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户用沼气池生命周期环境影响及经济效益评价 总被引：1，自引：0，他引：1
为了评价户用沼气池全生命周期的环境影响和经济效益,以中国农村8m3户用沼气池为研究对象,分别采用生命周期评价和生命周期成本方法对户用沼气池全生命周期的环境影响和经济效益进行了定量评价。研究结果表明,8m3户用沼气池全生命周期(功能单元为400m3沼气)对环境影响负荷为1.641 8人当量,各种环境影响类型的相对贡献大小依次为富营养化、全球变暖、酸化。生命周期成本为3 082元,经济收益为835元,成本回收期为3.69年。基于上述分析得出沼肥的不合理利用和沼气池建设材料的弊端是影响沼气池环境排放和经济效益的主要因素,并提出了户用沼气行业减少环境排放和提高经济效益的对策和建议。 相似文献
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基于LCA方法的秸秆沼气发电和制备生物天然气的环境排放评价 总被引：3，自引：0，他引：3
为对比特大型沼气工程沼气资源化不同方式所带来的环境影响差异,文章运用生命周期评价方法(Life cycle assessment,LCA),对特大型秸秆沼气发电工程(日均发电量4万kWh)及生物天然气工程(日产气量1.2万方)进行环境影响评价并比较两者的环境影响及敏感性因素分析。其中包括边界划分、清单分析、各生产阶段的能耗、环境排放计算。根据计算结果显示,沼气发电时,对环境排放影响最大的是秸秆沼气发酵阶段,最敏感因素为单位干物质产气率(mL·g^-1 TS);制备生物天然气时以上两个指标分别为:沼气的提纯过程和沼气提纯技术的选择。从进行能源替代减少环境排放影响的角度来看,生物燃气替代民用散煤要优于沼气发电替代燃煤发电。 相似文献
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为对比研究大型沼气工程不同沼液处理方式造成的综合性能差异,文章以某禽畜养殖厂沼气工程为例,以生命周期评价法为基础,对发酵出料直接排放及固液分离后排放两种情况进行对比,在此基础上从经济、能效和环境影响3个方面进行评价。设定情况一为发酵出料排放灌溉;情况二为固液分离后沼渣作为有机肥基质出售。结果表明,经济性方面,当沼渣售价为300元·m-3时,情况二下动态投资回收期9. 8年、自筹资金动态投资回收期3. 21年,明显优于情况一的无法在运行周期20年内收回成本、自筹资金投资回收期9. 7年;当沼渣售价低于90元·m-3时,情况一有更好的经济性。能效评价中可得情况一、情况二能量产出比分别为7. 75,17. 26,情况二较情况一单位能耗升高26. 2%,单位产能增加2. 8倍。环境影响分析结果表示环境一、情况二的综合环境影响潜力为0. 072,0. 067。综合考虑经济、能效及环境影响三方面因素,情况二是经济、节能、相对环境友好的沼气工程运行模式。 相似文献
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【目的】社会经济的发展、商品性能源的普及和种养结构的调整,使农户对户用沼气池的能源依赖性逐步弱化,户用沼气池的使用率逐年降低,闲置率和废弃率逐步升高,需要及时盘活现有沼气资源,妥善处置闲置废弃的沼气设施,发挥其综合效益。【方法】研究小组通过实地调研,以户用沼气建设时间早、涉及范围广、有养殖条件的云南省峨山县作为“一低两高”现象的调查对象,了解农村户用沼气池的使用现状,对现有“沼改厕”处置方式进行了分析,找出了处置后出现的难题,并提出了针对性对策,丰富“沼改厕”模式下的处置方式。【结果】农户用能结构和户用沼气池能源属性的改变,是导致户用沼气池使用率较低的主要原因。一口农村户用沼气池改建厕所,每个厕所可节约50%的成本,从而盘活当地沼气设施资产约540万元,不仅有效盘活了农村废弃闲置沼气资产,还可以为农村人居环境整治和厕所革命建设提供助力。【结论】应进一步提高农户对户用沼气池的使用与认知水平,因地制宜推进“一池多改”模式,并建立“一池多改”后的长效管护机制,推动农村绿色发展。 相似文献
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随着工业化、城镇化如火如荼的推进,山区农村常住人口锐减,散户养殖萎缩,规模化养殖场增加,农村户用沼气使用率逐步下降已成必然趋势。山区规模畜禽养殖场的大量发展,对周边农田和环境势必造成严重污染,而中小型沼气工程＂能源生态型＂（或＂能源环保型＂）工艺,是治理规模化养殖场污染。 相似文献
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随着我国经济建设和社会文明的高度发展,环境和资源问题日益突出,节能减排的压力越来越大。在我国社会总能耗中,新能源开发能耗占据了相当大的比例。在新能源开发能耗中,寒区沼气工程加热增温能耗的问题尤为突出。为此,以寒区沼气工程加热增温节能标准、能耗监测技术导则为依据,在分析研究能耗监测系统体系的基础上提出了寒区沼气工程加热增温能耗数据存储与处理系统的设计思路,并在生产现场搭建了能耗监测系统的基础平台。该系统能够对寒区沼气工程加热增温的能源利用率和消耗水平进行统计计算,为下一步建立基于寒区沼气工程加热增温节能的能源环境最优控制模型提供基本依据和基础资料。 相似文献
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生态文明视角下沼气能源评价指标体系构建 总被引：1，自引：0，他引：1
把农业废弃物转变为沼气能源是实现生态文明建设和农村能源消费可持续发展的一种有效路径。为此,国家出台一系列政策推动沼气能源的开发和推广使用。为了评估政策实施的绩效,文章在参考国内外学者对沼气能源效益评价指标的基础上,从环境、经济、社会、安全等4个方面进行了较为全面、详细的总结。然后基于指标设置的合理性、指标数据的可获得性以及指标定义的重要程度等因素对相关评价指标进行增加和删减,提出了一套较为完整、科学的沼气能源效益评价指标体系。研究结果力图为沼气能源效益评价、项目绩效评估、政策完善提供参考依据。 相似文献
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Muhammad Nadeem Asghar Muhammad Kaleem Ullah Muhammad Mohsin Hafeez 《Irrigation and Drainage Systems》2008,22(3-4):239-252
Stream salinity management is of prime importance for ensuring environmental sustainability of rivers, streams, lakes and other water bodies. Saline groundwater inflows are the main cause of deteriorating quality of stream flows; especially during periods of low flows. The Murray-Darling Basin is a good example for reducing groundwater recharge from irrigated agricultural areas with successful implementation of land and water management plans (LWMPs). In most cases, these plans help minimize the influence of saline groundwater flows on the stream salinity, as a preventive measure. As a remedial measure, this paper introduces a simple but an innovative approach for regulating saline groundwater inflows to natural streams in irrigated agricultural areas. The approach uses the flap gate with an automatic lowering and raising mechanism. During low stream flow, this gate is kept in a raised position. Depending upon the upstream inflows, the ponding situation will develop hydraulic gradient away from the stream; groundwater inflows to the creek will become minimal. During high stream flows, the gate is kept in a lower position to let the diluted water flows through the stream uninterrupted. To install, operate and manage such gates on multiple sites along the stream(s), the individual control panels can be joined into a central control station via telemetric link up. This approach, which holds a key for successfully regulating groundwater induced salinity to natural streams, should be considered in conjunction with other LWMPs to improve stream salinity in an irrigated agricultural area. 相似文献
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科学诊断水文序列的突变特性,对于认识水文循环的演变规律,研究环境变化对水文过程的影响具有重要的科学意义。基于漳河观台水文站1951-2015年实测径流序列,利用降水-径流双累积曲线、有序聚类突变检测法、Mann-Kendall突变检测法、基于水文模拟的突变检测法等多种方法对比分析了其突变特征。结果表明:1951年以来,观台水文站实测年径流序列呈现出显著的下降趋势,20世纪50和60年代处于丰水期,从70年代初开始年径流持续下降,80年代以后进入连续枯水期。4种突变检测方法得到观台水文站实测年径流序列的突变点位于1971-1978年。4种方法相比,降水-径流双累积曲线检测的突变点反映的是流域降水-径流关系发生明显改变的时刻;有序聚类突变检测方法检测的突变点反映的是径流序列的聚类特征;Mann-Kendall突变检测方法检测的突变点反映的是径流序列的综合突变特征;基于水文模拟的突变检测方法检测的突变点反映的是人类活动对流域降水径流关系干扰的起始点。 相似文献
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A study was conducted to understand the contributions of tile flow and baseflow to total nitrate-N (NO3-N) loadings in two subsurface (tile)-drained watersheds, namely the Big Ditch (BD) and the Upper Embarras River (UER) watersheds in Illinois. Two stream sections were selected in the watersheds and rectangular cutthroat flumes were installed at the upstream and downstream ends of the stream sections to calculate the flow mass balance for separating baseflow. The stream section at BD site had two tile outlets draining into it. The stream section at UER watershed did not have any tile drain. Tile flow was also measured along with stream flow. Water samples were collected not only from the stream sections using auto-samplers but also manually from the tile drains. Average baseflow rates per unit lengths of the stream sections at BD and UER sites were 3.5 × 10−04 and 9.4 × 10−05 m2 s−1, respectively. At BD site, for six study periods, the percentages of baseflow and tile flow contributions of NO3-N loads within the stream section were 90 and 10%, respectively. Annual NO3-N contributions by the upstream subwatersheds for BD and UER stream sections were 61,819 and 16,155 kg, respectively. Annual NO3-N loss from these two subwatersheds within BD and UER watersheds was 42.9 and 7.0 kg ha−1, respectively. For the stream section at BD site, baseflow seemed to play a more important role than tile flow in raising the NO3-N concentration level in the stream water. Land use seemed to play a major role in the significant difference in NO3-N concentrations at the two subwatersheds upstream from the project sites. Nitrate-N loadings primarily depended on precipitation, antecedent moisture condition (AMC), fertilizer application time, and evapotranspiration (ET). 相似文献
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文章基于ASTV-2实验系统,使用计算机制作TS码流,通过USB传输线传输至数字电视实验系统,以射频方式发射,通过实验终端接收广播信息和TS码流,实现节目专用信息的分析。 相似文献
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John Finlayson Andrew Bathgate Tivi Theiveyanathan Russell Crosbie Ziaul Hoque 《Agricultural Systems》2010,103(3):161-170
It has been widely suggested that changing land use from annual to perennial crops reduces land and stream degradation due to salinisation. However, annual crops are financially attractive and increases in perennials can reduce stream flows with adverse effects on stream values. As such, salinity control is likely to involve tradeoffs between public and private costs and benefits. This study quantifies the expected on-farm economic and catchment-level water yield and salinity effects of altering land use among trees, perennial pastures and cereals. The structure of a two stage linear-programming (LP) process is described. The first stage is the MIDAS farm-level model of mixed cropping and sheep enterprises which provides inputs to a second stage catchment-level LP. It was concluded that perennial pastures can be used in conjunction with trees as a stream salinity-management tool in low to intermediate rainfall areas in New South Wales. The results indicate that land-use decisions should be informed by site-specific information if adverse effects on streams are to be avoided. 相似文献
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黄土坡面细沟侵蚀及水动力学参数的时空变化特征 总被引：5，自引：0，他引：5
坡面细沟侵蚀速率和水动力学参数在坡面细沟发育过程中存在明显的时空变化。基于间歇性人工模拟降雨和三维激光扫描技术提取的高精度DEM,分析了黄土坡面细沟发育不同主导过程中细沟侵蚀和水动力学参数的时空分布规律。结果表明,细沟侵蚀速率和总侵蚀速率的最大值出现在以细沟沟底下切侵蚀为主的细沟发育活跃期,最小值出现在以沟头溯源侵蚀为主的细沟发育初期。细沟侵蚀速率与总侵蚀速率随降雨历时的变化皆呈先上升后趋于稳定,并在一定范围内波动的变化趋势,且总侵蚀速率早于细沟侵蚀速率达到稳定。细沟侵蚀量随单位斜坡长呈先上升后下降的抛物线形式分布,细沟侵蚀速率的最大值出现在坡面中下部。90 mm/h降雨强度下径流剪切力、径流功率和单位径流功率分别是60 mm/h降雨强度下的1.3、1.1、1.4倍。细沟间水流和细沟流的水动力学参数随降雨历时的增加呈不同的变化趋势。两种降雨强度下,径流剪切力、径流功率和单位径流功率随单位坡长的分布均呈波动上升趋势。单宽细沟侵蚀量与水动力学参数之间呈线性正相关关系,细沟发育初期坡面侵蚀发生的临界径流剪切力、临界径流功率和临界单位径流功率最大。 相似文献
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当今汽车各部分普遍采用电控系统,汽车诊断技术快速发展。新型的汽车诊断设备大多提供数据流读取功能。分析数据流可以有效地弥补故障码诊断的不足,通过对车辆进行全面的分析和判断,能够准确迅速地确定故障原因。 相似文献
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Unrestricted cattle access to streams in traditionally pastoral regions has been linked to increased concentrations of bacteria, suspended sediments and associated contaminants in streams. However, there is a dearth of data available regarding the impact of cattle access to streams in poorly drained landscapes of the Midwest. In this study, we investigate changes in water quality on a 1005 m long stream section impacted by cattle grazing on the upper 130 m. We monitor discharge, water quality [nitrate, ammonium, total Kjeldahl nitrogen (TKN), total phosphorus (TP), total suspended sediments (TSS), turbidity, Escherichia coli] and chloride, atrazine, silica and major cation concentrations over a 12-month period. Cattle access to the stream does not significantly affect nitrate concentration but leads to large increases in TKN (fourfold increase), TP (fivefold increase), ammonium (fourfold increase), TSS (11-fold increase), turbidity (13-fold increase) and E. coli (36-fold increase) in the summer/fall period. In particular, E. coli concentration in the stream in the summer/fall period exceeds 235 colony forming unit (CFU)/100 ml 64% of the time upstream from the section impacted by cattle, but exceeds this same threshold 89% of the time immediately downstream. Despite the negative impact of cattle access to the stream on water quality, data indicate that dilution, in-stream processes, and natural stream geometry downstream from the impacted section help mitigate this pollution. We expect that this study will be an incentive for policy makers to promote stream rehabilitation and develop more stringent guidelines limiting cattle access to streams in many Midwestern states and other regions with poorly drained soils where the impact of cattle access to streams on water quality is often ignored. 相似文献