Seasonal and treatment-process variations in invertebrates in drinking water treatment plants

• Seasonal and treatment-process variations in invertebrates in a DWTP were analyzed. • The propagation and leakage of invertebrates in BAC filter were the most serious. • Invertebrates can survive and reproduce in chlorine disinfected clear water tanks. • Proportions of endogenous invertebrates increased along the treatment process. Problems associated with excessive propagation and leakage of invertebrates in drinking water have received increasing attention in recent years. We performed a monthly survey of invertebrate abundance and taxa in the effluent of each treatment stage in a drinking water treatment plant between May 2015 and April 2016 and analyzed seasonal and treatment-process variations in invertebrates. The results showed that invertebrate abundances in raw water, effluent of the biological activated carbon (BAC) filter, and finished water significantly correlated with water temperature, whereas no correlation was observed between water temperature and invertebrate abundance in the effluents of the sedimentation tank and sand filter. The dominant taxa in the effluent of each treatment stage were rotifers, nematodes, and crustaceans. The sedimentation tank could efficiently remove invertebrates with an annual average removal rate of 92%. The propagation and leakage of invertebrates occurred in the sand and BAC filters but more seriously in the latter. The average reproduction rate in the BAC filter was 268.8% with rotifers as the taxon that leaked the most. Invertebrate survival and reproduction were also observed in the chlorine-disinfected clean water reservoir with an average reproduction rate of 41.9%. Owing to differences in chlorine resistance, the reproduction ability of the dominant taxa was in the order nematodes>crustaceans>rotifers. The proportion of endogenous invertebrates gradually increased along the treatment process. The average proportion of endogenous invertebrates in the finished water was higher than 79.0%. Our findings suggested that waterworks should pay more attention to endogenous invertebrate growth.     

典型大宗工业固体废物产生现状分析及产生量预测

针对大宗工业固体废物产生量大、历史堆存量多的问题,基于历史年份产废量和行业贡献度分析结果,运用灰色GM(1,1)模型预测了 2021-2025年特定行业典型大宗工业固体废物产生量.结果表明,尾矿、粉煤灰、煤矸石、冶炼废渣、炉渣、脱硫石膏等6种典型大宗工业固体废物普遍集中产生于1～2个特定行业,且特定行业的贡献程度普遍超...     

Nitrogen removal from summer to winter in a field pilot-scale multistage constructed wetland-pond system

A pilot-scale multistage constructed wetland-pond（MCWP） system with a "pre-ecological oxidation pond, two-stage horizontal subsurface flow constructed wetland（HSCW） and surface flow constructed wetland（SFCW） as the core and postsubmerged plant pond" as the process was used to treat actual polluted river water in the field, and the variation in nitrogen removal from summer to winter was investigated. The results showed that the average total nitrogen（TN） removal efficiency in the MCWP was approxi...     

新型换热器的传热性能研究

提出一种适合污泥处理过程中的余热回收的新型隔板管壳换热器,并与同样规格的普通管壳换热器性能进行对比。建立了简化的壳程计算模型,应用FLUENT计算软件分别对普通管壳换热器和新型隔流板式换热器进行数值模拟,获得了2种热交换壳程内部的流动分布、温度分布和压力分布,并将模拟结果和试验数据进行对比。试验及模拟结果表明,新型隔板式换热器温度分布均匀、流动死区少、传热效率高,综合性能远高于普通管壳换热器。     

三维荧光光谱法分析巢湖CDOM的空间分布及其来源

利用三维荧光光谱法研究了巢湖有色溶解有机物(CDOM)及其相关组分的空间分布特征,并对CDOM来源进行了分析.结果表明,巢湖西半湖CDOM平均相对荧光强度为927.1,显著高于东半湖的平均相对荧光强度544.9;CDOM组分腐殖酸(HA)和类蛋白物质浓度空间变化特征类似于CDOM;南淝河和丰乐河是西半湖CDOM的重要污染源;巢湖西北区域和中部湖区CDOM分别主要来源于南淝河和白石山河排放源.三维荧光光谱法在大型湖泊和河流水质监测中具有潜在的应用前景.     

The Transboundary Nature of the Allende–Piedras Negras Aquifer Using a Numerical Model Approach

The Allende–Piedras Negras (APN) aquifer is located between the states of Texas (United States [U.S.]) and Coahuila (Mexico). The Rio Grande crosses the aquifer, acting as a natural and political divide between the countries. However, it remains unclear whether the APN aquifer can be considered a truly transboundary aquifer flow system, which would potentially require joint management by two different administrative jurisdictions. The main purpose of this study was to evaluate the transboundary nature of this aquifer. This was achieved by developing a detailed hydrogeological model to analyze the direction of volumetric fluxes within the APN aquifer using Visual MODFLOW. The model simulated a spatially averaged cumulative drawdown of 0.76 m for the entire aquifer over an 18‐year modeling period (2000–2017). The flow convergence zone, previously located below the Rio Grande, has shifted to the U.S. side in most locations, driven by higher pumping rates of the wells located near the river. This shift of the convergence zone from one country to the other means that groundwater recharge from one side flows underneath the river to the other side. This qualifies the APN aquifer as a “transboundary groundwater flow system.” The procedure followed in this study may be applied to other aquifers that straddle the U.S.–Mexico border and may motivate future modeling studies on other poorly studied transboundary aquifers around the world and thereby enable bi‐national aquifer management.     

Analytical solution of two-dimensional solute transport in an aquifer–aquitard system

This study deals with two-dimensional solute transport in an aquifer–aquitard system by maintaining rigorous mass conservation at the aquifer–aquitard interface. Advection, longitudinal dispersion, and transverse vertical dispersion are considered in the aquifer. Vertical advection and diffusion are considered in the aquitards. The first-type and the third-type boundary conditions are considered in the aquifer. This study differs from the commonly used averaged approximation (AA) method that treats the mass flux between the aquifer and aquitard as an averaged volumetric source/sink term in the governing equation of transport in the aquifer. Analytical solutions of concentrations in the aquitards and aquifer and mass transported between the aquifer and upper or lower aquitard are obtained in the Laplace domain, and are subsequently inverted numerically to yield results in the real time domain (the Zhan method). The breakthrough curves (BTCs) and distribution profiles in the aquifer obtained in this study are drastically different from those obtained using the AA method. Comparison of the numerical simulation using the model MT3DMS and the Zhan method indicates that the numerical result differs from that of the Zhan method for an asymmetric case when aquitard advections are at the same direction. The AA method overestimates the mass transported into the upper aquitard when an upward advection exists in the upper aquitard. The mass transported between the aquifer and the aquitard is sensitive to the aquitard Peclet number, but less sensitive to the aquitard diffusion coefficient.     

加砂压裂中固体支撑剂对压裂管道的冲蚀磨损研究

为研究压裂高压管汇在大排量携砂液输送过程中的管壁冲蚀磨损问题,应用CFD方法及Fluent软件,建立了高压管汇主要管件三通管的冲蚀模型,基于数值模拟计算研究了冲蚀发生机理及位置,探讨了高压管汇的冲蚀特点。结果表明:压裂液流动方向变化区域存在严重的冲蚀现象,如主管与支管连接处;三通主管下游段,内壁冲蚀主要是来自支管的固体支撑剂在运动方向改变时对内壁低角度切削;管汇里越靠近井口的三通因为压裂液流量增加,主管下游段两侧冲蚀越严重。该研究结果可为管汇设计制造、关键部位检测等提供技术参考。     

多壁碳纳米管固相萃取—高效液相色谱法测定水中7种三唑类农药残留

应用多壁碳纳米管自制固相萃取柱富集、净化,以乙腈-水为流动相,用乙酸乙酯洗脱,高效液相色谱进行分析检测,建立了环境水样中7种三唑类农药残留分析的方法。结果表明,在0.05~10.00mg/L线性范围内,方法检出限为0.000 9~0.047 7mg/L;农药的加标水平在0.25~1.00mg/L时,加标回收率为72.28%~106.60%,相对标准偏差为1.12%~9.73%。该方法操作简单,定性、定量准确,是对水样中三唑类农药残留液相色谱分析较理想的一种方法。