Effects of chemical modification on physicochemical properties and adsorption behavior of sludge-based activated carbon

This study aimed to explore the adsorption performance of sludge-based activated carbon (SBC) towards dissolved organic matters (DOMs) removal from sewage, and investigated the modification effect of different types of chemicals on the structure of synthesized SBC. Waste activated sludge (WAS) was used as a carbon source, and HCl, HNO₃, and NaOH were used as different types of chemicals to modify the SBC. With the aid of chemical activation, the modified SBC showed higher adsorption performances on DOMs removal with maximum adsorption of 29.05 mg/g and second-order constant (k) of 0.1367 (L/mol/sec) due to the surface elution of ash and minerals by chemicals. The surface elemental composition of MSBC suggested that the content of C-C and C-O functional groups on the surface of modified sludge-based activated carbon (MSBC) played an important role on the adsorption capacities of MSBC towards DOMs removal in sewage. Additionally, the residual molecular weight of DOMs in sewage was investigated using a 3-dimension fluorescence excitation-emission matrix (3D-EEM) and high-performance size exclusion chromatography (HP-SEC). Results showed that the chemical modification significantly improved the adsorption capacity of MSBC on humic acids (HA) and aromatic proteins (APN), and both of NaOH-MSBC and HCl-MSBC were effective for a wide range of different AMW DOMs removal from sewage, while the HNO₃-MSBC exhibited poorly on AMW organics of 2,617 Da and 409 Da due to the reducing content of macropore. In brief, this study provides reference values for the impact of the chemicals of the activation stage before the SBCs application.     

硫酸盐还原过程中乙酸型代谢方式的形成及其稳定性

通过产酸脱硫反应器处理高浓度硫酸盐废水的连续流试验,考察了不同试验阶段硫酸盐去除率和产气量稳定期,液相末端产物中挥发酸组成的变化、乙酸的分布特征、微生物种群组成和种群间关系.试验结果表明,各试验阶段液相末端产物中乙酸的分布比例高达50%～82%,微生物群体呈现特定的乙酸型代谢方式.乙酸型代谢方式本质上是产酸相反应器处理硫酸盐废水过程中,硫酸盐还原菌(SRB)与产酸菌(AB)建立起生物链式协同代谢关系,并通过非完全氧化型方式分解有机物,从而在末端产物中积累大量乙酸.乙酸型代谢方式的形成取决于利用乙酸的硫酸盐还原菌(ASRB)的竞争能力和它对乙酸的利用能力.乙酸型代谢方式可以为后续产甲烷相反应器提供适宜的底物,对提高硫酸盐废水处理系统的效率和运行稳定性具有重要意义.     

金属铁离子对农田土壤氮转化影响分析

以长春伊通河河谷阶地上部的农田土为研究对象,选用铁离子作为氮转化的一种影响因素,定性研究了不同浓度的铁离子对硝态氮、亚硝态氮、铵态氮三氮的变化影响。并且在建立方程组之后计算平衡常数,证明了铁的氧化作用,与实验所得相符合：铁促进铵态氮的吸附、促进硝化反应的进行。从实验和理论的角度说明了铁在三氮转化中起的作用,为进一步研究锰铁离子对氮转化的定量影响和氮素污染地下水的预测和定量评价提供科学依据。     

北京市饮用水中溴酸盐、卤代乙酸及高氯酸盐研究

调查了北京市饮用水厂源水及出厂水中消毒副产物溴酸盐、卤代乙酸及典型污染物高氯酸盐的污染现状,研究了其来源及环境影响因素.结果表明,北京市饮用水中基本不含溴酸盐;含有5种卤代乙酸和高氯酸盐.饮用水加氯消毒是产生卤代乙酸的主要原因.在所调查水厂出厂水中卤代乙酸的平均浓度为42.1～149.5μg/L;其中含氯卤代乙酸占总量的90%以上.5种卤代乙酸的含量顺序为三氯乙酸>二氯乙酸>氯溴乙酸>二溴乙酸>一溴二氯乙酸.饮用水中卤代乙酸受季节影响较大,9月份浓度最高,4月份浓度最低.高氯酸盐主要存在于以地下水为源水的水厂中,受地下水污染影响较大.各水厂出厂水中高氯酸盐含量为0.1～6.8μg/L.饮用水中高氯酸盐在11月份含量最高,7月份含量最低.     

废水中磷的监测和处理

本文介绍了钼锑抗光度法测定污水中总磷在实际应用中应该注意的问题，并介绍了不同类型污水处理设施的除磷效率。则结果证明，常规二级污水处理工艺对总磷的去除率只能达到４０－５０％左右，迄今，化学混凝与生物过程一体化的处理系统可能是除灰最经济有效的办法。     

聚硅酸溶胶和凝胶的电镜观察

用透射电子显微镜（ＴＥＭ）和扫描电子显微镜（ＳＥＭ）观察了硅酸溶胶的聚合过程。在ｐＨ值与Ｎａ２Ｏ·ｎＳｉＯ２模数一定时，其聚合速度与温度有关，温度高聚合快。聚硅酸溶胶粒子主要是圆形或椭圆形颗粒，粒子由于聚集变大，硅酸凝胶具有毛刷结构，其间隙被水填充。反应时，聚集、聚合和溶解同时进行，最后聚集起主要作用，凝胶形成。     

多氯代甲烷对鳝鱼红细胞微核率及核异常率的影响

试验采用外周血红细胞微核测试技术,通过分析鳝鱼外周血细胞的核异常率和微核率,研究多氯代甲烷的遗传毒性和生态安全性.结果表明:①96 h后,质量浓度为3 mg·L-,30 mg·L-1和300 mg·L-1的CCl4和CHCl3污染所产生的核异常率分别为:5.38%和4.26%,9.62%和6.50%,12.18%和9.54%,表明CCl4对细胞异常率的影响大于CHCl3对细胞核异常率的影响;②96 h后,质量浓度为3 mg·L-1,30 mg·L-1和300 mg·L-1的CCl4和CHCl3污染所产生的微核率分别为:0.64%和0.40%,0.94%和0.55%,1.31%和0.95%,说明CCl4对细胞微核率的影响大于CHCl3对细胞核微核率的影响.表明用微核测试的方法分析环境中的污染物对生物体危害的程度是一种最便捷和有效的手段.     

Fast transformation of roxarsone into toxic arsenic species with ferrous iron and tetrapolyphosphate

Environmental Chemistry Letters - Organoarsenic compounds have been widely used as feed additives in livestock and poultry breeding. They are excreted in manure and thus cause environmental...     

Efficient removal of cadmium ions from water by adsorption on a magnetic carbon aerogel

Environmental Science and Pollution Research - Carbon aerogels are attracting much attention as adsorbents due to their high specific surface and large accessible pores. Herein, we describe a...