Multi-function adsorbent-photocatalyst MXene-TiO2 composites for removal of enrofloxacin antibiotic from water

MXenes, a new family of two-dimensional transition metal carbides or nitrides, have attracted tremendous attention for various applications due to their unique properties such as good electrical conductivity, hydrophilicity, and ion intercalability. In this work, Ti₃C₂ MXene, or MX, is converted to MX-TiO₂ composites using a simple and rapid microwave hydrothermal treatment in HCl/NaCl mixture solution that induces formation of fine TiO₂ particles on the MX parent structure and imparts photocatalytic activity to the resulting MX-TiO₂ composites. The composites were used for enrofloxacin (ENR), a frequently found contaminating antibiotic, removal from water. The relative amount of the MX and TiO₂ can be controlled by controlling the hydrothermal temperature resulting in composites with tunable adsorption/photocatalytic properties. NaCl addition was found to play important role as composites synthesized without NaCl could not adsorb enrofloxacin well. Adding NaCl into the hydrothermal treatment causes sodium ions to be simultaneously intercalated into the composite structure, improving ENR adsorption greatly from 1 to 6 mg ENR/g composite. It also slows down the MX to TiO₂ conversion leading to a smaller and more uniform distribution of TiO₂ particles on the structure. MX-TiO₂/NaCl composites, which have sodium intercalated in their structures, showed both higher ENR adsorption and photocatalytic activity than composites without NaCl despite the latter having higher TiO₂ content. Adsorbed ENR on the composites can be efficiently degraded by free radicals generated from the photoexcited TiO₂ particles, leading to high photocatalytic degradation efficiency. This demonstrates the synergetic effect between adsorption and photocatalytic degradation of the synthesized compounds.     

膜生物反应器处理生活污水的膜污染研究

本文研究的是采用一体式膜生物反应器处理生活污水过程中膜污染问题.试验结果表明:运行初期,由于膜孔堵塞膜通量下降速率较快,但随着运行时间的延长,膜通量下降缓慢且趋于一定值,膜污染也基本保持稳定;膜生物反应器处理高效优质,出水水质不受冲击负荷的影响,膜对部分有机物的截留作用使系统对COD的去除率保持在较高水平上,但膜对总磷的去除不明显;污泥沉降性能与膜污染具有相关性,污泥沉降性能的恶化直接加剧了膜污染.     

COD负荷对MBSBBR脱氮除磷性能的影响研究

以模拟废水为处理对象,采用一套特定的MBSBBR系统,研究了COD负荷率对COD和NH4+-N去除率的影响,验证并分析了系统的SND现象。实验结果表明:COD负荷率为2.88～4.96kg/(m3·d)时,NH4+-N的去除率在70%左右,TP去除率在85%左右。系统对有机物具有良好的去除能力,可以承受较高的有机负荷率。系统中存在SND现象,反硝化菌大量存在,反硝化过程的碳源主要来自生物膜。系统的污泥产率较低,随着COD负荷率的增大而略有提高。     

固定化微生物法处理含甲硫醇恶臭气体

采用液相曝气方式驯化培养污水厂活性污泥，获得具有降解甲硫醇能力的优势微生物菌群。同时用海藻酸钠包埋固定化微生物，研究固定化微生物颗粒填充床去除甲硫醇恶臭气体的工艺过程。液相曝气培养研究表明：降解甲硫醇的微生物菌群适宜的ｐＨ值为５．２～９．０，最佳ｐＨ条件为弱碱性。已驯化微生物的离心浓缩回收率为７１．２％，颗粒填充床生物脱臭塔运行实验表明：在空塔停留时间不大于１３ｓ，对低浓度甲硫醇气体（〈１２．９ｍ     

生物除磷活性污泥系统微生物学研究进展

强化生物除磷工艺（enhanced biological phospho rusremoval，简称EBPR）是引起世界各国广泛关注并投入巨资研究的一种污水处理新型技术，但关于EBPR过程的微生物学知识却知之甚少，还存在一些模糊甚至错误的认识．近年来，以rRNA为基础的分子生物学技术的应用极大改变了以前对EBPR微生物群落的认识，但对其种群动态和作用机制方面的了解还远远不够．本文总结了近年来在EBPR系统微生物学研究方面的进展，并对EBPR技术的未来发展做一展望，以期推动此技术在污水处理业的应用．参40     

人工湿地对有机污染物的去除效果与动态特征

通过对荣成人工湿地污水处理系统1999年1月至2004年12月间监测数据进行分析,确定系统的处理效果及有机污染物去除效果的动态特征。结果表明,人工湿地对SS、COD、BOD5均有很好的去除效果,出水质量浓度分别为27.6±6.6、90.0±12.5和22.7±4.3 mg.L-1,去除率分别为73.9%、63.8%和72.5%。大肠菌群、粪大肠菌群去除率分别为99.7%和99.6%。对NH4 -N和TP去除效果较差,出水质量浓度分别为11.2±2.7和2.03±0.29 mg.L-1,去除率分别为45.1%和30.2%。BOD5、COD的去除效果和季节变化有一定关系,每年的4—7月BOD5去除效果最佳,1月和12月去除效果最差。COD的去除效果每年6月和7月最高,1月和12月最低。分析BOD5、COD和SS去除效果的年际变化发现,BOD5和COD年平均去除率从1999年到2004年有增加的趋势。     

Experimental evidence for helping and hindering by previous offspring in the cooperative-breeding Seychelles warbler Acrocephalus sechellensis

Prebreeding Seychelles warblers (Acrocephalus sechellensis) frequently act as helpers on their natal territory, aiding in territory defence, predator mobbing, nestbuilding, incubation (only females) and feeding dependent young of their parents. In some cases helpers could attain breeding status (e.g. by joint-nesting) in their natal group and become co-breeders. Comparisons of group size and reproductive success on a given quality territory suggest that the presence of alloparents (helpers and cobreeders) significantly affects the reproductive success of their parents. The influence of alloparents on reproductive success was examined by removing alloparents from breeding units and comparing the success of natural-sized and artificially reduced groups. Removal experiments, controlled for territory quality, group size and breeder age, showed that the presence of one alloparent significantly improved the reproductive success of its parents. Analysis strongly suggests that this was entirely due to helping behaviour (i.e. providing care to offspring of their parents), thereby improving the helper's inclusive fitness benefits from staying at home. However, these experiments showed also that the presence of two or more alloparents in medium-quality territories significantly decreased reproductive success, compared with groups with one alloparent. Several lines of evidence suggest that this may have been due to the joint-nesting and reproductive competition that could occur in breeding groups, or simply to resource depression when a large number of previous offspring remained on their natal territory.     

电子工业光致抗蚀剂乳化废水预处理试验研究

研究了光致抗蚀剂乳化废水用硫酸和含钙辅助破乳分离出有机物沉淀的预处理工艺。确定了最合适的预处理工艺参数和流程；用GC／MS法分析了废水的组成和浓度，并探讨了有机物的去除机理。试验结果表明，pH值控制在3，辅助剂A的浓度为300mg/L、静置时间为60min时，是最合适的工艺条件，废水的CODcr值从15600mg/L下降到3542mg/L，CODcr的去除率达77.4%，投加辅助剂后既提高了有机物的去除率，又改善了沉淀物的过滤性能，从而有利于降低后续工艺的处理成本。     

污泥颗粒化快速启动厌氧氨氧化反应器的探讨

厌氧氨氧化工艺处理成本低,被认为是有应用前景的废水脱氮技术.但是,厌氧氨氧化菌生长缓慢,厌氧氨氧化反应器启动困难.探讨了几种快速启动厌氧氨氧化反应器的方法,包括投加颗粒污泥、惰性载体、絮凝剂及多价阳离子等,并对其作用机理进行了分析.     

富营养化供水中的藻类控制与去除

综述了富营养化的供水原水中，藻类控制与去除方法的国内外研究进展。首先扼要介绍藻类过度繁殖对原水处理工艺的诸多影响。然后叙述富营养化湖泊中，藻类生物量的控制方法和给水原水处理的藻类去除工艺，并就此技术现状提出若干结论和建议。