Influence of start-up on PCDD/F emission of incinerators

This study aims to evaluate the influence of start-up on polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) concentration in the stack flue gas of incinerators and its contributing PCDD/F emission. The PCDD/F emission of the first sample among three consecutive stack flue gas samples of five intermittent incinerators, which sampled at a stable combustion condition after start-up, is 2-3 times higher than the mean of the others. For verifying the PCDD/F characteristics of incinerators during start-up, one continuous MSWI was investigated for two years. The elevated PCDD/F emissions of the MSWI during start-up could reach 96.9 ng I-TEQN m(-3) and still maintained a high PCDD/F emission (40 times higher than the Taiwan emission limit) even 18 h after the injection of activated carbon, indicating the memory effect. Taking the MSWI for example, which consists of four incinerators, the estimated annual PCDD/F emission from normal operational conditions was 0.112 g I-TEQ. However, one start-up procedure can generate approximately 60% of the PCDD/F emissions for one whole year of normal operations. And the PCDD/F emission, which is the result of the start-ups of four incinerators, was at least two times larger than that of a whole year's normal operations, without consideration for the PCDD/F emission contributed by the long lasting memory effect.     

Bioavailability to grains of rice of aged and fresh DDD and DDE in soils

DDT had been widely used around the world before 1980s and is still under production and use for non-agricultural purposes in China. Because of their special physicochemical properties, p,p'-DDT and its main metabolites, p,p'-DDD and p,p'-DDE, accumulated and persisted in the environment, presenting potential menace on biota. A green-house study was conducted to determine the bioavailability of p,p'-DDD and p,p'-DDE to grains of rice and the influences of traditional Chinese farming practices on their bioaccumulation. Paddy rice and dry rice were grown in submerged paddy soils and non-submerged upland soils, respectively. Two types of soil, Hydragric Anthrosols (An) and Hydragric Acrisols (Ac), were employed. Bioaccumulation factors (BAFs) of DDE ranged from 0.67 for rice grown in non-submerged An to 0.84 in submerged An in the control group, whilst BAFs were all below 0.04 in experimental groups. BAFs of DDD varied from 1.39 for submerged An to 2.26 for submerged Ac in original soils. In contrast, BAFs were between 0.05 for non-submerged Ac and 0.08 for submerged An in DDD-contaminated soils. Flooding seemed to have two contradictory effects on the DDE/DDD accumulation by rice: on one hand, it made the pollutants more mobile and bioavailable; while on the other hand, it enhanced the degradation and binding of POPs. Adding rice straw to the soils protected DDE from being taken up yet promoted DDD accumulation by rice. Furthermore, the distinct inorganic component of the soils might also play an important role in the environmental activities of POPs.     

A biomimetic absorbent for removal of trace level persistent organic pollutants from water

A novel biomimetic absorbent containing the lipid triolein was developed for removing persistent organic pollutants (POPs) from water. The structural characteristics of the absorbent were obtained by SEM and a photoluminescence method. Under optimum preparation conditions, triolein was perfectly embedded in the cellulose acetate (CA) spheres, the absorbent was stable and no triolein leaked into the water. Dieldrin, endrin, aldrin and heptachlor epoxide were effectively removed by the CA--triolein absorbent in laboratory batch experiments. This suggests that CA-triolein absorbent may serve as a good absorbent for those selected POPs. Triolein in the absorbent significantly increased the absorption capacity, and lower residual concentrations of POPs were achieved when compared to the use of cellulose acetate absorbent. The absorption rate for lipophilic pollutants was very fast and exhibited some relationship with the octanol--water partition coefficient of the analyte. The absorption mechanism is discussed in detail.     

Generalized models for prediction of pentachlorophenol dissipation dynamics in soils

Dissipation of pentachlorophenol (PCP) in soil was investigated and the chemical relationships with soil properties were addressed. The results indicate that the dissipation of extractable PCP residues can be described using first-order kinetics equations, with a half-dissipation time (T(1/2)) ranging from 6.5 to 173.3d. The sharply different patterns of PCP dissipation in different soils were closely related to soil properties. Correlations of stepwise regression equations obtained were significant at 0.01 probability level between soil parameters and extractable PCP residues (R(2)=0.974**) as well as T(1/2) values (R(2)=0.882**). Using pH together with organic carbon content (OC) and soil particle size distribution, the dissipation dynamics of PCP in soil could be accurately predicted.     

Comparison of vehicle activity and emission inventory between Beijing and Shanghai

Vehicle emission inventory is a critical element for air quality study. This study created systemic methods to establish a vehicle emission inventory in Chinese cities. The methods were used to obtain credible results of vehicle activity in Beijing and Shanghai. On the basis of the vehicle activity data, the International Vehicle Emission model is used to establish vehicle emission inventories. The emissions analysis indicates that 3 t of particulate matter (PM), 199 t of nitrogen oxides (NO(x)), 192 t of volatile organic compounds (VOCs), and 2403 t of carbon monoxide (CO) are emitted from on-road vehicles each day in Beijing, whereas 4 t of PM, 189 t of NO(x), 113 t of VOCs, and 1009 t of CO are emitted in Shanghai. Although common features were found in these two cities (many new passenger cars and a high taxi proportion in the fleet), the emission results are dissimilar because of the different local policy regarding vehicles. The method to quantify vehicle emission on an urban scale can be applied to other Chinese cities. Also, knowing how different policies can lead to diverse emissions is beneficial knowledge for other city governments.     

Remediation of soil contaminated with pyrene using ground nanoscale zero-valent iron

The sites contaminated with recalcitrant polycyclic aromatic hydrocarbons (PAHs) are serious environmental problems ubiquitously. Some PAHs have proven to be carcinogenic and hazardous. Therefore, the innovative PAH in situ remediation technologies have to be developed instantaneously. Recently, the nanoscale zero-valent iron (ZVI) particles have been successfully applied for dechlorination of organic pollutants in water, yet little research has investigated for the soil remediation so far. The objective in this work was to take advantage of nanoscale ZVI particles to remove PAHs in soil. The experimental factors such as reaction time, particle diameter and iron dosage and surface area were considered and optimized. From the results, both microscale and nanoscale ZVI were capable to remove the target compound. The higher removal efficiencies of nanoscale ZVI particles were obtained because the specific surface areas were about several dozens larger than that of commercially microscale ZVI particles. The optimal parameters were observed as 0.2 g iron/2 mL water in 60 min and 150 rpm by nanoscale ZVI. Additionally, the results proved that nanoscale ZVI particles are a promising technology for soil remediation and are encouraged in the near future environmental applications. Additionally, the empirical equation developed for pyrene removal efficiency provided the good explanation of reaction behavior. Ultimately, the calculated values by this equation were in a good agreement with the experimental data.     

石化企业事故应急预案中的安全防护距离探讨

对石化企业在事故应急预案中安全防护距离的确定给出了各种可以参考的计算方法及参考数据,为企业在事故应急中合理确定安全防护距离提供了决策参考。     

山东省民爆器材行业安全现状调查

民用爆破器材的易燃易爆属性,使得民爆生产、储存、运输、装卸过程具有较大的危险性,发生后果严重的燃烧爆炸事故概率相对较高。因此,民爆器材行业首要的任务就是搞好安全生产,保障人民生命财产的安全,维护社会的稳定。摸清行业的安全现状,研究制定切实的安全对策措施,也就成了搞好行业安全工作的重要内容。     

三维脚型测量技术及方法的研究

本文阐述了人体脚型的测量方法及特点,比较后得出人工测量与三维扫描测量技术之间的差别。以YETI三维脚型扫描仪为模型,详细分析了脚型扫描仪的结构原理,摸索并提出了简单实用的测量方法,讨论了YETI三维脚型扫描仪获得的原始数据、脚型横截面以及脚型投影图的特点。