Detention Outlet Retrofit Improves the Functionality of Existing Detention Basins by Reducing Erosive Flows in Receiving Channels

By discharging excess stormwater at rates that more frequently exceed the critical flow for stream erosion, conventional detention basins often contribute to increased channel instability in urban and suburban systems that can be detrimental to aquatic habitat and water quality, as well as adjacent property and infrastructure. However, these ubiquitous assets, valued at approximately $600,000 per km² in a representative suburban watershed, are ideal candidates to aid in reversing such cycles of channel degradation because improving their functionality would not necessarily require property acquisition or heavy construction. The objective of this research was to develop a simple, cost‐effective device that could be installed in detention basin outlets to reduce the erosive power of the relatively frequent storm events (~ < two‐year recurrence) and provide a passive bypass to maintain flood control performance during infrequent storms (such as the 100‐year recurrence). Results from a pilot installation show that the Detain H₂O device reduced the cumulative sediment transport capacity of the preretrofit condition by greater than 40%, and contributed to reduced flashiness and prolonged baseflows in receiving streams. When scaling the strategy across a watershed, these results suggest that potential gains in water quality and stream channel stability could be achieved at costs that are orders of magnitude less than comparable benefits from newly constructed stormwater control measures.     

Novel mesoporous microspheres of Al and Ni doped LMO spinels and their performance as cathodes in secondary lithium ion batteries

A facile, scalable, and solution-based technique is used to fabricate Al and Ni-doped (LiAl_0.1Mn_1.9O₄ and LiAl_0.1Ni_0.1Mn_1.8O₄) microspheres of lithium manganese oxide (LMO) spinels for use as reversible cathode materials for lithium ion batteries (LIBs). The spheres of the two samples exhibit different porosities. Cells with these LMO-based cathodes are then cycled between 4.5 V and 2 V to study their stabilities while simultaneously being subjected to the undesirable Jahn-Teller distortion that occurs around the ~3 V regime. The LiAl_0.1Mn_1.9O₄ (LAMO) and the LiAl_0.1Ni_0.1Mn_1.8O₄ (LANMO) cells exhibit comparable open circuit voltages (OCV) of 2.94 V and 2.97 V, respectively. During cell cycling, the LAMO cell exhibits a maximum specific capacity of 122.51 mAh g^?1 with a capacity fade of 65.35% after 75 cycles. The LiAl_0.1Ni_0.1Mn_1.8O₄ (LAMO) sample fares better and exhibits a maximum of 140.49 mAh g^?1 and a capacity drop of 52.59%. Detailed structural studies indicate that Ni doping and the greater degree of porosity of the LANMO sample to be a stabilizing factor. This is further confirmed by cyclic voltammetry (CV) and AC impedance spectra analysis.     

Composting of waste algae: A review

Although composting has been successfully used at pilot scale to manage waste algae removed from eutrophied water environments and the compost product applied as a fertiliser, clear guidelines are not available for full scale algae composting. The review reports on the application of composting to stabilize waste algae, which to date has mainly been macro-algae, and identifies the peculiarities of algae as a composting feedstock, these being: relatively low carbon to nitrogen (C/N) ratio, which can result in nitrogen loss as NH₃ and even N₂O; high moisture content and low porosity, which together make aeration challenging; potentially high salinity, which can have adverse consequence for composting; and potentially have high metals and toxin content, which can affect application of the product as a fertiliser. To overcome the challenges that these peculiarities impose co-compost materials can be employed.     

常温低基质厌氧氨氧化反应器启动及其稳定性

以上向流生物滤池为反应器,以实验室内氧化沟回流污泥为接种污泥,采用先培育好氧生物膜,后转为厌氧环境培育厌氧氨氧化生物膜的方式,成功实现了常温低基质浓度下厌氧氨氧化反应器的启动。控制反应器进水pH为7.50～7.80,NH4+-N为30～40 mg/L,NO2--N为35～50 mg/L,温度为20～25℃。224 d以后,反应器启动成功。在稳定运行阶段,出水亚硝氮和氨氮的平均浓度分别为1.4 mg/L和4.6 mg/L,平均去除率分别为95.3%和90.1%,去除比例为1～1.8∶1,主要集中在1.4～1.5∶1,亚硝氮和氨氮去除的容积负荷分别为104.2 mg/(L.d)和146.0 mg/(L.d)。     

不同来源高浓度有机废水的集中处理

按照水质情况,将多种来源于不同工业生产过程中的高浓度有机废水划分为高悬浮固体乳化液废水、难生化高浓度有机废水、高悬浮固体不含油有机废水、含铬有机废水和杂质含量较少的乳化液废水5类,分别采用酸化破乳/Fen-ton氧化/混凝/絮凝、Fenton氧化/混凝/絮凝、混凝/絮凝、还原/混凝/絮凝、震动膜过滤技术作为生化预处理技术,并通过小试和中试验证了各技术的效果。实验结果表明,按照上述分类结果,采用不同预处理技术可以得到良好的效果,废水水质明显改善,满足继续生化处理的基本条件。各预处理生产装置处理效果稳定,同时生化系统已经稳定运行120天以上,COD去除率超过90%,出水经过低剂量的Fenton试剂处理后可达到《污水排入城镇下水道水质标准》(CJ343-2012)。     

A hybrid method for quasi-three-dimensional slope stability analysis in a municipal solid waste landfill

Limited space for accommodating the ever increasing mounds of municipal solid waste (MSW) demands the capacity of MSW landfill be maximized by building landfills to greater heights with steeper slopes. This situation has raised concerns regarding the stability of high MSW landfills. A hybrid method for quasi-three-dimensional slope stability analysis based on the finite element stress analysis was applied in a case study at a MSW landfill in north-east Spain. Potential slides can be assumed to be located within the waste mass due to the lack of weak foundation soils and geosynthetic membranes at the landfill base. The only triggering factor of deep-seated slope failure is the higher leachate level and the relatively high and steep slope in the front. The valley-shaped geometry and layered construction procedure at the site make three-dimensional slope stability analyses necessary for this landfill. In the finite element stress analysis, variations of leachate level during construction and continuous settlement of the landfill were taken into account. The "equivalent" three-dimensional factor of safety (FoS) was computed from the individual result of the two-dimensional analysis for a series of evenly spaced cross sections within the potential sliding body. Results indicate that the hybrid method for quasi-three-dimensional slope stability analysis adopted in this paper is capable of locating roughly the spatial position of the potential sliding mass. This easy to manipulate method can serve as an engineering tool in the preliminary estimate of the FoS as well as the approximate position and extent of the potential sliding mass. The result that FoS obtained from three-dimensional analysis increases as much as 50% compared to that from two-dimensional analysis implies the significance of the three-dimensional effect for this study-case. Influences of shear parameters, time elapse after landfill closure, leachate level as well as unit weight of waste on FoS were also investigated in this paper. These sensitivity analyses serve as the guidelines of construction practices and operating procedures for the MSW landfill under study.     

地震滑坡地形剖面线多重分形特征及其在稳定性判别中的应用

"5.12"汶川地震诱发了大量的滑坡和不稳定斜坡体,这些滑坡和不稳定斜坡体的稳定性影响到灾区社会经济发展和灾后重建。地震滑坡的不同稳定性状态孕育了滑坡地形剖面线的演化特征,并且地震滑坡地形剖面线直接地反映了在地震力作用下坡体的演变过程和演化机制。根据实测的汶川地震诱发的滑坡地形剖面线特征,研究了相对稳定滑坡、蠕滑阶段滑坡和不稳定斜坡的地形剖面线的分布特征,以及地震滑坡不同稳定状态下的地形剖面线的多重分形维数演化特征。研究结果表明相对稳定滑坡的多重分形维数演化特征的具有明显的有序性,处于蠕滑状态的滑坡和不稳定斜坡的多重分形维数演化出现明显的特征性拐点。     

Developing Mechanism of Rubber-tea-chicken Agro-forestry Model in Tropical Area of China

As a typical tropical agro-forestry ecosystem in Wenchang,Hainan Province,China,rational mechanisms of the rubber-tea-chicken eco-agricultural model were studied with the Solow technological level index,stability indicator,harmonizing coefficient,grey correlation coefficient and production dominance.This study focused on rational hierarchical structure,the limiting factors and optimal strategies of the model development based on model structure,resource conditions and external market demands.Results showed that rational mechanism of the rubber-tea-chicken ecosystem model mainly included technological contributions,leverage function of dominance component(livestock husbandry),stability of the model structure and harmony of its components,the model dominant product’s market demand and government’s supporting policies.The contributions of fund,technology,information and talent resources played an important role in improving sustainability and productivity of the agro-forestry model.     

某高拱坝坝基辉绿岩脉改造特征及其工程影响

通过对我国西南某高拱坝坝基花岗岩体内穿插的辉绿岩脉的侵位和后期构造—热液作用以及浅表改造作用的研究,并对比各组不同走向辉绿岩脉的变形破坏特征,查明坝基辉绿岩脉在其活动后期热液蚀变的基础上,在同一构造应力作用下,各组辉绿岩脉具有不同的主要变形破坏方式,即脉壁张裂、剪切滑移和挤压破碎等,从而控制坝基岩体内与岩脉有关的各种软弱结构面、工程岩体结构及其力学性质,并简要讨论了各组岩脉对拱坝坝基抗滑稳定性和变形稳定性的影响。     

基于GIS的可视化土质边坡稳定性分析系统研究

结合GIS空间数据分析能力与极限平衡法开发了可视化的土质边坡稳定性分析系统GiSlope,介绍了边坡几何模型、外荷载与加筋结构模型、滑动面及地下水位线模型等分析模型的可视化建立过程,阐述了计算分析的设定、任意形状滑动面土条条分方法以及计算参数的确定方法。通过对几个典型实例的分析与国内外商业软件计算结果的对比,验证了系统计算的正确性和可靠性。