Generation and stability of bentonite colloids at the bentonite/granite interface of a deep geological radioactive waste repository

The possible mechanisms of colloid generation at the near field/far field interface of a radioactive repository have been investigated by means of novel column experiments simulating the granite/bentonite boundary, both in dynamic and in quasi-static water flow conditions. It has been shown that solid particles and colloids can be detached from the bulk and mobilised by the water flow. The higher the flow rate, the higher the concentration of particles found in the water, according to an erosion process. However, the gel formation and the intrinsic tactoid structure of the clay play an important role in the submicron particle generation even in the compacted clay and in a confined system. In fact, once a bentonite gel is formed, in the regions where the clay is contacted with water, clay colloids can be formed even in quasi-static flow conditions. The potential relevance of these colloids in radionuclide transport has been studied by evaluating their stability in different chemical environments. The coagulation kinetics of natural bentonite colloids was experimentally studied as a function of the ionic strength and pH, by means of time-resolved light scattering techniques. It has been shown that these colloids are very stable in low saline (approximately 1 x 10(-3) M) and alkaline (pH > or = 8) waters.     

固定源废气监测工作若干技术问题的探讨

从监测工况、测点位置、采样过程、结果计算等几方面出发，结合实际经验，对大气固定污染源的监测工作中存在的一些疑难问题进行探讨。     

On the hydro-dispersive equivalence between multi-layered mineral barriers

In the context of municipal solid waste and hazardous waste disposal, the notion of "equivalence" between different barrier designs appears in regulatory documents from several industrialized countries. While in the past, equivalence has been thought of mainly in terms of contaminant travel times, in recent years it has been defined more in terms of the magnitude of a disposal site's potential impact on groundwater resources. This paper presents some original analytical solutions to the problem of contaminant migration through a multi-layered mineral barrier. The solutions account for the two major mechanisms of subsurface contaminant migration, namely, advection and diffusion-dispersion. An example application using the proposed solutions and a numerical model illustrates how one multi-layered mineral barrier can be considered superior to another from a strictly hydro-dispersive viewpoint. The influence of partial saturation of the mineral barrier is investigated using a numerical solution to the Richards equation for unsaturated flow. It is emphasized that conclusions relative to the superiority of one multi-layered barrier, with respect to another, should not only consider hydro-dispersive aspects, but also other processes such as the mechanical and chemical evolutions of the different barrier components. Although such phenomena are poorly addressed by existing models, failure to take them into account, at least in a qualitative fashion, may lead to unconservative conclusions with respect to barrier equivalence.     

Airsolution液体在净化有机废气方面的应用

Airsoluton是一系列植物提取液复配而成的,这些植物提取液是含有气味的有机物,它们是从树、草和花等植物中提取的。这些有味的液体含有大量复杂的化合物,它们是绝大多数植物油的主要成分。本文根据Airsolution液体的氧化性,对处理含苯、甲苯和二甲苯的有机工业废气进行了净化研究,结果表明:Airsolution液体用于处理有机废气是可行的,处理后的苯、甲苯和二甲苯可实现达标排放。且该工艺具有运行费用低,投资少的特点。     

Occurrence, distribution, and potential influencing factors of sewage sludge components derived from nine full-scale wastewater treatment plants of Beijing, China

Millions of tons of waste activated sludge (WAS) produced from biological wastewater treatment processes cause severe adverse environmental consequences. A better understanding of WAS composition is thus very critical for sustainable sludge management. In this work, the occurrence and distribution of several fundamental sludge constituents were explored in WAS samples from nine full-scale wastewater treatment plants (WWTPs) of Beijing, China. Among all the components investigated, active heterotrophic biomass was dominant in the samples (up to 9478 mg/L), followed by endogenous residues (6736 mg/L), extracellular polymeric substances (2088 mg/L), and intracellular storage products (464 mg/L) among others. Moreover, significant differences (p < 0.05) were observed in composition profiles of sludge samples among the studied WWTPs. To identify the potential parameters affecting the variable fractions of sludge components, wastewater source as well as design and operational parameters of WWTPs were studied using statistical methods. The findings indicated that the component fraction of sewage sludge depends more on wastewater treatment alternatives than on wastewater characteristics among other parameters. A principal component analysis was conducted, which further indicated that there was a greater proportion of residual inert biomass in the sludge produced by the combined system of the conventional anaerobic/anoxic/oxic process and a membrane bioreactor. Additionally, a much longer solids retention time was also found to influence the sludge composition and induce an increase in both endogenous inert residues and extracellular polymeric substances in the sludge.     

A new process to improve short-chain fatty acids and bio-methane generation from waste activated sludge

As an important intermediate product, short-chain fatty acids(SCFAs) can be generated after hydrolysis and acidification from waste activated sludge, and then can be transformed to methane during anaerobic digestion process. In order to obtain more SCFA and methane,most studies in literatures were centered on enhancing the hydrolysis of sludge anaerobic digestion which was proved as un-efficient. Though the alkaline pretreatment in our previous study increased both the hydrolysis and acidification processes, it had a vast chemical cost which was considered uneconomical. In this paper, a low energy consumption pretreatment method, i.e. enhanced the whole three stages of the anaerobic fermentation processes at the same time, was reported, by which hydrolysis and acidification were both enhanced, and the SCFA and methane generation can be significantly improved with a small quantity of chemical input. Firstly, the effect of different pretreated temperatures and pretreatment time on sludge hydrolyzation was compared. It was found that sludge pretreated at 100°C for 60 min can achieve the maximal hydrolyzation. Further, effects of different initial p Hs on acidification of the thermal pretreated sludge were investigated and the highest SCFA was observed at initial p H 9.0with fermentation time of 6 d, the production of which was 348.63 mg COD/g VSS(6.8 times higher than the blank test) and the acetic acid was dominant acid. Then, the mechanisms for this new pretreatment significantly improving SCFA production were discussed. Finally,the effect of this low energy consumption pretreatment on methane generation was investigated.     

从COD测定废液中回收银

研究从COD测定的废液中回收银的工艺.在废液中分离出氯化银,经洗涤后加锌置换,还原为银.该工艺简便易行,原材料普通易得.适用于实验室及工业生产的应用.回收银的纯度可达99％以上.     

废物最少化审计中投入产出模型的建立及应用

根据“黑箱模型”原理,在工业废物最少化审计中建立并应用投入产出模型。本模型应用结果表明,它是工业废物最少化审计的有效工具,为分析工业生产物料流失原因,制订废物最少化方案提供科学依据,是推行清洁生产、实施工业废物最少化必要的技术方法之一。      

废石粉渣制备混凝剂及其除浊净水效果研究

利用废石粉渣制备无机混凝剂,并研究所得初产品对硅藻土悬浮液和受污湖水样品进行处理的适宜操作条件以及除浊净水效果,结果表明,利用某些废石粉渣制备的混凝剂有较好效果,但制备工艺有待改善。     

褐煤地下气化过程汞析出规律的研究

在褐煤地下气化模型试验的基础上 ,研究了褐煤中汞的赋存形态 ,褐煤地下气化煤气中汞含量的变化及存在形态 ,以及气化工艺的影响 ;分析了地下气化过程中汞的析出及反应机理 .实验结果表明 ,汞在试验褐煤中主要以硫化物结合态和残渣态形式存在 ;褐煤地下气化煤气中汞含量随气化时间的变化而变化 ,且主要以Hg0 (g)的形态存在 ;水蒸汽的存在会降低Hg0 (g)被其它气体氧化为Hg2 (g)的趋势 ;与地面气化及燃煤过程不同 ,煤地下气化产物中 ,气态汞占总汞比例低于 2 0 % ,明显低于地面气化及燃煤