• Bass Schulz posted an update 6 months, 2 weeks ago

    n thermal recycling of brominated flame retardants (BFRs).On the basis of the metabolic synergy between autotrophic denitrification (AuDen) and anaerobic ammonium oxidation (Anammox), the feasibility of a novel ferrous sulfide (FeS)-driven AuDen and Anammox coupled system (FS-DADAS) was investigated. The nitrogen removal performance of FS-DADAS was investigated in a lab-scale fluidized bed bioreactor fed with synthetic wastewater containing NH4+-N and NO3–N. The results of long-term operation (120 days) demonstrated the promising performance of the system with 100% NO3–N removal and NH4+-N concentrations lower than 8.11 mg L-1 in the effluent at a nitrogen loading rate of 0.20 g-N·(L·d)-1. Sufficient NO2–N was provided by the AuDen for Anammox where a high removal rate of total nitrogen (TN) was achieved. The contribution of Anammox to TN removal was at >80%. The reactor could maintain a stable pH with less SO42- production owing to the fact that Fe(II) and S acted as electron donors. FeS gradually transformed into a sheet-like secondary mineral, FeOOH. AuDen (Thiobacillus) and Anammox bacteria (Candidatus Kuenenia) were successfully retained in the bioreactor, with relative abundance values of 18.82%-23.64% and 3.52%-8.67%, respectively. FS-DADAS is a promising technology for the complete removal of TN from wastewaters with low C/N ratios at low energy consumption.Having rigorous mathematical models is essential for the design and scaling of adsorption columns. In this study, the dynamic behavior of the sulfamethoxazole adsorption on sugarcane bagasse was studied and compared using analytical models and a theoretical mechanistic model. Initially, fixed-bed column tests were carried out at different flow rates and bed heights. Then, the experimental data were fitted with the most widely used analytical kinetic models, and their fit and fixed-bed parameters were compared with the mechanistic model. Of all analytical models analyzed, the Log-Gompertz model was the one that had the best agreed with experimental data. Although some analytical models fitted the experimental data accurately, their usefulness was questionable. Their parameters did not show a clear relationship with the change in operating conditions, and in certain cases had different behavior from that observed in experimentation. see more Conversely, the mechanistic model not only predicted the breakthrough curves with great accuracy in the initial and transition stage (R2 > 0.92; SSE less then 0.06), but it also estimated relevant parameters. Additionally, the effects of the global mass transfer coefficient (Ki) and the axial dispersion coefficient (Dz) on breakthrough curves were studied using the mechanistic model. Increasing Ki increased the slope of the breakthrough curves with a faster adsorption rate. Similarly, high values of Dz produced lower adsorption capacities of the adsorbent; and it was established that the axial dispersion is relevant in SMX adsorption on SB. The theoretical model presented can be used for the design, scaling, and optimization of adsorption columns.Concentrations and profiles of unsubstituted and methylated polycyclic aromatic hydrocarbons (PAHs and Me-PAHs) were analyzed in airborne particulate matter (PM) samples collected from high-traffic roads in Hanoi urban area. Levels of PAHs and Me-PAHs ranged from 210 to 660 (average 420) ng/m3 in total PM, and these pollutants were mainly associated with fine particles (PM2.5) rather than coarser ones (PM > 10 and PM10). Proportions of high-molecular-weight compounds (i.e., 5- and 6-ring) increased with decreasing particle size. Benzofluoranthene, indenopyrene, and benzoperylene were the most predominant compounds in the PM2.5 samples. In all the samples, Me-PAHs were less abundant than unsubstituted PAHs. The PAH-CALUX assays were applied to evaluate aryl hydrocarbon receptor (AhR) ligand activities in crude extracts and different fractions from the PM samples. Benzopyrene equivalents (BaP-EQs) derived by the PAH-CALUX assays for low polar fractions (mainly PAHs and Me-PAHs) ranged from 300 to 840 ng/m3, which were more consistent with theoretical values derived by using PAH-CALUX relative potencies (270-710 ng/m3) rather than conventional toxic equivalency factor-based values (22-69 ng/m3). Concentrations of PAHs and Me-PAHs highly correlated with bioassay-derived BaP-EQs. AhR-mediated activities of more polar compounds and interaction effects between PAH-related compounds were observed. By using PAH-CALUX BaP-EQs, the ILCR values ranged from 1.0 × 10-4 to 2.8 × 10-4 for adults and from 6.4 × 10-5 to 1.8 × 10-4 for children. Underestimation of cancer risk can be eliminated by using effect-directed method (e.g., PAH-CALUX) rather than chemical-specific approach.With the new municipal solid waste classification policy implemented in China, attention on achieving the waste-to-energy disposal of “dry waste” has been growing. Pyrolysis conversion of organic waste into value-added chemicals is a promising method to treat solid waste. However, after removing the non-combustible components of “dry waste”, the obtained high-organic solid waste (HSW) contains various heavy metals, which requires urgent attention during thermochemical conversion. To mitigate heavy metals risk, kaolin was employed as additive during HSW pyrolysis, and intercalation-exfoliation and thermal activation modifications were performed on the kaolin to further immobilize and stabilize heavy metals in the derived chars. The characterization results illustrated that the interlayer spacing, pore volume and diameter of kaolin were expanded after intercalation-exfoliation modification, providing more opportunities for the adsorption of metals. The thermal activation method favored the transformation of kaolin into metakaolin via dehydroxylation to enhance its nonhexacoordinated Al proportion and chemisorption. During 450-650 °C, kaolin exhibited an effective solid enrichment performance for targeting heavy metals, and the intercalation-exfoliation and thermal activation modification further enhanced the adsorption capacity of the kaolin for Cd, Cr, Pb and Cr, Cu, Pb, Zn, respectively. Compared with Cu and Zn, additives demonstrated better stabilization effects for Cd, Pb, and Cr, transforming more bioavailable fractions to the residual speciation. Overall, a higher pyrolytic temperature (650 °C) and the addition of effective additives could simultaneously increase the residual fraction and decrease the bioavailable fraction of heavy metals in HSW-derived chars, reducing the potential ecological risk.

All content contained on CatsWannaBeCats.Com, unless otherwise acknowledged,is the property of CatsWannaBeCats.Com and subject to copyright.

CONTACT US

We're not around right now. But you can send us an email and we'll get back to you, asap.

Sending

Log in with your credentials

or    

Forgot your details?

Create Account