回灌渗滤液pH和VFA浓度对填埋层初期甲烷化的影响

采用人工配制渗滤液回灌模拟填埋柱的方法,研究了回灌渗滤液中pH和VFA对填埋层甲烷化的影响.实验结果表明,回灌渗滤液酸性条件(pH=6)下,且回灌渗滤液中存在一定量的VFA时,填埋层仍可迅速甲烷化;并且VFA浓度越低,填埋层甲烷化过程稳定时间越短.回灌渗滤液pH为7时,保证填埋层仍能快速进入甲烷化阶段的最高VFA浓度不应超过4000 mg·L-1(以C计).研究结果表明,生物反应器填埋初期,以回灌为目标的渗滤液预处理工艺的出水水质要求可适当降低,这既有利于控制渗滤液预处理的成本,也可避免预处理后渗滤液中有机酸浓度过低,导致填埋层可转化为甲烷的有机碳过量流失.     

Determination of VOCs in groundwater at an industrial contamination site using a homemade low-density polyethylene passive diffusion sampler

A home-made inexpensive passive diffusion bag （PDB） sampler, prepared by filling deionized water in low-density polyethylene （LDPE） tubes, was evaluated for volatile organic compounds （VOC） sampling in groundwater at industrial contamination sites. Impacts of environmentally relevant conditions on the sampling equilibration time and partitioning of VOCs between the sampler and the water sample were investigated. Sample salinity, agitation and temperature can influence the equilibration time, but generally sampling equilibration was obtained in 14 days under real field sampling of VOCs in groundwater. Both laboratory study and field testing in a contaminated site showed that the VOC concentrations in the developed sampler were equal to those in the water samples at equitibrium. Coupled with a purge and trap concentrator-gas chromatograph-mass spectrometer （P＆T-GC-MS）, the developed PDB sampler provided a low-cost sampling device for routine monitoring of VOCs in groundwater in wells, with LODs in the range of 2.9-10 μg/L. The proposed PDB was applied to determine VOCs in groundwater at an industrial contamination site, and the present results agreed well with those determined using conventional pump-and-sample monitoring. All the studied 13 VOCs were tested in the four wells in the industrial contamination sites, with their concentrations in the range of 12-73660 μg/L. In addition, while benzene and toluene were heavily contaminated up to a maximum concentration of 74000 μg/L and 6000 μg/L, respectively, 1,2,3-trichlorobenzene and bromobenzene had relatively low contamination levels （below 25 μg/L）.     

生物滴滤器处理高温甲苯废气的探讨

以甲苯为目标污染物,设计可控温的双塔生物滴滤器为净化装置,考察了高温条件下挥发性有机物的生物处理性能,镜检确定了高温条件下降解甲苯的优势菌种。结果表明:(1)液相驯化菌种对气相甲苯适应性较差,挂膜120～140h可形成稳定的生物膜;(2)随甲苯废气温度升高,甲苯去除效率下降,40℃效率最高,60℃仍有一定的去除能力;(3)短杆菌和球形菌为降解甲苯的优势菌种,球形菌是高温优势菌;(4)温度高于40℃时降解产物中检测到有机中间产物。     

废旧聚氨酯硬泡热解特性

采用热重分析仪对废旧聚氨酯硬泡在氮气中的热失重行为进行了研究,并对升温速率、热解终温对热解的影响进行了分析. 结果表明:在氮气气氛条件下,废旧聚氨酯硬泡热解主要发生在200～492 ℃;随着升温速率的提高,废旧聚氨酯硬泡热失重时挥发分初析温度向高温方向偏移,失重速率峰值(DTG_max)显著增大.利用热重-红外(TG-FTIR)联用方法对氮气气氛中10 ℃/min升温速率下的样品热解气体产物进行了检测. 结果表明:废旧聚氨酯硬泡热解产物有H₂O,CO₂,CO,CFC-11,以及含氯化合物、烯烃类、烷烃类和带有苯环等官能团的化合物,且主要气体产物有相似的析出规律.      

铜川市秋冬季大气VOCs特征及其O3和SOA形成潜势分析

VOCs是O₃和SOA形成的重要前体物,可增强大气氧化性,促进二次污染物形成,影响区域空气质量和人体健康.为研究铜川市秋冬季VOCs特征及其对O₃和SOA生成的潜力,利用TH-300B在线监测系统监测了铜川市区102种VOCs的体积分数,并结合最大增量反应活性系数法和气溶胶生成系数法分别计算VOCs的O₃及SOA生成潜力.结果表明,铜川市秋季和冬季φ（TVOC）分别为（50.52±16.81）×10^-9和（63.21±35.24）×10^-9,O₃生成潜势分别为138.43×10^-9和137.123×10^-9, SOA生成潜势分别为3.098μg·m^-3和0.612μg·m^-3.秋季VOCs中含量最多的2种组分为烷烃（26.19%）和芳香烃（26.04%）,冬季VOCs中含量最多的组分为烷烃（48.88%）.反-2-戊烯、甲苯和间/对-二甲苯是秋季OFPs最大的3个成分,...     

工业挥发性有机物排放控制的有效途径研究

挥发性有机物（VOCs）由于易挥发性,其控制途径有别于其他大气污染物.通过对VOCs排放特点的研究,提出了源头控制、有组织排放控制、无组织排放控制和总量控制四类控制途径,并对每类控制途径的控制方式进行了分析比较.     

南京工业区夏冬季节二次有机气溶胶浓度估算及来源解析

采用2015年6月15日~7月15日及2015年12月16日~2016年1月15日期间GC5000在线气相色谱仪得到的挥发性有机物(volatile organic compounds,VOCs)数据、DRI-2001A热/光碳分析仪对膜采样分析得到的EC(elemental carbon)、OC(organic carbon)数据,使用气溶胶生成系数法(fractional aerosol coefficient,FAC)、EC示踪法及正矩阵因子分析(positive matrix factorization,PMF)对南京工业区二次有机气溶胶(secondary organic aerosol,SOA)浓度进行估算及来源解析.研究发现南京工业区SOA污染主要来源于芳香烃类物质,其对夏、冬季节SOA贡献率分别为80.39%、94.63%,主要贡献者为苯、甲苯、乙苯、二甲苯(benzene、toluene、ethylbenzene、xylene,BTEX);对南京工业区SOA浓度进行估算,得到夏季SOA浓度值为5.84~20.88μg·m~(-3),平均浓度为12.15μg·m~(-3),冬季为2.17~17.73μg·m~(-3),平均浓度为6.91μg·m~(-3),冬季SOA浓度平均水平明显低于夏季.SOA浓度值随风速及降水量的增大而减小;使用PMF受体模型对VOCs进行源解析分析得到夏季SOA污染主要来源于涂料使用、石油加工及石油化工源,SOA贡献值分别为0.65、0.21、0.18μg·m~(-3).冬季SOA污染主要来自于涂料使用,SOA贡献值为0.94μg·m~(-3).     

4-氨基安替比林分光光度法测定土壤中挥发酚的影响因素研究

随着中国经济和农业的快速提高,石油化工项目的大力发展和农药使用量加大,越来越多挥发酚类物质通过各种途径进入土壤和沉积物,影响土壤的正常功能,从而影响食品安全,最终威胁到人体健康.文章对4-氨基安替比林分光光度法测定土壤中挥发酚的前处理过程进行研究,通过实验验证,确定了样品萃取时间,样品和提取液的保存条件及预蒸馏速度,优化了分析方法,使其适用于日常环境监测工作.     

Release of volatile organic compounds during bio-drying of municipal solid waste

Three treatments were tested to investigate the release concentrations of volatile organic compounds (VOCs) during the bio-drying of municipal solid waste (MSW) by the aerobic and combined hydrolytic-aerobic processes. Results showed that VOCs were largely released in the first 4 days of bio-drying and the dominant components were: dimethyl disulfide, dimethyl sulfide, benzene, 2-butanone, limonene and methylene chloride. Thus, the combined hydrolytic-aerobic process was suggested for MSW bio-drying due to fewer aeration quantities in this phase when compared with the aerobic process, and the treatment strategies should base on the key properties of these prominent components. Malodorous sulfur compounds and terpenes were mainly released in the early phase of bio-drying, whereas, two peaks of release concentrations appeared for aromatics and ketones during bio-drying. Notably, for the combined hydrolytic-aerobic processes there were also high concentrations of released aromatics in the shift from hydrolytic to aerobic stages. High concentrations of released chlorinateds were observed in the later phase. For the VOCs produced during MSW bio-drying, i.e., malodorous sulfur compounds, terpenes and chlorinateds, their release concentrations were mainly determined by production rates; for the VOCs presented initially in MSW, such as aromatics, their transfer and transport in MSW mainly determined the release concentrations.     

TiO_2光催化氧化室内VOCs的失活再生研究进展

半导体TiO2纳米材料由于其无毒无害,化学性质稳定等优点,目前已经成为环境污染控制领域和材料学领域共同研究的热点。TiO2纳米材料对环境污染物光催化氧化效果显著,但是随着TiO2的反复使用,其催化效率会减低,最终失去光催化的活性;文章主要对TiO2在光催化降解环境污染物后的失活和再生情况进行了综述,讨论了TiO2光催化剂失活的机理以及其再生的途径。