Advanced Materials Research Vols. 726-731

Abstract: Scorodite is an important arsenic carrier for the immobilization of arsenic generated in the metallurgical industries. The transformation of the amorphous ferric arsenate into scorodite was investigated in a mixed sulfate media (pH 1-2) and elevated temperature (80-95 °C). This transformation process has been traced via scanning electron microscopy (SEM) and X-ray diffraction (XRD). Thus, it was found that lower pH and higher temperature was favored to generate more stable scorodite. The scorodite with TCLP leachability of 3.58 mg/L As was produced at 95 °C and initial pH 1.2 for 12 h.

Abstract: An airtight gas electrical plasma reactor was designed with subsequent reaction column to estimate performance of this treatment operating in continuous mode for the remediation of wastewater contaminated by organic dye. It was found that subsequent reaction column contributed great for final dye removal because generated ozone was sufficiently utilized in this system and decolorization behaviors in continuous processes were fitted well with first-order kinetic model.And operating under the conditions of input voltage 45kV, gas flow rate 40 L/h, virgin liquid conductivity and unmodified initial pH, the decolorization efficiencies were, at liquid flow rate of 1.5 L/h, 99.7% for 10 mg/L, 99.5% for 20 mg/L, 97.3% for 30 mg/L and 96.7% for 40 mg/L.

Abstract: Dust particle which includes corpses and feces of the mite, animal dander, cockroaches, and mould spores can reach the lung of human and then trigger asthma disease easily. In this research, experimental studies were carried out in order to examine particle removal efficiency in a room with two ventilation systems: a ceiling exhaust system and a slit exhaust system. The results indicated that there was no clear relationship between removal efficiency and two different outlet locations. Also, from the results after the decay, the particle count in the case of the ceiling exhaust was higher than that in the case of the slit exhaust.

Abstract: In this study, we discussed the advanced treatment process of printing and dyeing wastewater with the patented compounded biological filtration equipment (ZL200610069538.3). The experimental samples were collected from the second effluents of a printing and dyeing wastewater treatment plant. With the experiments of four single factors and the dynamic process under four optimum parameters values, discussions were taken in terms of the effects of PFS dosing quantity, hydraulic loading, filter materials volume ratio, and gas water ratio on COD, chromaticity and ammonia nitrogen respectively. The experimental results indicated that the optimum parameter values were PFS dosing quantity of 25mg/L, hydraulic loading of 0.4m³/ (m²·h), filter materials volume ratio (biological carbon over biological zeolite) of 1.2:1, gas water ratio of 4:1 respectively. When influents values ranges of COD, chromaticity and ammonia nitrogen were 90-110mg/L, 60-80times and 3-8mg/L respectively, the effluents of COD, chromaticity and ammonia nitrogen were less than 46mg/L, 10times and 1 mg/L respectively, which could meet the National Standard of Recycling and Miscellaneous Usages of Municipal Sewage on COD, chromaticity and ammonia nitrogen requirements.

Abstract: Based on the vapor-liquid equilibrium principle, a new rotating packed absorption tower was presented against some traditional gas-liquid countercurrent tower defects. An experimental device was built to test CO₂ absorption efficiency in the packed absorption tower under the given experimental conditions. The experimental results show that the new packed absorption tower can capture the simulated flue gas CO₂ and have a higher efficiency 87.8%.

Abstract: This study evaluated the effect of sulfide to nitrate (S/N) ratios on elementary sulfur biotransformation in a simultaneous autotrophic and heterotrophic denitrifying sulfide removal (DSR) process, at a carbon to nitrate (C/N) ratio of 3/1. Four groups of batch tests were conducted at S/N ratios of 5/2, 5/5, 5/6 and 5/8, respectively. Results showed a low accumulation of elementary sulfur. Elementary sulfur was first obtained by the oxidizing of sulfide through DSR process and then was reduced back to sulfide with the interaction of surplus acetate. The highest elementary sulfur transformation rates at S/N ratios of 5/2, 5/5, 5/6 and 5/8 were 47.1%, 94.7%, 94.0% and 93.5%, respectively. It can be concluded from analysis of the stoichiometric proportion of the bio-chemical reactions that the proportion of acetate consumed in DSR process to the whole acetate consumption in the first 6 hours were no more than 50%, indicating a low efficiency of DSR process under high concentration of organic carbons, except for the condition under S/N of 5/6, during which period the highest proportion can be as much as 85.6%. Given the elemental sulfur transformation rate and the acetate consumption proportion in DSR process, it can be concluded that adjusting the ratio of sulfide to nitrate at an appropriate level (around 5/6) would be an appropriate strategy for higher elemental sulfur transformation.

Abstract: This research presented the kinetic performance of arsenic absorption by mesostructure SBA-15 functionalized with Al₂O₃. The SBA-15 was previously synthesised and subsequently functionalized via impregnation of alumina oxides. The absorption of arsenic(V) was studied as a function of absorbent dosage and contact time. The experimental data were fitted to kinetic pseudo-first order, pseudo-second order and the intra-particle diffusion model. The pseudo-second order model presented the best correlation with the experimental data. Both surface absorption and intra-particle diffusion were acting during arsenic uptake, except for absorbent dosage of 0.1g, which was mainly controlled by the intra-particle diffusion.

Abstract: The removal efficiencies for ammonium (NH₄⁺) and total phosphorus (TP) from runoff using two layered filtration systems (LFS-A, with a turf surface, and LFS-B, with a permeable brick surface) were investigated in six repeated experiments. The results indicated that the removal efficiencies for NH₄⁺ and TP from infiltrated water using LFS-A were as high as 90.92 and 91.60%, respectively, while the efficiencies resulting from LFS-B ranged from 86.67 to nearly 100% and 90.29 to 99.09%, respectively. However, there was a significant difference in the comprehensive removal rates (CRRs) for NH₄⁺ and TP between LFS-A (400 and 70 mg·m^-2·h^-1, respectively) and LFS-B (174 and 54 mg·m^-2·h^-1, respectively). Some engineering measures, such as the utilization of replanted turf, may reduce the CRRs for pollutants for long periods of time; while no significant relationships between the CRRs of NH₄⁺ and TP and their initial concentrations were observed.

Abstract: In this study, magnesium removal through reaction of alkaline liquors and magnesium cation in liquors of laterite leaching was investigated. Basic magnesium carbonate and magnesium carbonate with high filtration properties were obtained at 70°C or above, whereas magnesium hydrate colloid existed in the products at temperatures below 70°C, resulting in the difficulty of product filtration. When the molar ratio of Na₂CO₃ to Mg²⁺ was 2.25:1, the reaction temperature was 90-100°C and the reaction time was 30min, nearly 100% magnesium was removed from liquors.

Abstract: In the current study, on the behavior of dust particle, JIS-11 test particles were used as simulated particles. However, existing particles in the background might have influenced the measurement results of JIS-11 test particles. This study measured and selected particulate matter as dust particle in indoor environment using an experimental box. The concentration of riboflavin shows less effect from the background, therefore, riboflavin particles were used as the dust particulate matter.