复杂情况下桩基缺陷补救的施工方法

针对地下水丰富的巨厚砂层工程特点,采用沉井、机械钻孔 钢筋笼 滤网定喷固结桩孔周围土体等护壁、降水方案进行人工挖孔桩补桩,成功地对某工程桩基缺陷进行了补救。     

法国鲁昂试验路堤与大气相互作用数值模拟

 在土–大气相互作用的模型和计算方法的基础上，采用现场记录的气象数据，对法国鲁昂试验路堤中心轴线上的温度、体积含水量和吸力随气候的变化进行一维数值模拟，并与现场实测结果进行对比。数值计算模拟与现场实测结果的对比分析表明，计算所采用的模型是合适的，但需要设置合理的边界条件以及土性参数。另外，由于试验路堤的压实使得填土具有较低的渗透性(＜10－8 m/s)，因而该试验中大气降雨和蒸发对路堤含水量和吸力的影响主要局限于距离路堤表面一定深度范围内。     

Modelling biological and chemically induced precipitation of calcium phosphate in enhanced biological phosphorus removal systems

The biologically induced precipitation processes can be important in wastewater treatment, in particular treating raw wastewater with high calcium concentration combined with Enhanced Biological Phosphorus Removal. Currently, there is little information and experience in modelling jointly biological and chemical processes. This paper presents a calcium phosphate precipitation model and its inclusion in the Activated Sludge Model No 2d (ASM2d). The proposed precipitation model considers that aqueous phase reactions quickly achieve the chemical equilibrium and that aqueous-solid change is kinetically governed. The model was calibrated using data from four experiments in a Sequencing Batch Reactor (SBR) operated for EBPR and finally validated with two experiments. The precipitation model proposed was able to reproduce the dynamics of amorphous calcium phosphate (ACP) formation and later crystallization to hydroxyapatite (HAP) under different scenarios. The model successfully characterised the EBPR performance of the SBR, including the biological, physical and chemical processes.     

Influence of mineral precipitation on the performance and long-term stability of Fe 0 -permeable reactive barriers: A review on the basis of 19 Fe 0 -reactive barrier sites

A comparative evaluation of the monitoring results from 19 Fe⁰-permeable reactive barriers (PRBs) is presented which considers changes of groundwater composition within the Fe⁰-PRBs, the type and distribution of mineral phases that precipitate, porosity reductions, extent of the load of inorganic groundwater constituents and the overall performance. The findings show that the changes in groundwater composition within the PRBs are extremely similar, independent of flow velocities, residence times, and concentrations of inorganic substances. In addition, the type and distribution of mineral precipitates do not show great variances with the largest mineral accumulations within the first 10 to 30 cm from the entrance face of the PRBs. From these comparisons it can be concluded that loads of dissolved inorganic species higher than 200 kg?·?a^–1?·?m^–2 limit the long-term performance of Fe⁰-PRBs up to a few years due to porosity losses caused by mineral precipitation, independent of the type of construction. Moreover, detailed calculations of porosity and hydraulic conductivity decreases of the PRBs at the Rheine and Tübingen sites show that the influence of mineral fouling on the hydraulic permeability of a PRB can only be estimated by accounting for the interaction between reduction in porosity, permeability and flow rate. The findings suggest that it is possible to pre-estimate the porosity and permeability development for a potential PRB.     

Investigation of Nd3+ incorporation in Ce-rhabdophane: Insight from structural flexibility and occupation mechanism

LnPO₄ · 0.667H₂O rhabdophane has been considered as a potential material for the precipitation of actinides from radioactive waste liquid, owing to its outstanding characteristics of high actinide bearing and easy synthesis in acid solutions. However, a comprehensive understanding of the actinide occupation and the precipitation response of rhabdophane to remove actinides has yet to be established. In this study, the effect of ions concentration and pH values on the detailed precipitation reaction of Ce_xNd_1-xPO₄ · 0.667H₂O rhabdophane in acid solutions are systematically investigated. Some specific issues such as structural distortion and flexibility, and occupation mechanism are discussed by combining with experiments and density functional theory (DFT) calculation. The results reveal that ions concentration and pH values have a significant impact on the crystallization nucleation step before 12 h. The obtained removal rate of Nd³⁺ is more than 99% in pH 1–5 solutions with the ions concentration of 0.05–0.1 mol/L. Moreover, incorporating Nd in CePO₄ · 0.667H₂O rhabdophane will easily result in the lattice distortion in b-axis. DFT calculation and X-ray photoelectron spectroscopy (XPS) results reveal that Nd is preferentially incorporated in nonhydrated site to form a weaker binding energy of NdO₈ polyhedron.     

硫酸盐还原菌法固定酸性矿山废水中重金属的研究进展

硫酸盐还原菌（SRB）法是一种极具潜力的酸性矿山废水（AMD）处理技术,如何将多种重金属分级沉淀并且分相分离出来,是SRB工艺走上工程应用的关键。本文综述了SRB法固定AMD中重金属的国内外研究进展,主要包括SRB法去除AMD中重金属的原理、SRB法分级沉淀AMD中多种重金属的工艺（分离式多级pH控制工艺及厌氧折流板反应器工艺）和SRB法厌氧污泥中金属硫化物的生物矿化（SRB介导的生物矿化成矿、生物矿化成矿影响因素及生物矿化过程微观机理）,分析了此方面研究工作存在的问题。最后文章针对SRB法的深入研究及应用进行展望,认为硫酸盐还原体系中硫化物成矿的调控、成矿物相演变与微生物群落演替过程的解析以及矿化固定AMD中重金属成矿机理的探索将是今后重点关注的研究内容。     

光稳定剂对水工闸门用PE-HD/高岭土复合材料性能的影响

采用共混造粒制备含有不同光稳定剂的水工闸门用高密度聚乙烯(PE-HD)/高岭土复合材料,讨论和研究光老化前后复合材料的力学性能变化规律。通过偏光显微镜观察复合材料试样表面形貌、采用傅里叶变换红外光谱和核磁共振氢谱对表面析出物进行分析,讨论比较不同受阻胺光稳定剂的析出原因及抗光老化作用差异。结果表明,添加光稳定剂2020、光稳定剂944、光稳定剂123、光稳定剂770和光稳定剂292的复合材料光老化后力学性能保留率平均值分别为87.1%,81.7%,79.1%,78.2%和75.6%,抗光老化性能依次变弱;分子量大的光稳定剂2020和光稳定剂944更容易与复合材料体系相容,不容易析出,具有更好的抗光老化作用,同时带有较稠密的受阻胺结构的光稳定剂2020具有出色的抗光老化作用,这可为PE-HD/高岭土复合材料光稳定剂选配和抗光老化性失效分析提供参考。     

The Development and Application of Phosphorus Removal from Wastewater using Biological and Metal Precipitation Techniques

The paper describes a programme of technology development in phosphate removal which was carried out by Anglian Water in response to the requirements of the urban waste water treatment Directive Trials covered pilot and large-scale biological nutrient-removal plants, and iron-salt dosing to activated-sludge plants and biological filters. The fundamentals of the processes are discussed and results are presented.     

Reactor development for peroxidase catalyzed polymerization and precipitation of phenols from wastewater

Horseradish peroxidase enzyme catalyzes the oxidation of toxic aromatic compounds, especially phenols and aromatic amines, in the presence of hydrogen peroxide. The reaction products polymerize to form high molecular weight materials which readily precipitate from solution; hence, providing a means for the treatment of wastewaters which contain aromatic compounds. The catalytic lifetime of horseradish peroxidase enzyme can be extended by optimizing treatment conditions such as pH and temperature and by maintaining a low instantaneous enzyme concentration in the reaction mixture. The enzyme catalyzed polymerization process was implemented in a continuous stirred tank reactor (CSTR) configuration because reactant and enzyme concentrations are lowered immediately upon entering the reactor causing a reduction in inactivation of HRP through free radical bonding and compound III formation. Catalytic turnovers achieved in single and multiple CSTRs in series were significantly higher than those observed in batch reactors when sufficient retention time was provided.     

城市化对城市降雨径流的影响及城市雨洪控制

介绍了城市化造成的城市气候对降水、降雨径流、降雨径流水质的影响，分析了这些影响带来的不良后果，并提出了必要的收集、处理和雨水再利用措施。