(M)VOC and composting facilities. Part 2: (M)VOC dispersal in the environment

BACKGROUND, AIMS AND SCOPE: Composting facilities are known to release odorous volatiles due to biodegradation of municipal waste and plant residues. Although odour perception and its grading is influenced by experience, attitude and adaptation, these emissions have created a lack of acceptance for residents in the vicinity of composting facilities. Enclosure of compost pile halls, ventilation systems and biofilters are often insufficient to minimise the burden of compost-derived compounds in the air. Moreover, economic considerations forced smaller communities to establish less sophisticated facilities with open storage areas and other relevant sources for wind-borne dispersal of bioaerosols. Aim of the present study was to characterise the immission and dispersal of microbial volatiles (MVOC) and, besides, to find coincidences between MVOC and compost odour. METHODS: In the course of this study, the surroundings of two composting facilities, differing in their type of process engineering, were investigated for emission of volatiles in the environment. Both microbially and plant-derived substances were assessed, several of which have low odour thresholds. Air samples were taken in distances ranging from 50 to 800 m in a downwind direction from each facility. RESULTS AND DISCUSSION: Compost-derived and microbial volatile organic compounds (MVOC) were found at distances of up to 800 m from the composting facilities. Terpenes like alpha-pinene, camphene and camphor were the dominant compounds and coincided with typical compost odour, whereas several typical MVOC were not found at greater distances. The terpenes in combination with certain MVOC may play an important role in the perception of compost odour. Exposure concentrations were not of toxicological relevance, but sensory irritation and psychohygienic effects due to an annoyance potential of such compounds should not be dismissed. RECOMMENDATIONS AND OUTLOOK: Although terpenes are generally associated with pleasant odour characteristics, they seemed to contribute to malodours in a mixture with other VOC, in this context of volatile waste from compost facilities. Malodorous emissions from biowaste have to be considered as sources of health complaints and the investigation of mixtures of compost-derived volatiles is still inevitable. Exposure levels have to be discussed taking VOC mixtures into account. Within composting facilities, technical devices have to be improved to minimise dispersal of volatiles to prevent residents from immissions eventually causing health complaints.     

活性炭固定床操作参数的优化

研究了操作参数对活性炭固定床处理有机废气的影响。温度升高，吸附容量下降。湿度的存在会减少活性炭对有机物的吸附容量。适当的操作气速为0.1-0.5m/s，在此范围内，气速与压降在对数坐标上呈线性关系。     

Baseline study of methane emission from open digesting tanks of palm oil mill effluent treatment

Anthropogenic release of greenhouse gases, especially CO₂ and CH₄ has been recognized as one of the main causes of global warming. Several measures under the Kyoto Protocol 1997 have been drawn up to reduce the greenhouse gases emission. One of the measures is Clean Development Mechanisms (CDM) that was created to enable developed countries to cooperate with developing countries in emission reduction activities. In Malaysia, palm oil industry particularly from palm oil mill effluent (POME) anaerobic treatment has been identified as an important source of CH₄. However, there is no study to quantify the actual CH₄ emission from the commercial scale wastewater treatment facility. Hence, this paper shall address the CH₄ emission from the open digesting tanks in Felda Serting Hilir Palm Oil Mill. CH₄ emission pattern was recorded for 52 weeks from 3600 m³ open digesting tanks. The findings indicated that the CH₄ content was between 13.5% and 49.0% which was lower than the value of 65% reported earlier. The biogas flow rate ranged between 0.8 l min⁻¹ m⁻² and 9.8 l min⁻¹ m⁻². Total CH₄ emission per open digesting tank was 518.9 kg day⁻¹. Relationships between CH₄ emission and total carbon removal and POME discharged were also discussed. Fluctuation of biogas production was observed throughout the studies as a result of seasonal oil palm cropping, mill activities, variation of POME quality and quantity discharged from the mill. Thus only through long-term field measurement CH₄ emission can be accurately estimated.     

一种新型烟气脱硫技术在燃煤锅炉上的扩大试验

介绍了用硫化碱加TFS添加剂进行燃煤锅炉煤气脱硫并副产硫代硫酸钠的中试成果。     

挥发性有机硫化合物释放的研究与展望

在介绍硫的生物地球化学循环的基础上，概述了几种挥发性有机硫气体ＤＭＳ，ＣＯＳ，ＭＳＨ，ＣＳ２和ＤＭＤＳ从各种自然源（主要是生物源）释放的情况，着重阐述了陆地生态系统中各种生物硫源的释放情况，列举了测定这些释放的硫通量的方法，并且对有机硫气体的大气行为及环境影响也作了论述。     

氯苯紫外光降解产物对生物过滤塔运行性能的影响

生物过滤技术对难生物降解VOCs的处理效果较差,构建紫外光降解-生物过滤联合处理工艺是解决难生物降解VOCs处理的一个有效手段.已有研究表明,紫外光降解预处理对氯苯生物过滤塔的去除性能有促进作用.为了考察紫外预处理对生物过滤塔的影响机理,本研究分别考察了氯苯紫外光降解主要产物氯酚、乙酸以及副产物臭氧对生物过滤塔运行性能的影响.研究结果表明,加入乙酸降低了生物过滤塔的氯苯去除性能,在增加喷淋量后去除性能有所恢复.加入邻氯酚使生物过滤塔的氯苯去除性能略有降低.臭氧明显促进了生物过滤塔的氯苯去除性能,当进口臭氧浓度在60～120mg.m-3时,氯苯平均去除率可由70%提高到90%以上.因此,臭氧是紫外预处理促进生物过滤塔运行性能的主要因素.     

Gaseous emissions from weaned pigs raised on different floor systems

Gaseous emissions from agriculture contribute to a number of environmental effects. Carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) are greenhouse gases taking part to the global problem of climate change. Ammonia (NH₃) emissions are responsible of soil acidification and eutrophication and contribute also to indirect emissions of N₂O. This work evaluated the influence of the type of floor on the emissions of these gases in the raising of weaned pigs. Two trials were carried out. In the first trial, the animals were kept either on fully slatted floor or on straw-based deep litter and, in the second one, either on fully slatted floor or on sawdust-based deep litter. For each trial and on each type of floor, 2 successive batches of weaned pigs were raised without changing the litter or emptying the slurry pit between the 2 batches. The rooms were automatically ventilated to maintain a constant ambient temperature.The performance of the animals was not significantly different according to the floor type. In trial 1, the nitrogen contents of the straw deep litter (including the substrate) and slurry were respectively 276 and 389 g pig⁻¹. In trial 2, the sawdust deep litter and slurry nitrogen contents were respectively 122 and 318 g pig⁻¹.Raising pigs on straw deep litter produced proportionately around 100% more NH₃ than raising pigs on slatted floor (0.61 g NH₃-N d⁻¹ pig⁻¹ vs. 0.31 g NH₃-N d⁻¹ pig⁻¹; P < 0.05). Differences in CO₂, H₂O and CH₄ emissions were not significant between systems. Raising pigs on sawdust deep litter produced also proportionately more NH₃ (+52%; 0.55 g NH₃-N d⁻¹ pig⁻¹ vs. 0.36 g NH₃-N d⁻¹ pig⁻¹; P < 0.01) but also more CO₂ (+25%; 427 g d⁻¹ pig⁻¹ vs. 341 g d⁻¹ pig⁻¹; P < 0.001) and H₂O (+65%; 981 g d⁻¹ pig⁻¹ vs. 593 g d⁻¹ pig⁻¹; P < 0.001) and less CH₄ (−40%; 0.52 g d⁻¹ pig⁻¹ vs. 0.86 g d⁻¹ pig⁻¹; P < 0.001) than raising pigs on slatted floor. Practically no N₂O emission was observed from rooms with slatted floor while the N₂O emissions were 0.03 and 0.32 g N₂O-N d⁻¹ pig⁻¹ for the straw and sawdust deep litter respectively. The warming potential of the greenhouse gases (N₂O + CH₄), were about 22, 34 and 168 g CO₂ equivalents per day and per pig on fully slatted floor, straw or sawdust deep litter respectively.In conclusion, pollutant gas emissions from rearing of weaned pig seem lower with fully slatted plastic floor system than with deep litter systems.     

粘胶化纤厂废气治理试验

采用ＴＦ－ＴＡ工艺治理粘胶化纤厂废气。先以ＴＦ脱硫液选择脱除ＨＺＳ,再以ＴＡ液体脱除ＣＳ２。Ｈ２Ｓ脱除和再生能一步完成,脱除率９８％以上,其表达ηＨ２ｓ＝９９．５＋４．７１×１０－４ｘ－３．６８×１０－７ｘ２。ＣＳ２脱除率在气液比２００—３００时达８０％─９０％,其表达式：ηＣＳ２＝９８．９－１．３２×１０－３ｘ—２．００×１０－４ｘ２。文中还讨论了粘胶化纤厂废气总体治理意见。     

烟气中SO2/NOx同时吸收催化脱除的研究

根据同时脱硫脱硝的要求,对以ＣＵＯ为主要活性组分催化剂的制备和反应过程进行研究,活性测试的结果表明,催化剂的最佳活化温度和活化时间分别为４５０℃和２ｈ。当反应温度为４００℃,空间速度为２×１０＾４ｈ＾－１以及ＣｕＳＯ４／ＣｕＯ摩尔比和Ｃｕ／Ｓ分别保持在１．４６和０．８３以上时,ＳＯ２和ＮＯｘ的脱除率可达９０％以上。