垃圾渗滤液与城市污水同时处理系统优化运行策略探讨

采用倒置A2/O工艺处理垃圾渗滤液与城市污水的混合污水.模型试验结果表明,水力停留时间是影响混合污水氮和有机物去除的控制因素;水温为23～30℃、泥龄为20 d时,最优运行参数为:水力停留时间9h、DO2 mg/L、外回流比80％、内回流比200％,此时COD、NH3-N和TN去除率分别为76.4％～78.2％、95....     

Spatial and temporal variations in NO2 distributions over Beijing,China measured by imaging differential optical absorption spectroscopy

During the CAREBEIJING campaign in 2006, imaging differential optical absorption spectroscopy (I-DOAS) measurements were made from 08:00 to 16:00 on September 9 and 10 over Beijing, China. Detailed images of the near-surface NO₂ differential slant column density (DSCD) distribution over Beijing were obtained. Images with less than a 30-min temporal resolution showed both horizontal and vertical variations in NO₂ distributions. For DSCD to mixing ratio conversion, path length along the lines of I-DOAS lines of sight was estimated using the light-extinction coefficient and Ångstrom exponent data obtained by a transmissometer and a sunphotometer, respectively. Mixing ratios measured by an in-situ NO₂ analyzer were compared with those estimated by the I-DOAS instrument. The obtained temporal and spatial variations in NO₂ distributions measured by I-DOAS for the two days are interpreted with consideration of the locations of the major NO_x sources and local wind conditions. I-DOAS measurements have been applied in this study for estimating NO₂ distribution over an urban area with multiple and distributed emission sources. Results are obtained for estimated temporal and spatial NO₂ distributions over the urban atmosphere; demonstrating the capability of the I-DOAS technique. We discuss in this paper the use of I-DOAS measurements to estimate the NO₂ distribution over an urban area with multiple distributed emission sources.     

Conceptual classification model for Sustainable Flood Retention Basins

The aim of this paper is to recommend a rapid conceptual classification model for Sustainable Flood Retention Basins (SFRB) used to control runoff in a temperate climate. An SFRB is an aesthetically pleasing retention basin predominantly used for flood protection adhering to sustainable drainage and best management practices. The classification model was developed on the basis of a database of 141 SFRB using the River Rhine catchment in Baden (part of Baden-Württemberg, Germany) as a case study. It is based on an agglomerative cluster analysis and is intended to be used by engineers and scientists to adequately classify the following different types of SFRB: Hydraulic Flood Retention Basin, Traditional Flood Retention Basin, Sustainable Flood Retention Wetland, Aesthetic Flood Retention Wetland, Integrated Flood Retention Wetland and Natural Flood Retention Wetland. The selection of classification variables was supported by a principal component analysis. The identification of SFRB in the data set was based on a Ward cluster analysis of 34 weighted classification variables. Scoring tables were defined to enable the assignment of the six SFRB definitions to retention basins in the data set. The efficiency of these tables was based on a scoring system which gave the conceptual model for the example case study sites an overall efficiency of approximately 60% (as opposed to 17% by chance). This conceptual classification model should be utilized to improve communication by providing definitions for SFRB types. The classification definitions are likely to be applicable for other regions with both temperate oceanic and temperate continental climates.     

Ground-level ozone in the Pearl River Delta and the roles of VOC and NO(x) in its production

In many regions of China, very rapid economic growth has been accompanied by air pollution caused by vehicle emissions. In one of these regions, the Pearl River Delta, the variations of ground-level ozone and its precursors were investigated. Overall, the ambient concentrations of NO(2) increased quickly between 1995 and 1996, but then slightly decreased due to stringent nitrogen oxide (NO(x)) emission controls. Nonetheless, ambient NO(2) levels in the Pearl River Delta remained high. The regional average concentrations of volatile organic compounds (VOCs) were 290 ppbC in summer and 190 ppbC in autumn. Local emissions and long-distance transportation of pollutants play important roles in the regional distribution of VOCs. Ambient O(3) production is significant in urban areas and also downwind of cities. The relative incremental reactivities (RIRs), determined by an observation-based model, showed that ground-level ozone formation in the Guangzhou urban area is generally limited by the concentrations of VOCs, but there are also measurable impacts of NO(x).     

三峡库区不同水保措施下紫色土水分特征曲线特征及模型拟合

土壤水分特征曲线是反映土壤持水性、供水性及水分有效性等基本特性的重要曲线,是定量研究土壤水滞留与运移十分重要的土壤水动力学参数之一。通过分析比较等高绿篱农业系统和石坎梯田农业系统的紫色土水分特征曲线,探讨不同水保措施下紫色土水分特征曲线特征,将实测数据对国内外常见的几种土壤水分特征曲线模型分别进行拟合,并优选一种适合三峡库区紫色土的水分特征曲线模型。结果表明：不同处理紫色土水分特征曲线存在较大差异。同一土壤水吸力水平下,新银合欢处理土壤持水量最高,其次为石坎梯田处理,自然坡面处理土壤持水量最小。随土壤水吸力增大,各处理间差异越明显。Gardner模型和Van Genuchten模型均可用于描述三峡库区紫色土水分特征曲线,根据不同的需要选取不同的模型,Gardner模型适合简单快捷的田间土壤水分管理,Van Genuchten模型适合进一步土壤水力传导参数的推求应用.     

侧沟式膜泥法一体化OCO工艺中水力停留时间对脱氮除碳的影响

在传统OCO工艺基础上设计了一体化OCO工艺,在厌氧区放置填料,将二沉池和生物反应器合建,并就水力停留时间(HRT)对生物反应器脱氮除碳的影响进行研究。在进水COD为260～360 mg/L,好氧区DO为2 mg/L左右,缺氧区<0.5 mg/L,MLSS为4 500 mg/L左右时,分别研究了不同HRT下的脱氮除碳效果。研究结果表明：随着HRT的逐渐增大,出水COD值无明显波动,COD去除率达到90%以上,出水氨氮随着HRT的增大而降低;但仅当HRT为12 h左右时,氨氮和总氮均有良好的去除效果,去除率分别可达到93%和80%。     

Improving Anammox start-up with bamboo charcoal

Three Upflow Anaerobic Sludge Blanket (UASB) reactors were compared for Anammox enrichment using synthetic wastewater with Spherical Plastic (SP) and Bamboo Charcoal (BC) addition, and without carrier (CK). After four months of operation, the Anammox activity occurred in all reactors allowing continuous removal of ammonium and nitrite. Ammonium and nitrite removal efficiencies were all higher than 98% in steady phase with the effluent concentrations below 1 mg L⁻¹. The start-up time could be shortened from 117 to 97 d in CK and SP reactor to 85 d in BC amendment reactor. Quantitative PCR (q-PCR) analyses indicated a significant increase in the number of Anammox bacteria in BC amended reactor as compared with CK and SP during the entire start-up periods. The copy numbers of Anammox of 16S rRNA gene in the reactor with BC amendment could reach up to 6 × 10⁹ copies g⁻¹ Volatile Suspended Solids, around 22.5 times and 12.3 times greater than that in CK and SP reactor, respectively. BC addition could accelerate the start-up of Anammox and significantly increase the Anammox bacteria number.     

Consequence of altered nitrogen cycles in the coupled human and ecological system under changing climate: The need for long-term and site-based research

Anthropogenically derived nitrogen (N) has a central role in global environmental changes, including climate change, biodiversity loss, air pollution, greenhouse gas emission, water pollution, as well as food production and human health. Current understanding of the biogeochemical processes that govern the N cycle in coupled human–ecological systems around the globe is drawn largely from the long-term ecological monitoring and experimental studies. Here, we review spatial and temporal patterns and trends in reactive N emissions, and the interactions between N and other important elements that dictate their delivery from terrestrial to aquatic ecosystems, and the impacts of N on biodiversity and human society. Integrated international and long-term collaborative studies covering research gaps will reduce uncertainties and promote further understanding of the nitrogen cycle in various ecosystems.     

Socioeconomic Driving Factors of Nitrogen Load from Food Consumption and Preventive Measures

To diagnose environmental nitrogen (N) load from food consumption and to suggest preventive measures, this study identified relationships between nitrogen load from food consumption and driving factors by examining six representative countries and regions for the period 1970–2009 as an example. The logarithmic mean Divisia index technique was used to disassemble nitrogen load growth into four driving factors: population, economic activity, food intensity of the economy, and nitrogen content of food. In all study areas, increased economic activity was the main factor driving nitrogen load increase. The positive effect of population growth was relatively small but not negligible and changes in food intensity had a decreasing effect on nitrogen load. Changes in nitrogen content of food varied between areas. Broad strategies to reduce and mitigate nitrogen loading and decouple nitrogen load from economic growth in both developed and developing countries are suggested.     

水力停留时间对MBR中溶解性微生物产物生成的影响

考察水力停留时间(HRT)对MBR中膜污染的主要污染物——溶解性微生物产物(SMP)生成的影响。结果表明,在装置稳定运行期间,MBR中SMP随运行时间出现累积。与HRT为8 h相比,HRT为12 h时,SMP在MBR中平均累积量要少10.1%,SMP中多糖含量平均高7 mg/L左右,而蛋白质含量平均低45.6%。SMP的平均粒径随装置运行呈下降趋势,并且HRT较短有利于粒径较小的SMP生成,从而堵塞膜孔;HRT较长有利于粒径较大的SMP生成,从而形成凝胶层,两种情况导致膜污染的机制不同。