Probabilistic distribution coefficients (Kds) in freshwater for radioisotopes of Ag,Am, Ba,Be, Ce,Co, Cs,I, Mn,Pu, Ra,Ru, Sb,Sr and Th – implications for uncertainty analysis of models simulating the transport of radionuclides in rivers

The objective of this study was to provide operational probability density functions (PDFs) for distribution coefficients (K_ds) in freshwater, representing the partition of radionuclides between the particulate and the dissolved phases respectively. Accordingly, the K_d variability should be considered in uncertainty analysis of transport and risk assessment models. The construction of PDFs for 8 elements (Ag, Am, Co, Cs, I, Mn, Pu and Sr) was established according to the procedure already tested in Durrieu et al. [2006. A weighted bootstrap method for the determination of probability density functions of freshwater distribution coefficients (K_ds) of Co, Cs, Sr and I radioisotopes. Chemosphere 65 (8), 1308–1320]: (i) construction of a comprehensive database where K_ds values obtained under various environments and parametric conditions were collected; (ii) scoring procedure to account for the ‘quality’ of each datapoint (according to several criteria such as the presentation of data (e.g. raw data vs mean with or without replicates), contact time, pH, solid-to-liquid ratio, expert judgement) in the construction of the PDF; (iii) weighted bootstrapping procedure to build the PDFs, in order to give more importance to the most relevant datapoints. Two types of PDFs were constructed: (i) non-conditional, usable when no knowledge about the site of concern is available; (ii) conditional PDFs corresponding to a limited range of parameters such as pH or contact time; conditional PDFs can thus be used when some parametric information is known on the site under study. For 7 other radionuclides (Ba, Be, Ce, Ra, Ru, Sb and Th), a simplified procedure was adopted because of the scarcity of data: only non-conditional PDFs were built, without incorporating a scoring procedure.     

Analysis of Coupling between Soil and Water Conservation and Economic-social Development

The coupling relation exists in water and soil conservation and economic-social development. The article analyses the relation of soil and water conservation and economic-social development stages as well as the coupling analytical method. Then calculates the expecting income by dispersing Markov decision and calculates the correlation coefficient and the relationship degree. The article obtains the relationship of soil and water conservation investments and all kinds of incomes. Finally, it analyzes the important meaning in socio-economic development of water and soil conservation.     

铝矿赤泥强化聚合氯化铝混凝除磷试验研究

对聚合氯化铝(PAC)投加赤泥前后的除磷效果及絮体进行了研究.结果表明,赤泥对PO3-4有吸附作用;投加一定量赤泥,提高了实验室模拟废水和实际污水中磷的去除率;与单用PAC相比,赤泥的加入增强了絮体的持磷性,增加了絮体的密实度,缩小了底泥的体积,强化了PAC的除磷性能.     

密云水源水的预臭氧化及强化常规处理研究

针对北京密云水库水的水质特征,分别进行了实验室烧杯和现场中试研究.实验结果表明,预臭氧化能使原水中较大粒径颗粒数目减少,并能显著降低原水中不饱和有机物的含量;高效聚合氯化铝在颗粒物及有机物的去除上明显优于传统的聚合氯化铝和硫酸铝;预臭氧化与常规处理的联合工艺对浑浊度、有机物和大肠菌群有很高的去除率.     

超声强化混凝去除蓝藻实验研究

研究了超声波对藻类的混凝去除强化,证明超声波可以快速、高效地提高藻类混凝去除效率,减少混凝剂用量.在混凝剂投加量为0.8 mg/L时,5 s超声处理,藻类去除效果比对照样好30%.同样,藻类去除率都为92%时,5 s超声预处理可以将混凝剂投加量降低至1/3.超声预处理时间对强化混凝效果有很大的影响,在实验条件下,1～5 s的超声处理均可产生满意的结果,1 s为最优、最经济时间,而预处理超过30 s反而降低混凝效果.低频下不同处理频率对超声强化混凝效果影响不大,在80 kHz的频率下,最佳功率为50 W.最佳pH值在8～9范围内.     

混凝强化除磷的模拟实验研究

以模拟污水为研究对象,考察了不同絮凝剂(聚合氯化铝、三氯化铁及硫酸亚铁)对污水中磷的去除效果及其影响因素,并对氢氧化铁的吸附除磷规律,以及氢氧化铁与絮凝剂复配除磷的效果进行了探讨,提出了聚合氯化铝、三氯化铁及硫酸亚铁可行的投加量.     

预处理-混凝-水解酸化-循环式活性污泥法处理制革废水

制革废水水质、水量波动大,污染负荷重,有毒性,较难处理。本工程采用“预处理-混凝-水解酸化-循环式活性污泥法”处理制革废水,研究了C-TECH池曝气时间与CODCr、NH3-N负荷及DO的变化规律。结果表明,控制水解酸化池HRT12.5h,曝气时间8h,C-TECH池污泥浓度4.5g/L,CODCr污泥负荷0.4kg/(kg.d),NH3-N污泥负荷0.07kg/(kg.d),出水可达一级排放标准;通过可编程逻辑控制器PLC、在线DO测定仪及鼓风机变频装置控制DO浓度,用DO浓度作为循环式活性污泥池过程和反应时间控制参数,可节约能耗。     

铁盐和铝盐混凝微滤工艺除As(V)的比较研究

选择FeCl₃和Al₂(SO₄)₃作混凝剂,采用小试规模的混凝微滤膜反应器比较了铁盐和铝盐混凝微滤工艺的除As(V)效果、相关性能指标及适用范围.结果发现,Fe³⁺投加量为4 mg/L、Al₂(SO₄)₃投加量为50 mg/L时,铁盐和铝盐工艺的除As(V)效果大致相当,均可使水中As(V)的浓度从100 μg/L左右降低到10 μg/L以下,最低为1.68 μg/L.出水浊度均小于0.1 NTU,出水中铁、铝和SO^2-₄浓度均符合饮用水标准.铁盐工艺出水pH值比原水大约高0.5,铝盐工艺处理前后水的pH值基本不变.反应器运行结束静沉24 h后,铁盐工艺浓缩比为1 791,是铝盐工艺的2.54倍,污泥中As(V)的含量也大大高于铝盐工艺,去除同等重量的As(V)所产生的污泥量较铝盐工艺少得多.因此,对于仅有砷超标的饮用水,应优先考虑铁盐工艺.按除氟所需混凝剂数量投加Al₂(SO₄)₃,铝盐工艺即可在去除As(V)的同时去除氟,铁盐工艺则不能去除氟.因此,对于砷和氟均超标的饮用水,可采用铝盐工艺同时去除砷和氟.     

胶态水合二氧化锰絮凝粒子的结构形貌及其混凝机理

采用透射电镜技术观察了胶态水合二氧化锰絮凝粒子的结构形貌并采用Zeta电位测定仪对粒子的荷电特征进行了研究;利用红外光谱、XRD等技术对粒子的界面性质进行了表征;通过混凝试验考察了KMnO₄ 还原法制备的水合二氧化锰胶体对原水的混凝性能并探讨了混凝机理.结果表明,胶态水合二氧化锰粒子在去离子水和原水中荷负电,在去离子水中,粒子直径为10　nm并形成网状结构,有利于发挥吸附架桥作用;粒子具有丰富的表面羟基,比表面积为151.422　m²/g,为δ-MnO₂,表现出优良的吸附污染物的界面特性;较低投量的胶态水合二氧化锰表现出对原水的优良混凝效能和去除有机微污染的效能.     

马尔科夫链在环境质量预测中的应用

鉴于目前环境质量预测在理论方法和实践经验上的缺乏,把马尔科夫链引入环境质量的预测中,将各种污染物的浓度变化过程视作马尔科夫过程,通过预测各种污染物的污染负荷系数来推知其浓度值。实例中通过多元回归分析计算出马尔科夫转移矩阵,以2005年辽宁省5种大气污染物的污染负荷系数作为初始向量,预测了今后5年的变化。然后利用GM(1,1)模型预测出降尘的具体浓度值,由此计算出了2006-2010年辽宁省5种污染物的浓度值。