德国可再生能源政策与沼气工程简介

本文介绍了德国可再生能源政策,政策对沼气、光伏太阳能及风力发电行业的影响,沼气工程技术现状。德国的经验表明,政策激励是农场沼气工程发展的主要动力。     

沼气工程的自动化应用——昌平区东新城村沼气集中供气工程PLC模式

本文以北京市昌平区东新城沼气集中供气工程为例,该工程利用三菱PLC可编程控制系统对沼气工程的进料系统、发酵系统、沼气净化系统和沼气存储系统等实施监测与控制,提高了沼气工程的管理水平,降低了工人的劳动量,降低了运行成本.     

农村沼气能源开发利用模式分析

中国沼气发展已进入产业化发展时期,对沼气能源开发利用模式进行分析,将有助于沼气产业化的发展进程.从沼气工程规模和沼气能源开发利用与种养业之间的关系两个角度探讨农村沼气能源开发利用模式,并对目前沼气工程数量最多、推广面最广的农村户用沼气利用模式效益进行定量或定性分析,为农村沼气能源开发利用提供对策建议.     

养殖场沼气工程应用模式

介绍了厌氧发酵制沼气的技术、沼气的应用，及我国农村沼气发展模式，分析了养殖场沼气工程的应用模式以及沼气利用的市场前景。     

中小型养殖场沼气工程技术的应用

中小型养殖场采用厌氧污泥床处理有机污水取得了较好的效果.工程实践证明,该工艺不仅投资省,运行费用低,而且产生可供利用的沼气,利用沼气发酵的残余物沼渣和沼液可培植无公害农产品.该技术具有很好的推广价值.     

沼气工程及综合利用与生态农业的关系

从沼气工程及综合利用与生态农业的深刻内涵入手,阐述了沼气工程及综合利用与生态农业互促共进的关系。指出发展沼气工程及综合利用将促进生态农业建设,生态农业发展必将推动沼气工程及综合利用开发,并提出福建省加快发展沼气工程及综合利用促进生态农业建设的对策措施。     

中外沼气发展史略

产甲烷菌是一种古细菌(Archebacteria),有机物在厌氧条件下的产甲烷现象早在远古便有。而有文字记载的人类发现、认识以及研究开发并利用厌氧消化产生沼气的历史还是近两千年内的事情。本文通过大量史料、史实,从化学、生物、地质和比较历史学的角度,论证了西汉四川“火井”浅层生物生成气与沼气在形成机理上的相同性,从而提出了中国是世事上最早发现并利用沼气的国家(年代可追朔到公元前一世纪)的新观点,这一研究结果比以往中国沼气史的计算方法提早了约2000年。本文还用详尽的文字论述了中外沼气的发现、沼气实验,厌氧消化工艺研究及人工制取沼气技术的发展史。     

厌氧发酵沼气工程的工艺及存在的问题

利用厌氧消化技术处理畜禽养殖废水，制取清洁能源——沼气，在治理污染的同时变废为宝，减少温室气体的排放，从而实现国民经济的可持续性发展。本文概述了集约化畜禽养殖场废污水处理中采用的厌氧发酵工艺，以及厌氧发酵沼气工程中存在的问题。     

沼气连续压力水洗提纯试验与分析

沼气的水洗法提纯是一种重要的沼气提纯生物质天然气的方式,由于拥有环境友好、工艺简单、处理效率高等优势而广泛应用于欧洲的大中型沼气工程中。依据相关理论与实践经验,搭建了一套沼气连续压力水洗提纯设备。利用该设备在不同压力及气水比下进行试验,得到了相关的试验数据。试验中提纯沼气中CO_2的浓度最低降到了3.8%,达到了天然气的标准。试验结果与常压雾化水洗设备的试验结果进行了对比分析,得出了压力是沼气水洗法提纯的最重要的工艺参数。将试验数据进行函数拟合,得到一条关于压力、气水比和CO_2去除率的沼气水洗法提纯的经验公式。     

大棚式沼气工程在畜禽粪便污染治理中的应用

畜禽养殖污染已成为农村环境污染的主因,介绍了大棚式沼气工程在治理农村畜禽养殖污染上的应用,该技术可解决冬季沼气工程不产气问题,保障沼气工程正常运行,环境效益、社会效益显著。该技术为畜禽粪便污染治理提供了经验借鉴。     

规模化养猪场沼气工程发展的金融政策研究

沼气工程是养猪场废弃物污染治理的主要途径，可在一定程度上缓解农村的环境压力和能源问题。金融政策对具有正外部性的沼气项目具有激励作用，并可通过市场手段提高其综合效率。文章通过对影响养猪场的融资因素进行分析并对国内外金融政策进行比较，提出了促进规模化养猪场沼气工程发展的建议。     

Determining Ecological Equivalence in Service-to-Service Scaling of Salt Marsh Restoration

The amount of ecological restoration required to mitigate or compensate for environmental injury or habitat loss is often based on the goal of achieving ecological equivalence. However, few tools are available for estimating the extent of restoration required to achieve habitat services equivalent to those that were lost. This paper describes habitat equivalency analysis (HEA), a habitat-based “service-to-service” approach for determining the amount of restoration needed to compensate for natural resource losses, and examines issues in its application in the case of salt marsh restoration. The scientific literature indicates that although structural attributes such as vegetation may recover within a few years, there is often a significant lag in the development of ecological processes such as nutrient cycling that are necessary for a fully functioning salt marsh. Moreover, natural variation can make recovery trajectories difficult to define and predict for many habitat services. HEA is an excellent tool for scaling restoration actions because it reflects this ecological variability and complexity. At the same time, practitioners must recognize that conclusions about the amount of restoration needed to provide ecological services equivalent to those that are lost will depend critically on the ecological data and assumptions that are used in the HEA calculation.     

The Effect of Long-Term Marsh Management on Land-Loss Rates in Coastal Louisiana

3 ha) studied previously were obtained, expanded, and tested statistically to provide empirically valid conclusions over a longer management period than previously available (1–32 years compared to 6–37 years). There was no statistically significant difference between managed and nearby reference sites. The effects of changes in the regional environment appear to have had much greater influence on the land-loss rates than did management at individual sites.     

Recommended Design for More Accurate Duplication of Natural Conditions in Salt Marsh Creation

Construction of 653 ha of salt marsh habitat from dredged material near the Aransas National Wildlife Refuge, Texas, has been proposed, with the goal of increasing the area of habitat available to endangered whooping cranes (Grus americana). We assessed prototype created wetlands, and their similarity to natural reference sites, in terms of topography, vegetation, and hydrology. The created sites were steeply sloped relative to natural sites and were dominated by monotypic stands of Spartina alterniflora. Natural sites were dominated by vegetation more tolerant of desiccation and hypersalinity and by unvegetated salt pans. Differences in vegetation communities and distributions of habitat types resulted from efforts to enhance habitat diversity in created marsh cells through manipulation of marsh topography. However, the scale at which this diversity occurred in natural marsh of the study area was not considered. When constructing wetlands in cellular configurations, we recommend creation of large complexes of adjoining, hydrologically linked, cells wherein the desired habitat diversity is created at the scale of the entire complex, rather than within a single cell. Suggested design modifications would increase the similarity of created marshes to natural reference sites, potentially improving habitat function.     

Impacts of Adjacent Land Use and Isolation on Marsh Bird Communities

Over the next half century the human population is expected to grow rapidly, resulting in the conversion of rural areas into cities. Wetlands in these regions are therefore under threat, even though they have important ecosystem services and functions. Many obligate marsh-nesting birds in North America have shown declines over the past 40 years, and it is important to evaluate marsh bird community response to increased urbanization. We surveyed 20 coastal marshes in southern Ontario, Canada, and found that obligate marsh-nesting birds preferred rural over urban wetlands, generalist marsh-nesting birds showed no preference, while synanthropic species showed a trend towards increased richness and abundance in urban marshes. The Index of Marsh Bird Community Integrity (IMBCI) was calculated for each wetland and we found significantly higher scores in rural compared to urban wetlands. The presence of a forested buffer surrounding the marsh was not an important factor in predicting the distribution of generalists, obligates, synanthropic species, or the IMBCI. More isolated marshes had a lower species richness of obligate marsh-nesters and a lower IMBCI than less isolated marshes. Based on our results, we recommend that urban land use is not the dominant land use within 1000 m from any wetland, as it negatively affects the abundance and richness of obligate marsh-nesters, and the overall integrity of the avian community. We also recommend that all existing wetlands be conserved to mitigate against isolation effects and to preserve biodiversity.     

Salt Marsh Diking and Restoration: Biogeochemical Implications of Altered Wetland Hydrology

Experimental short-term desalination and drainage of salt marsh cores in greenhouse microcosms caused Spartina production to increase after one growing season, reflecting decreased salt stress and sulfide toxicity. However, production thereafter declined, likely due to pyrite oxidation and acidification in drained treatments and sulfide accumulation in waterlogged treatments. A survey of longer-term (decadal) effects of diking on peat composition of Cape Cod, Massachusetts, USA, marshes revealed acidification, Fe(II) mobilization, and decreased organic content in drained sites. Despite the aerobic decomposition of organic matter, abundant nutrients remained as sorbed NH₄ and mineral-bound PO₄. In diked, seasonally waterlogged sites, porewater alkalinity, sulfide, ammonium and orthophosphate were much lower, and organic solids higher, than in adjacent natural marsh. Seawater was added to cores from diked marshes to study the effects of tidal restoration. Salination of the drained peat increased porewater pH, alkalinity, ammonium, orthophosphate, Fe, and Al; copious ammonium N, and Fe(II) for sulfide precipitation favored Spartina growth. Salination of diked–waterlogged peat increased sulfate reduction and caused 6–8 cm of sediment subsidence. The resulting increase in porewater sulfides and waterlogging decreased vigor of transplanted Spartina alterniflora. Results indicate that seawater restoration should proceed cautiously to avoid nutrient loading of surface waters in drained sites or sulfide toxicity in diked–waterlogged marshes.