串联垂直流人工湿地去除河水中磷的效果

利用在温室内构建的串联垂直流人工湿地模拟装置,以芦苇为湿地植物,填充砾石,研究两种水力负荷(0.2和0.4 m/d)、3个串联级数、有/无植物等对处理北京市清河河水磷去除的影响,试验共持续144 d. 结果表明:①在进水ρ(TP)为0.50~1.77 mg/L(平均值为1.15 mg/L)、ρ(DTP)为0.41~1.53 mg/L(平均值为0.9 mg/L)的条件下,TP去除率随进水ρ(TP)的升高而升高. ②水力负荷为0.2 m/d时,有、无植物3级串联系统磷的去除率分别为38.36%、26.85%;水力负荷为0.4 m/d时,分别为32.42%,23.99%,说明低水力负荷与有植物的条件利于除磷. ③有植物3级串联系统TP去除率平均值为38.36%,大于2级串联系统(28.30%);无植物3级串联系TP去除率平均值为26.85%,大于2级串联系统(21.81%)和1级串联系统(14.98%),串联级数增加,磷去除率升高. 研究显示,水力负荷为0.2 m/d时,有植物3级串联系统的TP去除率最高.      

页岩气开发中压裂返排液的水质污染特征研究

页岩气压裂返排液成分复杂,为了解页岩气开采过程中压裂返排液的污染情况,对四川某页岩气典型井场不同时期的压裂返排液污染物组成进行了分析,采用超滤膜法测定溶解性有机物(DOM)相对分子质量分布特性,通过建立水质矩阵开展污染特性评价,并进行了综合生态毒性研究。结果表明,该区域不同时期压裂返排液中污染物特征相似,主要污染因子为总有机碳(TOC)和氯离子,并且生物毒性高、可生化性差。研究结果可为该区域压裂返排液处理技术的选择提供参考。     

美人蕉根系对不同基质结构水平潜流人工湿地水力特性的影响

为了研究植物根系对不同基质结构潜流人工湿地水力特性的影响,根据填料渗透系数,分别设置单层及多层基质结构潜流人工湿地小试实验系统,以美人蕉作为湿地植物,在植物栽种前与成熟后对两系统分别开展示踪试验研究.实验结果表明,美人蕉根系对于单层结构人工湿地水力特性有较明显的改善作用,有效体积从0.49提高到了0.53,短路值由0.60降低到0.41,水力效率提高最大由43%提高到59%.比较而言,植物根系对多层结构湿地有效体积和短路值有轻微负面影响,而对水力效率则有明显的改善作用(由64%提高到83%).此外,植物成熟后,两人工湿地系统中示踪剂回收率均有所下降,其中,单层结构湿地降低较显著,回收率由72%降到62%.可见,植物根系对系统水力特性有较大影响,应在人工湿地设计过程中给予考虑.     

渭河陕西段潜流带沉积物重金属变化初步分析

为厘清潜流带沉积物重金属时空变化及与水量交换、沉积物颗粒结构间的关系,于2013年春夏两季对渭河陕西段5个研究断面66个测试点位沉积物的野外原位渗透系数、颗粒粒径、重金属含量进行分析.结果表明:影响渭河沉积物渗透系数的主要因素是沉积物粒径,同时沉积物垂向分层、排列组合也影响其渗透性能;沉积物重金属Cu、Zn、Pb、Cd质量分数在垂向上不同深度其含量大小不同,在时间上总体呈现春季夏季,富集系数(EF指数)分析结果显示春季Cu、Zn(除华县)、Pb(除眉县)、Cd富集严重且主要受人为输入源影响,夏季除Cd元素外,Cu、Zn、Pb的EF值均1.5,说明其含量主要来源于地壳和岩石圈的自然风化过程;Pearson相关分析发现粘土与粉砂(粒径0.075 mm)百分比与沉积物重金属质量分数呈弱相关,重金属粒径效应不显著,粒径不是控制重金属含量的主要环境影子;对单一重金属垂向不同深度含量进行相关性研究发现除Cd外,其余3种重金属在垂向上的相关系数均0.5(p0.01),说明单一重金属在垂向上具有同源性且存在相互迁移与转化.     

水力停留时间对活性污泥系统的硝化性能及其生物结构的影响

利用微生物呼吸醌指纹谱图结合传统分析方法研究了水力停留时间(HRT从30 h逐步缩短至5 h)对活性污泥硝化性能及种群结构的影响.结果表明,对于NH₄⁺-N浓度为500 mg·L^-1的废水,在HRT≥20 h时,氨氮去除率可达98%以上.若继续缩短HRT,污泥流失严重,尽管进水NH₄⁺-N浓度降低,出水NH₄⁺-N和NO₂     

MODIFIED WATER QUANTITY RECEIVING MODEL FOR FLORIDA CONSERVATION AREAS1

ABSTRACT: The Conservation Areas in South Florida have been considered as one of the major water storage areas to provide a water supply for the Everglades National Park and Lower East Coast (LEC). Due to the increasing water demands of the area, additional backpumping of the surplus runoff from the LEC area into the Conservation Areas has been considered as one of several alternative plans. The Receiving Water Quantity (EPA, 1971) model has been adapted and modified to be applicable in the Conservation Areas to investigate the possible impact of additional inflow under various backpumping cases. The modification of the model included Manning's roughness coefficient, depth of flow, width of hypothetical channels through marsh areas, rainfall input, seepage rate, etc. The use of the Monte Carlo technique for area computations was found to be easy and time saving both in area and weighting rainfall input to each node. Comparison of results generated by this modified model with the recorded values in Conservation Areas 1 and 2A indicated that the model not only can be a very good evaluation tool to simulate the hydraulic regime of the Conservation Areas system but also a proper tool for investigating the impact of additional inflow resulting from the backpumping related to the water use planning and management.     

INTERACTIVE COMPUTER-AIDED HYDRAULIC DESIGN: CULVERTS1

ABSTRACT: Regular use of interactive computer programs in hydraulic design can materially increase the productivity of designers without sacrificing accuracy. This article considers the hydraulic design of culverts by interactive use of a computer program; this approach most profitably combines the speed and accuracy of the computer with the experience of the designer.     

COMPARATIVE STUDY OF FRESH-SALT WATER INTERFACES USING FINITE ELEMENT AND SIMPLE APPROACHES

ABSTRACT: The fresh-salt water interface in artesian aquifers has been investigated by various techniques on the basis of its analogy to the free surface in earth dams or cores of dams. Although various approximations are used, some more or less exact solutions exist. One of the simple methods, that would appeal to practical workers, was developed by the analysis of hydraulic forces. However, this method has not been checked thoroughly due to the lack of wide ranges of coverage by the more or less exact solutions. In this paper a suggested finite element method is used for the purpose of comparing with the method of hydraulic forces. The presented procedure eliminates some of the difficulties and uncertainties in current finite element procedures. Both methods proved to be in close agreement. Moreover, the hydraulic heads along the upper boundary of the artesian aquifer were found to be in close agreement with Dupuit's equation. The results of this investigation would greatly simplify the more complex management problems when the effects of discharge and/or recharge wells are added to the natural flow effects.     

SURFACE WATER RESOURCES OF ST. JOHNS RIVER,FLORIDA1

ABSTRACT: The St. Johns River basin is the largest watershed entirely within the State of Florida, and is one of the few northward flowing rivers in the United States. The river basin contains 11,431 square miles, of which 9,430 square miles are drained by the river and its tributaries. The remainder drains into the Atlantic Ocean or the Intracoastal Waterway. Its largest sub-basin is the Oklawaha River basin, which has a drainage area of 2,870 square miles. Ground elevations range from sea level to 200 feet above mean sea level in the main river basin and as high as 300 feet above mean sea level in the Oklawaha River basin. This study was designed to investigate the surface water resources of the St. Johns River and the existing consumptive uses. The analysis revealed that the river is an extremely large and valuable resource which has been under-utilized and could play a much stronger role in serving the needs of the people in the basin.     

INFLUENCES OF A FOREST ON THE HYDRAULIC GEOMETRY OF TWO MOUNTAIN STREAMS1

ABSTRACT The influence of a forest on the formation of steps in two small streams of the Colorado Rocky Mountains was studied. Steps provided by logs fallen across the channel added to flow energy reduction. The streams required additional gravel bars to adjust to slope. Average step length between logs and gravel bars was strongly related to channel gradient and median bed material size. Based on the average number of log steps per 50 feet of channel, an average of 116 percent of gravel bars were added at Fool Creek and 60 percent at Deadhorse Creek. The latter had 52 percent more logs in the channel and therefore required less bed material movement than the former. Although these are “rushing mountain streams,” most flow velocities ranged between 0.5 and 2.5 f.p.s. Exponents of a function relating rate of change of depth or velocity to discharge indicated that dynamic stream equilibrium was attained. Implications for forest management are that sanitation cuts (removal of dead and dying trees) would not be permissible where a stream is in dynamic equilibrium and bed material movement should be minimized.