简析超声波声能密度对污泥减量的影响

介绍了超声波用于污泥减量的机理,研究了超声波声能密度对污泥减量的影响.研究表明当超声波频率为200 KHz,声能密度1.1W/mL,t=300 s,MISS减少率max=28.3%;SCOD从30 mg/L上升到110 mg/L.在声能密度0.22 W/mL时,t=450 s,MISS减少率max=12.8%;SCOD从30 mg/L上升到85 mg/L.另外,试验中还发现大功率超声波不利于提高污泥的脱水能力.     

人工湿地处理皂素废水生产性试验研究

黄姜是生产“药用黄金”——皂素的主要原材料，生产过程中会产生大量的工业废水。皂素废水是一种难降解、污染物浓度高的酸性废水，目前还没有成功应用于工程实际的废水处理工艺。本文主要采用人工湿地处理经两相厌氧工艺一好氧工艺组合工艺处理之后的废水，以满足达标排放的要求。经过4个月试验研究得出如下结论：人工湿地COD平均去除率为47．79％，氨氮平均去除率为75．64％，总磷平均去除率为88．82％。水平潜流型人工湿地作为皂素废水深度处理工艺是可行的。     

INCREASED BASEFLOW IN IOWA OVER THE SECOND HALF OF THE 20TH CENTURY1

ABSTRACT: Historical trends in annual discharge characteristics were evaluated for 11 gauging stations located throughout Iowa. Discharge records from nine eight‐digit hydrologic unit code (HUC‐8) watersheds were examined for the period 1940 to 2000, whereas data for two larger river systems (Cedar and Des Moines Rivers) were examined for a longer period of record (1903 to 2000). In nearly all watersheds evaluated, annual base flow, annual minimum flow, and the annual base flow percentage significantly increased over time. Some rivers also exhibited increasing trends in total annual discharge, whereas only the Maquoketa River had significantly decreased annual maximum flows. Regression of stream discharge versus precipitation indicated that more precipitation is being routed into streams as base flow than as storm flow in the second half of the 20th Century. Reasons for the observed stream flow trends are hypothesized to include improved conservation practices, greater artificial drainage, increasing row crop production, and channel incision. Each of these reasons is consistent with the observed trends, and all are likely responsible to some degree in most watersheds.     

ECONOMIC COSTS AND BENEFITS OF INSTREAM FLOW PROTECTION FOR ENDANGERED SPECIES IN AN INTERNATIONAL BASIN1

ABSTRACT: The U.S. Endangered Species Act (ESA) restricts federal agencies from carrying out actions that jeopardize the continued existence of any endangered species. The U.S. Supreme Court has emphasized that the language of the ESA and its amendments permits few exceptions to the requirement to give endangered species the highest priority. This paper estimates economic costs associated with one measure for increasing instream flows to meet critical habitat requirements of the endangered Rio Grande silvery minnow. Impacts are derived from an integrated regional model of the hydrology, economics, and institutions of the upper Rio Grande Basin in Colorado, New Mexico, Texas, and Mexico. One proposal for providing minimum streamflows to protect the silvery minnow from extinction would provide guaranteed year round streamflows of at least 50 cubic feet per second in the San Acacia reach of the upper Rio Grande. These added flows can be accomplished through reduced surface diversions by New Mexico water users in dry years when flows would otherwise be reduced below the critical level required by the minnow. Based on a 44‐year simulation of future inflows to the basin, we find that some agricultural users suffer damages, but New Mexico water users as a whole do not incur damages from a policy that reduces stream depletions sufficiently to provide habitat for the minnow. The same policy actually benefits downstream users, producing average annual benefits of over $200,000 per year for west Texas agriculture, and over $1 million for El Paso municipal and industrial water users, respectively. Economic impacts of instream flow deliveries for the minnow are highest in drought years.     

泥石流输沙对小江中下游河床演变的影响

对小江中下游近90km河床及两岸泥石流进行了调查研究。得到：泥石流输沙年际和季节变化大；泥石流高强度的输沙造成小江河床特殊的平面和剖面特征；泥石流堵塞小江河道，对纵比降有再造作用；泥沙使小江河床以年均20cm～50cm速度抬升。     

黄河断流成因及人文思考

日益严峻的黄河断流现象严重地影响了黄河流域经济和社会的可持续发展，也制约了西部大开发战略的实施。在分析了黄河断流的危害、成因的基础上，提出了在工程措施之外，要从人口、法律制度、产业结构等人文因素方面入手缓解黄河断流。     

生态条件和瘤胃菌丛密度与纤维分解的关系

在自行设计装配的人工模拟瘤胃发酵装置内，用90523-1瘤胃菌丛进行瘤胃体外发酵试验，结果表明纤维素的分解与瘤胃细菌的密度及其类群变化有着密切关系，都受生态环境条件的制约。在发酵温度40℃，搅拌速度为60～70r／min的条件下搅动20min／h，C／N为10：1的生态条件环境中的细菌密度和纤维素分解率都高于相同生态条件的其它梯度组。     

IMPACT OF COAL SURFACE MINING ON THREE OHIO WATERSHEDS - SURFACE-WATER HYDROLOGY1

ABSTRACT: A study was conducted to determine the effects of mining and reclaiming originally undisturbed watersheds on surface-water hydrology in three small experimental watersheds in Ohio. Approximately six years of data were collected at each site, with differing lengths of premining (Phase 1), mining and reclamation (Phase 2), and post-reclamation (Phase 3) periods. Mining and reclamation activities showed no consistent pattern iii base-flow, and caused slightly more frequent higher daily flow volumes. Phase 2 activities can cause reductions in seasonal variation in double mass curves compared with Phase 1. Restoration of seasonal variations was noticeably apparent at one site during Phase 3. The responses of the watersheds to rainfall intensities causing larger peak flow rates generally decreased due to mining and reclamation, but tended to exceed responses observed in Phase 1 during Phase 3. Natural Resources Conservation Service (NRCS) curve numbers increased due to mining and reclamation (Phase 2), ranging from 83 to 91. During Phase 3, curve numbers remained approximately constant from Phase 2, ranging from 87 to 91.     

人为泥石流灾害严重等级的定量模糊综合评判

根据神府－东胜矿区人为泥石流的调查分析，选择１５个因素（含５个主控因素）作为其严重程度的评价因子，确定了四值逻辑（严、中、轻、否）评判的定量标准。应用模糊综合评判和分层定量模糊综合评判两种方法对该煤田６５条泥石流沟的严重等级进行综合判别，准确性达９３．１％，它为保护该地煤田建设和工农业生产提供了重要的科学依据。     

建筑火灾区域模拟竖孔流动的计算

本文根据建筑火灾双层区域模拟思想，给出其常微分控制方程组，并分析了其压力求解方法，然后，运用伯努力利方程推导了相邻房间通过矩形竖孔（门或窗）的质量流率计算公式，还讨论了竖孔流动中性面产生条件。在此基础上，结合一两房间、两孔建筑中烟气运动实例，运用Ｃ．Ｗ．Ｇｅａｒ刚性稳定算法对火灾发展及烟气流动过程进行了数值模拟；给出各竖孔中性面位置、数量和各主环境之间通过竖孔的质量流率；还给出各房间气体平均温升、