基于CA-MAS的水域总有机碳扩散模拟研究

当前水环境污染扩散研究一般基于普通数值模型模拟,忽略了水污染扩散微观驱动力的影响。为能更真实地反映其动态扩散过程,针对水域总有机碳(TOC)扩散机理,基于CA和MAS技术,将影响TOC扩散的自然和社会经济因素抽象为微观的水流Agent、风速Agent、径流量Agent、污水排放口Agent、人工管理Agent以及农业生产地Agent,将研究水域抽象为CA元胞空间,建立了CA-MAS水域总有机碳扩散模型,对水域总有机碳的动态演化过程进行模拟,并以武汉理工大学鉴湖水域作为实验区域,借助NetLogo仿真平台完成了模型的实现与验证。模拟结果表明,该模型基本能够反映水体总有机碳的扩散规律,可以为水环境污染控制提供参考。     

微波再生载苯酚活性炭过程中再生产物分析

研究了载氮气和无载气2种条件下,微波再生载苯酚活性炭过程中再生产物的成分和苯酚随再生过程的去向分布。结果表明,无载气时,微波功率越高,再生反应器内温度越高,吸附质的高温裂解反应越彻底,再生产物以挥发性气体为主,有机质种类很少;而当微波功率较低或载氮气再生时,反应器内温度相对较低,苯酚难以被彻底分解,再生产物中含多种复杂的链状或环状有机物。此外,载氮气时,经气提、挥发而去除的苯酚量约占总吸附量的一半,再生炭上无苯酚残留,活性炭吸附性能可完全恢复乃至优化;无载气时,经挥发而去除的苯酚量只有19.9%,其余大量苯酚则在微波作用下裂解或缩合为其他物质随尾气而去除,且再生炭上仍有少量苯酚未被解吸出来。因此,前者活性炭再生的效果优于后者。     

降解SO2功能菌的16S rRAN基因测序及降解特性

用低浓度SO2诱导驯化方法获得高效脱硫菌群,并用分离培养与16S rRNA基因测序技术相结合的方法鉴定菌群种属,分析驯化过程中种群结构的动态变化,同时研究分离纯菌种的脱硫性能。结果表明,从诱导驯化7 d和14 d菌液中分别分离出23株菌和22株菌,16S rRNA序列分析发现这些菌归属于13个种,其中有6个种(Rhodococcus erythropolis、Pseudomonas putida、Microbacterium oxydans、Sphingomonas koreensis、Acinetobacter junii、Acinetobacter johnsonii)对SO2-3有较强的降解能力,并在持续驯化过程中稳定的生长传代,降解产物以硫酸根为主,还有极少量的单质硫。与含混合菌的驯化菌液降解SO2-3的能力相比,单一脱硫菌的脱硫性能较弱。脱硫功能菌株及其基本特性的研究为微生物处理SO2烟气提供了丰富的菌源信息和理论基础。     

厌氧系统中碱处理对污泥减量的影响

碱解预处理污泥和原污泥按一定比例进行混合后,投入厌氧反应器中进行消化,研究其对污泥减量化的影响。结果表明,该处理既可以提高污泥减量率,又能改善污泥厌氧消化性能,提高污泥产气量。当碱处理污泥和原污泥混合比为1∶3时,在混合初期由于稀释作用和水解中和作用,溶液的pH能迅速恢复到中性。SS减少48%,较对照组提高了10%;SCOD减少约80%,较对照组提高20%,而空白对照组因未发生溶胞作用,各参数值均处于较低水平,降解率也维持在较低水平。     

Transhumant pastoralism,sustainable management of natural resources and endemic ruminant livestock in the sub-humid zone of West Africa

Transhumant pastoralism is one of the dominant livestock production systems in West Africa, and it is characterized by seasonal and cyclical movement of varying degrees between complementary ecological areas. The common pattern of transhumance is moving herds from areas with pasture and water scarcity such as the Sahelian zone to areas where the forage and water are found, often in the sub-humid zone. Whereas the transhumant herds from the Sahel are mainly Zebu breeds, endemic ruminant livestock (ERL) are the dominant breeds in sub-humid zone of West Africa because of their tolerance to tsetse-borne trypanosomosis disease. These livestock fulfill different functions in the livelihood of rural communities in the region. To identify potential areas of interventions for sustainable natural resource management to improve ERL productivity, a desk study that included spatial mapping was performed to review and document the existing knowledge on transhumance in West Africa. Additionally, group discussions were held to analyze the (actual or potential) effects of transhumant herds on natural resource management and ERL in the sub-humid zone. This study covered sub-humid zone in The Gambia, Guinea, Mali and Senegal. The key question we addressed in this study was as follows: What are the key trends and changes in transhumant pastoralism and how do these impact sustainable management of natural resources including endemic livestock? The results of the desk study and group discussions showed that there have been more southerly movements by transhumant pastoralists into the sub-humid zone over the past three decades and this has contributed to growing competition for grazing resources. The presence of transhumant herds in the sub-humid zone has a potential impact on management and conservation of ERL through crossbreeding with transhumant Zebu breeds from the Sahel but only study sites in Mali showed a high risk.     

The Use of Nahcolite Ore and Bag Filters For Sulfur Dioxide Emission Control

This paper describes some technical and economic aspects of the nahcolite ore injection process for the simultaneous removal of fly ash and sulfur oxides from stack gases. The process is capable of removing greater than 99% of the particulate matter and greater than 70% of the sulfur oxides present in such gases. In the process, nahcolite ore, a naturally occurring material containing 70 to 90% sodium bicarbonate, is ground to 90% passing through —200 mesh screens. Approximately 20% of the ground ore is used to precoat the filter bags in a baghouse filter while the remainder of the material is fed into the flue gas Just ahead of the baghouse. The flue gas is drawn through the baghouse by induced draft fans and sent up the stack. Most of the SO₂ and practically all of the fly ash in the flue gas can be removed as the gas passes through the filter bags. The spent nahcolite ore and fly ash are collected and conveyed to waste disposal as landfill, or alternatively processed for insolubilization by coprecipitation prior to landfilling. The technical feasibility of the process has been demonstrated in both bench scale and pilot scale engineering studies. Economic analyses performed for the cases of plants located in the midwest and southwest indicate lower capital costs for the nahcolite injection process when compared to wet scrubbing. On an annual cost basis, the nahcolite ore Injection process is comparable in cost to wet scrubbing for the case of the southwestern power plant, and somewhat more expensive for the case of the midwestern plant.     

Transmissometer Measurement of Participate Emissions from a Jet Engine Test Facility

The body of information presented in this paper is directed toward those individuals involved with handling hazardous materials, whether in actual use of such chemicals, or in monitoring atmospheric emissions. Although specifically relating experience in the design and testing of phosgene emission control equipment, it attempts to establish general guidelines for effectively dealing with emissions of hazardous materials. An approach for handling chemical pollutants having no established air quality emission standards is developed. The paper presents a technique for establishing process emissions at acceptably low levels to insure the health and safety of the general population as well as that of the process workers themselves. Methods, suitable for measuring phosgene at these low levels, have been investigated, and problems associated with such an investigation are discussed. While complete theoretical scrubber design criteria are beyond the scope of this paper, many of the "real world" problems which affected scrubber performance are presented. Finally, the practical aspects of process emissions control are illustrated by actual results from the system test.     

Urban-Center CO Air Quality Projections

The distribution of mutagenic activity and nitroaromatic components of polycyclic organic matter (POM) in ambient air at industrial, urban, suburban, rural, and remote sites was studied using organic extracts from high volume aerosol samples. Direct-acting mutagens including 1-nitropyrene (1-NP), dinitropyrenes (DNP), and hydroxynitropyrenes (HNP) were measured by high performance liquid chromatography while the mutagenicity was determined in the Salmonella bioassay with strain TA-98. Benzo(a)pyrene (BaP), one of the possible precursors of nitroaromatic compounds in POM, was also measured. In comparing samples from a range of sites, TSP and the concentration of BaP per mass of particulate matter decreased, as expected, at greater distances from urban and industrial combustion sources. However, the concentrations of polar nitroaromatic POM compounds per mass of particles were higher at a remote site than in nonindustrial urban and suburban areas. The mutagenicity in particulate matter extracts from the remote area was predominantly (>90 percent) in the very polar fractions. There were also high atmospheric levels of nitroaromatic compounds and mutagenicity in heavily industrialized areas. These observations may reflect the influences of source emissions, atmospheric transformations of POM compounds, and ther atmospheric processes on the composition of ambient suspended particulate matter.     

Trends and Relationships of O3, NOx and HC in the South Coast Air Basin of California

A basin-wide air quality trend analysis for the South Coast Air Basin of California is conducted for hydrocarbons (HC), NO_x, O₃ and CO using multi-station composite daily maximum-hour average ambient concentrations for the third quarter (July, August and September) from 1968 to 1985. Emissions and air quality trends are compared for the period 1968-1984. Ambient HC and NOX trends are somewhat different from estimated emission trends of HC and NO_x, while a definite, downward trend of ambient CO is consistent with vehicular emission control measures. Basin-wide ambient HC, NO_x and O₃ appear to show downward trends for the period 1970-1985, but because of high fluctuations it is difficult to delineate trends for shorter periods. The meteorology (850 mb temperature)-adjusted O₃ shows a more consistent downward trend than does unadjusted O₃. Polynomial and multiplicative regression models for basin-wide empirical O₃-HC-NO_x relationships Indicate that the O₃ variation is explained largely by the meteorological variable (850 mb temperature) although model estimations are improved by adding HC and NO_x concentration terms.