Downstream channel changes after a small dam removal: Using aerial photos and measurement error for context; Calapooia River,Oregon

Dam removal is often implemented without adequate baseline monitoring to distinguish background variability from channel changes due to the removal. This study evaluated aerial photos as substitutes for multiple‐year pre‐removal field data to assess downstream channel changes associated with a small dam removal. The Brownsville Dam, a 2.1 m tall concrete dam on the Calapooia River, Oregon, was removed in 2007. We mapped bars and the low flow channel downstream from the dam and in an upstream control reach using aerial photos (1994–2008) and in the field prior to (2007) and following (2008) removal. The locations and magnitudes of changes in bar area and wetted width, relative to errors, indicate that downstream channel changes were a result of the removal. The maximum changes (?3520 ± 1460 m² for bar area, 32 ± 8 m for wetted width) observed prior to dam removal with aerial photos were far downstream. In contrast, the maximum changes after removal were immediately below the dam (200 ± 90 m² for bar area, ?11 ± 3 m for wetted width), and small in the upstream control (?150 ± 130 m² for bar area, 9 ± 4 m for wetted width). The dominant errors were photo specific: exposure error for spring to summer comparisons, position error for photos not processed for this study and identification error for small scale photos not scanned from film. We found aerial photos to be an acceptable but coarse substitute for multi‐year pre‐removal field data, and suggest best practices to minimize errors. Copyright © 2009 John Wiley & Sons, Ltd.     

好氧颗粒污泥脱氮除磷效率研究

以实验室模拟废水为进水,在SBR反应器中利用好氧颗粒污泥进行N、P的去除效率研究.研究表明:在运行周期约为4h,进水COD控制在500～1200 mg/L之间,室温条件下,好氧颗粒污泥对COD、氨氮、硝氮、TP的去除率稳定维持在97％、95％、92％、86％,说明好氧颗粒污泥特有的结构特性和生物特性有利于脱氮除磷.     

3种吸附剂对东莞运河吸附效果比较研究

针对东莞运河氮、磷浓度较低的污染特点,以人造沸石、活性炭、高岭土为吸附剂进行吸附实验研究,确定不同吸附剂的最佳反应时间和最佳投入量。结果表明,活性炭对水中TN的去除效果最佳,去除率达61.9%;高岭土具有优异的除磷效果,去除率达79.21%;人造沸石对TN的去除效果一般,而对TP完全没有去除效果,反而会提高TP的浓度。     

白洋淀开卡除堼及其防洪作用

白洋淀特殊的自然地形及防洪调度的重要性决定了枣林庄闸前除堼及淀内开卡的必要性,文章讲述了历次开卡的背景及标准,通过1996年实测数据佐证了工程效果。     

北京市农村污水处理方法及效果

为研究农村污水特点,针对性选择处理工艺,对北京市通州、房山、昌平、怀柔、密云等5个区县的4种类型村庄的污水结构、用水量、污水排放量、污染物浓度进行调查研究,同时对6种污水处理工艺进行污染物去除率、建设运行费用、占地面积进行调查研究。结果显示:京郊农村污水主要由厨房污水、生活洗涤污水、冲厕污水、养殖污水组成;污水排放规律为夏季大、冬季小,污水污染物种类多,城乡结合部村水质最差,山区村水质最好。综合分析表明,MBR、MBR+土地渗滤、A/O+土地处理系统工艺适宜在平原地区经济条件较好的村庄及城乡结合部村庄使用;人工湿地工艺适宜在面积大、经济条件较差、对出水水质要求不高的平原区村庄使用;山区村庄可考虑采用厌氧生物滤池处理技术;民俗旅游村等经济条件较好、出水水质要求较高的村镇地区可考虑采用MBR工艺及一些高效组合工艺。     

Design Methodology and Area Sensitivity Analysis of Horizontal Subsurface Flow Constructed Wetlands

An approach is presented to satisfy the demand for simple criteria, guidelines and models for the preliminary sizing of horizontal subsurface flow (SF) constructed wetland systems. This approach eliminates time-consuming calculations and iterations by providing graphical solutions for wetland system sizing. Therefore, it can be used for the preliminary assessment of new or performance evaluation of existing subsurface flow constructed wetland systems. The validity of this methodology is checked with data from existing systems and is found to be quite satisfactory. This methodology is combined with simple equations predicting the maximum wetland capacity in summer, so as to assist designers in sizing installations in tourist areas with increased summer populations. Furthermore, based on this methodology, a sensitivity analysis is performed of the area requirements for wastewaters of various strengths and various design conditions and performance criteria. The results provide a useful overview to engineers and further simplify the design methodology of new subsurface flow constructed wetland systems.     

TNT炸药废水三维电解氧化实验研究

以不锈钢作为阳极的三维电解反应器对废水的实验研究表明:在最佳电解条件下(极板间距4 cm、电压15 V、pH为3,绝缘粒子与活性炭粒子质量比为0.3,电流强度0.15 A时),电解3 h后TNT和COD的去除率分别为93 %和78 %.并探讨了电化学氧化处理TNT废水的机理.     

粉末状骨炭用于饮用水除氟的试验研究

对粉末状骨炭的除氟性能进行了多组试验研究,结果表明:粉末状骨炭的吸附容量与原水中氟离子的浓度呈线性关系,吸附等温式符合Freundlich公式。骨炭吸附容量受骨炭粒径、pH值、水温及水中其他离子的影响,骨炭粒径还会影响吸附反应的速度。骨炭采用5%的NaOH溶液再生,再生效果良好。     

河道水体磷的存在形态及混凝去除效果研究

研究北京转河磷的形态分布及混凝对各形态磷的去除效果。试验表明,颗粒态总磷约占水体总磷的67.57%,可溶性总磷占32.43%。从季节分布看,总磷质量浓度在当年的7~9月份达到最高,接近270μg/L,在12月,次年1月达到最低,接近120μg/L。在混凝沉淀后各形态磷大部分得以去除,颗粒态磷去除率达88.8%,缩合态磷去除率相对最低,为61.72%,正磷酸盐几乎完全被去除。