Experimental evaluation of PCDD/Fs and PCBs release and mass balance of a WTE plant

The behaviour of waste incineration plants with respect to organic toxic trace contaminants such as PCDDs, PCDFs and, to a minor extent, PCBs, is still a matter of concern for the public opinion and the decision makers. It is therefore very important, first, to evaluate the release of these organic toxic trace contaminants in the environment during waste incineration, not only through the stack gas emission but also with the solid and liquid residues, and then to compare the total release with the input through the treated waste in order to assess the plant behaviour as a “sink” rather than a “source” of organic toxic trace contaminants. The experimental investigation carried out on an Italian full scale incineration plant has shown a total 17 PCDD/Fs and 12 dioxin-like PCBs release of 5.5-27 μg WHO-TEQ per tonne of treated waste and an input flux of 1.6-44 μg WHO-TEQ per tonne of waste, with the difference between the input and the output fluxes rather small and the plant behaviour toward organic trace toxic contaminants in average neutral. Results are compared with similar evaluations conducted in the last decade on a number of waste-to-energy (WTE) plants operating in Italy.     

我国生活垃圾焚烧工程分析

分析了我国生活垃圾的基本特征、垃圾焚烧厂的效益和垃圾焚烧厂的现状,展望了我国垃圾焚烧工程的发展趋势。     

多孔矿物载体厌氧固定床处理有机废水研究

通过天然浮石和塑料多孔空心球而制成复合式多孔矿物载体应用于厌氧固定床反应器中,研究反应器挂膜性能,以及处理生活污水、啤酒废水效果,应用扫描电镜观察生物膜微生物相的形态结构.结果表明,反应器挂膜69 d后COD去除率稳定在70%以上,初次启动成功;处理生活污水中平均COD去除率为61.72%;处理啤酒废水中COD去除率高...     

固定化对氯苯酚降解菌在生物流化床中的降解特性

为了获得固定化对氯苯酚降解菌在生物流化床中的降解特性,用海藻酸钠-壳聚糖-活性炭微胶囊对实验室保存的对氯苯酚降解菌株进行固定化,在生物流化床中用固定化菌株在不同单因素实验条件下降解对氯苯酚废水,用气相色谱仪测定废水中对氯苯酚的降解率.结果表明,固定化对氯苯酚降解菌株处理污水的适宜条件为:HRT为72 h,微胶囊接种体积...     

Treatment of dynamic mixture of hexane and benzene vapors in a Trickle Bed Air Biofilter integrated with cyclic adsorption/desorption beds

One of the main challenges that face successful biofiltration is the erratic loading pattern and long starvation periods. However, such patterns are common in practical applications. In order to provide long-term stable operation of a biofilter under these conditions, a cyclic adsorption/desorption beds system with flow switching was installed prior to a biofilter. Different square waves of a mixture containing n-hexane and benzene at a 2:1 ratio were applied to the cyclic adsorption/desorption beds and then fed to a biofilter. The performance of this integrated system was compared to a biofilter unit receiving the same feed of both VOCs. The cyclic adsorption/desorption beds unit successfully achieved its goal of stabilizing erratic loading even with very sharp peaks at the influent concentration equalizing influent concentrations ranging from 10-470 ppmv for n-hexane to 30-1410 ppmv for benzene. The study included different peak concentrations with durations ranging from 6 to 20 min. The cyclic beds buffered the fluctuating influent load and the followed biofilter had all the time a continuous stable flow. Another advantage achieved by the cyclic adsorption/desorption beds was the uninterrupted feed to the biofilter even during the starvation where there was no influent in the feed. The results of the integrated system with regard to removal efficiency and kinetics are comparable to published results with continuous feed studies at the same loading rates. The removal efficiency for benzene had a minimum of 85% while for n-hexane ranged from 50% to 77% according to the loading rate. The control unit showed very erratic performance highlighting the benefit of the utilization of the cyclic adsorption/desorption beds. The biofilter was more adaptable to concentration changes in benzene than n-hexane.     

河道原位处理技术研究进展

原位修复是一种可靠、卓有成效的河道水体净化修复技术,具有治理费用低和最大程度降解污染的特点,适合于污染严重、流量较小的河流水体。本文概述了河道曝气法、生物接触氧化、河流湿地处理和生态浮床等河道原位处理技术的原理、发展及应用情况,其中河道曝气和生物接触氧化起步早,技术较为成熟,为早期污染水体治理贡献很大,相对河流湿地处理和人工浮床起步晚,但成本低,耗资少,处理效率又高,具有很大的发展空间。这些工艺都是经济、有效以及符合可持续发展要求的生物生态技术,在国内外发展比较迅速,但在进一步改进的前提下,其应用前景将十分广阔。     

从荷兰、德国的实践看污泥的能源回收利用——浅议污水厂的污泥处理

进入21世纪后,随着城市发展和环境污染的加剧,我国城镇污水处理厂的建设开始加速发展。至2010年,城市污水处理率约为70%,随着大量污水处理厂投入运行,污泥处置问题已经迫在眉睫。本文介绍了荷兰污泥处理的发展历程和方法,以SNB污泥处理中心、慕尼黑Gut Groβlappen污泥处理厂为实例介绍了集中式污泥处理及能源利用。我们认为,荷兰、德国污泥处理的经验和方法对我国的污泥处理具有借鉴价值。     

铁床+立式氧化槽治理农药废水

介绍了某农药生产企业采用铁床＋立式氧化槽工艺处理农药废水,给出了工艺流程、工艺参数和处理效果。废水处理运行结果：CODcr、色度、SS平均去除率分别大于95％、90％、97％。     

Options for management of municipal solid waste in New York City: a preliminary comparison of health risks and policy implications

Landfill disposal and waste-to-energy (WTE) incineration remain the two principal options for managing municipal solid waste (MSW). One critical determinant of the acceptability of these options is the different health risks associated with each. In this analysis relying on published data and exposure modeling, we have performed health risk assessments for landfill disposal versus WTE treatment options for the management of New York City's MSW. These are based on the realistic scenario of using a waste transfer station (WTS) in Brooklyn and then transporting the untreated MSW by truck to a landfill in Pennsylvania or using a WTE facility in Brooklyn and then transporting the resultant ash by truck to a landfill in Pennsylvania. The overall results indicate that the individual cancer risks for both options would be considered generally acceptable, although the risk from landfilling is approximately 5 times greater than from WTE treatment; the individual non-cancer health risks for both options would be considered generally unacceptable, although once again the risk from landfilling is approximately 5 times greater than from WTE treatment. If one considers only the population in Brooklyn that would be directly affected by the siting of either a WTS or a WTE facility in their immediate neighborhood, individual cancer and non-cancer health risks for both options would be considered generally acceptable, but risks for the former remain considerably higher than for the latter. These results should be considered preliminary due to several limitations of this study such as: consideration of risks only from inhalation exposures; assumption that only volume and not composition of the waste stream is altered by WTE treatment; reliance on data from the literature rather than actual measurements of the sites considered, assuming comparability of the sites. However, the results of studies such as this, in conjunction with ecological, socioeconomic and equity considerations, should prove useful to environmental managers, regulators, policy makers, community representatives and other stakeholders in making sound and acceptable decisions regarding the optimal handling of MSW.     

The Impacts of Human Visitation on Mussel Bed Communities Along the California Coast: Are Regulatory Marine Reserves Effective in Protecting These Communities?

Rocky intertidal habitats frequently are used by humans for recreational, educational, and subsistence-harvesting purposes, with intertidal populations damaged by visitation activities such as extraction, trampling, and handling. California Marine Managed Areas, particularly regulatory marine reserves (MRs), were established to provide legal protection and enhancement of coastal resources and include prohibitions on harvesting intertidal populations. However, the effectiveness of MRs is unclear as enforcement of no-take laws is weak and no regulations protect intertidal species from other detrimental visitor impacts such as trampling. The goal of this study was two-fold: (1) to determine impacts from human visitation on California mussel populations (Mytilus californianus) and mussel bed community diversity; and (2) to investigate the effectiveness of regulatory MRs in reducing visitor impacts on these populations. Surveys of mussel populations and bed-associated diversity were compared: (1) at sites subjected to either high or low levels of human use, and (2) at sites either unprotected or with regulatory protection banning collecting. At sites subjected to higher levels of human visitation, mussel populations were significantly lower than low-use sites. Comparisons of mussel populations inside and outside of regulatory MRs revealed no consistent pattern suggesting that California no-take regulatory reserves may have limited effectiveness in protecting mussel communities. In areas where many people visit intertidal habitats for purposes other than collecting, many organisms will be affected by trampling, turning of rocks, and handling. In these cases, effective protection of rocky intertidal communities requires an approach that goes beyond the singular focus on collecting to reduce the full suite of impacts.