Control factors of partial nitritation for landfill leachate treatment

Anaerobic ammonium oxidation (ANAMMOX) technology has potential technical superiority and economical efficiency for the nitrogen removal from landfill leachate, which contains high-strength ammonium nitrogen (NH4 -N) and refractory organics. To complete the ANAMMOX process, a preceding partial nitritation step to produce the appropriate ratio of nitrite/ammonium is a key stage. The objective of this study was to determine the optimal conditions to acquire constant partial nitritation for landfill leachate treatment, and a bench scale fixed bed bio-film reactor was used in this study to investigate the effects of the running factors on the partial nitritation. The results showed that both the dissolved oxygen (DO) concentration and the ammonium volumetric loading rate (Nv) had effects on the partial nitritation. In the controlling conditions with a temperature of 30±1℃, Nv of 0.2-1.0 kg NH4 -N/(m3d), and DO concentration of 0.8-2.3 mg/L, the steady partial nitritation was achieved as follows: more than 94% partial nitritation efficiency (nitrite as the main product), 60%-74% NH4 -N removal efficiency, and NO2--N/NH4 -N ratio (concentration ratio) of 1.0-1.4 in the effluent. The impact of temperature was related to iVv at certain DO concentration, and the temperature range of 25-30癈 was suitable for treating high strength ammonium leachate. Ammonium-oxidizing bacteria could be acclimated to higher FA (free ammonium) in the range of 122-224 mg/L. According to the denaturing gradient gel electrophoresis analysis result of the bio-film in the reactor, there were 25 kinds of 16S rRNA gene fragments, which indicated that abundant microbial communities existed in the bio-film, although high concentrations of ammonium and FA may inhibit the growth of the nitrite-oxidizing bacteria and other microorganisms in the reactor.     

Di（2-ethylhexyl）phosphoric acid-coconut oil supported liquid membrane for the separation of copper ions from copper plating wastewater

Permeation of Cu(II) from its aqueous solution through a supported liquid membrane (SLM) containing di(2-ethylhexyl)phosphoric acid (D2EHPA) carrier dissolved in coconut oil has been studied. The effects of Cu(II), pH (in feed), H2SO4 (stripping) and D2EHPA (in membrane) concentrations have been investigated. The stability of the D2EHPA-coconutoil has also been evaluated. High Cu(II) concentration in the feed leads to an increase in flux from 4.1 × 10-9 to 8.9 × 10-9 mol/(m2·s) within the Cu(II) concentration range 7.8×10-4-78.6×10-4 mol/L at pH of 4.0 in the feed and 12.4 × 10-4 mol/L D2EHPA in the membrane phase. Increase in H2SO4 concentration in strip solution leads to an increase in copper ions flux up to 0.25 mol/L H2SO4, providing a maximum flux of 7.4 × 10-9 mol/(m2·s). The optimum conditions for Cu(II) transport are, pH of feed 4.0, 0.25 mol/L H2SO4 in strip phase and 12.4 × 10-4 mol/L D2EHPA (membrane) in 0.5 (m pore size polytetrafluoroethylene (PTFE) membrane. It has been observed that Cu(II) flux across the membrane tends to increase with the concentration of copper ions. Application of the method developed to copper plating bath rinse solutions has been found to be successful in the recovery of Cu(II). rane. It     

Rapid determination of phenolic compounds in water samples by alternating-current oscillopolarographic titration

A rapid, simple and sensitive method was demonstrated for the determination of phenolic compounds in water samples by alternating-current oscillopolarographic titration. With the presence of sulfuric acid, phenol could be transferred into a nitroso-compound by reacting with NaNO2. The titration end-point was obtained by the formation of a sharp cut in the oscillopolarographic with infinitesimal NaNO2 on double platinum electrodes. The results showed that phenol concentration had an excellent linear relationship over the range of 4.82×10-6-9.65×10-3 mol/L, the RSD of the proposed method was lower than 1.5%, and the spiked recoveries of three real water samples were in the range of 95.6%-106.9%.     

Temperature dependence of the absolute rate constant for the reaction of ozone with dimethyl sulfide

Absolute rate constants for the reaction of ozone with dimethyl sulfide (DMS) were measured in a 200-L Teflon chamber over the temperature range of 283-353 K. Measurements were carried out using DMS in large excess over ozone of 10 to 1 or greater. Over the indicated temperature range,the data could be fit to the simple Arrhenius expression as KDMS = (9.96±3.61)×10-11exp(-(7309.7±1098.2)/T)cm3/(molecule·s). A compared investigation of the reaction between ozone and ethene had a kc2H4 value of(1.35±0.11)×10-18 cm3/(molecule·s) at room temperature.     

Remove cooking fume using catalytic combustion over Pt/La-Al2O3

Five monolithic catalysts with low noble metal content were prepared by irnmerge method （Pt/γ=Al2O3, Pt/La-Al2O3, Pt/YSZ-AI203, Pt＋Pd/La-Al2O3 and Pd/La-Al2O3） and their activity measurements were carried out in a conventional fixed-bed flow reactor. The results show that La-Al2O3 can promote activity of the prepared catalysts and can decrease the complete conversion temperature of cooking fume. The Pt/La-Al2O3 catalyst has the highest activity and can be applied in wide range of gas hourly space velocity （GHSV）. Some characterizations （XRD, TPR） were carried out with the objective to explain differences in catalytic behaviors. The prepared catalyst showed a great potential for application.     

Numerical investigation and analysis of indoor gas explosion: A case study of “6·13” major gas explosion accident in Hubei Province,China

Taking the ' 6·13 ′ major gas explosion accident in Shiyan, Hubei Province, China as an example, three problems were studied in this work: (1)The determination of the volume of natural gas involved in the explosion; (2)The propagation process of shock wave inside the building and the damage evolution process of the accident-related building; (3)The overpressure and fragment injury to the person outside the building. Through the numerical simulation in ANSYS/LS-DYNA software, the volume of natural gas involved in the explosion is determined to be 10240 × 1400 × 400 cm (length × width × height) from three perspectives: the damage to the building, the distribution of overpressure inside the building, and the TNT equivalent of the explosion energy. The simulation results are in good line with the accident, which verifies the effectiveness of the scheme and the accuracy of the numerical model. Based on the reasonable filling scheme, the propagation process of shock waves inside the building, the damage evolution process of the building, and the injury ranges of overpressure and fragments outside the building are analyzed. It can be found that the propagation of shock waves in confined space is complex and variable. The explosion shock waves are first reflected and superimposed in the watercourse, resulting in pressure rise. At about 8ms, the shock waves rushed into the first-floor space of the building, and the maximum overpressure was about 0.56 MPa. At about 50 ms, the shock waves rushed into the second-floor space, and the maximum overpressure was about 0.139 MPa. The first and second-floor slabs and infilled walls were almost completely destroyed. The interior walls of the infilled walls are mainly collapsed, and the exterior walls are ejection around the building as the center. The peak displacement and peak velocity of the interior walls of each floor are about 15% of the exterior walls. The fragments which cause fragment injury mainly come from the retaining wall above the watercourse, the maximum velocity is about 89 m/s, and the maximum displacement is 8.9 m. The safety distance of fragment injury is about 8.8 m, while the safety distance of overpressure injury is about 4.6 m. The lethal distance of fragment injury is greater than that of overpressure injury. Compared with the distance between different damage levels of overpressure injury, the difference in fragment injury is small. Therefore, the safety assessment at the engineering level only needs to consider the safety distance of fragment injury. This study can provide suggestions for evaluating the damage of natural gas cloud explosions in confined spaces and is helpful for accident investigation and safety protection.     

湖北省60年代以来气温日较差的变化趋势

利用湖北省７２站１９６１￣１９９５年逐月最高、最低气温资料,计算并详细分析了湖北省年、四季及逐月气温日较差的线性变化趋势。结果表明：（１）年最低气温呈明显上升趋势,而最高气温为下降趋势,因此气温日较差呈显著减少趋势。（２）就四季来看,最高气温在春、夏、冬季均呈下降趋势,但只有夏季的下降趋势是显著的,秋季呈弱上升趋势;最低气温在四季均呈上升趋势,但只有冬季的上升趋势是显著的;气温日较差在冬季与夏季均     

煤层群下保护层开采保护范围的数值模拟

为确定煤层群下保护层开采上部被保护煤层的保护范围,结合金佳矿一采煤工作面保护层顶底板煤岩层的物理力学参数和地质特征,采用FLAC3D软件模拟下保护层开采中被保护层的应力场及变形场的变化过程,得出保护层的保护效果;并根据保护层开采的应力卸压保护准则和变形保护准则,确定保护层沿倾向和走向的保护范围。结果表明,由于岩性及岩层结构的影响,通过数值模拟确定的各被保护层的保护范围与按照卸压角确定的保护范围有一定差异;分别用现场考察与数值模拟这2种方法所确定的下保护层保护范围基本一致。     

尾矿库溃坝风险定量评价方法探讨

针对目前尾矿库安全评价中无定量评价尾矿库溃坝风险的现状,坝体稳定性计算中未考虑到坝体实际为非均质体的特点,本文提出将容重、内摩擦角和凝聚力三者视为随机变量,采用蒙特卡洛模型计算尾矿坝溃坝失效概率;综合运用水文学、水动力学、非牛顿流体的运动理论,建立尾矿库溃坝后尾矿下泄模型,以计算溃坝淹没范围;综合考虑尾矿库溃坝后生命损失、财政损失和环境损失,计算尾矿库溃坝风险损失度;最终确定尾矿库溃坝风险度,以期提高尾矿库安全评价技术、确保尾矿库安全健康运行.     

QuickPanel在油浆过滤自动控制系统中的应用研究

阐述了油浆过滤控制系统的硬件配置、分程控制及顺序控制等．通过控制系统的控制,过滤器A、B轮流进行过滤、再生步骤,将油品内51μm以上的颗粒过滤掉,达到提高油品质量、延迟装置检维修期的目标．图1,参5．