Investigation on low energy-consumed embedded selective catalytic reduction technology for pelletizing flue gas and the CO2 emission reduction assessment.

Based on the unique technique property of grate-kiln pellet production process and its demand of ultra-low emission of NOx, a low energy-consumed embedded selective catalytic reduction (SCR) denitration technology was proposed. The temperature of the NOx-containing tributary flue gas was 350-500 °C, which basically accorded with the temperature range of SCR by V2O5-based catalyst. Considering the potential inhibition effect of high SO2 concentration (8000-10000 mg/m3) and metal-containing dust in the pelletizing flue gas, the catalyst compositions were optimized to V2O5 (0.5%) and WO3 (5%), giving NO conversion over 90% with low yield of N2O by-product. Compared with the low-medium temperature SCR technology, it was no longer necessary to reheat the flue gas, showing a remarkable CO2 emission reduction effect. The CO2 emission reduction ratios were 94% and 66% contributed by the decrease of fuel and electricity consumption for the embedded SCR technology, respectively. The operating cost was also greatly reduced from 11.4 CNY/t-pellet to 3.1 CNY/t-pellet (Chinese Yuan).

Competitive adsorption of lead and cadmium on soil aggregate at micro-interfaces: Multi-surface modeling and spectroscopic studies.

Aggregates are the basic structural units of soils and play a crucial role in metal migration and transformation. Combined contamination of lead (Pb) and cadmium (Cd) is common in site soils, and the two metals may compete for the same adsorption sites and affect their environmental behavior. Herein, the adsorption behavior of Pb and Cd on aggregates of two soils and contributions of soil components in single and competitive systems were studied by combining cultivation experiments, batch adsorption, multi-surface models (MSMs), and spectroscopic techniques. The results demonstrated that < 2 µm size aggregate was the dominant sink for Pb and Cd competitive adsorption in both soils. Compared with Pb, the adsorption capacity and behavior of Cd were affected greatly under competition. MSMs prediction revealed that soil organic matter (SOM) contributed the most to Cd and Pb adsorption on aggregates (> 68.4%), but the dominant competitive effect occurred on different sites for Cd adsorption (primarily on SOM) and Pb adsorption (primarily on clay minerals). Further, 2 mM Pb coexistence caused 5.9 - 9.8% of soil Cd conversion to unstable species (Cd(OH)2). Thus, the competitive effect of Pb on Cd adsorption cannot be ignored in soils with high content of SOM and fine aggregates.

A lifelong journey of lead in soil profiles at an abandoned e-waste recycling site: Past, present, and future.

Heavy metal pollutants resulting from human activities consistently move from the topsoil to the subsoil profiles under the influence of rainfall leaching. This study intends to predict the long-term transport of heavy metals at an abandoned e-waste recycling site with respect to historical pollution activities, land use, and metal pollutant dynamics. Our results showed that the site was seriously contaminated with heavy metals (Cd, Cu, Pb, and Zn) in the soil profiles. More specifically, Cu and Zn accumulated primarily in the upper layers of the soil profile owing to their weak mobility, while significant migration of Cd and Pb was observed in the deeper soil layers. Furthermore, to clarify the fate of Pb in soil profiles, Pb isotopes and the Hydrus model were used to trace the sources of Pb contamination and predict its long-term distribution. The Pb isotope results suggest that past e-waste recycling activities significantly contributed to the heavy metal concentration in the soil profiles; however, other anthropogenic sources such as vehicle exhaust had smaller impacts. Moreover, our model findings predicted that within the next 30 years, 60% of Pb contaminants will be concentrated in the surface soil. Together these results provide a theoretical foundation and scientific basis for evaluating, controlling, and remediating abandoned e-waste recycling sites.

Contribution of components in natural soil to Cd and Pb competitive adsorption: Semi-quantitative to quantitative analysis.

Cadmium (Cd) and lead (Pb) are two of the most common elements found in contaminated sites. The behavior of specific metals in the soil may be affected by other metals because of the competition for adsorption sites. In this study, adsorption experiments after chemical extraction, multi-surface models, and advanced spectroscopy technology were jointly used to explain the adsorption mechanism of Cd and Pb and to determine the contribution of each component in the competitive system. The results show that pH is the key factor in determining the contribution of soil components to metal adsorption. Soil organic matter (SOM) is the dominant adsorbent for both Cd and Pb. Clay minerals play an adsorption role at low pH, whereas Fe/Al oxides adsorb metals primarily in the high pH range. Further, the competitive effect of Pb on Cd occurred primarily on SOM rather than on clay minerals. When the Pb concentration increased from 0 to 500 mg/L, the adsorption of Cd on SOM decreased by 132.0 mg/kg, whereas it decreased only by 1.9 mg/kg on clay minerals. Therefore, the competitive effect of Pb on Cd cannot be ignored in soils with high organic matter content.

Source apportionment of soil heavy metals: A new quantitative framework coupling receptor model and stable isotopic ratios.

Tracing the source of heavy metals in soils is crucial for reversing the worrisome situation of heavy metal contamination. In this study, the origins of heavy metal pollution in soil were examined in a primary electronic waste treatment and disposal hub in China, using a synergistic source apportionment framework consisting of the positive matrix factorization (PMF) model and the Bayesian stable-isotope analysis mixing model (MixSIAR). Industrial activity is significant to heavy metal contamination in both industrial park and farmland soils, however, the contribution varied through PMF model (industrial park, 64.2%; farmland, 35.6%). In the industrial park, Pb was identified as the major pollutant in the soils, and the local children suffered from noncarcinogenic risks. Moreover, the contribution of Pb contamination sources were allocated more accurately (electronic waste dismantling, 25.1%; industrial production, 23.7%; vehicle exhaust from leaded gasoline, 9.1%; vehicle exhaust from unleaded gasoline, 20.2%; natural process, 21.9%) using MixSIAR for the first time. The main soil contaminants in surrounding farmland were Cd, Cu, and Zn. The variations in heavy metal pollution sources in soils were found to be associated with local policies and regulations, such as the phasing out of leaded gasoline and the conversion of industrial park from electronic waste demolition switched to production and storage. The identification of the source of heavy metals in soil will support targeted reduction of the associated emissions, which can immediately help alleviating soil contamination and control human health risks.

Novel insights into probabilistic health risk and source apportionment based on bioaccessible potentially toxic elements around an abandoned e-waste dismantling site.

The study of potentially toxic element (PTE) hazards around e-waste recycling areas has attracted increasing attention but does not consider elemental bioaccessibility. Here, the respiratory and oral bioaccessibilities were incorporated into probabilistic health risk evaluation and source contribution apportionment. The results showed that soil Cd yielded the highest respiratory and oral bioaccessibility, whereas Cr in soils and vegetables attained the lowest oral bioaccessibility. When incorporating metal bioaccessibility into health risk assessment, a 48.3%-55.7% overestimation of non-cancer and cancer risks can be avoided relative to the risk assessment based on the total concentrations of PTEs. More importantly, priority control metals were misidentified without consideration of bioaccessibility. Cadmium, As, and Cr were screened as the priority metal(loid)s for targeted risk control based on the total PTEs, whereas Cd, Zn, and Cu were the priority metal(loid)s based on the bioaccessible PTEs. Furthermore, source apportionment revealed that >50% of oral bioaccessible Cd, Cu, Ni, Pb, and Zn in farmland were contributed by e-waste dismantling activities, whereas bioaccessible As and Cr mainly originated from agrochemical applications and natural sources, respectively. This study emphasizes the refinement of risk estimation and source apportionment through metal bioaccessibility adjustment, which facilitates the realistic assessment of adverse health effects in humans and the precise identification of high-risk sources.

Determination and occurrence of bisphenol A and thirteen structural analogs in soil.

Bisphenol A is a phenolic plasticizer used in the production of various plastic products. Its endocrine-disrupting effects on ecological and human health lead to replacement with its structural analogs. The occurrence of these analogs in the soil environment, which is an important sink for bisphenols, has been rarely reported. In this study, a robust method was developed to determine bisphenol A and 13 analogs in soil using accelerated solvent extraction combined with in-line purification for fast and efficient extraction and ultra-performance liquid chromatography-tandem mass spectrometry for simultaneous and accurate quantification. The method detection limits of 14 bisphenols were between 0.01 and 0.39 ng g-1, and the recoveries were in the range of 80%-120%. The developed method was applied to 29 agricultural and urban soil samples from 21 provinces in China, and 12 bisphenols were detected. Among them, the contents of bisphenol A, F, and P were up to 166.0, 212.9, and 78.2 ng g-1 dry weight, respectively. The maximum concentration of bisphenol P was at least ten times higher than literature values in food and other environmental matrices. The results of this study showed that "hot spots" existed for bisphenol pollution in soil and that further investigations were necessary to avoid regrettable substitutions.

Sim-DRS: a similarity-based dynamic resource scheduling algorithm for microservice-based web systems.

Microservice-based Web Systems (MWS), which provide a fundamental infrastructure for constructing large-scale cloud-based Web applications, are designed as a set of independent, small and modular microservices implementing individual tasks and communicating with messages. This microservice-based architecture offers great application scalability, but meanwhile incurs complex and reactive autoscaling actions that are performed dynamically and periodically based on current workloads. However, this problem has thus far remained largely unexplored. In this paper, we formulate a problem of Dynamic Resource Scheduling for Microservice-based Web Systems (DRS-MWS) and propose a similarity-based heuristic scheduling algorithm that aims to quickly find viable scheduling schemes by utilizing solutions to similar problems. The performance superiority of the proposed scheduling solution in comparison with three state-of-the-art algorithms is illustrated by experimental results generated through a well-known microservice benchmark on disparate computing nodes in public clouds.

Homologous region 3 from Bombyx mori nucleopolyhedrovirus enhancing the transcriptional activity of heat shock cognate 70-4 promoter from Bombyx mori and Bombyx mandarina in vitro and in vivo.

The heat shock cognate 70-4 protein gene promoter (HSC70-4p) from Bombyx mori (BmHSC70-4p) is an ideal candidate for the transgenic silkworm due to its high transcriptional activity, and the homologous region 3 from Bombyx mori nucleopolyhedrovirus (BmNPVhr3) functions as an enhancer for several promoters. Using luciferase as a reporter gene and transient expression system in vivo and in vitro, we found that BmNPVhr3 can significantly increase the transcriptional activity of BmHSC70-4p and HSC70-4p from Bombyx mandarina (BmandHSC70-4p). Moreover, the transcriptional activity of the combination of BmHSC70-4p and BmNPVhr3 changed with developmental stages and hormone titers. These results suggest that the combination of BmHSC70-4 promoter and BmNPVhr3 enhancer is more effective candidate for the transgene or stable cell expression system in Bombyx mori.

The ecdysteroid UDP-glucosyltransferase gene promoter from Autographa californica multicapsid nucleopolyhedrovirus.

The ecdysteroid UDP-glucosyltransferase (egt) gene promoter fragments of different lengths were generated from the genomic DNA of the Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) by PCR. After being purified and enzymatic digestion, they were cloned into the pGEM-3Z vector for construction of reporter plasmids pAcegt542-luc, pAcegt309-luc and pAcegt159-luc with the luciferase gene driven by the AcMNPV egt promoter. The results of transient expression in the Spodoptera frugiperda cell line-21 (Sf21) showed that the transcriptional activity of the AcMNPV egt promoter required the transactivation of viral factor(s). The expression of luciferase gene driven by the AcMNPV egt promoter was first detected at 24 h post infection. The egt promoter from the Bombyx mori nucleopolyhedrovirus (BmNPV), closely related to AcMNPV, revealed similar properties to that of the AcMNPV egt promoter. When BmNPV homologous region 3 was subcloned downstream the luciferase gene, the luciferase activity of the reporter plasmid was enhanced by over 1000-fold, but the property of the promoter was not changed. As a substrate of ecdysteroid UDP-glucosyltransferase (EGT), foreign insect ecdysone showed negative effects on egt promoter transcriptional activity. Ecdysone of 1.0-2.0 microg/ml significantly down-regulated the promoter activity. Promoter activities of different lengths showed that an AcMNPV egt promoter fragment of 159 bp has the basal transcriptional activity but it was almost abolished only about 0.2% of that of 309 bp and 542 bp, respectively, and the nucleotide sequence from - 159 to - 309 nt upstream the translation initiation site includes the main cis-acting elements interacting with viral factors.