tests showed that equilibrium sorption data were better represented by Langmuir model and the sorption capacity of rice straw was found to be 3.15 mg/g.

Triclocarban enhances short-chain fatty acids production from anaerobic fermentation of waste activated sludge.

Triclocarban (TCC), one typical antibacterial agent being widely used in various applications, was found to be present in waste activated sludge at significant levels. To date, however, its effect on anaerobic fermentation of sludge has not been investigated. This work therefore aims to fill this knowledge gap. Experimental results showed that when TCC content in sludge increased from 26.7 ± 5.3 to 520.5 ± 12.6 mg per kilogram total suspended solids, the maximum concentration of short-chain fatty acids (SCFA) increased from 32.6 ± 2.5 to 228.2 ± 3.6 (without pH control) and from 211.7 ± 2.4 to 378.3 ± 3.2 mg COD/g VSS (initial pH 10), respectively. The large promotion of acetic acid was found to be the major reason for the enhancement of total SCFA production. Although a significant level of TCC was degraded in the fermentation process, SCFA was neither produced from TCC nor affected by its major intermediates at the relevant levels. It was found that TCC facilitated solubilization, acidogenesis, acetogenesis, and homoacetogenesis processes but inhibited methanogenesis process. Microbial analysis revealed that the increase of TCC increased the microbial community diversity, the abundances of SCFA (especially acetic acid) producers, and the activities of key enzymes relevant to acetic acid production.

Changes in heavy metal mobility and availability from contaminated wetland soil remediated with combined biochar-compost.

The combination of biochar and compost has been proven to be effective in heavy metals contaminated wetland soil restoration. However, the influence of different proportions between biochar and compost on immobilization of heavy metals in soil has been less studied up to date. Therefore, we investigated the effect of different ratios of biochar-compost mixtures on availability and speciation distribution of heavy metals (Cd, Zn and Cu) in wetland soil. The results showed that applying all amendment combinations into wetland soil increased gradually the total organic carbon (TOC) and water-extract organic carbon (WEOC) as the compost percentage rose in biochar-composts. The higher pH was obtained in a certain biochar addition (20% and 40%) in combinations due to efficient interaction of biochar with compost. All amendments could significantly decrease availability of Cd and Zn mainly from pH change, but increase available Cu concentration as the result of increased water-extract organic carbon and high total Cu content in compost. Moreover, amendments can decrease easily exchangeable fraction and increase reducible of Cd and Zn greatly with increase of compost content in combinations, while amendments containing compost promote transformation of Cu from Fe/Mn oxide and residual fractions to organic bindings. These results demonstrate that different ratios of biochar and compost have a significant effect on availability and speciation of heavy metals in multi-metal-contaminated wetland soil.

Effects of exogenous calcium and spermidine on cadmium stress moderation and metal accumulation in Boehmeria nivea (L.) Gaudich.

Cadmium (Cd) is a detrimental metal in the environment and it is easily taken up by plants, thus entering the food chain and posing a severe threat to human health. Phytoremediation being low cost, highly stable, and environmentally friendly has been considered as a promising green technology for Cd remediation. The addition of exogenous substances to the culture media has been recognized as an efficient strategy to improve plant phytoremediation capability. Pot trials were conducted to investigate the combined effects of exogenous calcium (Ca) and spermidine (Spd) on Cd-induced toxicity in Boehmeria nivea (L.) Gaudich. (ramie). Results showed that the application of 5-mM exogenous Ca significantly alleviated Cd toxicity in ramie by reducing Cd accumulation, depressing H2O2 and malondialdehyde contents, increasing plants dry weights and chlorophyll concentrations, as well as altering the activities of total superoxide dismutase and guaiacol peroxidase. Furthermore, as a non-Cd hyperaccumulator plant, ramie hyperaccumulated Cd and suffered more severe toxic effects of Cd by the treatment of 1 mM Ca/Cd. The aggravated Cd toxicity could be compensated by the addition of exogenous Spd via the promotion of plant growth and the reduction of the oxidative stress. Overall, the combination effects of 1 mM Ca and Spd appeared to be more superior compared to other treatments in the plants under Cd stress with a higher Cd accumulation ability and the evaluated Cd stress tolerance.

Enhancing effect of iron on chromate reduction by Cellulomonas flavigena.

Cr(VI) is considerably toxic and the detoxification of Cr(VI) is of great importance. This study investigated the effect of iron on Cr(VI) reduction by Cellulomonas flavigena. The results demonstrated that addition of FeCl3 or lepidocrocite promoted Cr(VI) reduction, with the reduction ratio of above 90 and 80% achieved, respectively, but addition of hematite did not lead to the increase of reduction ratio, which suggests that the effect of iron on chromate reduction appears different with the diversity of iron-oxides. In this study, the effect of initial Cr(VI) and Fe(III) concentration on Cr(VI) reduction and the change of pH value were also investigated. The reduction ratio increased with the increase of the initial concentration ratio of Fe(III)/Cr(VI). The value of pH gradually increased from 7.0 to around 9.0.

Effects of physico-chemical parameters on the bacterial and fungal communities during agricultural waste composting.

The goal of this study was to identify and prioritize some of the physico-chemical parameters that contributed to bacterial and fungal community compositions during agricultural waste composting. Relationships between those parameters and microbial community compositions determined by PCR-DGGE were simultaneously evaluated by redundancy analysis (RDA). The results showed that the temporal variation of bacterial community composition was significantly related to water soluble carbon (WSC), ammonium and nitrate (P<0.05), while the most variation in distribution of fungal community composition was statistically explained by pile temperature, WSC, and moisture content (P<0.05). Significant amounts of the variation (54.9% and 56.0% for bacterial and fungal species data, respectively) were explained by those parameters, suggesting that those parameters were the most likely ones to influence, or be influenced by the bacterial and fungal species. Variation partitioning analyses indicated that WSC and pile temperature showed predominant effect on the bacterial and fungal community composition, respectively.

Removal of triazophos pesticide from wastewater with Fenton reagent.

The catalytic oxidation of triazophos pesticide from wastewater using Fenton reagent was investigated at bench-scale in this study. Synthesized wastewater and actual industrial triazophos pesticide wastewater taken from a pesticide company were examined sequentially. The COD values of the synthesized and actual industrial triazophos pesticide wastewater samples were 3242 and 3418 mg/L, respectively, and the triazophos concentration in these wastewater samples was 0.06% by weight. The effects of reaction conditions including the dosages of FeSO(4).7H(2)O and H(2)O(2), the pH value of the environment, and the stirring time on COD removal from the synthesized wastewater were evaluated, and COD removal efficiency of 96.3% with a corresponding effluent COD value of 120 mg/L was achieved under optimal reaction conditions of a pH value of 4, a dosage of 2.5 g/L of FeSO(4).7H(2)O and 100 mL/L of 30% H(2)O(2) solution, and a stirring time of 90 min. Results also showed that 71.2% of nitrogen and 68.5% of phosphorous in the synthesized triazophos wastewater were converted to NO(3)(-) and PO(4)(3-), respectively, at the optimal reaction condition. When the actual industrial wastewater was treated at a pH value of 4, COD removal efficiency of 85.4% with a corresponding effluent COD value of 499 mg/L were reached at optimal condition of a dosage of 5.0 g/L of FeSO(4).7H(2)O and 75 mL/L of 30% H(2)O(2) solution, and a stirring time of 90 min. The results of this study can be referred for the design of a treatment process for the actual industrial triazophos wastewater.

Removal of cationic dyes from aqueous solution using magnetic multi-wall carbon nanotube nanocomposite as adsorbent.

A magnetic multi-wall carbon nanotube (MMWCNT) nanocomposite was synthesized and was used as an adsorbent for removal of cationic dyes from aqueous solutions. The MMWCNT nanocomposite was composed of commercial multi-wall carbon nanotubes and iron oxide nanoparticles. The properties of this magnetic adsorbent were characterized by scanning electron microscopy, X-ray diffraction and BET surface area measurements. Adsorption characteristics of the MMWCNT nanocomposite adsorbent were examined using methylene blue, neutral red and brilliant cresyl blue as adsorbates. Experiments were carried out to investigate adsorption kinetics, adsorption capacity of the adsorbent and the effect of adsorption dosage and solution pH values on the removal of cationic dyes. Kinetic data were well fitted by a pseudo second-order model. Freundlich model was used to study the adsorption isotherms. The prepared MMWCNT adsorbent displayed the main advantage of separation convenience compared to the present adsorption treatment.

[Application of white-rot fungi in composting lead-contaminated waste].

Simulative lead polluted wastes which containing unpolluted soil, household waste, straw, bran and lead nitrate were prepared. Inoculation of white-rot fungi and uninoculation in composting of lead-contaminated waste were studied. Change of chemical factor, biological parameter and biological toxicity analyses with time during the composting process were determined to study effect of heavy metal on composting process and probability of application of white-rot fungi in composting of metal-contaminated waste. The results show the composting of lead-contaminated waste inoculated white-rot fungi could be successfully processed, which lead to the reduction of the bioavailability of Pb in compost and alleviate the potential harm from heavy metal. Under this composting process, for the final compost, pH, water-soluble organic carbon/nitrogen, volatile solid, lignin and coarse fibre remained reached 7.9, 4.01, 36.1%, 22.4g, 30.1g, respectively. In addition, 63.38% of Pb in residual fraction and 0% of Pb in soluble-exchangeable fraction were found in final compost, and the germination index of final compost reached 121%.

[Effect of millimeter therapy in burning mouth syndrome].

OBJECTIVE: To observe the millimeter wave therapy responses in patients with burning mouth syndrome. METHODS: Eighty patients were randomized divided into 4 groups. The first group was treated with both millimeter wave irradiation and routine medication, the second group with millimeter wave irradiation, the third with pretending millimeter wave irradiation and routine medication and the fourth with routine medication. Pain, extravasated blood level and autonomic nerve system condition were double-blindly evaluated either before or after the treatment. RESULTS: Statistically significant difference (P < 0.05) was found as the degree of pain was compared before and after treatment of all the 4 groups. The first and second group, which were affected by the millimeter wave irradiation, had obvious improvements in the extravasated blood level and autonomic nerve system condition (P < 0.05). When the 4 groups were compared with each other, there were significant differences (P < 0.05) between the first and the fourth groups, and the second and the fourth groups regarding the reduction of pain. According to extravasated blood level, significant differences (P < 0.05) were found in the first and third or fourth groups, the second and third or fourth groups. CONCLUSIONS: The irradiation of holographic point by millimeter wave can improve the patients' pain, extravasated blood level and autonomic nerve system condition. It might provide a new treatment method for burning mouth syndrome.