Advanced Materials Research Vols. 1073-1076

Abstract: Bioaerosol is commonly present indoors, which may affect human health. In this study, the feasibility of water-soluble chitosan as a biochemical environment protestant to remove bioaerosol from the outpatient clinic was evaluated. Results indicated the predominant bacteria existed in the outpatient clinic included Klebsiella pneumoniae, Bacillus amyloliquefaciens, Corynebacterium callunae, Bacillus cereus and Moraxella sp. The minimum inhibitory concentration (MIC) and inhibition zone of water-soluble chitosan against these strains ranged from 3500-6500 ppm and 2-6 mm, respectively. When the vaporized water-soluble chitosan (500-4000 ppm) was applied in removing bioaerosol from the outpatient clinic, >90% efficiency was achieved at 50 ml/h after 4 h treatment. However, the bioaerosol removal was also attained to 90% after 50 h continuous treatment by a diluted water-soluble chitosan solution (100 ppm). Based on the cost and efficiency consideration, the bioaerosol reduction using a diluted water-soluble chitosan solution for a long-term treatment was practical. These results clearly illustrated that water-soluble chitosan has a great potential as a biochemical environment protestant to remove bioaerosol.

Abstract: Flue gas desulfurization (FGD) is one of the most effective techniques to control the emission of SO₂ from the combustion of coal. The by-products of FGD may occupy much land and cause the second pollution. The resourceable technology of FGD changes SO₂ from flue gas to sulfur-containing by-product, by which it is possible to solve the problem of desulfurization by-product treatment. This paper reviews the recent development of resurceable technology of FGD with special reference to removal of SO₂ from flue gas.

Abstract: External carbon sources provide additional nutrients that improve the efficiency of nitrate removal in constructed wetlands. Typha angustifolia L. were planted in four vertical subsurface-flow constructed wetlands. Different external carbon sources were fed into the columns, to investigate and compare their treatment of nitrate in synthetic wastewater, with initial influent C/N ratio of 1:1. Wetland A (WA) with 50g wheat straw as external carbon source, wetland B (WB) with 50g woodchips, wetland C (WC) with additional 10mg/L glucose and wetland D (WD) without external carbon source to serve as the control, were used in the lab-scale experimental study. WA, WB, WC and WD within a period of 24 days, cumulatively removed 109.38mg/L, 93.75mg/L, 85.14mg/L, and 64.01mg/L nitrate, respectively, from the influent. The nitrate-nitrogen (NO₃–N) removal efficiency as aided by the external carbon sources was in the order: wheat straw > woodchips > glucose > control. Wheat straw treated 93% NO₃–N, woodchips 78%, glucose 72% and the control 53%. The results indicate that WA, WB and WC outperformed the control system, due to the additional carbon sources. In general, the wheat straw had a better performance than wood chips and glucose. Thus, wheat straw as low cost biological waste product is recommended for the treatment of nitrate in wetlands.

Abstract: Due to the potential of kaolin as an adsorbent for removal of heavy metals from solution, the competitive adsorption of Lead (Pb) and Copper (Cu) by kaolin was investigated to provide further understanding on the binding behaviors and capacities of these two metals onto kaolin. The Langmuir and Freundlich isotherms were applied to further explain the competition between the metals. Three different solutions were used, each at concentrations 10, 20, 30, 45, 60 and 75mg/L: single-metal solution of Pb (Pb-Only), single-metal solution of Cu (Cu-Only), and solution of both metals at the same concentrations (Binary solution). The kaolin adsorbed Pb about twice more than Cu, both for the binary solution and for the single-metal solutions. This correlated well with predictions of maximum adsorption capacity (Q) for kaolin, where Q for Pb was about twice as much as that for Cu, both in the binary solution and in the single-metal solution. Competition from Cu in binary solution reduced Pb adsorption by 9%, while Cu rather increased by 4.1%, relative to their respective adsorptions in Pb-Only and Cu-Only, respectively. However, during competitive adsorption in the binary solution, the relative proportions of adsorbed Pb increased by 11.4% as the initial metals concentration increased from 10 – 75mg/L, while that of Cu reduced by the same proportion. This was explainable by their respective separation factors (R_L), which indicated higher favorability of kaolin for Pb than for Cu. Furthermore, bonding energy (K_L) of Pb unto kaolin during competition was about 2.5 times that of Cu, and was likely able to cause Pb to displace Cu from kaolin surface. This study reveals greater adsorption capacity of kaolin for Pb than for Cu, and could provide the basis for future projects/studies that would employ kaolin in Pb and Cu removal.

Abstract: Column experiments were conducted to investigate the effect of montmorillonite colloid on ammonia nitrogen transport in porous media. Results show that the breakthrough curves of ammonia nitrogen present as three stages including ‘begin to penetrate’, ‘rapid penetration’, ‘stable penetration’, the shape looks like the letter ‘S’. When montmorillonite colloid concentrations are 0, 50, 100, 200mg·L^-1, the change rates of relative concentration are 0.139/PV, 0.153/PV, 0.163/PV, 0.187/PV, the maximum relative concentrations are 0.89, 0.92, 0.97, 0.97, the ammonia nitrogen penetration rates are 61.70, 77.16, 77.86, 78.87. That is to say, the montmorillonite colloid can facilitate ammonia nitrogen transport in porous media, and the higher the colloid concentration, the more obvious the promoting effect is.

Abstract: Composite oxide MnFe₂O₄ have been synthesized via the hydrothermal process and then modified by S=O. These compounds were characterized by X-ray diffusions, and ultraviolet-visible diffusion reflectance spectroscopy. MnFe₂O₄ exhibits stronger photocatalytic activity, with 95.5% degradation ratio of methyl orange and 91% degradation ratio of basic fuchsin, after 120 minutes visible-light irradiation in the presence of H₂O₂. In addition, the effect of pH values on photocatalytic activity were also investigated.

Abstract: In order to solve practical problems of rural sewage treatment, constructed wetland waste water treatment system is chose to simulate, analyze and evaluate in laboratory. Sand and gravel, granular activated carbons were used as the filter media in the constructed wetland. Experimental results show that the removal rate of filter for the water treatment increases with the rise of the hydraulic retention time and the rise of the temperature. It can be satisfied with the treatment effect at an ambient temperature of 15°C, maintained for 4 days or more hydraulic retention time.

Abstract: The dechlorination of perchloroethylene (PCE) in aqueous solution is significant for the decontamination of water. Previous study based on batch tests was conducted on the degradation of PCE using zero-valent metal. The degradation reaction fit well with pseudo-first-order kinetic model. In this study a hypothesized reaction sequence for reduction of chlorinated ethylene and related compounds was presented to describe the reticulation degradation pathway of PCE. Mathematical model was developed to predict the subsequent degradation of PCE and intermediates; results showed that 170 days were needed to transform all of PCE to non-chlorinated hydrocarbons in degradation reactors contained zero-valent iron, while 240 days were needed for zero-valent zinc. The variation of each species probably occurred in degradation process were also predicted, and the intermediates showed the same variation tendency of increasing in the first stage, reaching to peak value, and then decreasing in later period.

Abstract: Post hydrothermal liquefaction wastewater (PHWW) was generated during biocrude oil production. It contains lots of carbon, nitrogen and phosphorous elements, which can cause environmental pollution and resource waste. Using photosynthetic bacteria (PSB) to treat this kind of wastewater can realize pollutants elimination and resource recovery. In this work, the feasibility of using PSB to treat PHWW was firstly investigated, and the treatment conditions were optimized. Results showed that the PSB can effectively degrade PHWW. The optimal initial COD concentration, inoculum size and light intensity for PSB to treat PHWW were 6000-10000 mg/L, 50 mg/L and 1000-3500 lux, respectively. With the initial COD concentration of 9000 mg/L, inoculum size of 50 mg/L and light intensity of 1000 lux, the COD, NH₃-N, TP removal and biomass production reached to 71%, 90%, 47.2% and 773 mg/L, respectively. This showed that using PSB to treat PHWW can be an alternative method for PHWW nutrients recovery and pollutant treatment.

Abstract: After biochemical treatment, coking wastewater still contains some organics that are difficult to be degradeda and lot of dissolved salt. Therefore, the biologically treated coking wastewater should be further treated through advanced treatment processes before reuse. The discussions on the advanced treatment technology and the problem analysis in terms of the reuse of coking wastewater are conducted in this study. Possible improvement measures are analyzed and recommended.