Nitrate in drinking water and risk of death from colon cancer in Taiwan

The relationship between nitrate levels in drinking water and colon cancer has been inconclusive. A matched case-control and a nitrate ecology study were used to investigate the association between colon cancer mortality and nitrate exposure from Taiwan's drinking water. All colon cancer deaths of Taiwan residents from 1999 through 2003 were obtained from the Bureau of Vital Statistics of the Taiwan Provincial Department of Health. Controls were deaths from other causes and were pair matched to the cases by sex, year-of-birth, and year-of-death. Each matched control was selected randomly from the set of possible controls for each case. Data on nitrate-nitrogen (NO3-N) level of drinking water throughout Taiwan have been collected from Taiwan Water Supply Corporation (TWSC). The municipality of residence for cases and controls was assumed to be the source of the subject's nitrate exposure via drinking water. The adjusted odds ratios for colon cancer death for those with high NO3-N levels in their drinking water, as compared to the lowest tertile, were 0.98 (0.84-1.14) and 0.98 (0.83-1.16), respectively. The results of the present study show that there was no statistically significant association between NO3-N in drinking water at levels in this study and risk of death from colon cancer.     

污泥堆肥及其应用研究

随着城市化进程的不断推进,城市污水厂所处理的污水量不断增大,由此产生了数量庞大的污泥,致使城市污水厂的污泥的合理处理处置成为研究热点.目前污泥的主要处理方法有卫生填埋、污泥堆肥以及焚烧等,其中污泥堆肥为诸多学者所赞同.文章探讨了污泥堆肥的基本原理与过程,介绍了条垛式堆肥系统、强制通风静态垛系统、反应器堆肥系统以及槽式堆肥系统的发展与污泥堆肥在农业以及绿化方面的应用情况,以期为污泥堆肥的发展与应用提供一定的参考.     

生活垃圾在不同湿解条件下蛋白质含量的动态分析研究

垃圾湿解处理工艺是一种新型的垃圾处理工艺,将垃圾中的有机物回收利用,只将少量的垃圾进行填埋或焚烧处理,不仅减少了垃圾量且使资源利用达到最大化。研究所得成果,能够促进垃圾湿解处理工艺的不断改进和完善。以烟台市生活垃圾处理厂经过湿解处理的垃圾筛下物作为实验样品。通过控制变量法、平行实验法以及考马斯亮蓝法进行比色实验,最终分析得出生活垃圾湿解的最佳条件。根据试验样品所给湿解条件范围以及实验数据的综合分析可推断出当湿解压强为0.6 MP、湿解温度为110℃、湿解时长为50 min时湿解后垃圾中蛋白质含量最高,湿解效果最好。     

宁夏风区分布特征及输电线路防风策略研究

针对宁夏输电线路经常因大风引起故障的问题, 结合地形及大气环流等因素,研究了宁夏风区的分布特征,并根据风区分布特征提出了宁夏输电线路防风策略。应用结果表明:防风策略实施后,输电线路因大风引起的故障明显减少,避免了输电线路风偏、舞动故障的发生,大大减少了宁夏电网因非计划停运造成的经济损失,保证了输电线路的安全稳定运行。     

Treatment of Sulfate/Sulfide-Containing Wastewaters Using a Microbial Fuel Cell: Single and Two-Anode Systems

The microbial fuel cell (MFC) was employed to convert reductive potential in sulfate-laden wastewaters to electricity via reducing sulfate to sulfide by sulfate-reducing bacteria and then oxidizing sulfide to sulfur by exoelectrogens. The excess sulfide presented in the anodic solution inhibited the activities of functional strains in MFC. This study proposed the use of a two-anode system, with a sulfate-reducing bacteria anode and an exoelectrogen (C27) anode in the anodic cell, to efficiently convert reductive potential of sulfate into electricity. The microbial community of sulfate-reducing bacteria anode and the electrochemical characteristics of the studied MFCs were reported.     

Interaction between Cu2+ and different types of surface-modified nanoscale zero-valent iron during their transport in porous media

This study investigated the interaction between Cu²⁺ and nano zero-valent iron (NZVI) coated with three types of stabilizers (i.e., polyacrylic acid [PAA], Tween-20 and starch) by examining the Cu²⁺ uptake, colloidal stability and mobility of surface-modified NZVI (SM-NZVI) in the presence of Cu²⁺. The uptake of Cu²⁺ by SM-NZVI and the colloidal stability of the Cu-bearing SM-NZVI were examined in batch tests. The results showed that NZVI coated with different modifiers exhibited different affinities for Cu²⁺, which resulted in varying colloidal stability of different SM-NZVI in the presence of Cu²⁺. The presence of Cu²⁺ exerted a slight influence on the aggregation and settling of NZVI modified with PAA or Tween-20. However, the presence of Cu²⁺ caused significant aggregation and sedimentation of starch-modified NZVI, which is due to Cu²⁺ complexation with the starch molecules coated on the surface of the particles. Column experiments were conducted to investigate the co-transport of Cu²⁺ in association with SM-NZVI in water-saturated quartz sand. It was presumed that a physical straining mechanism accounted for the retention of Cu-bearing SM-NZVI in the porous media. Moreover, the enhanced aggregation of SM-NZVI in the presence of Cu²⁺ may be contributing to this straining effect.     

Zn(Ⅱ)对生物质碳源处理酸性矿山排水中厌氧微生物活性影响

通过厌氧批实验的方法,探讨了在硫酸盐还原菌(SRB)法处理模拟酸性矿山排水(AMD)的过程中,以油菜秸秆为碳源时,Zn2+浓度对SRB活性的影响.结果表明,在60 d实验中,以油菜秸秆为碳源时,当Zn2+初始浓度在73.7～196.8 mg.L-1范围时,SRB具有良好活性,实验结束时,pH从初始的5.0上升至中性范围,硫酸根还原率达到96%以上,同时Zn2+浓度降至0.05 mg.L-1以下.Tessier固体形态分类、场发射扫描电镜(FE-SEM)和X射线衍射仪(XRD)分析发现,Zn以有机物及硫化物的形态被固定,其中硫化物主要为闪锌矿(ZnS).当Zn2+初始浓度为262.97 mg.L-1时,SRB的活性受到强烈的抑制,实验结束时,pH从初始的5.0降至4.0左右,硫酸根还原率只有27%,Zn2+维持在较高浓度范围(25 mg.L-1).油菜秸秆可以作为SRB法长期处理AMD的缓释碳源,能为微生物生长繁殖提供物质和能量;秸秆的吸附性可降低Zn2+的生物毒性,使得SRB可以适应高浓度的Zn2+;SRB可以通过形成硫化物矿物的形式固定元素Zn.     

Water quality prediction of copper-molybdenum mining-beneficiation wastewater based on the PSO-SVR model

● Data acquisition and pre-processing for wastewater treatment were summarized. ● A PSO-SVR model for predicting COD_eff in wastewater was proposed. ● The COD_eff prediction performances of the three models in the paper were compared. ● The COD_eff prediction effects of different models in other studies were discussed. The mining-beneficiation wastewater treatment is highly complex and nonlinear. Various factors like influent quality, flow rate, pH and chemical dose, tend to restrict the effluent effectiveness of mining-beneficiation wastewater treatment. Chemical oxygen demand (COD) is a crucial indicator to measure the quality of mining-beneficiation wastewater. Predicting COD concentration accurately of mining-beneficiation wastewater after treatment is essential for achieving stable and compliant discharge. This reduces environmental risk and significantly improves the discharge quality of wastewater. This paper presents a novel AI algorithm PSO-SVR, to predict water quality. Hyperparameter optimization of our proposed model PSO-SVR, uses particle swarm optimization to improve support vector regression for COD prediction. The generalization capacity tested on out-of-distribution (OOD) data for our PSO-SVR model is strong, with the following performance metrics of root means square error (RMSE) is 1.51, mean absolute error (MAE) is 1.26, and the coefficient of determination (R²) is 0.85. We compare the performance of PSO-SVR model with back propagation neural network (BPNN) and radial basis function neural network (RBFNN) and shows it edges over in terms of the performance metrics of RMSE, MAE and R², and is the best model for COD prediction of mining-beneficiation wastewater. This is because of the less overfitting tendency of PSO-SVR compared with neural network architectures. Our proposed PSO-SVR model is optimum for the prediction of COD in copper-molybdenum mining-beneficiation wastewater treatment. In addition, PSO-SVR can be used to predict COD on a wide variety of wastewater through the process of transfer learning.     

地震应急快速触发响应系统的需求分析与总体设计

介绍了中国数字地震观测网络项目应急分项软件"地震应急快速触发响应系统"的需求分析和总体功能设计,并对各子系统的技术实现方案以及软件的数据流程等内容进行了比较详细的说明。