Influence of filtration velocity on DON variation in BAF for micropolluted surface water treatment

Biological aerated filters (BAFs) are widely used for the treatment of micropolluted surface water. However, the biological process produces dissolved organic nitrogen (DON), which, as precursors of nitrogenous disinfection by-products, pose potential threats to drinking water safety. Therefore, to control DON in BAF effluent, it is necessary to study the influence of BAF operation parameters on DON production. In this study, the influence of filtration velocity in a BAF on DON production was investigated. Under different filtration velocity (0.5, 2, and 4 m/h) conditions, profiles of DON concentrations along the media layer were measured. The profile at a filtration velocity of 0.5 m/h showed a decreasing trend, and the ones under filtration velocities of 2 and 4 m/h fluctuated in a small range (from 0.1 to 0.4 mg/L). Moreover, the relatively high filtration velocities of 2 and 4 m/h resulted in a lower level of DON concentration. Additionally, 3D excitation-emission matrix fluorescence spectroscopy was used to characterize DON. It is found that the patterns of DON at a relatively high filtration velocity condition (4 m/h) were obviously different from the ones under low filtration velocity conditions (0.5 and 2 m/h).     

The comparison of fossil carbon fraction and greenhouse gas emissions through an analysis of exhaust gases from urban solid waste incineration facilities

In this study, in order to understand accurate calculation of greenhouse gas emissions of urban solid waste incineration facilities, which are major waste incineration facilities, and problems likely to occur at this time, emissions were calculated by classifying calculation methods into 3 types. For the comparison of calculation methods, the waste characteristics ratio, dry substance content by waste characteristics, carbon content in dry substance, and ¹²C content were analyzed; and in particular, CO₂ concentration in incineration gases and ¹²C content were analyzed together. In this study, 3 types of calculation methods were made through the assay value, and by using each calculation method, emissions of urban solid waste incineration facilities were calculated then compared. As a result of comparison, with Calculation Method A, which used the default value as presented in the IPCC guidelines, greenhouse gas emissions were calculated for the urban solid waste incineration facilities A and B at 244.43 ton CO₂/day and 322.09 ton CO₂/day, respectively. Hence, it showed a lot of difference from Calculation Methods B and C, which used the assay value of this study. It is determined that this was because the default value as presented in IPCC, as the world average value, could not reflect the characteristics of urban solid waste incineration facilities. Calculation Method B indicated 163.31 ton CO₂/day and 230.34 ton CO₂/day respectively for the urban solid waste incineration facilities A and B; also, Calculation Method C indicated 151.79 ton CO₂/day and 218.99 ton CO₂/day, respectively.

Implications: This study intends to compare greenhouse gas emissions calculated using ¹²C content default value provided by the IPCC (Intergovernmental Panel on Climate Change) with greenhouse gas emissions calculated using ¹²C content and waste assay value that can reflect the characteristics of the target urban solid waste incineration facilities. Also, the concentration and ¹²C content were calculated by directly collecting incineration gases of the target urban solid waste incineration facilities, and greenhouse gas emissions of the target urban solid waste incineration facilities through this survey were compared with greenhouse gas emissions, which used the previously calculated assay value of solid waste.     

Suppression of precipitation by dust particles originated in the Tibetan Plateau

Dust aerosols play an important role in modulating the hydrologic cycle. The Tibetan Plateau (TP) is little polluted by human activities as an ideal site to study the effect of dust aerosol on precipitation. In this study, observational data of dust storms and precipitation in the TP and its vicinities as well as CALIPSO satellite data were used to analyze the distributions and vertical structure of dust storms on the plateau. The results showed that dust storms occur with high frequency and raise dust particles into the troposphere from ground level to a height of 5–9 km to modulate the hydrologic cycle in the TP. There are significant negative correlations between dust aerosol and precipitation in the dust source regions during the period of both 40 and 200 years. It is found that the role of precipitation in suppressing dust storms could be unimportant, while dust aerosol may play an important role in suppressing precipitation in the hinterland of the TP. Our study provides a potential approach to better understand the climate changes in the TP.     

三级串联人工快渗系统处理养殖废水

人工快速渗滤系统（constructed rapid infiltration,CRI）是在传统的污水快速渗透系统上发展起来的一种新的生物处理方法。采用猪粪浸泡污水模拟实际猪场处理系统的厌氧出水,研究三级串联人工快渗系统对其污染物的去除效果。试验结果表明,三级串联系统对废水COD、NH3N的去除率稳定在81%和94.5%,出水均满足了《畜禽养殖行业污染物排放标准》（GB18596-2001）的要求,同时三级串联系统还可以有效预防系统的堵塞。     

恩施市发展循环农业的思考

循环农业作为一种新的农业发展方式,可促进资源的有效利用,实现农业和相关产业的迅速发展.恩施市是一个以山地为主的农业城市,发展循环农业的意义重大.分析了恩施市发展循环农业的必要性以及有利因素和制约因素,提出了发展循环农业的相关对策建议.     

选择性催化还原烟气脱硝技术在玉环电厂4×1000MW机组上的应用

以华能玉环电厂4×1000MW机组增设烟气选择性催化还原法（SCR）脱硝装置的技术改造为例,简要介绍了玉环电厂原机组增加SCR脱硝系统的工艺构成和流程特点、设计参数、总体布置,并对该工程中相关设备的改造进行了描述,为我国大型燃煤机组的脱硝改造工程提供参考。     

关于我国发展循环经济的思考

循环经济在我国还处于研究探索的阶段,其理论基础和实践途径有待进一步发展.发展循环经济,建设资源节约型社会,需要积极发挥政府的主导作用,努力实现企业行为的转变,大力倡导社会公众的积极参与,以及尽快建设绿色技术支撑体系.但是,我国的现实情况是,政府在循环经济发展中主导作用不强;企业生态化转型滞后;公众对发展循环经济的意识淡薄.     

产品废弃物管理是企业的基本职能

企业是产品废弃物的源头,产品废弃物管理理应成为企业的基本职能.项目环评、区域规划和战略环评是强制和引导企业做好废弃物管理的有效手段.     

垃圾处理产业化的内涵

垃圾处理产业化是造就一种特定模式,聚合已进入垃圾处理行业的事业体并培育核心事业体的一种过程,一般包括导入、扩散、发展和聚变等4个子过程.产业化应将垃圾处理由公有公益性服务事业转化成服务产业,并最终转化成物质生产的基础产业,涉及到社会再生产的4个环节.宏观来看,涉及到经济、文化和政治等层面.