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1.
污水的水解(酸化)——好氧生物处理工艺   总被引:13,自引:0,他引:13  
介绍了水解(酸化)过程的原理、影响因素、判断指标、动力学过程,以及与好氧生物处理技术串联处理污水工艺的优点。水解(酸化)-好氧工艺可有效地用于城市污水和难降解工业废水的处理,对水解(酸化)过程进行优化,使其串联系统更有效。  相似文献   

2.
利用改进折流式生物反应器,研究了好氧渐变厌氧交替工艺对洗浴废水中氮、磷和有机污染物的去除效果。结果表明:洗浴废水中COD和BOD值分别从98.0-190.6mg/L和68.3-81.7mg/L下降到6-10mg/L和1-2mg/L,含氮化合物和含磷化合物的浓度则分别从13.5—25.2mg/L和9.9—13.5mg/L下降到1mg/L和0.5mg/L。在运行过程中,不需要添加甲醇,利用洗浴废水自身的有机物就能达到很好的脱氮、除磷和降解COD与BOD的效果,而且该工艺的动力消耗仅为传统活性污泥法的三分之一。  相似文献   

3.
低溶解氧条件下生物脱氮研究中的新现象   总被引:24,自引:1,他引:24  
活性污泥法中 ,曝气主要起供氧和扰动混合的作用 ,曝气提供的氧被微生物用来氧化有机物并合成细胞 .反应器中的溶解氧 (DO)浓度是重要的运行参数 ,曝气池中DO偏低 ,好氧微生物不能正常生长和代谢 ;DO过高 ,不仅能耗增加 ,而且细菌的活力也会降低 .一般要求曝气池中DO不低于 2mgL-1的水平 ,但在实践中常常会出现曝气强度过高的情况 .因而有必要通过有效手段将DO控制在适当的水平 ,既不影响微生物的正常生长和有机物的去除 ,同时又避免过多能耗 .传统观点认为 ,低DO条件会促进丝状菌生长 ,破坏污泥絮体的沉降性能 ;使胞外多聚物的产生量…  相似文献   

4.
好氧颗粒污泥因具有良好的沉降性能、较高的生物量、对污染物较高的去除能力,以及在工程应用中占地面积较少和运行成本较低,近年来被广泛关注.本文综述了絮状污泥的颗粒化过程,好氧颗粒污泥形成的影响因素及其物理、化学和生物学特性.研究发现,好氧颗粒污泥在生活污水、高浓度有机废水和富含有毒有害物质的废水处理中均可发挥重要作用,可以高效去除污水中的氮磷污染物、工业废水中的有机物、毒性物质和重金属等.好氧颗粒污泥的形成机理存在4种假说,基于絮状污泥颗粒化过程中形成的胞外聚合物及其助凝作用被普遍认为是好氧颗粒污泥的形成机理.最后进行了问题分析和前景展望,认为突破培养过程相对漫长、培养条件相对严苛技术瓶颈的好氧颗粒污泥技术对废水处理效能的提升具有重要意义.图3参110  相似文献   

5.
收集Carrousel 2000型氧化沟工艺启动过程中活性污泥样品,直接提取微生物的基因组DNA并纯化,然后对细菌16S rDNA的V3高变区进行PCR扩增和DGGE分离,通过比较DGGE图谱的相似性来研究工艺调试过程中微生物种群的变化情况.研究表明,活性污泥中具有非常丰富的微生物种群.调试初期水质波动对氧化沟中微生物种群的影响非常明显,但接种的成熟活性污泥中微生物种群能够很快适应新型氧化沟工艺的结构及水力特性.调试从4月开始,4月氧化沟中微生物种群相似性Cs最大值为68.9%,5~6月Cs最大值为70.8%,8月Cs最大值为73.0%,可见氧化沟中微生物种群相似性逐渐增加,直至稳定.在此过程中,系统对COD、氨氮的处理效果同步提高并趋于稳定.综合分析好氧活性污泥在氧化沟中驯化期为2个月.图4表4参12  相似文献   

6.
城市污泥毒性有机物对草履虫综合毒性研究   总被引:1,自引:0,他引:1  
本文以好氧发酵处理前、后城市污泥中毒性有机物提取液为实验液,以草履虫为实验动物进行了综合毒性研究。结果表明:好氧发酵前的实验液对草履虫的半致死浓度为5593mg/l,发酵后的实验液对草履虫的半致死浓度为56053mg/l。  相似文献   

7.
氯代苯及氯代酚类优先污染物好氧生物降解动力学的研究   总被引:2,自引:0,他引:2  
利用测定微生物呼吸耗氧量的方法,对氯代苯及氯代酚类中的7种优先污染物,用经它们分别驯化的活性污泥对其好氧生物降解动力学进行了研究。  相似文献   

8.
32种芳香化合物的好氧生物降解性表征   总被引:6,自引:0,他引:6  
本文采用芳香化合物生物降解产生的二氧化碳量作为表征其生物降解性的指标,测定了32囊芳香化合物好氧生物降解12d产生的二氧化碳量,在此基础上提出了定性划分有机物生物降解性的标准,按照此标准对32种芳香化合物的生物降解性进行了划分;另外还探索了影响生物降解性的诸因素。  相似文献   

9.
城镇污水处理厂废水中存在大量生物毒性物质,但该废水对动物的生殖能力影响研究还十分缺乏。利用大型溞暴露实验,检测广州市某采用A~2/O工艺的城镇污水处理厂出水的急性毒性和生殖毒性。48 h急性毒性实验表明,所有水样均未表现出急性毒性效应。慢性生殖毒性(14 d)测试结果表明:(1)从进水到缺氧池出水均能显著提高第一胎产溞数量;(2)进水和沉砂池出水显著增加受试期总产溞数量;(3)从厌氧池到出水工艺段受试溞的第一胎产溞时间均推后;(4)好氧池出水的毒性显著降低,但仍然对大型溞具有生殖毒性。研究表明,好氧池(A~2/O)工艺能够显著去除具有大型溞生殖毒性的物质,但污水处理厂废水的生殖毒性仍需要引起关注。  相似文献   

10.
采用强化生物絮凝工艺处理生活污水,试验结果验证了好氧反硝化的存在;好氧反硝化的效率依赖三个因素:溶解氧浓度、絮体大小、有效碳源。低溶解氧质量浓度有利于好氧反硝化脱氮,当ρ(DO)为0.5mg·L-1时,TN去除率达到57.7%。结合理论分析,对好氧反硝化的机理以及影响因素进行了探讨。  相似文献   

11.
Conservation science is a crisis discipline in which the results of scientific enquiry must be made available quickly to those implementing management. We assessed the extent to which scientific research published since the year 2000 in 20 conservation science journals is publicly available. Of the 19,207 papers published, 1,667 (8.68%) are freely downloadable from an official repository. Moreover, only 938 papers (4.88%) meet the standard definition of open access in which material can be freely reused providing attribution to the authors is given. This compares poorly with a comparable set of 20 evolutionary biology journals, where 31.93% of papers are freely downloadable and 7.49% are open access. Seventeen of the 20 conservation journals offer an open access option, but fewer than 5% of the papers are available through open access. The cost of accessing the full body of conservation science runs into tens of thousands of dollars per year for institutional subscribers, and many conservation practitioners cannot access pay‐per‐view science through their workplace. However, important initiatives such as Research4Life are making science available to organizations in developing countries. We urge authors of conservation science to pay for open access on a per‐article basis or to choose publication in open access journals, taking care to ensure the license allows reuse for any purpose providing attribution is given. Currently, it would cost $51 million to make all conservation science published since 2000 freely available by paying the open access fees currently levied to authors. Publishers of conservation journals might consider more cost effective models for open access and conservation‐oriented organizations running journals could consider a broader range of options for open access to nonmembers such as sponsorship of open access via membership fees. Obtención de Acceso Abierto a la Ciencia de la Conservación  相似文献   

12.
Summary Interactions were studied among alkaloid-containing legumes (Erythrina corallodendrum andSpartium junceum) and non-toxic plants (Citrus sinensis, Cucurbita moschata andEuphorbia tirucalli), several polyphagous homopterans,Aphis craccivora (Aphididae),Icerya purchasi, I. aegyptiaca (Margarodidae),Lepidosaphes ulmi (Diaspididae) andPlanococcus citri (Pseudococcidae), and some major natural enemies of these homopterans. Significant reductions in survival due to negative effects of alkaloid containing as compared with non-alkaloidal plants were recorded for the predatorsRodolia cardinalis andChilocorus bipustulatus, but not forCryptolaemus montrouzieri (Coleoptera: Coccinellidae),Chrysoperla carnea (Neuroptera: Chrysopidae) andSympherobius sanctus (Neuroptera: Sympherobiidae). The development time of the larvae or pupae ofR. cardinalis, C. carnea andS. sanctus was longer on the toxic plants than on the non-toxic ones. The percentage of parasitism ofA. craccivora collected from the non-alkaloidal plantsVicia palaestina andMelilotus albus was much higher than that onS. junceum. The parasitoid complexes ofA. craccivora differed between both plant groups. The nutritive value of honeydew ofI. purchasi andA. craccivora, as expressed by the life span ofEncyrtus infelix (Hymenoptera: Encyrtidae) adults, was also investigated. Life spans were significantly longer when the wasps fed on honeydew produced on non-alkaloidal plants (C. sinensis andPittosporum tobira) than on alkaloid containing plants whenI. purchasi — but notA. craccivora — was the producer. It is suggested that the chemical defense ofE. corallodendrum andS. junceum is exploited by polyphagous phytophages to reduce predation. In nature, population growth and density of four of the investigated homopterans are conspicuously high when they developed on the alkaloid containing plant species, and very low on non-alkaloid plants. The efficiency of their natural enemies may be reduced by sequestration of alkaloids (or other toxic plant compounds) or their transfer into excreted honeydew. Therefore it is assumed that a generalist phytophagous homopteran may be protected from its natural enemies, although at different rates of efficiency, if it can safely sequester the host allelochemical when it develops on toxic species within its host range.  相似文献   

13.
A bioblitz inexpensively and quickly generates biodiversity data, but bioblitzes are often conducted with haphazard, unreplicated sampling. Results tend to be taxonomically, geographically, or temporally biased, lack metadata, and consist of lists of observed taxa that do not enable further analyses or correction for imperfect detection. A rapid, recurring, structured survey (RRSS) uses a structured sampling design and temporal and spatial replication to survey randomly selected sites on a conservation property. We participated in a loosely structured bioblitz and a subsequent RRSS at Big Canoe Creek Nature Preserve in Springville (St. Clair County), Alabama (USA) to compare observed richness derived from the 2 survey approaches. The RRSS data structure enabled us to fit models that accounted for imperfect detection to estimate abundances, occupancy probabilities, and habitat associations. The loosely structured bioblitz data could not be used in such models. We present a new integrated multispecies abundance model that we applied to avian RRSS data. Our model extension enables estimation for the community, employs data augmentation to estimate the number of undetected species, and incorporates covariates. The RRSS generated a more comprehensive and less biased list of observed taxonomic richness than the loosely structured bioblitz (e.g., 73 vs. 45 bird species and 104 vs. 63 insect families from the RRSS vs. loosely structured bioblitz, respectively). Models fit to the RRSS data identified seasonal patterns in avian community composition and allowed for estimation of habitat–occupancy relationships for insect taxa. The RRSS protocol has potential for broad transferability as a standardized, quick, and inexpensive way to inventory biodiversity and estimate ecological parameters while providing an outreach opportunity.  相似文献   

14.
Summary Two South American polyphagous leaf beetles,Diabrotica speciosa andCerotoma arcuata, selectively accumulated the bitter tasting compound 23,24-dihydrocucurbitacin D in their body after ingesting root tissues of cucurbit plants. Similarly, three Asian Cucurbitaceae-feeding specialists in the genusAulacophora were found to sequester the same compound. Cucurbitacin analogs were shown to deter feeding by a bird predator, indicating an allomonal role for these compounds in cucurbitacin-associated chrysomelid leaf beetles both of New and Old Worlds. The strong affinity to cucurbitacins, selective sequestration of the analogs and consequent protection from predators suggested an ecological adaptation mechanism developed in common among these two geographically isolated subtribes in the Luperini.  相似文献   

15.
Abstract: In East Africa fire and grazing by wild and domestic ungulates maintain savannas, and pastoralists historically set fires and herded livestock through the use of temporary corrals called bomas. In recent decades traditional pastoral practices have declined, and this may be affecting biodiversity. We investigated the effects of prescribed fires and bomas on savanna bird communities in East Africa during the first and second dry seasons of the year (respectively before and after the rains that mark the onset of breeding for most birds). We compared abundance, richness, and community composition on 9‐ha burned plots, recently abandoned bomas, and control plots in the undisturbed matrix habitat over a 3‐year period. Generally, recently burned areas and abandoned bomas attracted greater densities of birds and had different community assemblages than the surrounding matrix. The effects of disturbances were influenced by interactions between primary productivity, represented by the normalized difference vegetation index, and time. Bird densities were highest and a greater proportion of species was observed on burned plots in the months following the fires. Drought conditions equalized bird densities across treatments within 1 year, and individuals from a greater proportion of species were more commonly observed on abandoned bomas. Yearly fluctuations in abundance were less pronounced on bomas than on burns, which indicate that although fire may benefit birds in the short term, bomas may have a more‐lasting positive effect and provide resources during droughts. Several Palearctic migrants were attracted to burned plots regardless of rainfall, which indicates continued fire suppression may threaten their already‐declining populations. Most notably, the paucity of birds observed on the controls suggests that the current structure of the matrix developed as a result of fire suppression. Traditional pastoralism appears critical to the maintenance of avian diversity in these savannas.  相似文献   

16.
Land-use change via human development is a major driver of biodiversity loss. To reduce these impacts, billions of dollars are spent on biodiversity offsets. However, studies evaluating offset project effectiveness that examine components such as the overall compliance and function of projects remain rare. We reviewed 577 offsetting projects in freshwater ecosystems that included the metrics project size, type of aquatic system (e.g., wetland and creek), offsetting measure (e.g., enhancement, restoration, and creation), and an assessment of the projects’ compliance and functional success. Project information was obtained from scientific and government databases and gray literature. Despite considerable investment in offsetting projects, crucial problems persisted. Although compliance and function were related to each other, a high level of compliance did not guarantee a high degree of function. However, large projects relative to area had better function than small projects. Function improved when projects targeted productivity or specific ecosystem features and when multiple complementary management targets were in place. Restorative measures were more likely to achieve targets than creating entirely new ecosystems. Altogether the relationships we found highlight specific ecological processes that may help improve offsetting outcomes.  相似文献   

17.
An argument is presented in which areas of natural arsenic contamination of modern groundwaters throughout Asia have a common origin. Arsenic originally accumulated in oceanic ferro-manganoan sediments of the eastern Palaeo-Tethys. This was further concentrated through oceanic crustal extinction in what later became the south-east Chinese accreted mineralised terrain. Proto-Himalayan uplift of this area created the palaeo-drainage systems of the Ganges – Brahmaputra, Irrawaddy, Mekong, and Red Rivers, with consequent headwater erosion of arsenic-rich sediments. Their downstream deposition as immature and easily redistributed Neogene sandstones, silts, and iron-rich clays has created secondary and tertiary reservoirs of adsorbed and authigenic arsenic, from which the current arsenic-rich groundwaters have evolved. Considering river basins within the above palaeo-hydrogeological framework provides a basis for assessing the risk of arsenic in groundwater basins of south and south-eastern Asia.  相似文献   

18.
Abstract: The last century has seen the ascendance of a core economic model, which we will refer to as Walrasian economics. This model is driven by the psychological assumptions that humans act only in a self‐referential and narrowly rational way and that production can be described as a self‐contained circular flow between firms and households. These assumptions have critical implications for the way economics is used to inform conservation biology. Yet the Walrasian model is inconsistent with a large body of empirical evidence about actual human behavior, and it violates a number of basic physical laws. Research in behavioral science and neuroscience shows that humans are uniquely social animals and not self‐centered rational economic beings. Economic production is subject to physical laws including the laws of thermodynamics and mass balance. In addition, some contemporary economic theory, spurred by exciting new research in human behavior and a wealth of data about the negative global impact of the human economy on natural systems, is moving toward a world view that places consumption and production squarely in its behavioral and biophysical context. We argue that abandoning the straightjacket of the Walrasian core is essential to further progress in understanding the complex, coupled interactions between the human economy and the natural world. We call for a new framework for economic theory and policy that is consistent with observed human behavior, recognizes the complex and frequently irreversible interaction between human and natural systems, and directly confronts the cumulative negative effects of the human economy on the Earth's life support systems. Biophysical economics and ecological economics are two emerging economic frameworks in this movement.  相似文献   

19.
Effects of Coffee Management on Deforestation Rates and Forest Integrity   总被引:1,自引:0,他引:1  
Knowledge about how forest margins are utilized can be crucial for a general understanding of changes in forest cover, forest structure, and biodiversity across landscapes. We studied forest‐agriculture transitions in southwestern Ethiopia and hypothesized that the presence of coffee (Coffea arabica)decreases deforestation rates because of coffee's importance to local economies and its widespread occurrence in forests and forest margins. Using satellite images and elevation data, we compared changes in forest cover over 37 years (1973–2010) across elevations in 2 forest‐agriculture mosaic landscapes (1100 km2 around Bonga and 3000 km2 in Goma‐Gera). In the field in the Bonga area, we determined coffee cover and forest structure in 40 forest margins that differed in time since deforestation. Both the absolute and relative deforestation rates were lower at coffee‐growing elevations compared with at higher elevations (?10/20% vs. ?40/50% comparing relative rates at 1800 m asl and 2300–2500 m asl, respectively). Within the coffee‐growing elevation, the proportion of sites with high coffee cover (>20%) was significantly higher in stable margins (42% of sites that had been in the same location for the entire period) than in recently changed margins (0% of sites where expansion of annual crops had changed the margin). Disturbance level and forest structure did not differ between sites with 30% or 3% coffee. However, a growing body of literature on gradients of coffee management in Ethiopia reports coffee's negative effects on abundances of forest‐specialist species. Even if the presence of coffee slows down the conversion of forest to annual‐crop agriculture, there is a risk that an intensification of coffee management will still threaten forest biodiversity, including the genetic diversity of wild coffee. Conservation policy for Ethiopian forests thus needs to develop strategies that acknowledge that forests without coffee production may have higher deforestation risks than forests with coffee production and that forests with coffee production often have lower biodiversity value. Efectos de la Administración Cafetalera sobre las Tasas de Deforestación y la Integridad de los Bosques  相似文献   

20.
As drivers of terrestrial ecosystems, humans have replaced large carnivores in most areas, and human influence not only exerts striking ecological pressures on biodiversity at local scales but also has indirect effects in distant corners of the world. We suggest that the multibillion dollar cashmere industry creates economic motivations that link western fashion preferences for cashmere to land use in Central Asia. This penchant for stylish clothing, in turn, encourages herders to increase livestock production which affects persistence of over 6 endangered large mammals in these remote, arid ecosystems. We hypothesized that global trade in cashmere has strong negative effects on native large mammals of deserts and grassland where cashmere‐producing goats are raised. We used time series data, ecological snapshots of the biomass of native and domestic ungulates, and ecologically and behaviorally based fieldwork to test our hypothesis. In Mongolia increases in domestic goat production were associated with a 3‐fold increase in local profits for herders coexisting with endangered saiga (Saiga tatarica).That increasing domestic grazing pressure carries fitness consequences was inferred on the basis of an approximately 4‐fold difference in juvenile recruitment among blue sheep (Pseudois nayaur)in trans‐Himalayan India. Across 7 study areas in Mongolia, India, and China's Tibetan Plateau, native ungulate biomass is now <5% that of domestic species. Such trends suggest ecosystem degradation and decreased capacity for the persistence of native species, including at least 8 Asian endemic species: saiga, chiru (Pantholops hodgsoni), Bactrian camel (Camelus bactrianus), snow leopard(Panthera uncia), khulan(Equus hemionus), kiang (E. kiang), takhi (E. przewalski), and wild yak (Bos mutus). Our results suggest striking yet indirect and unintended actions that link trophic‐level effects to markets induced by the trade for cashmere. Globalización del Mercado de Cachemira y la Declinación de Mamíferos Mayores en Asia Central  相似文献   

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