Arsenic removal from contaminated soil via biovolatilization by genetically engineered bacteria under laboratory conditions

In Rhodopseudomonas palustris, an arsM gene, encoding bacterial and archaeal homologues of the mammalian Cyt19 As(III) S-adenosylmethionine methytransferase, was regulated by arsenicals. An expression of arsM was introduced into strains for the methylation of arsenic. When arsM was expressed in Sphingomonas desiccabilis and Bacillus idriensis, it had 10 folds increase of methyled arsenic gas compared to wild type in aqueous system. In soil system, about 2.2%–4.5% of arsenic was removed by biovolatilization during 30 days. This study demonstrated that arsenic could be removed through volatilization from the contaminated soil by bacteria which have arsM gene expressed. These results showed that it is possible to use microorganisms expressing arsM as an inexpensive, efficient strategy for arsenic bioremediation from contaminated water and soil.     

Performance of biotrickling filters packed with structured or cubic polyurethane sponges for VOC removal

Two identical bench-scale biotrickling filters (BTFs), BTF 1 and BTF 2, were evaluated for toluene removal at various gas empty bed contact times (EBCTs) and organic loadings. BTF 1 and BTF 2 were packed with structured and cubic synthetic polyurethane sponges, respectively. At a constant toluene loading of 16 g/(m3 hr), toluene removal efficiencies decreased from 98.8% to 64.3% for BTF 1 and from 98.4% to 74.1% for BTF 2 as gas EBCT decreased from 30 to 5 sec. When the toluene loading increased from 35 to 140 g/(m3 hr) at a gas EBCT of 30 sec, the removal efficiencies decreased from 99.1% to 77.4% for BTF 1 and from 99.0% to 81.5% for BTF 2. The pressure drop for both BTFs increased with increased air flow rate, and did not significantly vary while the toluene loading was increased under similar operation conditions. BTF 1 and BTF 2 could start up successfully within 19 and 27 days, respectively, when packed with fresh sponge media, and the performances could be restored in 3–7 days after biomass was removed and wasted from the media. BTF 2 displayed higher removal efficiency even under shorter EBCT or higher loading rate than BTF1 when other operation conditions were similar, while it showed lower pressure drop than BTF 1 during the whole period of operation. These results demonstrated that both BTFs could treat waste gas containing toluene effectively.     

不同预处理的木薯渣水解液生物酸化特性比较

木薯渣富含纤维素,是理想的沼气生产原料。由于木薯渣含水量大,颗粒分散,不易固态发酵,作为沼气生产原料需对其进行水解处理。不同的水解方式得到的水解液对后续酸化过程的产酸速率和酸分布都有很大影响。对经过酶处理和水热处理得到的木薯渣水解液进行了生物酸化处理。结果显示,与直接投加木薯渣相比,投加酶水解液、投加150℃水解液水解20min和150℃水解液水解45min后,反应器达到最大产酸量所需的时间由96h分别缩短至30,48和24h,最大产酸量由4558mg/L分别增加至5277,6209和4734mg/L,且3种水解液在酸化24h后挥发性脂肪酸(VFAs)均达到最优分布,其中乙酸和正丁酸之和占总VFAs的90%左右。根据产酸速度及酸分布情况得出,木薯渣最佳可溶化方法为150℃高温水解20min,后续生物水解酸化时间为24h。     

挥发性氯代烃在干燥土壤中的平衡吸附研究

吸附是挥发性氯代烃（volatile chlorinated hydrocarbons,VCHs）污染土壤的主要机制之一.采集长三角地区3类典型水稻土,用静态平衡吸附实验进行干燥土壤对6种VCHs的平衡吸附研究.结果表明,干燥土壤的平衡吸附等温线难以用Langmuir方程和BET方程描述,但用Dubinin-Astak...     

4-氨基安替比林直接光度法测定污水中高浓度挥发酚

以50.00mg/L的苯酚标准溶液配制校准曲线系列,按4-氨基安替比林直接光度法加入试剂进行显色反应,于510nm波长,用5mm比色皿测定溶液的吸光度,可将测定上限扩大到12.5mg/L。高浓度的含酚污水往往直接或稀释较少倍数就能测定。本法的检出限为0.06mg/L,显色体系可稳定60min,相对标准偏差RSD〈4%,加标回收率为96.8%～102.5%,与标准法的测定结果无显著性差异。     

生物通风技术修复挥发性有机污染土壤研究进展

生物通风法作为物理处理方法与生物处理方法相结合的一种土壤原位修复方法,因具有高效、处理费用和尾气处理成本低等特点而对挥发性有机物(Volatile Organic Compounds)污染土壤的治理具有广阔的应用前景。本文概述了生物通风系统的原理、适用范围、优点,并对生物通风的国内外研究现状进行了阐述,包括现场应用、实验室研究、模型模拟研究(非生物过程和生物降解过程模拟)及影响因素(土壤理化性状、污染物因素及微生物因素),提出了生物通风技术存在的问题及需要作的进一步研究。     

VOCs生物净化技术研究现状与发展趋势

生物法处理挥发性有机化合物(VOCs)具有反应条件温和、运行费用低,二次污染小等优点。文章综述了生物过滤、生物滴滤、生物洗涤、膜生物反应器等4种净化工艺;总结了前人就废气性质、降解菌、填料结构与特性、pH与温度等因素对反应体系降解性能的影响;综述了研究废气生物降解过程和研究生物量积累与运行性能关系等的动力学模型。最后论述了该技术当前存在的问题和发展趋势。     

湘江衡阳段重金属在水体、悬浮颗粒物及表层沉积物中的分布特征研究

采用ICP-MS研究湘江衡阳段上覆水、悬浮颗粒物、表层沉积物及孔隙水中重金属的含量及分布特征.结果表明,湘江衡阳段主要的重金属污染元素是Cd,上覆水中Cd的平均含量为0.26μg·L-1,高于美国水质基准的持续基准浓度CCC(USEPA2009),已经对部分水生生物表现出潜在的毒性效应;悬浮颗粒物和表层沉积物中Cd的富集含量较高,分别为42.03μg·g-1和29.62μg·g-1,达到加拿大淡水沉积物保护准则最初影响水平TEL的70倍和50倍,其中,从沉积物中取得的孔隙水中Cd平均含量为3.8μg·L-1,该值是CCC的15倍甚至高于最大基准浓度(CMC),已经对部分水生生物表现出实际的急性毒性效应.湘江衡阳段重金属的空间分布特征表现为中下游污染较上游严重,在衡阳水口山地区等污染企业密集区,重金属含量较高,表明人类活动输入已经成为湘江重金属的重要来源.研究结果还表明,悬浮颗粒物及沉积物相作为水体重金属污染物的主要赋存介质,对重金属污染的迁移、沉积、转化及生物富集作用具有决定性的意义,其重要性不容忽视.     

食品垃圾好氧降解过程中挥发性有机物(VOCs)排放特征

采用实验室模拟方法,研究了混合食品垃圾(FW)及以橙子、生菜、土豆和西红柿为代表的4种植物性易降解有机垃圾组分好氧降解过程中排放出来的117种挥发性有机物(VOCs)的排放量和组成特征.结果表明,混合食品垃圾好氧降解过程中VOCs总排放量为951.80mg·kg-1,主要为有机硫、含氧化合物和萜烯,分别占VOCs总排放量的43.1%、53.3%和2.1%.橙子、生菜、土豆和西红柿4种植物性易降解有机垃圾好氧降解过程中VOCs的总排放量分别为12736.72、118.67、57.40和228.08mg·kg-1,主要成分均为含氧化合物和萜烯;含氧化合物分别占橙子、生菜、土豆和西红柿4种植物性易降解有机垃圾VOCs总排放量的13.5%、80.9%、85.9%和79.5%,萜烯分别占4种植物性易降解有机垃圾VOCs总排放量的86.5%、16.6%、8.2%和15.6%.     

制药行业VOCs排放特征及控制对策研究 ——以浙江为例

以浙江省为例,对制药行业VOCs的主要来源和特点进行了分析.采用气相色谱法,对该地区制药行业释放的VOCs作了定性和定量分析,识别出16种VOCs,分别为甲醇、丙酮、苯、甲苯、二甲苯、二氯甲烷、乙酸乙酯、三乙胺、二甲基甲酰胺、醋酸丁酯、正丙醇、乙醇、异丙醇、乙腈、环氧乙烷、甲醛.通过源成分谱图,确定出不同制药类型的主要VOCs污染物.结果表明, 发酵类为丙酮(65%)、乙酸乙酯(30.41%),提取类为丙酮(56.05%)、乙酸乙酯(36.64%)、乙醇(6.97%),化学合成类为异丙醇(44.27%)、丙酮(35.39%)、乙醇(9.78%)、甲苯(3.89%),生物工程类为丙酮(60.99%)、二氯甲烷(14.77%)、乙醇(12%)、甲醛(11.91%).并对上述主要VOCs进行了优先控制排序.最后,结合该行业VOCs的排放特点,提出了制药行业VOCs有效可行的防治对策.