堆肥生物过滤器净化苯、甲苯混合废气的实验研究

选取木块和多孔塑料为填料,选择苯为VOCs代表,研究堆肥生物过滤器对高低浓度的苯生物降解性能。实验结果表明,（1) 以木块和多孔塑料为填料的堆肥生物过滤器对高、低浓度苯净化效率呈现降低后升高,最后再降低的过程,对高低浓度甲苯均呈现缓慢升高后降低的过程,高浓度苯的最大净化效率为90.5%和97.7%,甲苯的最大净化效率为71.34%和66.45%;（2) 以多孔塑料为填料的堆肥生物过滤器对高浓度苯具有较好的抗冲击性和抗负荷性,以木块为填料的堆肥生物过滤器对高浓度甲苯有更好的净化效果;（3) 堆肥生物过滤器对高低浓度苯、甲苯的平均净化率为68%和56%以上,低浓度苯和甲苯的平均去除能力分别为0.122和0.012 g/（m³·h）,最大去除能力为0.148和0.015 g/（m³·h）,而高浓度苯和甲苯的平均去除能力为0.94和0.11 g/（m³·h）,最大去除能力为1.32和0.135 g/（m³·h）。     

In-situ surfactant/surfactant-nutrient mix-enhanced bioremediation of NAPL (fuel)-contaminated sandy soil aquifers

SCOPE AND BACKGROUND: Contamination of soils, aquifers and groundwater by nonaqueous phase liquid (NAPL) pollutants constitutes a major environmental issue of concern, worldwide. The residual (biodegradation-resistant) hydrophobic fuel hydrocarbons entrapped in the soil porous matrix, possess a particular bioremediation challenge due to their becoming virtually immobile, nor desorbable, or water dispersible. Consequently, they are not available as substrates to the micro-organism-based biodegradation. MATERIALS AND METHODS: Our research involves the development of economically feasible, surfactant/surfactant-nutrient mix (SSNM)-enhanced bioremediation methodologies for sustainable, in situ bioremediation of fuel-contaminated aquifers. This requires, methodologically, (a) the optimization, via in vitro 'flow' (columns) lab experiments and screening processes, of an effective mixture for the intended SSNM-enhanced bioremediation; and (b) the study of the combined effect of the optimized SSNM on the solubilization/mobilization and biodegradation of NAPL (fuel) in in vitro site/aquifer-simulated bioremediation. RESULTS AND DISCUSSION: The essence of our findings: (1) kerosene's maximum enhanced mobilization - f = 3.6, compared with that of deionized water, was achieved with an SSNM having the composition of linear alkylbenzene sulfonate (LABS): coco-amphodiacetate (containing N): surfactant-nutrient X (containing both N and P) = 0.15: 0.15: 0.05 g/L, respectively; (2) 62-64% of the initial amount of kerosene in the initially saturated soil matrix, 'packed' in a column, has been eluted from it during approximately 30 days, compared with 68% of kerosene biodegradation in 'vessel' settings, in 21 days. CONCLUSIONS: (1) The indigenous microorganisms present in th vadose zones of fuel-contaminated sandy soil aquifers are potentially capable of unassisted removal of approximately 80% of the initially contained fuel (kerosene), during a period of about 42 days; (2) the major effects of the SSNM addition are (a) enhanced mobilization of the bulky NAPL; and (b) enhanced desorbtion/ solubilization/dispersion of the entrapped NAPL which, in turn, facilitate their enhanced biodegradation. RECOMMENDATIONS AND PERSPECTIVE: Our findings suggest that pre-optimized, biodegradable SSNM is essential for surfactants-based bioremediation of NAPL-contaminated aquifers, in order to make this in-situ methodology both technologically and economically feasible.     

差分光谱法连续监测空气中SO2、NO2、苯、甲苯方法探讨

差分光谱法(简称DOAS)已广泛用于空气中SO2、NO2、苯、甲苯监测.通过对差分光谱法监测结果与其他传统仪器进行时比,发现用DOAS监测SO2、NO2与点式仪器有较好的一致性,但用DOAS系统监测苯、甲苯与气相色谱法有机物连续监测结果差异较大,相关性较差,运行有一定的局限性.另外,本文对DOAS的最佳运行条件进行了探讨,发现影响光强的氙灯老化和气候条件对DOAS系统运行有较大影响.     

盆栽植物净化甲苯废气

采用动态模拟法模拟盆栽植物对甲苯污染气体的净化,考察吊兰和金绿萝两种盆栽植物在净化甲苯过程中,甲苯入口浓度与植物对甲苯净化速率的关系。结果表明,2种盆栽植物对低浓度甲苯废气具有长期明显的净化效果。在相同条件下,吊兰茎叶和土壤的净化速率优于金绿萝体系。在植物的耐受浓度范围内,2种植物茎叶和土壤的净化速率均随着甲苯入口浓度的升高而增大,且白天的净化速率明显高于黑夜时的净化速率。在实验过程中,吊兰土壤体系的降解率随着甲苯浓度的升高逐渐下降;金绿萝土壤体系的降解率基本不受甲苯入口浓度的影响。吊兰盆栽体系的降解率明显大于金绿萝的降解率。两种植物盆栽体系的降解率随甲苯进口浓度的影响可以忽略。     

水中甲苯、对二甲苯磁化-光解耦合过程动力学研究

以甲苯、对二甲苯两种典型苯系污染物为研究对象 ,对其在水中的紫外光解(UV)、磁化 紫外光解 (PM UV)进行了过程动力学比较研究 ,结果证实高强度永久磁场 ( >0 1T)有促进光解的效应 ,并阐述了磁场通过影响污染物光解时 ,自由基对系间跃迁速度的变化而影响反应速度的作用机理 .     

GC-MS在电子束辐照降解甲苯中的应用

用甲苯作为挥发性有机化合物的代表物质,建立了活性炭吸附-二硫化碳解吸气相色谱-质谱分析方法,对电子束辐照甲苯的静态实验和动态实验进行了定性、定量分析。实验结果表明：电子束辐照能有效地降解甲笨,其降解率随吸收剂量的增加而增大;同时,甲苯降解过程中也会生成部分有毒有害物质。该分析方法的检出限为0．02mg／L,工作曲线的线性范围为10～1000mg／L,相关系数为0．9998,活性炭吸附、解吸甲苯的加标回收率大于90％。     

Physiological changes associated with aging result in lower internal doses of toluene and perchloroethylene in simulations using pharmacokinetic modeling

Physiologically based pharmacokinetic (PBPK) models were developed in order to translate external concentrations into internal dose estimates, but most PBPK models were developed for younger adults. A set of physiological parameters for ages 65, 75, and 85 of both genders were developed and were used with previously established human PBPK models of exposure to toluene and perchloroethylene (PERC) in order to investigate internal dose changes with increasing age. The predicted compartmental concentrations of toluene and PERC for aged adults were lower than predicted concentrations for younger adults, and this suggests that body composition changes with aging do not increase internal doses of inhaled toxicants alone after acute exposure. Hence, susceptibility to either toxicant was not expected to increase solely based on the physiological changes associated with aging. Predictions for a metabolite of PERC, however, were similar in magnitude across ages, which may lead to enhanced susceptibility if metabolic capacity changes with aging.     

生物滴滤器净化低浓度甲苯废气的非稳态工况研究

生物法处理大气污染物时,经常会遇到条件波动或污染物间歇排放等非稳态工况。在不同非稳态条件下,考察了甲苯废气间歇排放对生物滴滤器净化性能的影响。实验方案分3种情况:无甲苯废气排放、无循环液供应或同时没有甲苯废气和循环液的供应。间歇排放时间从2~47 d不等。结果表明,不管何种形式的停运或故障,甲苯净化能力4 d以内基本不下降;停运时间超过5 d,则甲苯去除能力严重下降,仅为原来的1/3~1/2;停运时间在10 d以内,24 h内即可恢复,47 d的长期停运,3 d内也可恢复净化能力。     

水溶性离子液体对甲苯的吸收效果及影响因素

选择3种水溶性离子液体（十二烷基咪唑氯盐（DDMIM Cl）、十二烷基咪唑硝酸盐（DDMIM NO3）、十二烷基咪唑双氰胺盐（DDMIM DCA））作为研究对象,对模拟甲苯废气进行吸收实验,研究了吸收液的吸收性能、甲苯浓度、吸收液浓度、进气气速以及盐度等因素对吸收效果的影响以及加热蒸馏法对吸收液的再生与甲苯回收的可行性。结果表明：不同的离子液体对甲苯的吸收率不同,DDMIM DCA的吸收效果最好,在质量分数为5%时,初始吸收率达到98%,饱和吸收量为53.39 mg·L-1,而DDMIM Cl、DDMIM NO3对甲苯的初始吸收率在92%左右,饱和吸收量分别为33.60、37.01 mg·L-1;甲苯饱和吸收量与吸收液浓度、甲苯进气浓度呈正相关,与进气气速、含盐度呈负相关;传质系数与甲苯进气浓度、进气气速以及含盐度呈正相关,与吸收液浓度呈负相关;采用加热蒸馏法进行甲苯回收及吸收液再利用时,甲苯的回收效率达到85%~90%,且甲苯的饱和吸收量随着重复利用次数的增加而基本保持不变。因此利用离子液体溶液处理甲苯废气理论上是可行的。     

Mn-Ag/13X的焙烧温度对等离子体催化氧化吸附态甲苯的影响

采用等体积浸渍法制备一系列在不同温度下焙烧的Mn-Ag/13X分子筛催化剂,并用SEM、BET、XRD和XPS对催化剂进行表征。在低温等离子体反应器中,考察了不同焙烧温度制备的催化剂对甲苯的吸附和低温等离子体催化氧化甲苯的性能。研究结果表明,在对甲苯的吸附中,不同温度下焙烧的催化剂的吸附穿透时间依次为：600 ℃ > 500 ℃ > 400 ℃ > 300 ℃ > 700 ℃,600 ℃的Mn-Ag/13X催化剂比表面积最大,到达甲苯吸附穿透的时间最长;在低温等离子体催化氧化甲苯中,不同温度下焙烧的催化剂催化氧化所产生的COx浓度大小依次为：500 ℃ > 600 ℃ > 400 ℃ > 300 ℃,CO2选择性依次为：600 ℃ > 500 ℃ > 400 ℃ > 300 ℃,焙烧温度为500 ℃的Mn-Ag/13X催化剂的晶格氧多,产生的COx多,对甲苯的催化氧化活性高。