Performance Assessment of Rain Gardens1

Abstract: The most widely used approach for evaluating the performance of stormwater best management practices (BMPs) such as rain gardens is monitoring, but this approach can involve a long time period to observe a sufficient number and variety of storm events, a high level of effort, and unavoidable uncertainty. In this paper, we describe the development and evaluation of three approaches for performance assessment of rain gardens: visual inspection, infiltration rate testing, and synthetic drawdown testing. Twelve rain gardens in Minnesota underwent visual inspection, with four determined to be nonfunctional based on one or more of the following criteria: (1) presence of ponded water, (2) presence of hydric soils, (3) presence of emergent (wetland) vegetation, and (4) failing vegetation. It is believed that these rain gardens failed due to a lack of maintenance. For the remaining eight rain gardens, an infiltrometer was used to determine the saturated hydraulic conductivity (K_sat) of the soil surface at several locations throughout each basin in what is termed infiltration rate testing. The median K_sat values for the rain gardens ranged from 3 to 72 cm/h. Synthetic drawdown testing was performed on three rain gardens by filling the basins with water to capacity where possible and recording water level over time. The observed drain times for two of those rain gardens were in good agreement with predictions based on the median of the infiltrometer measurements. The observed drain time for the third rain garden was much greater than predicted due to the presence of a restrictive soil layer beneath the topsoil. The assessment approaches developed in this research should prove useful for determining whether the construction of the rain garden was performed properly, a rain garden is functioning properly, and for developing maintenance tasks and schedules.     

建设项目安全管理的智能化技术研究

明确建设项目安全管理的意义;简述建设项目安全管理技术的国内外研究现状;指出当前的建设项目安全管理研究存在的主要不足;提出笔者研究的思路和研究的主要内容;收集详细的施工现场资料,参考相关历史文献资料,提取可能引起安全事故的原始不确定风险因素,建立安全管理风险评价指标体系;并利用人工神经网络(ANN)强大的非线性函数逼近能力,将BP神经网络引入建设项目风险控制,构建基于BP神经网络的建设项目安全控制系统,从而实现建设项目安全管理的智能化。通过工程实例验证:该方法具有可行性和有效性,为实现建设项目安全管理目标及工期、成本、质量目标打下坚实的基础。     

3种植物人工浮岛对生活污水水质动态净化特性的比较

在同等条件下开展了3种植物人工浮岛对生活污水水质处理比较研究,并对它们动态净化处理结果进行比较。结果表明,水体交换时间为7 d时,灯心草、菖蒲、美人蕉3种人工浮岛对总氮的平均去除率分别为48.4%、53.7%和59.3%;对总磷的平均去除率分别为59.3%、65%和69.3%;对COD的平均去除率分别为41.5%、40.5%和40.9%。显然美人蕉对总氮和总磷的去除效果最好,实验证明了美人蕉人工浮岛在对于生活污水处理中有广阔的应用前景。     

Decentralized Groundwater Recharge Systems Using Roofwater and Stormwater Runoff1

Stephens, Daniel B., Mark Miller, Stephanie J. Moore, Todd Umstot, and Deborah J. Salvato, 2011. Decentralized Groundwater Recharge Systems Using Roofwater and Stormwater Runoff. Journal of the American Water Resources Association (JAWRA) 48(1): 134‐144. DOI: 10.1111/j.1752‐1688.2011.00600.x Abstract: Stormwater capture for groundwater recharge in urban areas is usually conducted at the regional level by water agencies. Field and modeling studies in New Mexico indicate that stormwater diverted to retention basins may recharge about 50% of precipitation that falls on the developed area, even in dry climates. Comparable volumes of recharge may be expected at homes, subdivisions, or commercial properties with low‐impact development (LID) technologies for stormwater control that promote recharge over evapotranspiration. Groundwater quality has not been significantly impacted at sites that have been recharging stormwater to aquifers for decades. Distributed recharge systems may be a good alternative to centralized regional facilities where there is limited land for constructing spreading basins or little funding for new infrastructure. LID technologies borrowed from stormwater managers are important tools for groundwater managers to consider to enhance recharge.     

四川望佳人工湿地系统生活污水净化效果

取样监测分析了望佳人工湿地系统各组成单元对COD、TN、NH3-N、TP和SS的去除效果。在水力负荷为0.18 m3/m·d、温度为8~19℃、p H为6~8的条件下,分析结果表明,各单元COD、TN、NH3-N、TP和SS的系统去除率满足:人工快渗池>厌氧调节池>1号表流湿地>潜流湿地>氧化塘>2号表流湿地>1号水平潜流湿地>2号水平潜流湿地,其中人工快渗池单元的系统去除率平均值分别为21.21%、22.74%、22.49%、25.58%和30.85%。监测期间COD、TN、NH3-N、TP和SS的总去除率平均值分别为89.41%、90.27%、89.89%、89.89%和92.28%,系统出水达《城镇污水处理厂污染物排放标准》GB18918-2002一级标准的B标准。监测表明,该湿地设计偏于保守,还可以优化设计单元以减少建设和运行成本。     

阿科蔓介质生物接触氧化法预处理微污染原水

随着库区经济的发展,大量点源或面源污染物未经有效处理便直接排入水体致使许多可作为生活饮用水的水源变成了"微污染"水源,鉴于常规的预处理工艺不能很好地适应现有"微污染"水源水质的变化,采用挂膜成功的阿科蔓介质生物接触氧化法对微污染水源水进行预处理实验研究,并与挂膜成功的组合介质生物接触氧化法进行对比,结果表明,阿科蔓介质挂膜速度较快,效果较好,且对水源水质的变化具有较好的适应性,是微污染水原水质改善较为理想的人工介质;对于相同的微污染水源,阿科蔓介质的处理效果明显优于组合介质且处理效果良好,其对"微污染"水源水中TN、氨氮、COD和总磷的平均去除率分别为67.4%、87.2%、54.1%和40.1%,其中较适宜的阿科蔓介质生物接触氧化预处理进水溶解氧浓度为4.0~6.0 mg/L。阿科蔓介质生物接触氧化不失为一种开展饮用水源地生态防护与饮用水质改善的技术。     

无GGH湿法脱硫工艺的“石膏雨”防治设计与运行优化

为了解决火力发电厂无GGH湿法脱硫工艺出现的“石膏雨”问题,神华万州发电厂从脱硫吸收塔内部流场调整、结构设置、烟气流速、边界条件设定、烟囱结构优化等方面进行设计和优化运行,在很大程度上减少了湿法脱硫的“石膏雨”现象的发生。     

火电厂湿法脱硫石膏雨和白雾治理措施及效果分析

安装有湿法烟气脱硫装置的火电厂一般都存在石膏雨及白雾现象,从烟气的成份与状态出发阐述了石膏雨及白雾的表现形态,并从吸收塔、烟道及烟囱、环境3个环节分析了石膏雨及白雾现象形成的途径,以及净烟气中固体颗粒、液态水、烟道冷凝水、烟囱冷凝水、环境冷凝水和白雾等6个治理要素,系统地从吸收塔、烟道及烟囱环节提出了石膏雨及白雾现象治理的措施,并分析了各种措施的优缺点及效果。     

Rain‐washing of mimic®, RH‐5992, from balsam fir foliage following application of two formulations

Abstract

Two formulation concentrates of the insecticide, RH‐5992 [N'‐t‐butyl‐N'‐(3,5‐dimethylbenzoyl)‐N‐(4‐ethylbenzoyI) hydrazine], an aqueous flowable (2F) and an emulsion‐suspension (ES), were diluted with water to provide spray mixes containing dosage rates ranging from 35 to 150 g of the active ingredient (AI)/ha. The mixes were sprayed in a laboratory chamber, onto balsam fir branch tips collected from field trees and greenhouse‐grown seedlings. Droplet spectra and spray mass recovery were determined on artificial samplers. Simulated rainfall of two different intensities was applied at different rain‐free periods, and rain droplet sizes were determined. Foliar washoff of RH‐5992 was assessed after application of different amounts of rain, and the increase in soil residues was evaluated.

A direct relationship was indicated between the amount of rainfall and RH‐5992 washoff. The larger the rain droplet size, the greater the amount washed off. Longer rain‐free periods made the deposits more resistant to rain. Regardless of the amount of rainfall, rain droplet size and rain‐free period, foliar deposits of the 2F formulation were washed off to a greater extent than the ES formulation. The increase in soil residues due to foliar washoff was greater for the 2F than for the ES formulation. The deposits of the emulsion‐suspension were consistently more resistant to rain‐washing than those of the aqueous flowable formulation.     

广州市白云人工湖生态修复工程设计

广州市白云湖是广州市最大的人工生态服务湖泊,通过对白云湖生态修复工程进行设计,采用了炭素纤维生态草、微纳米气泡发生装置及纯氧发生器和人工干预与生物处理相结合生态浮床等环保新技术对白云湖水体进行综合生态修复,并对白云湖水质进行跟踪监测。结果显示,白云湖水质提升工程实施之后,白云湖各项水质指标都有一定的改善。白云湖生态修复工程的设计经验对于类似人工水体的水质改善和生态修复工程建设具有参考意义。