粉煤灰基陶瓷微滤膜处理水中悬浮物的抗污染特性

粉煤灰基陶瓷微滤膜是一种新型的廉价无机膜,为研究其抗污染性能,研究了自制的管式膜在处理几种典型料液中的分离性能和渗透性能.考察了过滤不同料液过程中的阻力构成和膜的抗污染特性,并且和文献报道的同类过程中其他膜材料的性能进行了比较.实验进行了2～45 h无反冲、无清洗的连续运行.在过滤粉煤灰悬浮液、高龄土悬浮液和斜生栅藻悬浮液过程中,截留率可以达到100％,过滤阻力低于类似条件下的其他膜材料,在长时间运行后仍能保持较高的通量,表现出良好的抗污染性能.在过滤活性污泥时,截留率达到99.8％,单位压力下过滤通量达到1 170 L/(m·h·MPa).和其他膜材料相比,单位压力下的过滤通量表现出明显的优势.     

家居环境PM_(2.5)控制用空气滤料

针对目前家居环境净化PM2.5的要求,在现有空气过滤材料的基础上,探讨一种适合于家居环境移动式空气净化装置用低阻、高效和长寿命的过滤材料。采用实验研究的方法对常用玻纤滤纸以及驻极体空气过滤材料进行了过滤特性、电镜、孔径测试的对比实验研究。结果表明,当过滤风速为5 cm/s时,3种驻极体滤料对粒径≤4.5μm的颗粒物的分级过滤效率要高于玻纤滤纸且都在90%以上,其过滤阻力在4.9~6.4 Pa之间,而高效滤纸的过滤阻力在57.8~78.6 Pa之间;在实验风速条件下,驻极体滤料对PM2.5的过滤效率和过滤阻力分别高于和低于高效玻纤滤纸;对驻极体滤料进行蒸馏水洗涤后,其对颗粒物的过滤效率下降,驻极体滤料静电效应具有不稳定特性;电镜测试发现,玻纤滤纸纤维层排布致密,纤维存在断裂现象,而驻极体滤料较为蓬松,无纤维断裂现象;孔径实验表明,驻极体滤料的平均孔径为玻纤滤纸的11.9~14.7倍,驻极体滤料具有良好的透气和容尘特性。     

Influence of plants on the reduction of hexavalent chromium in wetland sediments

This work addresses the effect that plants (Typha latifolia and Carex lurida) have on the reduction of Cr(VI) in wetland sediments. Experiments were carried out using tubular microcosms, where chemical species were monitored along the longitudinal flow axis. Cr(VI) removal was enhanced by the presence of plants. This is explained by a decrease in the redox potential promoted by organic root exudates released by plants. Under these conditions sulfate reduction is enhanced, increasing the concentration of sulfide species in the sediment pore water, which reduce Cr(VI). Evapotranspiration induced by plants also contributed to enhance the reduction of Cr(VI) by concentrating all chemical species in the sediment pore water. Both exudates release and evapotranspiration have a diurnal component that affects Cr(VI) reduction. Concentration profiles were fitted to a kinetic model linking sulfide and Cr(VI) concentrations corrected for evapotranspiration. This expression captures both the longitudinal as well as the diurnal Cr(VI) concentration profiles.     

粒状滤料过滤理论浅析

粒状滤料过滤理论的主要内容是过滤机理、过滤方程式和反冲洗机理。过滤机理有悬浮颗粒的迁移机理、悬浮颗粒的吸附机理和脱落机理等。过滤在水澄清的同时，滤层的水头损失增加，整个过程涉及因素多而且复杂，过滤方程式很难得到解析性的答案，所以过滤方程对过滤过程只起定性的作用。现在反冲洗机理的研究认为，悬浮颗粒从滤料表面脱落是水流剪切和颗粒碰撞综合作用的结果。     

微絮凝强化过滤工艺处理低温低浊水的实验研究

以北京市某水厂冬季沉后水为研究对象,分别采用常规过滤工艺和强化过滤工艺对其进行处理.通过改变聚合氯化铝(PACl)投加量、滤料粒径d和微絮凝时间,并结合水头损失、颗粒数、总有机碳(TOC)、化学需氧量(COD)等实验数据,对低温低浊水体强化过滤工艺条件进行了研究.结果表明,强化过滤工艺与常规过滤工艺相比具有较强的除浊、去除有机物和颗粒物的能力,当微絮凝时间为2min时可以得到较好的过滤效果;PACl投药量为1.5mg·L-1时,浊度可降到0.04NTU,而常规过滤工艺最多只能将浊度降到0.2NTU.在滤料选用方面,当滤料粒径d=0.6～1.2mm时滤后水中颗粒数(2～5μm)、浊度、COD等指标均达到最优值.同时,电感耦合等离子体光谱(ICP-OES)检测结果表明,滤后水中Al3+含量小于0.2mg·L-1,并未因二次投加PACl而升高,因此,不会对水的饮用产生任何健康和安全风险.     

Molecular characterization of root exudates using Fourier transform ion cyclotron resonance mass spectrometry

The release of root exudates (REs) provides an important source of soil organic carbon. This work revealed the molecular composition of REs of different plant species including alfalfa (Medicago sativa L.), bean (Phaseolus vulgaris L.), barley (Hordeum vulgare L.), maize (Zea mays), wheat (Triticum aestivum L.), ryegrass (Lolium perenne L.) and pumpkin (Cucurbita maxima) using electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS). The combination of positive ion mode (+ESI) and negative ion mode (-ESI) increased the number of the molecules detected by ESI FT-ICR MS, and a total of 8758 molecules were identified across all the samples. In detail, lipids and proteins and unsaturated hydrocarbons were more easily detected in +ESI mode, while aromatic compounds with high O/C were readily ionized in -ESI mode, and only 38% of the total assigned formulas were shared by -ESI and +ESI modes. Multivariate statistical analysis of the formulas indicated that the close related plants species secreted REs with similar molecular components. Moreover, the unsaturation degree and nitrogen content were the two key parameters able to distinguish the similarities and differences of molecular components of REs between plant species. The results provided a feasible analysis method for characterization of the molecular components of REs and for the first time characterized the molecular components of REs of a variety of plant species using ESI FT-ICR MS.     

接触氧化过滤一体化生物反应器处理城市污水

针对一种采用组合填料的接触氧化过滤一体化生物反应器,进行了以间歇方式处理城市污水的试验研究.结果表明,在曝气时间为60 min,DO为2～3 mg/L,反应器上部填料层容积负荷率(以COD计)为2.4 kg/(m~3·d),生物滤床初始滤速为5 m/h时,反应器出水COD、NH_4~+-N、浊度的平均去除率分别为90.6%、81.4%和96.7%,但TP去除效果欠佳,平均去除率为60.1%.     

Beijing Tong Ren Tang Company Limited Scientific Research Institute, Beijing 100011, China

By dynamic method under UV irradiation,commercial melt-blown polypropylene(PPMB)filter element was modified with acrylamide(AAm)using benzophenone(BP)as initiator.Attenuated total reflection-Fourier transform infrared spectroscopy and scanning electron microscope verified that polyacrylamide chain was grafted on the fiber surface of PPMB filter element.Elemental content analysis with energy dispersive X-ray of fibers revealed that the polymerization content in the inner part of filter element was relatively higher than that in the outer.Degree of grafting changed with initiator concentration,monomer concentration,reaction temperature and reached 2.6% at the reaction condition:C_(BP)=0.06 mol/L,C_(AAm)=2.0 mol/L,irradiation time:80 min,temperature: 60℃.Relative water flux altered with the hydrophilicity and pore size of filter element.In the antifouling test,the modified filter gave greater flux recovery(approximately 70%)after filtration of the water extract of Liuweidihuang,suggesting that the fouling layer was more easily reversible due to the hydrophilic nature of the modified filter.     

生物过滤法处理污泥干化尾气

城市污水处理过程中产生大量污泥,其热干化所产生的尾气主要存在以下特点：气味属刺激性臭气,主体为各种无机、有机化合性气体;热干化过程产生的尾气含有大量的热值,容易对环境造成二次污染。关于污泥干化尾气的处理,目前国内采用的工艺并不很成熟。为了避免污泥干化尾气的二次污染,本着经济适用的原则,本文根据尾气的性质,对生物过滤法处理污泥尾气进行了研究,具体分析了原结构的不合理之处,提出了增湿塔与生物滤塔的改进性建议。     

铁屑过滤-SBR工艺处理印染废水的研究

采用铁屑过滤－ＳＢＲ工艺对印染废水进行了处理研究,当进水ＣＯＤ为１０００－１６００ｍｇ／Ｌ,色度为２００－８００倍,ＢＯＤ５在２００－４００ｍｇ／Ｌ时,ＣＯＤ去除率可达８５％,ＢＯＤ５去除率和脱色率均在９０％以上,出水达到排放标准,该工艺具有投资少,运行费用低,处理效果稳定等特点,尤其适合中小型印染厂的废水治理。