人工快速渗滤系统处理温榆河原水试验研究

提出以天然河砂与沸石和火山岩混合的人工快速渗滤填料改进方式,考察了新型人工快速渗滤系统处理温榆河原水的可行性与净化效果。结果表明,相比单独天然河砂填料,混合填料下人工快速渗滤系统出水的CODCr、NH3—N和TN去除率得到显著提高。当天然河砂与沸石混合比为3:1时,系统出水CODCr、NH3—N、TN和TP的平均去除率分别达到了64.7%、97.1%、31.8%和44.9%。当天然河砂与火山岩混合比为3:1时,系统出水CODCr、NH3—N、TN和TP的平均去除率分别达到了58.2%、98.6%、40.8%和34.5%。运行稳定后,天然河砂与沸石混合填料的滤池平均水力负荷达到了4.1m/d和3.6m/d,分别是单独天然河砂的1.52倍和1.33倍。     

Phosphorus retention and sorption by constructed wetland soils in Southeast Ireland

It may be necessary to use constructed wetlands as a land use practice to mitigate phosphorus (P) loss from agriculture in Ireland. The objectives of this study were to determine the ability of two constructed wetland site soils to retain and sorb P. Intact soil/water column studies were used to determine P release/retention rates during a 30-day incubation period. Soil columns flooded with distilled water released P during the first 2 days; however, soluble reactive P (SRP) concentrations in overlying floodwaters decreased thereafter. Soils with overlying floodwaters spiked at 5 and 15 mg SRP L(-1) retained highest amounts of P (p < 0.05) with retention at these concentrations controlled by SRP in overlying waters. Retention rates by soils ranged between 0.3 and 60.9 mg Pm(-2) d(-1). Maximum P sorption capacity (Smax) was higher for wetland soils at Dunhill, Waterford (1464 mg P kg(-1)) in comparison to soils at Johnstown Castle, Wexford (618 mg P kg(-1)). Equilibrium P concentrations (EPC0) were low (in the microg SRP L(-1) range), indicating a high capacity of these soils to sorb P. Phosphorus sorption parameters were significantly related to ammonium oxalate extractable aluminium (Al) and iron (Fe) content of soils.     

Sulphate reduction and the removal of carbon and ammonia in a laboratory-scale constructed wetland

Sulphate is a normal constituent of domestic wastewater and reduced sulphur compounds are known to be potent inhibitors of plant growth and certain microbial activities. However, the knowledge about sulphate reduction and the effect on the removal of C and N in constructed wetlands is still limited. Investigations in laboratory-scale constructed wetland reactors were performed to evaluate the interrelation of carbon and nitrogen removal with the sulphate reduction by use of artificial domestic wastewater. Carbon removal was found to be only slightly affected and remained at high levels of efficiency (75-90%). Only at sulphate reduction intensities above 75 mgl(-1) (50% removal), a decrease of carbon removal of up to 20% was observed. A highly contrary behaviour of ammonia removal was found in general, which decreased exponentially from 75% to 35% related to a linear increase of sulphate reduction up to 75 mgl(-1) (50% removal). Since sulphate removal is considered to be dependant on the load of electron donors, the carbon load of the system was varied. Variation of the load changed the intensities of sulphate reduction immediately, but did not influence the carbon removal effectiveness. Doubling of the carbon concentration of 200 mgl(-1) BOD(5) for domestic wastewater usually led to sulphate reduction of up to 150 mgl(-1) (100% removal). The findings show that, particularly in constructed wetland systems, the sulphur cycle in the rhizosphere is of high importance for performance of the waste water treatment and may initiate a reconsideration of the amount of sulphate present in the tap water systems.     

Treatment of landfill leachate using an aerated, horizontal subsurface-flow constructed wetland

A pilot-scale subsurface-flow constructed wetland was installed at the Jones County Municipal Landfill, near Anamosa, Iowa, in August 1999 to demonstrate the use of constructed wetlands as a viable low-cost treatment option for leachate generated at small landfills. The system was equipped with a patented wetland aeration process to aid in removal of organic matter and ammonia nitrogen. The high iron content of the leachate caused the aeration system to cease 2 years into operation. Upon the installation of a pretreatment chamber for iron removal and a new aeration system, treatment efficiencies dramatically improved. Seasonal performance with and without aeration is reported for 5-day biochemical oxygen demand (BOD(5)), chemical oxygen demand (COD), ammonia nitrogen (NH(4)-N), and nitrate nitrogen (NO(3)-N). Since winter air temperatures in Iowa can be very cold, a layer of mulch insulation was installed on top of the wetland bed to keep the system from freezing. When the insulation layer was properly maintained (either through sufficient litterfall or replenishing the mulch layer), the wetland sustained air temperatures of as low as -26 degrees C without freezing problems.     

A comparative study of Cyperus papyrus and Miscanthidium violaceum-based constructed wetlands for wastewater treatment in a tropical climate

The treatment efficiencies of constructed wetlands containing Cyperus papyrus L. (papyrus) and Miscanthidium violaceum (K. Schum.) Robyns (synonymous with Miscanthus violaceum (K. Schum) Pilg.) were investigated in a tropical climate (Kampala, Uganda). Papyrus showed higher ammonium-nitrogen and total reactive phosphorus (TRP) removal (75.3% and 83.2%) than Miscanthidium (61.5% and 48.4%) and unplanted controls (27.9% ammonium-nitrogen). No TRP removal was detected in control effluent. Nutrients (N and P) were significantly higher (p<0.015) in papyrus than Miscanthidium plant tissues. Plant uptake and storage was the major factor responsible for N and P removal in treatment line 2 (papyrus) where it contributed 69.5% N and 88.8% P of the total N and P removed. It however accounted for only 15.8% N and 30.7% P of the total N and P removed by treatment line 3 (Miscanthidium violaceum). In addition, papyrus exhibited a significantly larger (p=0.000) number of adventitious roots than Miscanthidium. Nitrifying bacteria attached to papyrus (2.15 x 10(6)+/-1.53 x 10(5) MPN/g DW) and Miscanthidium roots (1.30 x 10(4)+/-8.83 x 10(2) MPN/g DW) and the corresponding nitrification activities were consistent with this finding. Epiphytic nitrifiers appeared more important for total nitrification than those in peat or suspended in water. Papyrus root structures provided more microbial attachment sites, sufficient wastewater residence time, trapping and settlement of suspended particles, surface area for pollutant adsorption, uptake, assimilation in plant tissues and oxygen for organic and inorganic matter oxidation in the rhizosphere, accounting for its high treatment efficiency.     

强化人工湿地处理城市生活污水研究

人工湿地是投资低、能耗低的一种污水处理技术,对于小城镇污水处理有着重要的意义.主要介绍了一种复合人工湿地的运行情况、处理效果及重庆地区一部分水生植物对湿地的适应性,实验结果表明水力停留时间对人工湿地的处理效果有着重要的影响,在36 h的水力停留时下,人工湿地的处理效果达到了<城镇污水处理厂污染物排放标准>一级B类标准的要求,并为西部地区的人工湿地设计提供一定的参考.     

具有结构化方向信息和特征点检测的指纹分类算法研究

针对大型指数数据库中的匹配难点,基于异常点检测及其相互位置关系和结构化方向信息,提出了一种针对指纹图像质量较差环境下的分类算法。实验结果表明,该算法具有良好的特性,满足实用要求。     

Aerobic degradation of acid orange 7 in a vertical-flow constructed wetland

Biological, aerobic degradation of an azo dye and of the resultant, recalcitrant, aromatic amines in a constructed wetland (CW) was demonstrated for the first time. A vertical-flow CW, planted with Phragmites sp. was fed with 127 mg l⁻¹ of acid orange 7 (AO7) at hydraulic loads of 28, 40, 53 and 108 l m⁻²day⁻¹. Color removal efficiencies of up to 99% clearly demonstrate cleavage of the azo bond, also confirmed by the similar AO7 removal and SO₄²⁻ release rates revealing that adsorption onto the matrix was constant. The positive redox potential at the outlet demonstrates that aerobic conditions were present. Chemical oxygen demand and total organic carbon removal efficiencies of up to 93% were also indicative of AO7 mineralization. The degradation of sulfanilic acid was confirmed by the presence of NO₃⁻, SO₄²⁻ and secondary metabolites, which suggest at least two degradation pathways leading to a common compound, 3-oxoadipate.     

多级人工湿地在风景园林中的应用研究 以西德维尔友谊学校为例

伴随着城镇化进程的不断加快,城市水资源短缺和水质恶化已经影响到我国可持续发展。与传统水处理基础设施相比,人工湿地作为一种生态水净化措施,由于其优美的景观特性和有效的水质改善功能,已成为研究和应用的热点,正日益受到重视。本文重点对多级人工湿地的概念、特征、优劣势和基本技术流程进行介绍,并以此为基础从多学科合作的视角重点探讨多级人工湿地与风景园林的结合,研究风景园林师在合作设计过程中的主要任务,并以西德维尔友谊学校中央湿地庭院为例从多学科协作设计、选址和场地设计、水净化系统设计、植物选择与设计等角度对其设计方法进行论述,为推动更加符合我国国情的人工湿地水净化技术和应用模式研究,以及未来示范推广奠定一定的基础。     

Inhibition kinetics of salt-affected wetland for municipal wastewater treatment

A mathematical model was developed in order to describe the system behavior and performance of a constructed wetland (CW) treatment under salt-affected conditions. The rate of biodegradation of organic wastes was modeled using the first-order kinetics while the effect of salt concentrations was accounted by growth inhibition. Experimental data were used to determine model constants of the mathematical model. The experimental units were planted with cattail (Typha angustifolia) and fed with spiked municipal wastewater. The hydraulic retention time varied from 12 to 120 h and wastewater conductivity was in the range of 4-32 mS/cm. At specified conditions the model was found to well describe the trend of the experimental data in terms of BOD removal with the Pearson correlation of 0.872. The model also permits construction of a nomograph which can be used to aid the design and prediction of CW treatment under salt-affected conditions.