Effects of Iron on Chemical Sulfide Oxidation in Wastewater from Sewer Networks

Effects of iron on the kinetics and stoichiometry of aerobic chemical sulfide oxidation in wastewater from two different sites were studied at pH 8 and 20°C. Iron(III) chloride was added to the wastewater in concentrations of up to 20?g?Fe?m?3. The rate of aerobic chemical sulfide oxidation increased linearly with the iron(III) additions resulting in equal effects with wastewater from the two sites. Despite the significant effect of the iron(III) additions, the background concentrations of iron cannot explain the significant temporal and spatial variability of aerobic chemical sulfide oxidation kinetics reported in this study and in the literature. In this respect, other metals are probably also important. In addition to the impacts on the oxidation kinetics, the iron(III) additions resulted in a change of the oxidation stoichiometry. With increasing amounts of iron(III) added to the wastewater, less dissolved oxygen was required for the sulfide oxidation.     

Influence of Wastewater Constituents on Hydrogen Sulfide Emission in Sewer Networks

Transport of wastewater in sewer networks causes potential problems associated with hydrogen sulfide in regard to odor nuisance, health risk, and microbially induced corrosion. To what extent these problems occur depends not only on the rate of sulfide formation but also on the rate of hydrogen sulfide emission into the sewer atmosphere. To gain understanding of the influence of wastewater constituents on the emission process, a number of batch experiments were conducted on domestic wastewater collected from sewer networks. The emission rate of hydrogen sulfide in the wastewater investigated was found to be approximately 60% of that in de-ionized water in terms of the overall mass-transfer coefficient, resulting in a correction factor (alpha) of 0.6. The alpha factor did not change significantly within the turbulence range studied (Froude numbers of 0.04–0.23). The Henry’s law constant for hydrogen sulfide in wastewater was observed to be close to that in de-ionized water, reflecting a correction factor (beta) of 1.0. By taking these results into account, modeling aspects of hydrogen sulfide emission in sewer networks are presented in this paper.     

Modeling Ventilation Phenomenon in Sanitary Sewer Systems: A System Theoretic Approach

Municipal wastewater collection systems, due to the nature of their functions, carry varying concentrations of odorous gases. The production rate and transport of these gases within and out of sewer systems depend on air flow rate in the system piping. However, municipal sewers are generally designed to only transport sewage flow without giving consideration to the air flow field. As a consequence, the movement of air into, along, and out of collection systems is for the most part uncontrolled. The purpose of this paper therefore is to provide a new design protocol based on system theoretic techniques to be used by municipal engineers and environmentalists involved in odor control and sewer foul air transport studies. The modeling formulation accounts for combined wastewater drag and pressure-induced air flows, and manhole pressurization. The developed framework is applied to both hypothetical and real sewer systems to only illustrate the applicability of the modeling formulation.     

铁矿石中硫化铁的分离方法研究

本文研究了有机酸在化学物相分析中的应用问题.通过对其酸效应影响的探讨,证明CH_8COOH-CH_8COONa—H_2O_2溶液(pH～4.5)是硫化铁矿物有效的选择性溶剂.其主要特点是共存的铁绿泥石、铁橄榄石等易溶性硅酸铁矿物均不干扰.方法用于铁矿石中硫化铁的分离测定,结果比较满意.     

Pilot Study for the Performance of a New Demand Control Ventilation System in Hong Kong

There are different ventilation control methods for outdoor air quantity in air-conditioned spaces to reduce the energy consumed in cooling the outdoor air. Demand controlled ventilation (DCV) is an important strategy to control the outdoor air quantity. However, the current practice in DCV systems creates several problems for air-conditioned office buildings. Although metabolic carbon dioxide (CO2) concentration is mainly used as a surrogate indicator for ventilation adequacy, the conventional DCV system does not seriously consider the placement location of the CO2 sensor, and it does not take into account the adverse effects of the consequential increase in pollutant concentrations in the indoor space when the fresh airflow rate is reduced. In this study, a long period of subjective and objective measurements were conducted in an occupied office to examine its suitability for conversion to a new demand controlled ventilation system (nDCV). After the feasibility investigation, an nDCV system was developed to optimize the energy consumed for outdoor air ventilation while providing the desirable thermal comfort and indoor air quality. The true optimization of this nDCV is achieved by a new concept of the optimized indoor air quality window which determines the most representative locations for the indicator sensors. A minimum ventilation rate is determined by a calibration procedure for the pollutant inventory of a building, taking into account the infiltration characteristics. Radon gas, which is a notorious carcinogenic indoor pollutant, is used as a reference to determine the minimum fresh airflow rate. The findings show that this nDCV system reduced 16% of fresh air cooling energy consumption without jeopardizing the thermal comfort and indoor air quality.     

烧结主抽风机的电控系统分析

介绍了高低压电气控制系统如何保证烧结厂主抽风机正常启动、运行及监控和保护两台高压同步电机的基本原理。     

Comparative Study between a Hybrid System and a Biofilm System for the Treatment of Ammonia and Organic Matter in Wastewaters

The efficiency of two similar gas-lift bioreactors, a biofilm reactor and a hybrid circulating floating bed reactor (CFBR), were studied and compared. In the biofilm CFBR the biomass grew preferably adhered on a plastic granular support, whereas in the hybrid CFBR both suspended biomass and biofilms were allowed to grow in the reactor. COD/NH4+ ratio (COD=chemical oxygen demand) was manipulated between 0.0 and 8.0?g/g, maintaining the ammonia influent concentration around 50?mg N–NH4+/L, the ammonia loading rate at 0.9?kg N–NH4+/m3?day and the hydraulic retention time at 1.36?h. At low COD/NH4+ ratio (0 and 0.5?g/g) both systems behaved similarly, achieving ammonia removal percentages higher than 95%. In the biofilm CFBR a reduction of the nitrification percentage from 95 to 20% was observed when a COD/N–NH4+ ratio up to 8?g/g was applied in the influent. However, at the same operational conditions, the nitrification process in the hybrid CFBR was slightly affected. In the hybrid-CFBR reactor heterotrophs growing in suspension consumed the COD source faster than those growing in biofilms as was monitored. The growth of heterotrophic microorganism in suspension had a beneficial effect for the nitrifying population growing in the biofilm of the hybrid CFBR. Nitrifying activity of the biofilm was not limited by the presence of heterotrophs consuming dissolved oxygen, displacing the nitrifying bacteria or creating mass transfer resistance as was observed in the biofilm CFBR.     

热电厂主控室系统弱电选线改造

本钢新建热电厂主控系统二次回路采用４８V弱电选线中间环节，但存在着许多问题．严重影响了正常的生产运行．在经过考察的基础上，自己动手将复杂的弱电控制系统改为回路简单、清晰明了的一对一控制，并完成了安全过渡工作．     

Performance of Wet Weather Treatment Facility for Control of Combined Sewer Overflows: Case Study in Cincinnati, Ohio

Efforts aimed at reducing pollutant loads from combined sewer overflows (CSOs) on the Muddy Creek receiving waters in Cincinnati, Ohio have been underway in recent years. This includes an investigation of the treatment performance of a flow-through wet weather treatment facility (WWTF) using off-line sedimentation tanks, fine screening and chemical disinfection (disinfection was inactive during this study). Calculations using hydrographs and water quality samples collected at the WWTF during rain events established the mass of biochemical oxygen demand (BOD)5, chemical oxygen demand, and total suspended solids (TSS) removed. Ten storm events sampled from January to September 2002 helped characterize pollutant removal efficiencies for flow-through treatment. Pollutant removal was classified into four components: flow to the wastewater treatment plant (WWTP), sedimentation, storage, and screening. Most pollutant removal was achieved through settling and storage in the treatment tanks, with removal efficiencies of 20–50% for BOD5 and 25–70% for TSS commonly observed. Owing to the high pollutant load in the early portion of the CSO hydrograph, first-flush containment, or capturing and conveying the early portion of the runoff event to the WWTP, was the most efficient treatment method for every storm investigated.     

安徽某金铅锌硫化矿选矿新工艺试验研究

针对安徽某金铅锌复杂多金属硫化矿选矿指标较低、药剂制度复杂且用量大等问题,分析了原矿的矿物组成及矿石性质,并开展了大量探索性试验,最后提出采用磁选脱除磁黄铁矿-金铅混合浮选-金铅分离浮选-尾矿活化选锌的原则流程处理该矿石。结果显示：闭路试验可获得金含量为43.68×10-6,回收率为46.12%的金精矿;铅精矿中金含量为162.00×10-6,回收率为35.39%,铅含量为38.53%,回收率为72.24%,金的累积回收率达81.51%;锌精矿中锌含量为42.79%,回收率为67.51%。与原有选矿工艺相比,新工艺不仅提高了选矿指标还大幅减少了药剂用量。     

垛板机控制系统中各种动作的时序分析

对热轧线上垛板机的结构,工作原理以及各种动作的时序关系进行了仔细的叙述和分析,并给出了垛板机的工作时序图.同时,对在垛板机调试中遇到的一些实际问题提出了处理的方法.这对垛板机的调试和维护工作具有重要的参考价值.     

基于西门子PLC在精炼炉控制系统的优化设计

针对精炼炉控制的工艺要求,设计了基于西门子的控制系统,提出应用西门子S7-400 PLC硬件及其编程软件STEP7的设计方案,对该控制系统的PLC组成、PLC硬件组态、程序设计做详细说明;并且使用STEP7软件的S7-PLCSIM仿真功能对控制系统的程序进行了调试和监控。该控制系统运用HMI操作系统,缩短了生产流程,减轻员工的工作量,大大提高了故障诊断和维护能力。     

唐钢高线厂主轧区FIX系统的优化

通过生产过程中主轧区上位机监控系统出现的故障现象,具体分析了产生故障的原因,并介绍了改进的步骤和方法。     

韶钢中板2500mm轧机主控系统跳闸故障分析与处理

本文对韶钢中板轧机2500kw直流电机主控系统几种跳闸故障现象进行了分析，并提出处理方法。     

热镀锌线镀层厚度自动控制系统研究

针对鞍钢股份有限公司冷轧厂5#热镀锌线锌层厚度偏差过大及成材率低的问题,提出了一种镀层厚度自动控制系统的设计方法。采用LabVIEW软件开发锌层厚度自动控制程序,应用OPC技术实现镀层厚度自动控制系统与气刀PLC之间的数据通讯,通过调节气刀压力和位置等实现镀层厚度控制。该系统投入运行后,产品镀层厚度精度和成材率大幅提高。     

三辊卷板机下辊移动装置中的电液位置控制系统

介绍了新设计的三辊卷板机的工作原理，下辊位置控制系统的组成，数模简化与分析等，在没有参考资料的情况下，经过反复研究，确定了设计方案，经过实际交装，调试，使用，证明各项指标均到了要求。     

冷连轧卡罗赛尔卷取机控制系统分析

介绍了鞍钢1450冷连轧生产线卡罗赛尔卷取机的生产工艺和运行状况,重点讨论了卡罗赛尔卷取机的运行过程,并对卷取机控制过程中的逻辑程序进行了分析,自主开发了卷取机顺序控制程序。应用结果表明,轮盘旋转顺序设计满足工艺要求,控制效果良好,提高了冷连轧机轧制效率。     

电液比例控制技术在铝电解多功能机组液压控制系统中的应用研究

介绍自行研发的一种铝电解多功能机组新型液压控制技术,分析该电液比例控制技术的特点以及在铝电解多功能机组的液压控制系统中的应用,说明该技术操作简单,工作稳定,效果良好,可以满足现场需要.