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791.
Complementary methods to investigate the development of clogging within a horizontal sub-surface flow tertiary treatment wetland 总被引:2,自引:0,他引:2
A combination of experimental methods was applied at a clogged, horizontal subsurface flow (HSSF) municipal wastewater tertiary treatment wetland (TW) in the UK, to quantify the extent of surface and subsurface clogging which had resulted in undesirable surface flow. The three dimensional hydraulic conductivity profile was determined, using a purpose made device which recreates the constant head permeameter test in-situ. The hydrodynamic pathways were investigated by performing dye tracing tests with Rhodamine WT and a novel multi-channel, data-logging, flow through Fluorimeter which allows synchronous measurements to be taken from a matrix of sampling points. Hydraulic conductivity varied in all planes, with the lowest measurement of 0.1 m d−1 corresponding to the surface layer at the inlet, and the maximum measurement of 1550 m d−1 located at a 0.4 m depth at the outlet. According to dye tracing results, the region where the overland flow ceased received five times the average flow, which then vertically short-circuited below the rhizosphere. The tracer break-through curve obtained from the outlet showed that this preferential flow-path accounted for approximately 80% of the flow overall and arrived 8 h before a distinctly separate secondary flow-path. The overall volumetric efficiency of the clogged system was 71% and the hydrology was simulated using a dual-path, dead-zone storage model. It is concluded that uneven inlet distribution, continuous surface loading and high rhizosphere resistance is responsible for the clog formation observed in this system. The average inlet hydraulic conductivity was 2 m d−1, suggesting that current European design guidelines, which predict that the system will reach an equilibrium hydraulic conductivity of 86 m d−1, do not adequately describe the hydrology of mature systems. 相似文献
792.
En-Rong Xiao 《Desalination》2010,250(2):781-786
A new SMBR-IVCW system, which combined a submerged MBR (SMBR) unit and an integrated vertical-flow constructed wetland (IVCW) unit, was applied to treat the high strength integrated wastewater. The study showed that this system of biological and ecological combination was stable and good at improving the quality and efficiency of polishing wastewater. Six runs under different HRT combinations were carried out in order to obtain the better purification performance of the SMBR-IVCW system. The results indicated that the better HRT combination was 7.7 h for SMBR and 11.52 h for IVCW. In such condition, the concentrations of COD, ammonia and TP in the final effluent were 11.0, 0.086 and 0.44 mg L− 1, respectively, which reached the Class III of the national environmental quality standards for surface water in China. In fact, the HRT of the two units had great effect on the purification efficiency and investment cost. By regulating the ratio of HRT between these two units, the optimum operation conditions could be obtained to reach the double wins of high purification and low costs. In the SMBR-IVCW system, the SMBR unit acted as the secondary treatment, contributing to removing the organics and nitrification. While the IVCW unit was more like as the tertiary treatment, contributing to the denitrification and further dephosphorization. 相似文献
793.
Wild birds are exposed to pollutants in their habitats. Top consumers of aquatic environments such as the fish-eating great cormorant (Phalacrocorax carbo sinensis) are especially affected due to the bioaccumulation of toxic substances in their tissues. This study analysed the livers of 80 great cormorants from Greece to estimate the concentration of organochlorines and mercury and to examine their possible toxic effects and origin. The results showed that mercury (geometric mean 8089 ng g−1 dw), p,p′-DDE (2628 ng g−1 dw), ∑ HCHs (47 ng g−1 dw) and HCB (116 ng g−1 dw) concentrations can be considered high compared with those found in great cormorant livers elsewhere except in highly polluted areas, whereas ∑ PCBs occurred in relatively low concentrations (1091 ng g−1 dw). β-HCH was the dominant HCH isomer. Pollutant levels were generally unrelated to area, age and gender. However, p,p′-DDE and p,p′-DDD showed intersite differences, whilst the proportion of PCBs with 8 chlorine atoms were significantly higher in adult than 1st year great cormorants. Pollution did not reflect local patterns but rather these along the Baltic and Black Seas, whilst differences in p,p′-DDE concentration and ∑ DDTs/∑PCBs ratios between Evros, Axios or Amvrakikos, found on common migration route, suggested different bird origins. Most birds had toxic mercury concentrations; 83.7% above 4000 ng g−1 dw and 16% above 17,000 ng g−1 dw. Other pollutant levels were too low to have adverse effects. 相似文献
794.
795.
以西安市兴庆湖为研究对象,对湖泊的水质进行了水平潜流和自由表面流净化的实验研究,比较两种湿地的净化效果。在相同的水力负荷、水深等条件下,分析了水力停留时间对城市湖泊中的有机物、氮、磷等主要污染物的净化效果的影响。 相似文献
796.
三种人工湿地填料对氨氮与磷的吸附特性 总被引:2,自引:0,他引:2
采用等温吸附、吸附动力学、填料饱和吸附后氨氮与磷解吸实验,研究了浮石、陶结和陶粒对氨氮和磷的吸附特征。结果表明,Langmuir和Freundlich等温吸附方程均能较好拟合各填料对氨氮和磷的吸附特征,各填料对氨氮的最大吸附量顺序依次为浮石(64.91 mg/kg)>陶结(36.11 mg/kg)>陶粒(22.23 mg/kg),对磷的最大吸附量顺序依次为浮石(127.77 mg/kg)>陶粒(15.38 mg/kg)>陶结(无吸附);各填料对氨氮与磷的全程平均吸附速率大小顺序与最大吸附量大小顺序一致;Bangham吸附速率方程能较好描述浮石与陶粒对氨氮与磷、陶结对氨氮的等温吸附动力学特征;氨氮解吸风险为陶粒>陶结>浮石,磷解吸风险为陶结>陶粒>浮石。综合考虑,浮石更适合作为去除污水中氨氮与磷的人工湿地填料。 相似文献
797.
798.
潜流人工湿地对农村生活污水处理特性试验研究 总被引:2,自引:0,他引:2
采用潜流人工湿地处理农村生活污水,考察了该工艺对COD、BOD5、NH3-N、TN和TP的去除效果。结果表明,湿地对COD、BOD5、NH3-N、TN和TP的去除效果较好,平均去除率分别达到87.4%、83.5%、63.8%、57.9%和90.1%,出水COD为11.2~23.3 mg.L-1,出水BOD5为6.7~11.3 mg.L-1,出水NH3-N、TN、TP的质量浓度分别为10.3~16.1、18.8~23.2、小于1.0 mg.L-1,出水水质优于GB 5084-2005要求。植物种植状况、温度变化及进水污染物含量等因素对湿地处理效率有较大影响,总体上来讲,温度大于20℃、植物种植密度越大、进水污染物含量越低处理效果越好。 相似文献
799.
人工湿地芦苇床污泥脱水和稳定化技术因其能耗、运行篱理费用低得到更多的研究。试验污泥为厌氧池加氧化沟工艺二沉池污泥,模拟人工湿地进泥负荷为0.658kgTS/m2.d.进泥中TS和VS平均含擐分别为19.68和6.93g/L,pH为6.78。试验期为1年,对第一个进混周期后的渗滤液中COD、NH4-N及Ts的含最进行了测定。试验结束后,湿地中表层和底部污泥TS含量分别达到51.5%和56.8%,底部污泥中VS含量降至12.3%。结果表明,人工湿地芦苇床对城市污泥有较好的脱水和稳定化效果。 相似文献
800.
人工湿地堵塞问题的探讨 总被引:9,自引:1,他引:8
近20年发展起来的人工湿地,作为一种对传统污水处理技术的廉价替代方案,越来越受到世界各国的普遍重视.通过对人工湿地运行过程中出现的填料堵塞现象进行全面分析,归纳和总结了人工湿地堵塞的影响因素,对其堵塞机理和堵塞模型进行了探讨,提出了避免堵塞的工程化解决措施和湿地堵塞后的恢复方法. 相似文献