曝气沉砂池除砂机理分析

针对曝气沉砂池小试装置模型,通过配砂实验对沉砂池除砂率进行统计分析,研究曝气强度与HRT对沉砂池除砂率的影响。实验结果表明,不同曝气强度下,随着HRT变化,除砂率逐渐上升,并最终趋于平衡状态;不同HRT下,曝气强度与除砂率近似呈现一定的线性关系,且随着曝气强度的增大,除砂率降低;在HRT小于1min时,砂粒的运行路径和沉降时间缩短,不利于砂粒的去除;在HRT大于1min时,其中1、3和4min,随着气水比的增加除砂率降低幅度相对较小,曝气所引起的横向环流在一定程度上有利于砂粒的沉降,而HRT为2min时,除砂率降幅却很大,这与砂粒在曝气沉砂池池体断面分布有关,即断面处旋转流速和水平流速的大小变化将影响砂粒的运动;相比曝气强度,HRT对除砂率的影响较大。     

四环素高效降解酵母菌Trichosporon mycotoxinivorans XPY-10降解特性

Trichosporon mycotoxinivorans XPY-10是一株分离自抗生素制药厂的高效四环素降解酵母菌。为了建立该菌株降解四环素的适宜条件,分别研究了碳源、有机氮源、金属离子等营养物质及初始底物浓度、接种量、pH、温度、装液量、摇床转速等理化因素对菌体生长及四环素降解效率的影响。结果表明,菌株XPY-10生长的最适碳源和氮源分别为蔗糖和蛋白胨。在含有0．05％FeSO4的培养基中,菌株XPY—10降解四环素的适宜条件为：接种量2％,pH8,温度3422,装液量100mL（250mL三角瓶）,摇床转速180r／min。在此条件下,菌株XPY—10在7d内对初始浓度为600mg／L的四环素降解率为83．63％。本菌株对养殖废水及制药废水中四环素的污染治理有一定的应用前景。     

大型测控设备的接地系统设计与探讨

介绍了接地的目的和种类,针对大型测控设备对接地电阻值的要求,提出了区域面积受限的接地系统设计方案,并对接地电阻进行了详细分析、计算和比较,选出了合理的接地方案进行施工,竣工后对接地系统的接地电阻值进行检测,检测结果满足测控设备接地电阻的要求.     

An Evaluation of Techniques to Control Problem Bird Species on Landfill Sites

Birds feeding on landfill sites cause problems in terms of nuisance to neighbors, flight safety, a threat to public health, and affecting the day to day site operation. A number of control measures exist to deter problem species; however, research into their effectiveness across sites and for multiple species has been limited. We use a modeling approach in order to assess the effectiveness of nine techniques — pyrotechnics, hand-held distress calls, static distress calls, blank ammunition, a combination of blank and lethal use of ammunition, the use of falcons, the use of hawks, wailers and helium-filled bird-scaring kites — at deterring three commonly recorded species — the Black-headed Gull (Larus ridibundus), the Herring Gull (Larus argentatus) and the Lesser Black-backed Gull (Larus fuscus) — from six landfill sites across the United Kingdom. The use of distress calls, falconry, and combinations of lethal and nonlethal use of ammunition were the most effective techniques for initially deterring birds from these sites. However, when habituation is considered, there is a clear difference between techniques such as falconry, which have a lethal aspect and may act to reinforce the deterrence, and the use of techniques such as distress calls, which do not. However there are problems related to legislation and public perception when lethal techniques are used.     

不同物质对垃圾渗滤液中腐殖酸的吸附研究

垃圾渗滤液是一种有毒有害的高浓度有机废水,其中含大量腐殖酸。腐殖酸具有离子交换能力、吸附能力和脱除杂质能力,因此在很多方面有实用价值。活性碳、土壤、堆肥对废水中的有机物有一定的吸附能力。本文采用正交设计的方法,研究了活性碳、土壤、堆肥在不同温度,液／固,腐殖酸初始浓度的条件下对垃圾渗滤液中腐殖酸的吸附效果。实验结果表明：四种实验因素对吸附剂的吸附能力的影响程度为：吸附剂类型〉腐殖酸的初始浓度〉吸附反应温度〉液固比。在温度为25℃,液固比为50／0．5（mL/g）,腐殖酸初始浓度为41．99（mg／L）,吸附剂类型为活性碳时,腐殖酸吸附量最大,为40．86mg。同时分析了响应指标随因素的变化趋势。     

20^#钢板镀铬在海洋环境条件下的腐蚀行为分析

本文根据20^#钢板镀铬材料在我国海洋环境的暴露结果,对20^#钢板镀铬材料在我国海洋环境条件下的腐蚀速度及腐蚀原因进行分析。     

安徽四大区域对外开放度与经济增长的分析

对外开放度是测量一个地区经济发展国际化程度的一个重要标志。以SPSS12．0为分析工具,运用回归分析方法,对安徽省四大区域对外开放度差异进行了测定和分析。2000年以来,安徽省四大经济区域对外开放度有了明显提高,但基础设施、区位条件、产业结构等方面的差异导致四大区域之间、区域内部以及地市之间的对外开放度存在明显差异。回归分析显示,对外开放度与安徽区域经济增长有着显著的相关性。     

Streambank Soil and Phosphorus Losses Under Different Riparian Land‐Uses in Iowa1

Abstract: Phosphorus and sediment are major nonpoint source pollutants that degrade water quality. Streambank erosion can contribute a significant percentage of the phosphorus and sediment load in streams. Riparian land‐uses can heavily influence streambank erosion. The objective of this study was to compare streambank erosion along reaches of row‐cropped fields, continuous, rotational and intensive rotational grazed pastures, pastures where cattle were fenced out of the stream, grass filters and riparian forest buffers, in three physiographic regions of Iowa. Streambank erosion was measured by surveying the extent of severely eroding banks within each riparian land‐use reach and randomly establishing pin plots on subsets of those eroding banks. Based on these measurements, streambank erosion rate, erosion activity, maximum pin plot erosion rate, percentage of streambank length with severely eroding banks, and soil and phosphorus losses per unit length of stream reach were compared among the riparian land‐uses. Riparian forest buffers had the lowest streambank erosion rate (15‐46 mm/year) and contributed the least soil (5‐18 tonne/km/year) and phosphorus (2‐6 kg/km/year) to stream channels. Riparian forest buffers were followed by grass filters (erosion rates 41‐106 mm/year, soil losses 22‐47 tonne/km/year, phosphorus losses 9‐14 kg/km/year) and pastures where cattle were fenced out of the stream (erosion rates 22‐58 mm/year, soil losses 6‐61 tonne/km/year, phosphorus losses 3‐34 kg/km/year). The streambank erosion rates for the continuous, rotational, and intensive rotational pastures were 101‐171, 104‐122, and 94‐170 mm/year, respectively. The soil losses for the continuous, rotational, and intensive rotational pastures were 197‐264, 94‐266, and 124‐153 tonne/km/year, respectively, while the phosphorus losses were 71‐123, 37‐122, and 66 kg/km/year, respectively. The only significant differences for these pasture practices were found among the percentage of severely eroding bank lengths with intensive rotational grazed pastures having the least compared to the continuous and rotational grazed pastures. Row‐cropped fields had the highest streambank erosion rates (239 mm/year) and soil losses (304 tonne/km/year) and very high phosphorus losses (108 kg/km/year).     

Characterizing Storm Hydrograph Rise and Fall Dynamics With Stream Stage Data1

Abstract: Storm‐flow transients (i.e., hydrograph rise and fall dynamics) may represent an important aspect of understanding streamflow dynamics. However, little is known about how temporal resolution of transient data and climate variability may color these potential indicators of hydrologic pattern or condition. Warm‐season stream stage and rainfall were monitored continuously (5 min) during the 2002 water year in eight tributaries of the Little Miami River (Ohio), which drain 17‐58 km² catchments. Rise rates generated using 5‐min data were different than those generated with mean daily data [calculated with the Indicators of Hydrologic Alteration (IHA) software], though fall rates were similar for fine and coarse temporal data. This result suggests that data with low temporal resolution may not be adequate to fully represent the dynamics of storm rise rates. Conversely, fall rates based on daily stage data (via IHA) were similar to those based on the 5‐min data, and so daily mean data may be appropriate for characterizing fall rates. We next analyzed the possible correlations between rainfall variability and storm‐flow stage dynamics. We derived rise and recession rates from storm stage hydrographs by assuming exponential rise and decay of a runoff peak. We found that raw rise rates (R_raw) were correlated with both the maximum rainfall rate and the time to the centroid of a rain event. We subsequently removed the trend based on these rainfall characteristics, which yielded new representations of rise rates abbreviated as R_rate and R_tcent, respectively, and that had lower variability than the uncorrected (raw) data. Fall rates were found to be independent of rainfall characteristics. Due to the predominant influence of stream hydrology upon aquatic biota and nutrient fluxes, our work suggests that these stage data analysis protocols can refine or otherwise reduce variability in these indices by accounting for relevant factors such as rainfall forcing. These protocols for derivation of transient indices should be tested for their potential to improve correlations between stream hydrology and temporally aligned biotic data and dissolved nutrient fluxes in streams.     

生态土壤渗滤系统启动周期研究

利用室内模拟试验装置,考察了4种生态土壤渗滤系统在0.1 m3/(m2·d)的水力负荷条件下对生活污水中TP、COD和NH3-N的去除效果及启动周期; 同时对整个系统及同类生态工艺启动周期的判断方法做了探讨.研究结果表明,生态土壤渗滤系统对TP、COD和NH3-N的启动周期分别为15～27 d、24～40 d和24～26 d; 土壤渗滤系统对TP的启动周期最短,对COD的启动周期最长; 处理系统启动周期的判断原则是综合考察系统对主要污染物各自的启动周期,以最长的作为系统启动周期.4组试验中,1#和2#系统的启动周期为40 d; 3#和4#的为24 d.