污泥流变特性是影响其传质效果的重要因素,对污泥管道输送、搅拌、混合以及热交换等处理处置单元的设计和运行均起到重要作用。本研究利用旋转黏度计测定了污水处理厂含水率分别为90%、93%和96%时污泥的流动曲线和黏度曲线,并分析了污泥含水率、温度对污泥流变特性的影响。实验结果表明,污泥属于典型的假塑性流体,其流变特性可以用Ostwald de Vaele模型,即幂律模型τ=K(D)n来拟合。污泥黏度随含水率的减小而增加,且剪切速率越小,这种增加趋势越明显;污泥黏度随温度升高呈现降低趋势,且这种趋势在低剪切速率时表现的比较明显,在高剪切速率时变化幅度很小。 相似文献
The demise of the soil fumigant, Midas, was heralded as a major environmental movement achievement, when Arysta LifeScience eventually deemed it economically non-viable and withdrew from US markets just before resolution of a lawsuit. Building on scholarship that focuses on strategy to understand how social movements sometimes win, we show how activist tactics were able to exploit the missteps of their opponents. These included the unreasonable expectations of Arysta for grower adoptions, the foibles of the director of California's Department of Pesticide Regulation in registering the chemical, and the reluctance of California's strawberry industry to discontinue use of methyl bromide. Although activist tactics, such as public comments and protests, had only a modest impact on the regulatory process, they had a major impact on grower adoptions of the chemical. This, together with a lawsuit that was not going well for the defendants, ultimately led to the withdrawal. Still, there was a great deal of luck involved, especially in the lawsuit in which the judge made rulings and statements favourable to the plaintiffs. Here, ‘scientization’, worked in favour of the movement rather than the industry. 相似文献
The purpose of this paper is to increase understanding of the dynamics of knowledge production in the context of large-scale environmental projects causing local conflict. In particular, the paper analyses the discourse coalitions that formed around an artificial groundwater recharge project for the Turku Region in Finland. The material for this study consists of over 400 articles and opinion pieces which were collected from local and regional newspapers between 1999 and 2010. The articles were analysed by using Hajer's [1995. The politics of environmental discourse. Ecological modernisation and the policy process. Oxford, UK: Clarendon] discursive framework, and the analysis was complemented with the concept of knowledge coalition by Van Buuren and Edelenbos [2004. Conflicting knowledge. Why is joint knowledge production such a problem? Science and Public Policy, 31 (4), 289–299]. Results of the study indicate that knowledge coalitions were formed among the researchers, lay residents, and policy-makers, and they all utilised similar expertise-based factual arguments to support their cause. Thus, the paper participates in the academic discussion on the use and interpretation of expert knowledge in environmental policy-making by reshaping the division between experts and lay residents. 相似文献
This paper describes the frustrating reality of sustainability implementation in the USA and New Zealand (NZ), an early adopter of sustainability mandates. Local government has a key role in implementation, but has been slow to uptake sustainable practices. We surveyed senior planners in small to medium-sized local government agencies in both countries to identify which features of local government support (or hinder) sustainability in practice.
Environmentally sustainable practices are not well entrenched in either country. In the USA, the framing of sustainability and public support are significant predictors of implementation. However, sustainability is rarely a priority. In NZ, local government capacity is the main driver of implementation. We recommend that planners promote sustainability values, reconcile economic development goals with sustainability (e.g., green economy model), and translate public support for sustainability into institutional priorities. NZ localities also need increased capacity and US localities need continued Federal and State support. 相似文献