Advanced Materials Research Vols. 356-360

Abstract: High contaminated level of polychlorinated biphenyl (PCBs) in soil could not be easily removed by routine method. Since thermal treatment technology becomes a promising method especially for removal of volatile organic compounds, it has not yet been widespread in China for some technical and economic reasons. Experiments were conducted in a horizontal quartz tube furnace with nitrogen as the unique carrier gas, and heating temperature was set at 500oC with retention time of flue gas desorbed from soil was about 1 min. It has been found that total removal efficiency of PCBs from soil increased with the heating time was prolonged. Thermal treated time of 60 min seems suitable for the removal of PCBs, with the removal efficiency of 95.8% in solid phase. It has also been concluded that the removal mechanism of PCBs from soil endures dechlorination and destruction reactions with anticipation of catalytic metals. Normal gaseous pollutants desorbed from soil were also studied, H₂O evaporation was favored with at the beginning of thermal process; after H₂O evaporation, the organic matters began to decompose; when the thermal treated time was longer than 20 min, the desorption of the normal gaseous pollutants were almost finished (except for NH₃).

Abstract: Nowadays, in order to meet the new standard of IMO for sewage discharged from ship treatment, membrane bioreactor (MBR) was widely used in this field. In this study, a novel bioreactor named integration membrane bioreactor (IMBR) was used to treat sewage from ship. A lab scale experiment was conducted to find the best controlling strategy of operation. The results were as follows: The IMBR had strong adaptability and effluent stability under wide change in VLR which was from 1.2kg/m³.d to 4.3kg/m³.d; The HRT of the IMBR was suggested to be controlled around 6h; The IMBR operator was better in alkali-resistant and weaker in acid-proof, which implied the pH of suitable living environment for aerobic microbe should be higher than 6.5. At the same time, a simulation model of operational parameters was established based on theory of back propagation neural network (BPNN). The simulation model realizes prediction of which were the key impact factor and optimum operational parameters of the IMBR system. Each parameter influencing the performance of the reactor was compared using the method of partitioning connection weights (PCW). The weight of the influence factors was pH value> DO>influent COD in the experimental range.

Abstract: Sustainable partial nitrification to nitrite has been proven difficult in treating low strength nitrogenous wastewater. Real-time aeration duration control was used to achieve efficient partial nitrification to nitrite in a sequencing batch reactor (SBR) to treat low strength domestic wastewater. Above 95% nitrite accumulation ratio was maintained for long-term operation at normal condition. Partial nitrification established by controlling aeration duration showed good performance and robustness even though some time encountering long-term extended aeration. Process control enhanced the successful accumulation of ammonia oxidizing bacteria (AOB) and washout of nitrite oxidizing bacteria (NOB).

Abstract: For the flue gas semi-dry desulfurizaiton technology, a new type of spouted bed with porous draft tube was put forward in this paper. The desulfurizaiton performance of it was studied, and some effects on SO² removal efficiency were examined, such as molar ratio of Calcium to sulphur, inlet concentration of SO², bed height, gas inlet temperature and approach to saturation temperature etc. This study also compared the SO² removal efficiency of spouted bed with porous draft tube with the nonporous one. The results show that the spouted bed with porous draft tube has better desulfurizaiton performance, the SO² removal efficiency of which is higher than the one with nonporous draft tube and the optimal operation condition was obtained for industrial application.

Abstract: Three folds stable surface flow wetlands (FSSFWs) were operated at different hydraulic loadings of 0.80, 0.53 and 0.27m³/ (m²•d) to treat the decentralized domestic sewage. And we investigated the effect of the hydraulic loading rate (HLR) on the removal efficiency of FSSFWs by measuring five indicators of chemical oxygen demand (COD), total nitrogen (TN), ammonium (NH₃-N), total phosphorus (TP) and suspended substance (SS). The research results indicated that the hydraulic loading had great impact on the removal efficiency of FSSFWs, and was looked upon as one crucial factor for FSSFWs design. The removal efficiency of FSSFWs presented a downward trend in various degrees along with the increase of hydraulic loading. Also the hydraulic loading had greater influences on the removal rate of NH3-N and TN than COD, TP and SS. Considering the operation costs, the treatment capacity and the purification effect in this experiment, we could ensure the efficient and stable operation of FSSFWs with HLR at 0.53 m³/ (m²•d) and HRT at 0.4 m³•d^-1, which were the most appropriate options.

Abstract: Natural manganese ore is a kind of arsenic removal mineral. It is low-cost and widely available. In order to enhance its removal efficiency and adsorption quantity of arsenic, this paper adopted TiCl₄ to modify natural manganese ore and optimized the conditions of modification. The results showed that the best modification condition was: TiCl₄ at a concentration of 10 mg•L^-1, dipping time of 18h, pH 3.05, reaction time of 60 min; under these conditions, the removal rates of As (Ⅲ) and As (Ⅴ) respectively reached 94.87% and 99.31%, much higher compared with natural manganese ore (82.95% and 77.93%). The saturated adsorption quantity of As (Ⅲ) and As (Ⅴ) reached 3.48 mg•g^-1 and 3.27 mg•g^-1, each increasing 1.25 mg•g^-1 and 1.21 mg•g^-1. The adsorption of As (Ⅲ) by modified manganese ore fits the Freundlich adsorption isotherm, while As (Ⅴ) fits the Langmuir adsorption isotherm best.

Abstract: Hyperbolic model could be established to describe the degradation performance of Methylene Blue (MB) using UV/H₂O₂ process. The effects of initial H₂O₂ dosage on MB removal, instant ▪OH concentration and reaction rate were investigated. The results show that the optimal H₂O₂ dosage is 13.24 mM and after 50min the MB removal is around 85%. The MB degradation process is followed the hyperbolic model which can calculate instant ▪OH concentration and reaction rate.

Abstract: A series of perovskite-type oxides catalyst LaAl_1-xNi_xO₃ (0≤x≤1) and modified by substitute noble metal La_0.4Al_0.2Ni_0.8M_0.6O₃ (M=Pt, Pd, Ru, Rh, Ir) prepared by the sol-gel method shows high activity, stability, good resistance to carbon deposition and sintering of the catalyst for the reforming of methane reaction. The reaction was studied under continuous flow using a mixture of CH₄:CO₂=1:1. Catalysts were characterized by using BET, XRD, SEM, EDS, and HR-TEM. The specific surface area of catalysts varied greatly from 3.07 to 10.18 m²/g with the different substitution (x) following calcination at 850°C. XRD analysis of the solids shows LaNiO₃ and/or LaAlO₃ as the main phases present on the solids depending on the degree of substitution and more intense peaks and cell parameters showed formation of Ni-Al solid solutions. SEM coupled to an energy dispersive X-ray spectrometer (EDS) shows the possibility to obtain a solid solution of LaAl_1-xNi_xO₃ (0≤x≤1) with propionic acid as solvent. The obtained results revealed that the Rh and Ru catalysts showed the highest activity and also showed a high catalytic stability without any decrease in methane conversion up to 3000min of reaction.

Abstract: In this study, the morphological responses of wheat to Cd during the whole growth stage were investigated in pot experiment with substrates containing 0, 1, 5, 10, 50 and 100 mg Cd/kg soil. The results showed that wheat was moderately tolerant to Cd stress, and the most sensitive endpoint to Cd toxicity was tiller number. The seed germination was not effected by Cd at all concentrations. The No Observed Adverse Effect Concentration (NOAEC) was 10 mg Cd/kg, and the Low Observed Adverse Effect Concentration (LOAEC) was 50 mg Cd/kg for the wheat.

Abstract: Based on the thoroughly analysis of two conventional PIV algorithm, a new velocity extracting methods called Pre-estimate Searching Algorithm(PESA) is presented in this paper which combines the superiorities of the two conventional PIV algorithms. And the realization procedure of this new algorithm is provided also. Both the synthetic images and real PIV images experiments show that the new algorithm has the advantage of high accuracy and fast computing speed.