水体曝气复氧工程充氧量计算与设备选型

从需氧量的计算、充氧量的确定和充氧设备的选择等方面阐述了污染水体曝气复氧工程中需要注意的环节，并提出了充氧设备选型的一般步骤和方法。     

混合曝气系统充氧效率的探讨

介绍了节能的混合曝气系统－在曝气池前端使用机械表曝，接之以鼓风微孔曝气。并根据笔者在英国Ｂ．Ｍ．污水厂实测的混合曝气系统的Ｋｌａ，充氧动力效率等参数，对之作出肯定的评价。     

用测试软件检测曝气设备的性能

结合实例对自行开发的曝气设备充氧性能测试软件进行了详细介绍。     

生物载体与曝气方式对氧化池氧转移特性的影响

对比研究了不同曝气量条件下,分别采用穿孔曝气和微孔曝气时,装填不同载体的接触氧化池的氧转移特性。结果表明,在试验范围内,各接触氧化池的氧总传质系数均随曝气量的增加而增大,但增加速度逐渐变缓。当曝气量为3.5 m3/h时,网格载体池的氧转移效率和动力效率达到最大值,分别为5.25%和3.22 kgO2/(kW.h),是竖管载体池和悬浮球载体池的1.14倍,是无载体池的1.22倍。当处理对象为生活污水时,接触氧化池内可采用微孔曝气+竖管(或悬浮球)载体;而当处理对象为高浓度有机废水时,可采用穿孔曝气+网格载体+悬浮球载体。     

曝气设备充氧性能测试装置及实验研究

本研究设计制作了一套曝气设备充氧性能测试装置,采用该装置对4种常用的曝气器进行了测试实验研究.研究表明,该装置设计灵活、测试方便,测试结果真实可靠,既可作为学生综合实验的平台,又可为实际工程提供测试服务.     

河流曝气复氧方式研究

本文对河流污染治理的几种曝气复氧技术进行分析比较，说明其适用条件和经济技术效果。以东莞运河一段3km河道为例。计算该段河流的需氧量为4810．3KgO2／d，估算相同充氧量条件下不同曝气方式的工程投资与运行成本。     

气提式增氧曝气装置在海水养殖池中的性能测定

为了考察气提式曝气增氧装置在海水养殖水池内的性能表现和溶氧扩散分布规律,自行设计了一种气提式曝气除沫装置,并安装于海水养殖生产车间水池内运行,通过定时定点取样测定池水中的溶解氧浓度,分析该装置运行时养殖池内溶解氧的分布状态,进而确定该装置增氧的性能指标。结果表明:安装自行设计的气提式曝气除沫装置后,通过实际测试,氧转移系数(K_(La(20)))为0.77h^(-1),氧转移效率(E_A)为5.20%,曝气动力效率(E_p,以O_2计)最高可达4.33 kg/(kW·h);经测定,在养殖水池内各个取样点溶解氧分布均匀,溶解氧浓度同步增加。研究表明,本研究中设计的曝气装置及其布置形式因省去动力循环能耗,曝气动力效率显著提高。     

气提式增氧曝气装置在海水养殖池中的性能测定

为了考察气提式曝气增氧装置在海水养殖水池内的性能表现和溶氧扩散分布规律,自行设计了一种气提式曝气除沫装置,并安装于海水养殖生产车间水池内运行,通过定时定点取样测定池水中的溶解氧浓度,分析该装置运行时养殖池内溶解氧的分布状态,进而确定该装置增氧的性能指标。结果表明:安装自行设计的气提式曝气除沫装置后,通过实际测试,氧转移系数(K_(La(20)))为0.77h~(-1),氧转移效率(E_A)为5.20%,曝气动力效率(E_p,以O_2计)最高可达4.33 kg/(kW·h);经测定,在养殖水池内各个取样点溶解氧分布均匀,溶解氧浓度同步增加。研究表明,本研究中设计的曝气装置及其布置形式因省去动力循环能耗,曝气动力效率显著提高。     

中空纤维膜无泡曝气氧传质性能试验研究

为探究中空纤维膜无泡曝气技术水体充氧性能,使用聚四氟乙烯(PTFE)和聚丙烯(PP)两种材质的中空纤维膜组件,分别在曝气压强为2、4、6 kPa,曝气流量为18、36、54 L/h条件下进行清水曝气测试,并对两种中空纤维膜的氧传质系数、氧传质速率以及曝气效率等进行分析。结果表明,PTFE和PP两种中空纤维膜组件均能实现无泡曝气,且PP中空纤维膜组件的充氧效果相比PTFE组件要好;当曝气压强为4 kPa、曝气流量为36 L/h时,PTFE和PP膜组件的氧传质速率分别为0.326、0.550 g/(m^2·h)。中空纤维膜无泡曝气技术具有操作压力小、氧传质速率高等特点,充氧效果优于传统曝气。     

Study the effect of recycled pressurized air on oxygen transfer design parameters in sequencing batch reactor technology

Aeration process consumes more than 60% of the total energy required for wastewater treatment. The present study aims to save power consumption within wastewater treatment aeration process through recycling of the air flow. A new technique of aeration is used to increase oxygen transfer efficiency via exploiting recycled pressurized air. A pilot plant has been constructed to study the effect of using recycled pressurized air within sequencing batch reactor (SBR) model. The results showed that the new technique comparing with the conventional SBR model improved Standard oxygen transfer rate (SORT), Standard oxygen transfer efficiency (SOTE) and Standard aeration efficiency (SAE). In particular, the new technique enhanced (SAE) with 10 and 4% at gauge pressure values 0.5 atm. and 2 atm. respectively. On the other hand, intermittent aeration enhanced (SAE) with 15 and 5% at gauge pressure values 0.5 atm. and 2 atm. respectively.     

Hypolimnetic aeration: practical design and application

Hypolimnetic aeration is becoming increasingly important as a fisheries management and water quality improvement technique, however its application has been restricted by a paucity of practical reference material. Hypolimnetic aeration includes partial and full lift designs and several air/oxygen injection systems. Positive displacement compressors flanged to three phase electric motors are the preferred air supply and power for most lake aeration projects. Internal combustion power is adequate for short term use and wind power is in the developmental stage. Rubber compressed air hose is recommended for lake aeration applications. Free air delivery is the air volume taken into the compressor at standard temperature and pressure however actual output volume is regulated by discharge pressure. Performance specifications of full lift hypolimnetic aerators are based on water:air ratios, oxygen increase, transfer efficiencies and oxygenation capacity. An empirical sizing method is proposed using hypolimnetic volume, hypolimnetic oxygen consumption, water flow, air flow and inflow tube radius. Outflow tube radius should equal or exceed inflow tube radius to achieve high flow rates and allow efficient removal of residual bubbles. Floatation requirements are calculated from the total weight of the separator box, inflow and outflow tubes and the theoretical water head.     

Factors influencing oxygen transfer in fine pore diffused aeration

A bench-scale experiment was conducted in a 701. tank of tap water to examine the effect of four design variables on oxygen transfer in a fine pore diffused aeration system. The experiment used non-steady state gas transfer methodology to examine the effect of air flow rate, air flow rate per diffuser, orifice diameter and reduced tank surface area on the overall oxygen transfer coefficient (K_La₂₀, h⁻¹); standard oxygen transfer rate (OT₂, g O₂ h⁻¹); energy efficiency (E_p, g O₂ kWh⁻¹) and oxygen transfer efficiency (E_o, %). The experiments demonstrated that K_La₂₀ and OT_s increased with air flow rate (9.4–18.8 1 min⁻¹) in the 40 and 140 μ diameter orifice range; however, E_p and E₀ were not affected. Reducing the air flow rate per fine pore diffuser (40 and 140 μ diameter pore size) significantly increased K_La₂₀, OT_s, E_p and E₀. A decrease in orifice diameter from 140 to 40 μ had no effect on K_La₂₀, OT_s, E_p and E₀. A reduction in tank surface area had a marginally significant inverse effect on K_La₂₀ and OT_s, and no effect on E_p and E_o. The mean bubble size produced by the 40 and 140 μ diffusers was 4.0 and 4.2 mm, respectively. There was no consistent effect of air flow rate on bubble size within the range of air flow rates used in this experiment. In clean water aeration applications, the optimum system efficiency will be obtained using the largest number of fine pore diffusers operated at low air flow rates per diffuser. In wastewater treatment plants, higher air flow rates per diffuser should be used to prevent diffuser biofouling and keep biological solids in suspension. Wastewater systems are purposely operated at less than optimum transfer efficiencies in exchange for reduced diffuser maintenance and improved mixing. In either situation, changes in tank surface area and diffuser pore size (provided that pore diameter remains between 40 and 140 μ) are unlikely to have any significant effect on aeration system efficiency.     

Effect of the moment transfer efficiency of a beam web on deformation capacity at box column-to-H beam connections

This paper investigates the effect of moment transfer efficiency of a beam web on deformation capacity at beam-to-column connections. Non-linear finite element analysis of five connection models was conducted. Analytical results showed that the moment transfer efficiency of the connection with a box column was poor when compared to a connection with an H-column; this was due to the out-of-plane deformation of the column flange. Based on previous test data, analytical results were compared with experimental results. Analytical and experimental results showed that the deformation capacity of the connection with a box column decreased due to the poor moment transfer efficiency of a beam web, followed by strain concentration at the beam flange.     

城市公共交通换乘枢纽体系效率评价

对城市公共交通换乘枢纽体系的效率评价问题进行了深入的分析,确立了换乘枢纽评价体系、明确各评价指标,提出了完整的评价方法,并依据此方法对城市公共交通换乘枢纽效率进行评价,提出了相应的提高城市公共交通换乘枢纽效率的方法。     

窗玻璃传热系数对建筑节能设计的影响

本文介绍了我国现行的建筑节能标准,通过对北京某居住建筑的围护结构热工性能权衡判断计算,分析了外围护结构各部分对建筑节能的影响,并得出了窗玻璃的传热系数在建筑节能中起着关键作用的结论.     

A study of optimum aeration efficiency of a lab‐scale air‐diffused system

Up to now, tremendous efforts have been devoted to modelling the oxygen transfer coefficient (k_La) for diffused aeration systems, while not considering the corresponding energy consumption. Enhancing k_La is favorable for an exemplary oxygenation process, but may come at the cost of greater energy withdrawal, an unwelcome tradeoff. Assessing the aeration efficiency (the rate of oxygen delivered per unit energy) reflects the overall effectiveness of an aeration process and guarantees a superior system performance. Presented here is a lab‐scale study that investigates the effect of the orifice diameter, the airflow rate and the water column on the aeration efficiency. Various combinations of the studied parameters were tested using a cylindrical tank with a single orifice for air injection. An optimal performance of the aeration efficiency was observed at an orifice diameter of 0.3 mm when tested under 0.91 m water column and an airflow rate of 0.05 SLPM. Furthermore, a new empirical formula of aeration efficiency was established with a high correlation index (R² = 0.97) to allow preliminary prediction of aeration efficiency.     

Application of the gas tracer method for measuring oxygen transfer rates in subsurface flow constructed wetlands

The oxygen transfer rate (OTR) has a significant impact on the design, optimal operation and modelling of constructed wetlands treating wastewater. Oxygen consumption is very fast in wetlands and the OTR cannot be determined using an oxygen mass balance. This problem is circumvented in this study by applying the gas tracer method. Experiments were conducted in an unplanted gravel bed (dimensions L × W × d 125 × 50 × 35 cm filled with a 30-cm layer of 10-11-mm gravel) and a planted horizontal subsurface flow constructed wetland (HSSFCW) (L × W × d 110 × 70 × 38 cm filled with a 30-cm layer of 3.5-mm gravel with Phragmites australis). Tap water saturated with propane as gas tracer (pure or commercial cooking gas, depending on the test) was used. The mass transfer ratio between oxygen and commercial propane gas was quite constant and averaged R = 1.03, which is slightly lower than the value of R = 1.39 that is usually reported for pure propane. The OTR ranged from 0.31 to 5.04 g O₂ m⁻² d⁻¹ in the unplanted gravel bed and from 0.3 to 3.2 g O₂ m⁻² d⁻¹ in the HSSFCW, depending on the hydraulic retention time (HRT). The results of this study suggest that the OTR in HSSFCW is very low for the oxygen demand of standard wastewater and the OTR calculations based on mass balances and theoretical stoichiometric considerations overestimate OTR values by a factor that ranges from 10 to 100. The gas tracer method is a promising tool for determining OTR in constructed wetlands, with commercial gas proving to be a viable low-cost alternative for determining OTR.     

西藏节能建筑围护结构传热系数朝向修正

针对现行供暖居住建筑节能设计标准应用于西藏地区存在有供暖能耗指标却没有完整的能耗计算基本参数,即没有围护结构传热系数的朝向修正系数的问题,以拉萨典型气象年气候参数为依据,采用反应系数法对围护结构各部分供暖负荷进行了动态模拟计算,得到了围护结构各朝向修正系数,对南窗传热系数提出了变系数修正方法。     

爆炸冲击震动隔离效果的能量传递率评价方法

基于能量方法评价隔震系统的隔震效率,建立了人体与隔震结构的二自由度隔震系统力学模型,通过分析隔震系统在爆炸冲击震动输入下的能量响应,参考传统的加速度传递率评价方法,提出了从人体承受冲击能量大小的角度评价爆炸冲击隔震系统隔震效率的方法,即能量传递率法。通过输入不同峰值和脉冲宽度的半正弦加速度脉冲信号,数值模拟了二自由度隔震系统在不同爆炸冲击震动输入工况下的能量响应,以及隔震系统的加速度传递率和能量传递率。通过对计算结果的分析,研究了隔震系统的输入与输出之间的关系,以及输入能量对隔震效率的影响规律。研究结果表明：与传统的加速度传递率相比,能量分析方法能够较好地反映爆炸冲击隔震系统的隔离效果。