曝气强度对膜污染的影响

混合液浓度的高低及其粒度分布特性是影响膜生物反应器膜污染的重要因素。在一定污泥浓度下,主要考察了曝气强度对污泥絮体粒度分布的影响,以及不同粒度下的膜污染特性。试验结果表明,曝气强度提高,可以起到减缓污泥颗粒在膜表面的沉积作用,但高的错流流速产生的剪切效应使得污泥颗粒变得琐碎,导致细小胶体粒子和溶解性部分增多,增加了膜孔吸附和堵塞的机会,加剧了膜污染的进程。膜污染速率在曝气强度提高初期阶段迅速降低,接着又随曝气强度增加而缓慢升高,在污泥质量浓度为8 g/L的试验条件下,对应的最适曝气强度为84 m3/(m2.h)。     

液体旋流分离器分离效率的研究

液体旋流分离器是水环境污染治理的主要设备之一.分离效率是衡量液体旋流分离器分离过程进行完善程度的最重要的技术指标,它能从质与量两方面反映出设备性能的优劣.当前液体旋流分离器设计过程还缺少具体量化的理论依据,为了给液体旋流分离器的设计提供理论依据,通过液体旋流分离器从水中分离固体粒子的性能实验,得出了液体旋流分离器各部结构尺寸、形状、相对比例对分离效率的不同影响程度,提出了结构参数的最佳取值范围.按照本研究提出的设计原则和方法,可以制造出性能优良的液体旋流分离器.     

水力停留时间对膜生物反应器复合工艺污水处理特性的影响

开发了厌氧-多级好氧/缺氧-膜生物反应器复合工艺,在不同水力停留时间(HRT)下,考察了系统对污染物去除效果及其膜污染的特性.结果表明,在试验选定的HRT范围内,系统对TN和TP的去除率随着HRT的降低而升高,当HRT为8.70、6.96、4.97 h时,系统对TN和TP的平均去除率分别为73.15%、79.76%、81.98%和67.79%、80.99%、92.16%.但是,较低HRT条件下膜通量较高,会加剧膜污染进程.解决这一问题的措施是增加膜组件个数,从而在不提高膜通量的情况下使系统保持较低的HRT,保证系统高效稳定的污染物去除效果.     

Glutathione-functionalized melamine sponge,a mimic of a natural antidote,as a quick responsive adsorbent for efficient removal of Hg(II) from aqueous solutions

Minamata disease is caused by methylmercury, which is produced by microorganisms from inorganic mercury ions, Hg(II), in the aquatic environment. Adsorption is a feasible method to remove Hg(II) from waters, but there are some drawbacks when using conventional adsorbents, for example, tedious solid–liquid separation, slow response, and excessive residual levels of mercury. In this work, a novel spongy adsorbent has been developed for Hg(II) removal via surface functionalization of melamine formaldehyde sponge by glutathione. This material mimics a natural antidote that removes trace heavy metals in the human body. Results show that the functionalized sponge displays a 99.99% removal efficiency for low concentrations of Hg(II) of 10 mg/L. As a consequence, the residual Hg concentration is lower than 0.005 mg/L, which is slightly below the standard for total mercury in drinking water, of 0.006 mg/L, formulated by the World Health Organization, and much lower that the discharge regulation standard, of 0.01 mg/L, set by the ministry of environmental protection of China. Adsorption kinetic studies indicate that the functionalized sponge has a fast response. Indeed, the adsorption equilibrium can be reached within 10 min, and about 80% of total adsorption capacities are reached in 1 min. Moreover, the maximum adsorption capacity of the glutathione-functionalized sponge is as high as 240.02 mg/g, as shown by adsorption isotherm. Overall our findings disclose the great potential of the developed sponge adsorbent for rapid and efficient removal of Hg(II) from water.     

CaCu3Ti4O12, an efficient catalyst for ibuprofen removal by activation of peroxymonosulfate under visible-light irradiation

Environmental Chemistry Letters - Contamination of waters by pharmaceuticals is a major health issue. Therefore, there is a need for efficient techniques to remove pharmaceutical pollutants. Here,...     

Synthesis of a three-dimensional network sodium alginate–poly(acrylic acid)/attapulgite hydrogel with good mechanic property and reusability for efficient adsorption of Cu2+ and Pb2+

Environmental Chemistry Letters - Water pollution caused by heavy metals has dramatically impacted ecosystems in recent years. For instance, 45.4% of lakes in China are in the category of moderate...     

石英ESR法在河流沉积物源示踪中的探讨及应用

使用石英ESR法示踪河流沉积物源是一种新方法和新理论的探索。本文从拟解决的科学问题出发,在着重分析石英ESR信号强度和CI值物源示踪理论基础之上,讨论了该方法在亚洲现代沙尘沉降物源示踪和地质历史时期风尘堆积物源示踪研究中的有效性,结合ESR测年可覆盖整个第四纪时期的特性,认为石英ESR法不仅可以为物源示踪提供良好的年代框架约束,而且还可以较好的反映地质历史时期沉积物质来源在不同时空尺度上的变化特征。随后,通过对指导思想、研究思路以及长江流域不同河段和主要支流的地质地貌背景、岩石类型分布、水系组合特征以及"源-汇"系统之间物质剥蚀-堆积过程的可通达性等方面的综合论述与分析,讨论了石英ESR法在河流沉积物源示踪上的有效性及其在研究长江流域水系发育历史和沉积演化过程中的可行性。     

Effect of chemical dose on phosphorus removal and membrane fouling control in a UCT-MBR

Phosphorus removal was enhanced effectively by dosing aluminum sulfate and effluent phosphorus concentration was lower than 0.5 mg/L. Sludge activity was not inhibited but improved slightly with addition of aluminum sulfate. EPS concentrations both in mixed liquid and on membrane surface were decreased, contributing to the effective mitigation of membrane fouling. To enhance phosphorus removal and make the effluent meet the strict discharge level of total phosphorus (TP, 0.5 mg/L), flocculant dosing is frequently applied. In this study, the performance of aluminum sulfate dosing in a University of Cape Town Membrane Bioreactor (UCT-MBR) was investigated, in terms of the nutrients removal performance, sludge characteristics and membrane fouling. The results indicated that the addition of aluminum sulfate into the aerobic reactor continuously had significantly enhanced phosphorus removal. Moreover, COD, NH₄⁺-N and TN removal were not affected and effluent all met the first level A criteria of GB18918-2002. In addition, the addition of aluminum sulfate had improved the sludge activity slightly and reduced trans-membrane pressure (TMP) increase rate from 1.13 KPa/d to 0.57 KPa/d effectively. The membrane fouling was alleviated attributed to the increased average particle sizes and the decreased accumulation of the small sludge particles on membrane surface. Furthermore, the decline of extracellular polymeric substance (EPS) concentration in mixed sludge liquid decreased its accumulation on membrane surface, resulting in the mitigation of membrane fouling directly.     

“煤改气”投资对宏观经济的拉动效应:基于北京市可计算一般均衡模型分析

“煤改气”是我国大气污染防治行动计划的政策措施之一,国内外目前对“煤改气”政策实施的环境效果研究较多,但对“煤改气”投资对宏观经济的拉动作用研究较少. 为综合评价“煤改气”政策的整体效果、探讨“煤改气”投资对宏观经济的拉动作用,以北京市为例,构建了北京市可计算一般均衡模型(MRDR-BJ),基于2017年北京市投入产出表,模拟不同情景下“煤改气”投资对宏观经济的拉动效应. 结果表明:随着“煤改气”投资的增加,北京市宏观经济增加值、温室气体排放量、就业量、家庭收入均增加;“煤改气”投资每增加20%,这些宏观指标分别增长0.05%、0.07%、0.07%和0.07%;“煤改气”投资对宏观经济的拉动系数为1.77. 研究显示,“煤改气”投资对宏观经济具有较大的拉动效应,建议全国各地尽快落实“煤改气”规划,以加快大气污染治理、促进生态环境建设,助力我国碳达峰、碳中和中长期目标的实现.      

液体旋流分离器压力损失的研究

液体旋流分离器是水环境污染治理的主要设备之一。压力损失是衡量液体旋流分离器分离过程能耗大小的重要技术指标,也是选择水泵扬程的依据。当前液体旋流分离器设计过程还缺少具体量化的理论依据。通过液体旋流分离器的性能实验,得出液体旋流分离器各部结构尺寸、形状、相对比例对压力损失的不同影响程度,提出结构参数的最佳取值范围。为液体旋流分离器的设计提供了依据及应遵循的原则。并在实验结果的基础上,归纳汇总出一般常用型液体旋流分离器压力损失的计算公式,该计算公式具有一般性。