复合混凝法处理高浓度聚丙烯酰胺生产废水

采用聚合氯化铝(PAC)混凝和活性炭吸附的复合混凝法处理高浓度聚丙烯酰胺(PAM)生产废水.实验结果表明,最佳处理条件为:废水 pH 6.5,废水温度 35℃,先加入 PAC 混凝后再加入活性炭,PAC 加入量250 mg/L,活性炭加入量 200 mg/L.在此最佳条件下,废水 COD 去除率达 52.0%.该复合混...     

黄土区薄层浮土道路侵蚀试验研究

为研究降雨强度和坡度对黄土区薄层浮土覆盖的土质道路产流产沙的影响,在野外调查的基础上,通过室内模拟降雨试验研究不同雨强(1.0、1.5、2.0、2.5 mm/min)和坡度(2°、4°、8°、16°)条件下0.5 cm厚度浮土道路径流和产沙特征。结果表明:1)相同坡度条件下,平均径流率随雨强增大呈递增趋势,其变化范围在0.80~2.73 L/min,且1.5~2.5 mm/min雨强条件下平均径流率是1.0 mm/min的1.34~3.04倍,各雨强条件下浮土侵蚀阶段产流量占比范围在5.22%~40.38%;2)次降雨平均含沙量随坡度和雨强的增大均呈递增趋势,其变化范围在11.75~194.25 g/L,且与坡度和雨强分别呈显著线性和指数函数关系(P<0.05),1.0~2.5 mm/min雨强下浮土侵蚀阶段产沙量占比为0.05%~71.51%,其占比随雨强和坡度的增大存在波动,且混合侵蚀阶段产沙量与坡度和雨强呈良好的线性关系(P<0.01);3)累计产沙量随累计产流量的增大而增大且满足线性函数关系,决定系数均在0.96以上。研究结果揭示了薄层浮土道路径流侵蚀规律,可为土质道路治理及道路侵蚀模型建立提供参考。     

活性炭-微波辐射法去除苯酚的机理研究

通过微波辐射前后水样的紫外分光扫描分析,以及微波辐射后水样中的苯酚浓度和COD浓度之间线性相关性分析表明,活性炭-微波辐射强化除酚效率的主要机理是微波使反应体系温度升高导致的活性炭加速吸附作用,而不是微波诱导催化氧化作用。通过对微波辐射前后活性炭的SEM扫描电镜分析说明,活性炭在微波场中由于“微域爆炸”导致其表面及内部孔隙结构的变化, 吸附性能得到改善,是强化苯酚去除的另一原因。 研究还表明,在较短的作用时间内,活性炭-微波辐射法的除酚效率高于常温吸附,但低于沸腾条件下的高温吸附。活性炭-微波辐射去除苯酚的规律遵循其吸附特性,温度越高,吸附反应速度越快。     

高压脉冲放电等离子体处理含偶氮染料活性红195废水

采用高压脉冲放电等离子体处理含偶氮染料活性红195 废水,实验结果表明:当电极间距为10 mm、空气流量为0.10 m3 / h、溶液初始pH 为3.05,放电反应时间为21 min 时,活性红195 去除率为98.72%;废水中加入Cu2+时,随Cu2+加入量的增加,活性红195 的去除率先减小后增大;加入自由基抑制...     

Ecological risks and potential sources of heavy metals in agricultural soils from Huanghuai Plain, China

A total of 224 agricultural soil samples from Huanghuai Plain in China were investigated for the concentrations of seven heavy metals (As, Cd, Cr, Hg, Ni, Pb, and Zn). The mean concentrations of the metals were 12, 0.17, 79, 0.04, 35, 25, and 74 mg/kg, respectively. These values are similar or slightly higher than background values in this region, except for Cd with a mean nearly twice the background value. The estimated ecological risks based on contamination factors and potential ecological risk indexes are also mostly low, but considerable for Cd and Hg. Multivariate analysis (including Pearson's correlation analysis, hierarchical cluster analysis, and principal component analysis) clearly revealed three distinct metal groups, i.e., Cr/Ni/Zn, As/Cd/Pb, and Hg, whose concentrations were closely associated with the distribution and pollution characteristics of industries in and around the plain. The main anthropogenic sources for the three metal groups were identified as atmospheric deposition, sewage irrigation/fertilizers usage, and atmospheric deposition/irrigation water, respectively. The present results are well suited for planning, risk assessment, and decision making by environmental managers of this region.     

Simulated photo-degradation of dissolved organic matter in lakes revealed by three-dimensional excitation-emission matrix with regional integration and parallel factor analysis

Simulated photo-degradation of fluorescent dissolved organic matter(FDOM) in Lake Baihua(BH) and Lake Hongfeng(HF) was investigated with three-dimensional excitationemission matrix(3 DEEM) fluorescence combined with the fluorescence regional integration(FRI),parallel factor(PARAFAC) analysis,and multi-order kinetic models.In the FRI analysis,fulvic-like and humic-like materials were the main constituents for both BH-FDOM and HF-FDOM.Four individual components were identified by use of PARAFAC analysis as humic-like components(C1),fulvic-like components(C2),protein-like components(C3) and unidentified components(C4).The maximum 3 DEEM fluorescence intensity of PARAFAC components C1-C3 decreased by about 60%,70% and 90%,respectively after photo-degradation.The multi-order kinetic model was acceptable to represent the photo-degradation of FDOM with correlation coefficient(R_(adj)~2)(0.963-0.998).The photo-degradation rate constants(k_n) showed differences of three orders of magnitude,from 1.09 x 10~(-6) to 4.02 x 10~(-4) min-1,and half-life of multi-order model(T_(1/2)~n)ranged from 5.26 to 64.01 min.The decreased values of fluorescence index(FI) and biogenic index(BI),the fact that of percent fluorescence response parameter of Region I(P_(Ⅰ,n)) showed the greatest change ratio,followed by percent fluorescence response parameter of Region II(P_(Ⅱ,n),while the largest decrease ratio was found for C3 components,and the lowest T_(1/2)~n was observed for C3,indicated preferential degradation of protein-like materials/components derived from biological sources during photodegradation.This research on the degradation of FDOM by 3 DEEM/FRI-PARAFAC would be beneficial to understanding the photo-degradation of FD OM in natural environments and accurately predicting the environmental behaviors of contaminants in the presence of FDOM.     

gsh1基因的克隆及其在巴斯德毕赤氏酵母中的表达

利用PCR技术克隆了来源于Saccharomyces cerevisiae ALJ036的γ-L-谷氨酰-L-半胱氨酸合成酶(γ-glutamyl-cysteine synthetase)编码基因gsh1,连接多拷贝表达载体pGAPZA,转化Pichia pastorisx-33,构建了重组菌P.pastorisx-33(pGAPZA-gsh1);在高浓度Zeocin平板上筛选多拷贝阳性转化子,并通过PCR进行了验证.对阳性转化子的γ-L-谷氨酰-L-半胱氨酸合成酶酶活力进行了测定,结果显示,重组酵母的γ-L-谷氨酰-L-半胱氨酸合成酶的酶活是宿主菌的3.0倍,在液体YEPD中重组菌GSH的产量为42.2mg/L,是宿主菌的1.6倍.图7表1参10     

产1,3-丙二醇新型基因工程菌的构建

以甘油为底物转化生产1,3-丙二醇的生物合成途径中,往往由于还原力NADH的不足,限制了1,3-丙二醇的合成,引起中间代谢产物3-羟基丙醛累积,进而抑制甘油脱水酶的活性,阻碍菌体的生长,严重影响1,3-丙二醇的合成途径.为了解决合成途径中还原力不足这一主要矛盾,本文以大肠杆菌和克雷伯氏菌染色体DNA为模板克隆得到yqhD和dhaB、dhaT基因,构建双启动子表达载体pEtac-dhaB-tac-yqhD及表达载体pUC-tac-dhaT,成功共转入E.coli JM109,得到可利用两种辅酶(NADH、NADPH)将片油转化为1,3-丙二醇且传代稳定的重组大肠杆菌双质粒系统,发酵结果表明,1,3-丙二醇产量提高了28.6%.图6表1参17     

表面活性剂强化抽出处理含水层中DNAPL污染物的去除特征

为明确表面活性剂强化抽出处理含水层中DNAPL污染物过程中表面活性剂的增强修复效果,及DNAPL自身理化性质和介质孔径的影响,利用数码图像分析技术对1,2-二氯乙烷和四氯乙烯2种DNAPL在石英砂填充的二维砂箱中的抽取迁移过程进行了实验模拟研究,并对抽出水样中DNAPL的浓度进行了测试分析。结果表明,实验条件下加入低浓度(0.18%)的十二烷基苯磺酸钠(SDBS)大幅提高了对弱透水层截留的2种DNAPL聚集体的抽出处理效率。1,2-二氯乙烷在该表面活性剂溶液中的表观溶解度远高于四氯乙烯,因此其短时间内的绝对去除率更高。SDBS强化抽出处理DNAPL的作用机理以增溶作用为主,而其增流作用使DNAPL迁移流动后分布面积增大,增加了与表面活性剂溶液接触的面积,对增溶作用起到促进效果。细粒介质中DNAPL迁移后的最大分布面积较大,因此体系中DNAPL的溶解速率较高。在DNAPL聚集体质量与水力梯度固定的条件下,油水界面张力越低,DNAPL的密度越大,DNAPL垂向迁移的风险就越大。本研究为修复工程中如何依据DNAPL种类与场地多孔介质的情况选择表面活性剂提供了参考。     

活性炭纤维负载功能化离子液体的脱硫性能

以等体积浸渍的方法将[C3O1Mim]+[H3CSO3]-(1-(2-甲氧基乙基)-3-甲基咪唑甲磺酸盐)和[C5O2Mim]+[H3CSO3] -(1-(2-甲氧基乙氧基乙基)-3-甲基咪唑甲磺酸盐)负载到活性炭纤维(ACF)上,并对其进行氮气吸附、热重等表征。对ACF固载的离子液体脱硫性能测试,结果表明:在离子液体负载量为10 wt%,模拟烟道气流量为40 mL/min,温度为20℃, SO2体积分数为0.2%条件下,[C3O1Mim]+[H3CSO3]-/ACF、[C5O2Mim]+[H3CSO3]-/ACF吸附量分别为45.34 mg SO2/g和60.08 mg SO2/g。经过5次吸附-脱附循环利用,其脱硫效果基本不变,说明[C3O1Mim]+[H3CSO3]-/ACF、[C5O2Mim]+[H3CSO3]-/ACF有良好的再生性能。