Gaseous pollutants emitted from a mechanical biological treatment plant for municipal solid waste: Odor assessment and photochemical reactivity

The concentrations and chromatographic profiles of gaseous pollutants emitted from a municipal solid waste (MSW) biological treatment plant were investigated to identify the major odor substances and atmospheric photochemical reactive species (PRS). Four methods were used to measure different gaseous pollutants in this study, including colorimetric tubes, gas chromatography with mass spectrometry/flame ionization detection/pulsed flame photometric detection (GC-MS/FID/PFPD) preceded by cold trap concentration, GC-FID preceded by solid-phase microextraction (SPME), and high-performance liquid chromatography (HPLC) after derivation by 2,4-dinitrophenylhydrazine (DNPH). Seventy-five gaseous compounds belonging to nine groups (nitrogen compounds, sulfur compounds, alkanes, alkenes, aromatics, terpenes, alcohols, carbonyls, and volatile fatty acids [VFAs]) were identified. In the pre-biotreatment facility, the total concentration of the gaseous pollutants reached the maximum value on day 7 (317 ppm). During the post-biotreatment process, the total concentration of gaseous pollutants decreased from 331 ppm at the beginning to 162 ppm in the end. The group with the greatest decrease was carbonyls, from 64 to 7.4 ppm, followed by alcohols, from 40 to 4.5 ppm, which were both oxygenated compounds. The proportion of aromatics was notably high in the pre-mechanical treatment facility, accounting for 50.6% of the total, revealing the xenobiotic compounds disseminated by stirring and agitating the waste in the initial stage. The proportions of nitrogen compounds were lower in the pre- and post-mechanical treatment facilities (1.5% and 6.9%) than in the pre- and post-biotreatment facilities (11.9% and 13.8%), suggesting that their generation was closely associated with waste degradation. The major odor compounds in the facilities were acetic acid, butyric acid, valeric acid, isovaleric acid, and dimethyl sulfide. The major PRS in the facilities were aromatics, acetaldehyde, butyraldehyde, hexanal, isopentyl aldehyde, alcohol, α-pinene, limonene, and terpinene. Outside the facilities, VFAs and aromatics were the most important compounds causing an environmental impact.

Implications: The aim of this work is to assess the gaseous environmental impacts of mechanical biological treatment technology. The emission of gaseous pollutants greatly affects the living quality of nearby residents and odor complaints are becoming a major problem now. In this study, the authors utilized various pretreatment and analytical methods to obtain integrated emission information of gaseous pollutants. The results showed the transformation and fate of the gas pollutants during the treatment processes, which would help to improve the processes and to mitigate gaseous pollution.

Supplemental Materials: Supplemental materials are available for this paper. Go to the publisher's online edition of the Journal of the Air & Waste Management Association for information on the concentrations of the nine compound families at different sampling locations in the plant.     

双波长紫外吸收法有机废水COD测量技术与仪器设计

紫外吸收法直接测定有机废水COD是一种无需化学试剂、无样品前处理、无二次污染的绿色无损检测技术,但在实际应用中发现,有机废水中的悬浮物对测量结果产生较大影响.以实际废水水样为例,详细阐述了双波长紫外吸收法测量有机废水COD的操作方法及其消除悬浮物干扰的原理,并介绍了运用该技术设计开发的COD在线测量仪器.该仪器采用嵌入式计算机系统实时采集和处理数据,根据实际废水在双波长测量条件下的有效紫外吸光度快速推算出其COD值,具有快速、准确、无污染的特点.     

Estimate of initial isoprene contribution to ozone formation potential in Beijing, China

Volatile organic compounds (VOCs) are important precursors of tropospheric ozone formation. Isoprene contributions to ozone formation by using ambient mixing ratios are generally underestimated because of rapid chemical losses. In this study, ambient mixing ratios of major VOC species were continuously measured at Peking university (PKU) and YUFA, urban and sub-urban sites in Beijing, the city that will host 2008 Olympic Games. The observed mixing ratios of methyl vinyl ketone (MVK), methacrolein (MACR) and isoprene were used to derive the mixing ratios of initial isoprene, which means the ambient isoprene level before it undergoes any photochemical reaction with OH radicals. The average mixing ratios of initial isoprene were 3.3±1.6 and 2.9±1.5 ppbv at PKU and YUFA sites, respectively. The percentages of initial isoprene in total initial VOCs were 10.8% at PKU site and 11.4% at YUFA site, in reasonable agreement with the isoprene contribution in total VOC emissions as derived from source inventories. Maximum increment reactivity (MIR) was used to evaluate the ozone formation potential (OFP) for major VOC species. The OFP for initial isoprene accounted for 23% of the total OFPs for all measured species, compared to 11% using ambient mixing ratios of isoprene at PKU site. Similarly, at YUFA site, the ambient measured isoprene and initial isoprene contributed 10% and 22%, respectively, to the OFPs for total measured VOCs. It seems that isoprene has similar contribution to ozone formation at both sites in Beijing city.     

Temporary stabilization of air pollution control residues using carbonation

Carbonation presents a good prospect for stabilizing alkaline waste materials. The risk of metal leaching from carbonated waste was investigated in the present study; in particular, the effect of the carbonation process and leachate pH on the leaching toxicity of the alkaline air pollution control (APC) residues from municipal solid waste incinerator was evaluated. The pH varying test was conducted to characterize the leaching characteristics of the raw and carbonated residue over a broad range of pH. Partial least square modeling and thermodynamic modeling using Visual MINTEQ were applied to highlight the significant process parameters that controlled metal leaching from the carbonated residue. By lowering the pH to 8-11, the carbonation process reduced markedly the leaching toxicity of the alkaline APC residue; however, the treated APC residue showed similar potential risk of heavy metal release as the raw ash when subjected to an acid shock. The carbonated waste could, thereby, not be disposed of safely. Nonetheless, carbonation could be applied as a temporary stabilization process for heavy metals in APC residues in order to reduce the leaching risk during its transportation and storage before final disposal.     

Application of magnetoelastic sensors for quantifying sediment deposition rates and sizes

This paper describes the application of magnetoelastic sensors for quantifying the size and deposition rate of sediment samples in costal areas, lakes, and rivers. The magnetoelastic sensor, which is made of inexpensive amorphous ferromagnetic alloy, measures parameters of interest by tracking the changes in its resonant frequency and/or amplitude. Since an increase in mass loading on the sensor surface changes its resonant frequency and amplitude, the deposition rate of sediment particles can be determined in real time by tracking these two quantities. Based on a theoretical model, the size distribution of the sediment particles was also estimated from the deposition rate.     

应用生物强化技术处理焦化废水难降解有机物

通过驯化富集培养,从处理 经废水的活性污泥中分离出2株萘降解菌WN1、WN2和1株吡啶降解菌WB1,研究了投加高效菌种及微生物共代谢对 经废水生物处理的增强作用,同时研究了高效菌种和共代谢初级基质组合协同作用的效果。结果表明,投加共代谢初级基质、Fe^3 和高效菌种均能促进难降解有机物的降解,提高焦化废水COD去除率,当3者协同作用时,效果最好。     

基于区域组团式水热能综合利用的化纤行业节能减排模式

介绍了区域组团式水热能综合利用的模式,区域组团式水热能综合利用以节能、降耗、减污、增效为目标,从大型企业、工业园区或镇市三个层面构建包含有工业企业、商业办公区、居民区、污水处理厂、热电厂及水体在内的多主体的水、热、能综合利用网络,形成以水为物质和能量载体的新的利用模式。以污水厂和热泵为中心的江苏恒力集团有限公司(简称恒力集团)的水热能综合利用网络,可实现集团内的废水零排放,回收的能源占恒力集团能源年消耗量的9.4%,年产生效益约4820万元。组团式水热能综合利用的思路为当前我国各行业的节能减排提供了一种新模式。     

基于全面风险管理的环境风险信息系统(ERIS)建设研究

建立环境风险信息系统(ERIS)是加强区域信息共享、提高综合决策能力、扩大公众参与程度的有效方式。针对当前环境风险信息应用中存在的异化问题,基于全面风险管理的理论内涵,遵循信息管理要求,结合环境风险信息特点,通过主体管理、要素控制和资源支持3个方面的协同作用创立了ERIS正四面体模型,提出了ERIS的全过程控制实践结构和信息数据库分层管理体系;从完善支撑体系、提高信息收集能力、强化信息处理决策、增进区域联动和公众参与等5个方面优化建设内容,为大规模区域开发形势下环境安全战略的实施提供参考。     

Heavy metals mobility in full-scale bioreactor landfill: initial stage

Selected heavy metals (HMs) including Cd, Cr, Cu, Ni, Pb and Zn initially released from a full-scale bioreactor landfill were monitored over the first 20 months of operation. At the initial landfill stage, the leachate exhibited high HMs release, high organic matter content (27000-43000gl(-1) of TOC) and low pH (5-6). By the fifth month of landfilling, the methanogenic stage had been established, and HMs release was reduced below the Chinese National Standards. Total released HMs accounted for less than 1% of landfill deposited during the investigated period. Most landfill HMs were inorganic. Fourier-transform infrared (FT-IR) spectra data and model calculations using Visual MINTEQ indicated that humic substances strongly affected the mobility of organic fractions of HMs in the methanogenic landfill. The initial rates of HMs release could be enhanced by recycling the leachate back to bioreactor landfill, but the total quantity released may be reduced by early establishment of methanogenic stage in bioreactor landfill.