污泥堆肥过程中致臭挥发性有机物的产生和释放

利用气相色谱/质谱联用仪分析了郑州八岗污泥处置厂污泥好氧堆肥发酵高温前期(第5天)的挥发性有机物(VOCs)产生与释放特征。结果表明,污泥堆肥过程中产生的主要致臭VOCs为甲硫醇、甲硫醚、二甲二硫醚、丙酮、1-丁烯;致臭VOCs从堆体内部到车间人员活动处的扩散过程中,其浓度可降低89.3%~99.9%,低于《工作场所有害因素职业接触限值》(GBZ 2—2002)和《恶臭污染物排放标准》(GB 14554—93)所规定的限值,厂区不存在VOCs污染风险。     

堆肥过程中臭气的产生和释放过程研究进展

堆肥过程中产生的臭气容易导致恶臭污染问题.总结了堆肥过程中主要臭气物质的产生机理、物理化学性质、影响因素及调控措施.堆肥过程中产生的臭气物质主要包括NH<,3>、H<,2>S和部分挥发性有机物;H<,2>S是堆肥过程产生的恶臭潜力最高的臭气;NH<,3>的最大释放浓度可达6 000 mg/m<'3>.堆肥原料的C/N值、调理剂种类、通风条件是影响氨气挥发的重要因素.指出过程控制是解决臭气问题的根本措施.     

污泥堆肥过程中氮素损失和氨气释放的动态与调控

通过不同鼓风强度、分层堆肥和添加吸湿剂的自动控制堆肥中试,研究了城市污泥堆肥过程中温度、挥发性固体含量、氮素含量和氨气释放浓度的变化.结果表明,在堆肥升温较快的处理中,挥发性固体的降解速度较快,污泥中的氮素容易向氨氮转化,使释放的氨气浓度升高;增大鼓风强度,有利于促进堆肥的升温和腐熟,加速无害化过程,但释放的氨气浓度较高;在保持整个堆体中污泥比例不变的前提下,分层堆肥可以显著提高堆肥的升温效果并减少氨气的释放.     

污泥好氧发酵过程中臭味物质的产生与释放

利用在线监测设备及GC-MS测试方法,分析了CTB工艺好氧生物发酵过程中释放的挥发性物质组分及主要臭味物质的产生与释放。结果表明,该发酵工艺条件下释放的挥发性物质主要是酮、芳香烃、醇、硫化物、萜烯等,扩散到发酵车间的臭味物质浓度均未超过《工作场所有害因素职业接触限值》(GBZ2—2002)和《恶臭污染物排放标准》(GB14554—93)的限值。发酵过程中产生的臭味物质从堆体释放并扩散到发酵车间,其浓度降低了84.3%～100%。CTB工艺除可有效控制发酵过程中恶臭物质的产生外,还可使产生的臭味物质绝大部分被固定在发酵池内部,可见CTB工艺具有良好的防止臭气产生和释放的效果。     

城市污泥堆肥厂臭气控制途径

过程控制和末端处理是控制堆肥厂臭气污染的两条途径。过程控制是指通过优化堆肥工艺参数,如调整物料配比、堆体孔隙度、通风量等工艺参数,在堆肥过程尽量减少臭味气体的产生。末端处理是指堆肥过程中产生的臭气经废气收集、处理后达标排放,减少臭气对环境的污染。堆肥臭气的过程控制是目前先进、经济和高效的臭气控制方式。通过减少堆肥过程中臭气的产生和释放,可改善堆肥车间的空气质量状况,减轻臭气对操作人员身体健康的影响,同时也减轻了后续的废气处理系统的负荷。     

污泥堆肥厂臭气的产生和处理技术研究进展

污泥堆肥厂产生的臭气成分复杂,主要为氮化物、硫化物、挥发性有机物,不同的物料和堆肥条件对恶臭物质的产生量影响较大。污泥堆肥过程中氨的释放浓度较高,为臭气的主要成分,但其臭气阈值相对较高;而有机硫化物的释放浓度虽然较低,但其臭气阈值很低,对臭气的总贡献较大,也应是恶臭控制和处理的目标污染物。在城市污泥堆肥过程中,可以通过优化堆肥条件等措施控制臭气的产生和释放,同时对厂区产生的臭气进行收集和集中处理。在各臭气处理方法中,生物除臭法适合处理低浓度、大流量的臭气,在堆肥气体除臭方面具有较好的应用前景。     

污泥堆肥过程中VOCs浓度水平和反应活性研究

采用气质联用(GC/MS)方法研究了污泥堆肥过程中挥发性有机物(VOCs)的浓度水平和反应活性。结果表明,污泥堆肥过程中产生和排放的VOCs主要包括烷烃、烯烃、芳香烃、含氧有机化合物,VOCs产生量和排放量分别为34 052.0、710.8μg/m3,排放量仅为产生量的2.1%。产生的VOCs主要组分浓度从高到低依次为1-丁烯、丙酮和乙醇,其中烯烃类产生量最大,占比为76.43%;排放的VOCs主要组分浓度从高到低依次为2-丁酮、乙醇和丙酮,其中以含氧有机物类浓度最大。VOCs组分的反应活性从高到低依次为烯烃类、含氧有机物类、芳香烃类和烷烃类,产生和排放的VOCs最大臭氧生成潜势分别为264 164.8、2 038.3μg/m3,从产生到排放VOCs最大臭氧生成潜势降低了99.2%。考虑到含氧有机物类VOCs光解反应对O3生成的贡献,用增量反应活性法评价污泥好氧发酵过程产生和排放的VOCs对近地层大气圈的危害更为适宜。     

污泥堆肥过程中温室气体及氨气释放规律研究

针对污泥好氧堆肥过程中有关温室气体及氨气释放的基础数据大量缺乏的问题,将污泥和木屑混合进行为期60天的好氧堆肥试验,考察污泥堆肥过程中二氧化碳、甲烷、氧化亚氮和氨气的释放规律。研究结果表明:温室气体的释放均主要集中在堆肥的升温期。堆体中的较高的溶解性有机碳的质量比会促进二氧化碳的产生,较差的氧传质情况和较高的温度有利于甲烷的产生,物料中亚硝态氮的质量比与氧化亚氮释放速率呈正相关。堆肥过程中氨气的释放主要集中在堆肥高温期,这归因于高温期的高氨氮高pH值环境会促进污泥中的铵态氮以氨气形式逸出发酵体系。     

内墙涂料中VOCs释放特征研究

利用自行设计的小型环境测试舱,使用热解吸气相色谱跟踪法,研究丙烯酸内墙乳胶漆中VOCs的释放特征.试验结果表明,丙烯酸内墙乳胶漆中的VOCs释放有一定规律性,但在一定条件下,内墙涂料中TVOC在空气中的释放浓度和产品中挥发性有机物的全含量并无明显线性关系.     

装饰材料挥发性有机化合物研究现状与进展

综述了挥发性有机化合物（VOCs）定义域、危害和我国与国外限制法规的差异,分析了气态环境、液态和固态装饰材料中VOCs测试研究的技术现状并将固态材料中VOCs测试方法归纳为单体总量、静态释放量、动态释放量三类,指出了装饰材料VOCs研究发展方向和动态释放量的应用价值。     

Emission of volatile organic compounds during composting of municipal solid wastes

The objective of this study was to identify and quantify volatile and semi-volatile organic compounds (VOCs) produced during composting of the organic fraction of municipal solid wastes (MSW). A laboratory experiment was conducted using organic components of MSW that were decomposed under controlled aerobic conditions. Mixed paper primarily produced alkylated benzenes, alcohols and alkanes. Yard wastes primarily produced terpenes, alkylated benzenes, ketones and alkanes, while food wastes primarily produced sulfides, acids and alcohols. Among 13 aromatic VOCs found in MSW composting facilities, toluene, ethylbenzene, 1,4-dichlorobenzene, p-isopropyl toluene, and naphthalene were in the largest amounts. Unseeded mixed paper, seeded mixed paper, seeded yard wastes, unseeded yard wastes, seeded food wastes and unseeded food wastes produced approximately 6.5, 6.1, 2.1, 0.83, 2.5 and 0.33 mg of 13 volatile and semi-volatile aromatic organic compounds combined, respectively, per dry kg. All VOCs were emitted early during the composting process and their production rates decreased with time at thermophilic temperatures.     

Critical components of odors in evaluating the performance of food waste composting plants

The current Taiwan government policy toward food waste management encourages composting for resource recovery. This study used olfactometry, gas chromatography-mass spectrometry (GC-MS) and gas detector tubes to evaluate the ambient air at three of the largest food waste composting plants in Taiwan. Ambient air inside the plants, at exhaust outlets and plant boundaries was examined to determine the comprehensive odor performance, critical components, and odor elimination efficiencies of various odor control engineering. Analytical results identified 29 compounds, including ammonia, amines, acetic acid, and multiple volatile organic compounds (VOCs) (hydrocarbons, ketones, esters, terpenes and S-compounds) in the odor from food waste composting plants. Concentrations of six components--ammonia, amines, dimethyl sulfide, acetic acid, ethyl benzene and p-Cymene--exceeded human olfactory thresholds. Ammonia, amines, dimethyl sulfide and acetic acid accounted for most odors compared to numerous VOCs. The results also show that the biotrickling filter was better at eliminating the concentrations of odor, NH(3), amines, S-compounds and VOCs than the chemical scrubber and biofilters. All levels measured by olfactometry at the boundaries of food waste composting plants (range, 74-115 Odor Concentration (OC)) exceeded Taiwan's EPA standard of 50 OC. This study indicated that the malodor problem continued to be a significant problem for food waste recovery.     

Identification and transport investigation of microbial volatile organic compounds in full-scale stud cavities

An experimental project was conducted to investigate mold products, namely spores and volatile organic compounds (VOCs) in the cavity of full-scale stud wall assemblies. Twenty specimens were constructed and tested to inquire the capacity of wall cavities to restrain mold products, emanating from studs with 10% of their surface covered with mold, from penetrating into the indoor space. The tests were designed primarily to study the movement of spores. The project was subsequently extended to investigate the identification of microbial volatile organic compounds (MVOCs) and their transport through the building envelope. This paper presents the experimental design, testing procedure and a summary of the analysis conducted to identify mold related VOCs and their transport from the cavity to the indoor space, and the evaluation of the influence of experimental factors on this transport. Six experimental factors were investigated: air leakage path; mold presence; wall construction configurations (insulation, vapor barrier and sheathing material) and ambient conditions (dry and wet conditions). The chemical analysis of VOCs (volatile organic compounds) was performed using gas chromatography/mass spectrometry (GC/MS). Results are analyzed using multiple regression analysis to identify the mold related VOCs, and to determine the transport through the building envelope. Five VOCs are confirmed to be related to the mold presence in the cavity and the transport of these MVOCs is supported by the data. However, no significant effect of the construction factors on MVOC transport is detected.     

集中空调系统控制室内污染物的非稳态模型

本文综合考虑室内污染源散发,室外污染物进入,净化器效率等因素对室内污染物浓度的影响。对采用集中空调系统的房间,建立了非稳态模型,以可挥发性有机物为例,理论分析了净化器效率和室外VOCs浓度对室内VOCs浓度的影响。该模型可为净化器效率的选择提供理论依据。     

Factors related to the attraction of flies at a biosolids composting facility (Bariloche, Argentina)

The composting process is used to treat biosolids from the Wastewater Treatment Plant of Bariloche (NW Patagonia, Argentina). Since 1998, an odourless, innocuous and stable organic amendment has been produced at the Biosolids Composting Plant of Bariloche. However, volatile compounds produced during this process, attract different vectors, mainly insects belonging to the Order Diptera, particularly in summer. To evaluate factors associated with the attraction of Diptera to composting windrows, volatile compounds, wind velocity, ambient and windrow temperatures were measured and their relationships with the taxa of flies found were determined. Sampling was conducted several months on newly formed windrows during 3 weeks of the thermophilic composting period. Composite samples from each windrow were taken on the first day of each sampling week, from November 1999 to March 2000 to analyze volatile compounds using an 'electronic nose'. Windrow and ambient temperatures and wind velocity were recorded on three consecutive days of each week, from January to March 2000; also the capture of flies was performed in this period. A weekly mean value was calculated for each environmental variable. Canonical Correspondence Analysis was employed to determine relationships between taxa of flies and the studied factors. The electronic nose discriminated among odours emitted, differentiating windrows by the bulking agent employed and by week of the thermophilic composting period. Ambient temperatures increased slightly during the sampling weeks; the highest values of wind velocity were registered during the second sampling week while windrow temperatures were sustained approximately 60 degrees C. Canonical Correspondence Analysis showed that attraction of flies to composting windrows was related to minimum and maximum ambient temperatures and volatile compounds for Muscina stabulans, Fannia sp. and Acaliptratae and to wind velocity for Ophyra sp., Sarcophaga sp., Cochliomyia macellaria and Phaenicia sericata.     

Total Volatile Organic Compounds (TVOC) in Indoor Air Quality Investigations*

Abstract The amount of volatile organic compounds (VOCs) in indoor air, usually called TVOC (total volatile organic compounds), has been measured using different definitions and techniques which yield different results. This report recommends a definition of TVOC referring to a specified range of VOCs and it proposes a method for the measurement of this TVOC entity. Within the specified range, the measured concentrations of identified VOCs (including 64 target compounds) are summed up, concentrations of non-identified compounds in toluene equivalents are added and, together with the identified VOCs, they give the TVOC value. The report reviews the TVOC concept with respect to its usefulness for exposure assessment and control and for the prediction of health or comfort effects. Although the report concludes that at present it is not possible to use TVOC as an effect predictor, it affirms the usefulness of TVOC for characterizing indoor pollution and for improving source control as required from the points of view of health, comfort, energy efficiency and sustainability.     

室内挥发性有机物的研究进展

室内挥发性有机物（VOCs）主要来源于建筑及建筑装修材料,具有极强的危害性,因此研究VOCs的散发、室内变化规律及其控制方法是极其必要的。本文介绍了国内外学者及团体对室内挥发性有机物研究的现场调查、实验模拟、理论模型探索方面的进展及控制策略,分析了目前研究中存在的问题,提出了今后研究工作的方向。     

Development of New Volatile Organic Compound (VOC) Exposure Metrics and their Relationship to “Sick Building Syndrome” Symptoms

Abstract Occupants of office buildings are exposed to low concentrations of complex mixtures of volatile organic compounds (VOCs) that encompass a number of chemical classes and a broad range of irritancies. “Sick building syndrome” (SBS) is suspected to be related to these exposures. Using data from 22 office areas in 12 California buildings, seven VOC exposure metrics were developed and their ability to predict self-reported SBS irritant symptoms of office workers was tested. The VOC metrics were each evaluated in a multivariate logistic regression analysis model adjusted for other risk factors or confounders. Total VOCs and most of the other metrics were not statistically significant predictors of symptoms in crude or adjusted analyses. Two metrics were developed using principal components (PC) analysis on subsets of the 39 VOCs. The Irritancy/PC metric was the most statistically significant predictor of adjusted irritant symptoms. The irritant potencies of individual compounds, highly correlated nature of indoor VOC mixtures, and probable presence of potent, but unmeasured, VOCs were variously factored into this metric. These results, which for the first time show a link between low level VOC exposures from specific types of indoor sources to SBS symptoms, require confirmation using data sets from other buildings.