Advanced Materials Research Vols. 356-360

Abstract: The removal and mechanism of ammonia nitrogen and total nitrogen were studie through three-step series of constructed rapid infiltration system by using high ammonia nitrogen domestic sewage of students' living area in a university. The result shows that the removal rate of ammonia nitrogen is 94.47% by using this system, which is 3% higher than conventional rapid infiltration system.The effluent can meet the standard Ⅰ—A of “Discharge standard of pollutants for municipal wastewater treatment plant(GB 18918-2002)”. The amount of ammonium oxidizing bacteria, nitrate oxidizing bacteria, nitrite oxidizing bacteria in this system is higher than that in conventional rapid infiltration system. The correlation between the removal of ammonia nitrogen and ammonium oxidizing bacteria, nitrate oxidizing bacteria, nitrite oxidizing bacteria is significant. The removal rate of total nitrogen is 47.38% by using this system, which is 20.72% higher than that in conventional rapid infiltration system. However, the effluent still can not meet the standard Ⅰ—A of “Discharge standard of pollutants for municipal wastewater treatment plant (GB 18918-2002)”. The amount of denitrifying bacteria in the three-step subsystem increased significantly, which improves the removal of total nitrogen. The correlation between the removal of TN and denitrification bacteria is significant.

Abstract: An enhanced visible-light-driven catalyst BiVO₄ doping with Cu was synthesized by hydrothermal method and characterized by XRD, UV-vis DRS, specific surface area. The characterization results indicated a better crystal structure of Cu-BiVO₄. The photocatalytic properties were evaluated by degrading wastewater with phenol, taking pH of catalysts prepared, dosage of catalyst and air flow as the research factors. The results showed that Cu-BiVO₄ has an effective photodegradation of phenol under the suitable conditions.

Abstract: Deep geological disposal (DGD) is selected for the long-term confinement of high-level radioactive waste (HLW) by many countries. Safety assessment of nuclear waste disposal in a deep geological repository requires understanding and quantifying radionuclide behavior through the hosting geological formation. This paper presents a numerical model to deal with the pore water composition in bentonite barrier in the evolving geochemical environment which includes bentonite, concrete and clay in a high level radioactive waste repository designed in clay formation, the model considers the following processes: advection, diffusion, aqueous complexation, mineral dissolution/precipitation and cation exchange. Bentonite porosity changes caused by mineral dissolution/precipitation reactions are taken into account in the model. The numerical sensitivity analysis to the accessible porosity of bentonite are performed, the results illustrate that the pH in bentonite is sensitive to changes in accessible porosity of bentonite, the concentrations of aqueous species are sensitive to bentonite porosity before 1000 years, and the effective diffusion coefficient of bentonite controls the extent of high pH plume in bentonite.

Abstract: Venturi device has important effect on pressure loss and flow field of flue-gas circulating fluidized bed desulphurization tower. Desulfurization tower is huge. Experimental study is difficult and costly. For these problems, PC-SIMPLE algorithm of Euler model of Fluent software is applied and flow condition of four different kinds Venturi tube are simulated in this paper. The pressure loss of curved Venturi is minimum. Three groups of Venturi tube can get uniform velocity field in the tower. Turbulence intensity of a group Venturi tube is maximum, followed by curved Venturi tube. But the turbulence intensity gradient of a group Venturi tube inside the absorber is also the largest. In order to get low pressure loss and better flow field, three groups Venturi tube is optimum.

Abstract: Aerobic granular sludge (AGS) was cultivated successfully in a sequencing batch reactor (SBR), which has floc sludge as seeding sludge in synthetic wastewater. Removal efficiency in the reactor during the entire working period was investigated. Controlling strategy for filamentous bulking and the effect of a filamentous microorganism on granulation of sludge were discussed. The results showed that whether filamentous bulking occurred or not, there was little impact on the removal rate of phosphorus and ammonia nitrogen, which maintain about 90% and 95%, respectively. Increasing the hydrodynamic shear force has certain effects on the controlling of filamentous bulking. Declining C/N ratio, balancing nutrition in feed water can fundamentally solve the problem of filamentous bulking in the cultivation process of aerobic granular sludge.

Abstract: Experiments for studying simultaneous removal of SO₂ and NO from simulated flue gas, with I₂ solutions as the absorbent, Fe³⁺ as the catalyst ,were investigated in a self-designed bubble reactor, while various influencing factors on the removal efficiencies examined.The maximum desulfurization and denitrification efficiency achieved is 100% and 69.9%, respectively.

Abstract: The RuO₂/TiO₂ photocatalyst was prepared by the dip-coating method, which use Ti mesh as the carrier and titanium tetrachloride and ruthenium chloride as the raw materials. In the same way, the mutil-walled carbon nanotubes (MWCNTs) air cathode was synthesized by using the stainless steel mesh as the supporter and the MWCNTs, manganese dioxide and Polytetrafluoethylene (PTFE) as the Substrate. The level of chemical oxygen demand (COD) and chroma are valuable reference index in the photoelectrocatalytic degradation of practical pesticide wastewater by the self-made pilot plant. The real pesticide wastewater is the typical high concentration organic wastewater and COD_cr concentration is above 10000mg/L. Practical running showed that the treated pesticide wastewater quality can meet the third grade standard for discharge of pollutants of the integrated wastewater discharge standard (GB8978-1996). The results showed that the removal efficiency of COD and decoloration efficiency were above 90.41% and 78.62%, respectively.

Abstract: The avermectin wastewater was treated with UASB technique. The paper was focused mainly on the removal rate of COD and the change of ammonia nitrogen of influent and effluent wastewater in the first running stage. At the stable phase of anaerobic operation, the removal rate of COD could be stabilized at 85% when the influent volume load was 9.21 kg/(m³•d), and the effluent COD was about 1400 mg/L. As for ammonia nitrogen concentration of influent and effluent wastewater, in the first 50 days, the former was larger than the latter, after then, it was opposite. In the condition of same volume load but different hydraulic retention time (COD concentration of influent being different), COD removal rate kept almost the same. In the second running stage, the influent COD volume load reached 9.21 kg/(m³•d) at the 16th day, with the COD removal rate being around 87%.

Abstract: The acetone extracts from Shenfu coal (SFC) of China was filtered into filtrate and cake, and analyzed by GC/MS and FTIR respectively. The results indicate that: The GC/MS identifiable fraction mainly consists of polycyclic aromatics with 2-4 rings and their alkyl derivatives as main components, and polar oxygen compounds with ketones and esters as main components. A variety of nitrogen compounds and several compounds containing phosphor, sulfur, and chlorine were identified. IR spectrum shows that functional groups including hydroxyl, carbonyl, polycyclic aromatic ring, methylene, methyl, etc. are among the main groups of GC/MS unidentified fraction.

Abstract: In this paper, the adsorption properties of TNT on Rice husk active carbon (RHAC) were investigated. The effects of contact time was examined. Kinetic data obtained at different concentrations were conducted using Lagergren’s pseudo first-order, pseudo second-order and diffusion models. The regression results showed that the adsorption kinetics was more accurately represented by pseudo second-order model. The study indicates that there is significant potential for RHAC as an adsorbent material for TNT removal from wastewater.