Restoration challenges for urban rivers.

Urban sources account for significant quantities of important diffuse pollutants, and urban watercourses are typically badly polluted. As well as toxic metals, hydrocarbons including PAHs, and suspended matter, priority urban pollutants include faecal pathogens and nutrients. Can urban watercourses be restored by sufficient reductions in pollution loads? Case studies in the UK and Sweden provide insights and some grounds for optimism. A major trans-Atlantic review of the performance of best management practices (BMPs) is informing BMP planning. New approaches such as the maximisation of self-purification capacity in the receiving waters may also need to be developed, alongside BMPs at source. Other initiatives in Europe, USA and China, including collaborative projects, are trying to address the intractable issues such as persistent pollutants from transport and urban infrastructure. The challenge is daunting, but there are clear ways forward and future research needs are evident.     

Flood risk mapping at European scale.

The aim of this article is to illustrate a framework for flood risk mapping at pan-European scale produced by the Weather-Driven Natural Hazards (WDNH) action of the EC-JRC-IES. Early results are presented in the form of flood risk index maps. We assess several flood risk factors that contribute to the occurrence of flood disasters. Among the causal factors of a flood disaster one is triggering a natural event in the form of extreme precipitation and consequently extreme river discharge and extreme flood water levels. The threatening natural event represents the hazard component in our assessment. Furthermore exposure and vulnerability are anthropogenic factors that contribute also to flood risk. In the proposed approach, flood risk is considered on the light of exposure, vulnerability and hazard. We use a methodology with a marked territorial approach for the assessment of the flood risk. Hence, based on mathematical calculations, risk is the product of hazard, exposure and vulnerability. Improvements on datasets availability and spatial scale are foreseen in the next phases of this study. This study is also a contribution to the discussion about the need for communication tools between the natural hazard scientific community and the political and decision making players in this field.     

Implementation of sustainable sanitation in existing urban areas: long-term strategies for an optimised solution.

If technologies for decentralised sanitation and reuse (DESAR) and for natural stormwater management should at least partially replace existing systems, then intensive reconstruction work becomes essential. A conversion can only be realised successively over a long period due to high construction and financial expenses and requires new strategies. This paper presents the development and practical implementation of a mathematical tool to find an optimised strategy for the realisation of alternative and more decentralised drainage and sanitation concepts in existing urban areas. The succession of construction measures (e.g. the implementation of decentralised greywater recycling) for the whole period of consideration is determined based upon a mathematical optimisation model on the condition that the favoured future state is known. The model describes the complex interdependencies of the urban water and nutrient cycle and enables the minimisation of both financial efforts and ecological impacts on the way toward the future state. The results of the implementation for a rural area in Germany show that the mathematical optimisation is an adequate instrument to support decision-making processes in finding strategies for the realisation of sustainable urban water management.     

Aqua-Biomant: integrated biological and electrochemical oxidation for industrial wastewater treatment.

An innovative technology for industrial wastewater treatment has been developed. The main focus of the new system is a transformation of persistent organic compounds (biorecalcitrant COD) into a biodegradable fraction, followed by high efficient biological elimination using specialised bacteria's. To fulfill these targets the Aqua-Biomant process integrates two treatment steps: an aerated biological upflow filter and a electrochemical oxidation technique using boron doped-diamond electrodes. The advantages of the process are high efficient COD removal with reduced energy consumption combined with low total residence time.     

灯泡式机组的零停机在线监测系统

在巴西伊加拉帕瓦水电站,通过监测电气气隙,避免了一台新水轮发电机发生重大破坏和昂贵的停机事故.     

Hindered and compression settling: parameter measurement and modelling.

The Vesilind settling velocity function forms the basis of flux theory used both in state point analysis (for design and capacity rating) and one-dimensional dynamic models (for dynamic process modelling). This paper proposes new methods to address known shortcomings of these methods, based on an extensive set of batch settling tests conducted at different scales. The experimental method to determine the Vesilind parameters from a series of bench scale settling tests is reviewed. It is confirmed that settling cylinders must be slowly stirred in order to represent settling performance of full scale plants for the whole range of solids concentrations. Two new methods to extract the Vesilind parameters from settling test series are proposed and tested against the traditional manual method. Finally, the same data set is used to propose an extension to one-dimensional (1-D) dynamic settler models to account for compression settling. Using the modified empirical function, the model is able to describe the batch settling interface independently of the number of layers.     

Conservation of water resources problems of small rivers in Russia

Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 8, pp. 1–5, August, 1994.