高盐度气田废水处理试验研究

以某污水厂好氧污泥为接种污泥,半软性纤维填料为载体,采用逐步提高盐度和有机负荷的方法对生物膜进行耐盐性和高有机负荷驯化。结果表明:经过一段时间驯化所得异养生物膜能够适应高盐度和高有机负荷的环境;生物膜对环境盐度变化的适应性有一定的波动;生物膜对有机物的降解能力随系统有机负荷增大而降低,连续进水、出水不回流且流量为0.292L/h,HRT为24h条件下,COD去除率最后保持在65%左右;COD去除率达到65%的时间与系统有机负荷呈线性正相关,相关系数为0.9112;驯化后耐盐微生物对温度和酸碱度不敏感,最佳生长温度为23℃,pH值为7~8。     

钢筋混凝土构件的最小隔火厚度

为了正确评估钢筋混凝土构件在实际火灾中的隔火作用,以一般室内火灾轰燃后的房间平均温度-时间曲线为升温曲线,以热传导理论为基础,以钢筋混凝土隔火构件的背火面的最高温度恰好达到220℃为判定准则,用数值计算方法给出钢筋混凝土隔火构件的最小厚度,并用最小二乘法导出其计算公式.火灾房间火灾荷载越大,开口因子越小,最小隔火厚度越大;反之越小.该文所给最小厚度可用于钢筋混凝土分隔构件的性能化耐火设计与评估:当火灾荷载密度较大,开口因子较小时加大构件的厚度以获得安全性,反之,减小厚度以获得经济性.     

燃煤锅炉测试过程中运行负荷测定方法探讨

锅炉运行负荷是锅炉监测获得准确数据的重要条件,但实际监测过程中受各种条件制约,许多锅炉房不具备测试的计量条件。通过一些理论经验公式推导出一个简单的计算锅炉负荷的公式,经过验证,该公式计算值与实测值有较好的一致性。     

Streamwater acid-base chemistry and critical loads of atmospheric sulfur deposition in Shenandoah National Park, Virginia

A modeling study was conducted to evaluate the acid-base chemistry of streams within Shenandoah National Park, Virginia and to project future responses to sulfur (S) and nitrogen (N) atmospheric emissions controls. Many of the major stream systems in the park have acid neutralizing capacity (ANC) less than 20 μeq/L, levels at which chronic and/or episodic adverse impacts on native brook trout are possible. Model hindcasts suggested that none of these streams had ANC less than 50 μeq/L in 1900. Model projections, based on atmospheric emissions controls representative of laws already enacted as of 2003, suggested that the ANC of those streams simulated to have experienced the largest historical decreases in ANC will increase in the future. The levels of S deposition that were simulated to cause streamwater ANC to increase or decrease to three specified critical levels (0, 20, and 50 μeq/L) ranged from less than zero (ANC level not attainable) to several hundred kg/ha/year, depending on the selected site and its inherent acid-sensitivity, selected ANC endpoint criterion, and evaluation year for which the critical load was calculated. Several of the modeled streams situated on siliciclastic geology exhibited critical loads <0 kg/ha/year to achieve ANC >50 μeq/L in the year 2040, probably due at least in part to base cation losses from watershed soil. The median modeled siliciclastic stream had a calculated critical load to achieve ANC >50 μeq/L in 2100 that was about 3 kg/ha/year, or 77% lower than deposition in 1990, representing the time of model calibration.     

白银市工业污染源重金属排放特征分析

以甘肃省白银市为例,利用等标污染负荷法和单位产值等标污染负荷法,从污染物种类、时间变化、空间分布、行业排放4个方面,分析了白银市工业污染源重金属的排放特征,重点比较了2000—2010年期间重金属排放特征的变化。结果表明,近11年以来白银市工业污染源重金属等标污染负荷大小排序为砷>铅>镉>汞>六价铬;重金属排放总量呈下降趋势,单位产值重金属排放总量呈显著下降趋势;但是定量趋势分析的结果则显示最近5年仅有砷和镉呈下降趋势,而汞和铅呈现明显上升趋势;2009年重金属等标污染负荷和单位产值等标污染负荷最大的行政区和流域分别为白银区和白银市东大沟流域;污染负荷和单位产值污染负荷最大的行业均为金属制品业。因此,白银市应将白银区东大沟流域沿线的金属制品业行业,特别是白银公司的重金属污染作为环境整治的重点。     

Estimating Contributions of Nitrate and Herbicides From Groundwater to Headwater Streams,Northern Atlantic Coastal Plain,United States1

Abstract: Groundwater transport often complicates understanding of surface‐water contamination. We estimated the regional flux of nitrate and selected herbicides from groundwater to nontidal headwater streams of the Atlantic Coastal Plain (New Jersey through North Carolina) based on late‐winter or spring base‐flow samples from 174 streams. Sampled streams were selected randomly, and flux estimates are based on resulting population estimates rather than on empirical models, which have been used previously for similar estimates. Base‐flow flux in the estimated 8,834 headwater streams of the study area are an estimated 21,200 kg/day of nitrate (as N) and 5.83, 0.565, and 20.7 kg/day of alachlor, atrazine, and metolachlor (and selected degradates), respectively. Base‐flow flux of alachlor and metolachlor is <3% of the total base‐flow flux of those compounds plus degradates. Base‐flow flux of nitrate and herbicides as a percentage of applications is typically highest in well‐drained areas and lowest in areas with abundant poor drainage and anoxic conditions. In Coastal Plain watersheds of Albemarle and Pamlico Sounds, <2% of applied nitrogen reaches headwater streams as base flow. On the Delmarva Peninsula part of the Chesapeake Bay watershed, however, more than 10% of such applications are transported through groundwater to streams, and base‐flow nitrate flux represents 70% of total nitrogen flux in headwater streams.     

路堤荷载下水泥土桩复合地基沉降理论计算

基于路堤荷载下桩土非等应变条件和考虑了桩土相互作用、桩间土竖向与径向位移、桩土侧面产生相对滑移以及桩侧产生负摩阻力等特点的复合地基桩间土竖向变形模式,推导了水泥土桩复合地基桩间土沉降的理论计算公式,并以桩土单元体范围内的桩间土平均沉降值作为复合地基沉降,进一步推导了水泥土桩复合地基总沉降量、下卧层压缩变形量的理论计算表达式(两者之差即为加固区压缩变形量)。理论分析表明,复合地基加固区压缩量小于同深度天然地基压缩量,复合地基下卧层压缩量小于天然地基下卧层压缩量,复合地基总沉降量小于天然地基总沉降量。同时,理论计算结果与有限元计算结果以及现场实测结果三者比较一致。     

负载对实际道路重型柴油车排放的影响研究

利用车载测试系统对重型柴油货车空载、50％负载和100％负载不同负载情况下在实际道路的排放进行测试,基于测试数据分析负载对重型柴油货车排放CO、HC、NOx和微小颗粒物(PM)等4种污染物的影响.不同速度区间和行驶模式下负载对排放的影响分析表明,在有负载时,大多数工况下4种污染物排放呈现增加趋势,但各速度区间和行驶模式下的增幅不尽相同,部分工况出现下降.空载时测试柴油车基于新欧洲行驶循环测试(NEDC)工况的标准化CO、HC、NOx和PM排放因子分别为3.38、0.39、6.27、0.39 g/km.对于柴油车重点污染物NOx和PM而言,与空载相比,50％负载时分别增加43％和59％,100％负载时分别增加62％和44％.