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151.
为探究人工强制混合充氧与诱导持续混合对水质改善的影响及人工强制混合与自然混合的衔接条件,以李家河水库为例,于2017年6月至2019年4月开展水质及水文气象指标监测,分析自然过程及人工诱导混合过程各时期水温、溶解氧及水质变化特征.结果表明:①自然过程分层期持续时间长,混合期仅为2.5个月,人工诱导混合过程通过扬水曝气系统的运行, 9月底水体达到完全混合且进入降温期,诱导自然混合条件具备,表层水温、平均气温分别为20.17℃和16.5℃,此时系统关闭后水体持续自然混合,混合周期延长至5.5个月;②自然过程污染物浓度较高,混合期表层污染物浓度呈现先增加后降低的趋势,氧跃层伴随热分层出现,底部厌氧周期达6个月;③相较于自然过程,人工诱导混合过程水体等温层厌氧消除且污染物控制效果良好, 10月至翌年3月同期底层NH+4-N、 TP、 Fe和Mn浓度的削减率为76.2%、 75.5%、 82.2%和82.1%,均达到地表水环境质量标准,人工诱导混合过程有利于水质改善及混合作用时效的延长. 相似文献
152.
赵喜萍 《辽宁城乡环境科技》2006,26(1):39-41
根据某污水处理场沉淀池的COD和SS去除率较低的情况,文中着重探讨了问题的产生原因,并针对平流式沉淀池及斜管式沉淀池提出了相应的改进方案,实践证明改进后提高了COD和SS去除率30%,并明显降低了二级生物处理阶段的有机物负荷,节省了大量的暴气量通过改进达到了降低处理场其它环节的负荷和降低污水处理成本的目的。 相似文献
153.
文中系统讲述了SBR旋转式滗水器的结构、工作原理及运行特点,列举了SBR旋转式滗水器的应用实例,使人们对SBR旋转式滗水器有更深的认识,使这种新型的污水处理设备得到更广泛的应用。 相似文献
154.
Implementing SDG 15: Can large‐scale public programs help deliver biodiversity conservation,restoration and management,while assisting human development? 下载免费PDF全文
Among the Sustainable Development Goals (SDGs), the proposed SDG 15 promotes activities that, inter alia, “Protect, restore and promote sustainable use of terrestrial ecosystems”. An important potential contribution in achieving SDG 15 is through public programmes designed to jointly promote human development through poverty alleviation and improvement of human livelihoods and biodiversity conservation/management/restoration. An analysis of twenty public programmes with such joint objectives yielded twelve lessons learned. In addition to financial commitments, government and intergovernmental agency input for such public programmes includes ensuring political will and appropriate legal frameworks. Local communities and civil society provide input through traditional and indigenous ecological knowledge and stewardship. Appropriate shared inputs in development and the implementation of such public programmes, with communication between local community, broader civil society, the scientific community and governments will result in: better use and management of biodiversity; alleviation of poverty; security of livelihoods and better governance systems. The Ecosystem Approach of the Convention on Biological Diversity provides an ideal framework when planning and implementing new programmes. Application of the lessons learned to new public programmes will ensure that the answer to the question posed in the title is an emphatic “Yes”, and assist with the achievement of SDG 15. 相似文献
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157.
Though dynamic operation of chemical processes has been extensively explored theoretically in contexts such as economic model predictive control or even considering the potential for cyberattacks on control systems creating non-standard operating policies, important practical questions remain regarding dynamic operation. In this work, we look at two of these with particular relevance to process safety: (1) evaluating dynamic operating policies with respect to process equipment fidelity and (2) evaluating procedures for determining the parameters of an advanced control law that can promote both dynamic operation as well as safety if appropriately designed. Regarding the first topic, we utilize computational fluid dynamics and finite element analysis simulations to analyze how cyberattacks on control systems could impact a metric for stress in equipment (maximum Von Mises stress) over time. Subsequently, we develop reduced-order models showing how both a process variable and maximum Von Mises stress vary over time in response to temperature variations at the boundary of the equipment, to use in evaluating how advanced control frameworks might impact and consider the stress. We close by investigating options for obtaining parameters of an economic model predictive control design that would need to meet a variety of theoretical requirements for safety guarantees to hold. This provides insights on practical safety aspects of control theory, and also indicates relationships between control and design from a safety perspective that highlight further relationships between design and control under dynamic operation to deepen perspectives from the computational fluid dynamics and finite element analysis discussions. 相似文献
158.
介绍了STW型生态土壤稳定剂对宁淮高速公路边坡膨胀土的胀缩性、水稳性、强度、抗冲刷性等的改性试验研究,并结合现场试验,分析了STW型生态土壤稳定剂用于膨胀土边坡坡面防护的效果。试验结果表明:STW型生态土壤稳定剂改性膨胀土的胀缩性,随着稳定剂掺量的增大而减小;改性土的水稳性,随着稳定剂稀释浓度的增大而增强;同时,改性土的强度得到显著提高,抗冲刷性能得到明显增强,具有显著的防治水土流失、促进表层固化、提高坡面稳定的效果。 相似文献
159.
Sheng‐Feng Kuo Chen‐Wuing Liu Shih‐Kai Chen 《Journal of the American Water Resources Association》2003,39(1):59-73
ABSTRACT: This study presents three optimization techniques for on‐farm irrigation scheduling in irrigation project planning: namely the genetic algorithm, simulated annealing and iterative improvement methods. The three techniques are applied to planning a 394.6 ha irrigation project in the town of Delta, Utah, for optimizing economic profits, simulating water demand, and estimating the crop area percentages with specific water supply and planted area constraints. The comparative optimization results for the 394.6 ha irrigated project from the genetic algorithm, simulated annealing, and iterative improvement methods are as follows: (1) the seasonal maximum net benefits are $113,826, $111,494, and $105,444 per season, respectively; and (2) the seasonal water demands are 3.03*103 m3, 3.0*103 m3, and 2.92*103 m3 per season, respectively. This study also determined the most suitable four parameters of the genetic algorithm method for the Delta irrigated project to be: (1) the number of generations equals 800, (2) population size equals 50, (3) probability of crossover equals 0.6, and (4) probability of mutation equals 0.02. Meanwhile, the most suitable three parameters of simulated annealing method for the Delta irrigated project are: (1) initial temperature equals 1,000, (2) number of moves equal 90, and (3) cooling rate equals 0.95. 相似文献
160.
目前生态影响评价研究中的评价对象、内容和方法缺乏统一的模式,本文以攀枝花高耗能园区的开发为例,尝试建立一套系统的工业园区开发生态影响评价方法,该方法以层次分析法为基础,将生态系统分解为经济发展、社会进步、环境保护、景观生态保护四个目标子系统,并在此基础上细化评价因子,通过专家打分和矩阵运算确定其权重,再根据适当的评价标准,运用指数法得出评价结果。结果表明该工业园区在建成前后,其生态综合指数由0.552提高到0.794.其级别由三级提高到二级,说明该园区生态系统总的状态得到改善,该工业园区项目开发可行。 相似文献