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Current designs of sanitary collection systems normally only consider the transport of wastewater without attention on the air movement in the sewer airspaces. Under anaerobic conditions, hydrogen sulfide (H 2 S) can be generated in the liquid phase in sewer systems. H 2 S is corrosive to concrete and steel structures and odorous or even toxic to human, which can cause corrosion and sewer odor issues. To develop a feasible sewer corrosion and odor control strategy, it is necessary to understand the mechanisms of air flow in sewer systems for developing practical tools to predict and control the air flow. This paper comprehensively reviewed previous efforts on modeling the air flow in sewer systems and provided recommendations on predicting the air flow for engineering applications. The air flow in a single pipe was firstly reviewed followed by the air flow in sewer structures as well as air flow models in sewer networks. Some other considerations such as temperature driven flow, transient water flow, and wind effect were also reviewed. The knowledge gaps were then identified, and recommendations on the further studies were provided. [ABSTRACT FROM AUTHOR]

Hydropower operations can induce significant variation of velocity field upstream of intakes and may lead to fish entrainment into turbines. In this study, the flow fields upstream of a high dam in China under different intake and spillway operation patterns were investigated theoretically using potential flow solution and computational fluid dynamic modeling, and experimentally in a 1:50-scale physical model. Flow fields induced by multiple intakes and by a line sink tends to be the same at about two times of the distance of adjacent operating intake upstream of the intakes. Different operation scenarios were analyzed to improve the general understanding of characteristics of upstream flow and to reduce the risk of fish entrainment. The extent of the risk zone for fish entrainment defined by specified thresholds of velocity and acceleration indicate that smaller water depth over submerged intake means a higher risk of fish entrainment. [ABSTRACT FROM AUTHOR]

Abstract: The rapid economic growth in China has caused ever-increasing pollution and gradual deterioration of surface water quality over the whole territory of China since 1978. Along with it, there have been 130 environmental protection policies publicized and enacted. Unfortunately, even though these contradictory phenomena have coexisted for almost three decades, the cause analysis and the effective evaluation of policy measures are still rare. The Jiaxing region, a lowland located at the Taihu Lake watershed, is a typical representative of this dilemma and was proposed as a case study area for an assessment on the effectiveness of the environmental policy measures mentioned above. The pollutant loads originating from point pollution sources were discharged into rivers at fixed in-stream sites, while pollutant loads from non-point pollution sources in rural areas were assumed to be rushed into rivers by stormwater runoff. The environmental policy measures concerning water quality in the Jiaxing region were specified quantitatively as parameters for estimating the variation of pollutant loads. The base case and other three cases with the effects of policy measures were then simulated by the surface water quality models. The results show that a significant improvement of the surface water quality can be achieved by controlling the non-point pollution in rural areas and the point pollution over the whole area, if the water protection policies are sustainable and executed completely, and if the local government is active in their administrative, supervising and educational responsibilities and the farmers assume voluntary activities on rural pollution control. [Copyright &y& Elsevier]

Abstract: Water permeability of woven geotextile, usually measured in uncompressed state or under compressive stresses, varies significantly under tensile loads. To study the permeability behaviours of woven geotextile in the tensioned state, a series of laboratory experiments were carried out on one type of woven polypropylene geotextile with tensile strength of 20–30 kN/m. The experimental results show that the permittivity of geotextile under tension load in the warp direction first decreases rapidly, then approaches to a value that is 10–25% of the one in the absence of the load. On the contrary, the permittivity increases with the increase of the tension force in the weft direction and no steady value is observed. Since the tension load in the warp direction has obviously influence on the water permeability of geotextile, about 2–3% tensile strain is recommended to be applied on the warp fibres initially for determining a reasonable permittivity in laboratory test. [Copyright &y& Elsevier]

Abstract: Three-dimensional (3D) TiO2 solid microspheres with different morphologies have been synthesized on a large scale by a simple hydrothermal method using titanium tetrachloride (TiCl4) as the titanium source and ammonium fluoride (NH4F) as the etchant. X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM) studies show that the 3D solid microspheres, with an average diameter from hundreds of nanometers to several micrometers, are composed of numerous anatase TiO2 particles. In addition, the morphologies of the as-prepared 3D solid microspheres can be controlled by adjusting the dosage of NH4F and the reaction temperatures. The present study has enlarged the family of 3D solid microspheres, and offers a possible route for the synthesis of other inorganic hierarchical structures. [ABSTRACT FROM AUTHOR]