A chemostat system for investigating pesticide biodegradation in continuous mixed bacteria cultures originating from surface water

To be able to predict the degradation (rate) of organic chemicals (e.g. pesticides) in the field, knowledge of the environmental conditions that are of influence on the degradation process are of importance. In the present study an experimental system is described which is used to study the degradation of organic pollutants in mixed bacteria cultures originating from surface water. With this system the degradation of compounds can be followed for relatively long experimental periods (months). In addition, it is possible to vary different environmental parameters in order to investigate their influences on the degradation of the chemical. These preliminary experiments show that growth and ‘composition’ of the bacteria culture have comparable patterns in parallel experiments. The first order degradation rate constant for the test compound dichloran, as calculated from these experiments under these circumstances, is about 0.002 h⁻¹.     

Leachate formation and characteristics from gasification and grate incineration bottom ash under landfill conditions

Characteristics and formation of leachates from waste gasification and grate firing bottom ash were studied using continuous field measurements from 112 m³ lysimeters embedded into landfill body for three years. In addition, the total element concentrations of the fresh ash were analysed and laboratory batch tests were performed to study leachate composition. The three-year continuous flow measurement showed that about one fifth of the leachates were formed, when the flow rate was >200 l/d, covering <3.5% of the study time. After three years, the liquid/solid-ratio for the quenched grate ash was 1 (l/kg (d.m.)) and for the initially dry gasification ash 0.4 (l/kg (d.m.)). The low initial water and residual carbon content of the gasification ash kept the leachate pH at a high level (>13) major part of the study. In the grate ash leachate pH was lower (<8) due to the presence of organic carbon and biodegradation indicated by biological oxygen demand and redox potential measurements. In the gasification ash the high pH probably delayed leaching of major elements such as Ca, therefore, raising the need for a longer after-care period. The high pH also explains the higher leaching of As from the gasification ash compared to the grate ash both in the batch test and under landfill conditions.     

环境空气自动监测系统与连续监测系统监测数据的比较

本文对两套监测系统的监测数据进行比较和相关性分析,结果表明：两套监测系统的监测数据之间存在显著的线性相关,相关系数在0．6705～0．9345之间;自动监测系统的监测数据均高于连续监测系统的监测数据,S02平均高53％～64％,NQ平均高78％～82％,PM10平均高37％～42％。     

Replace the NOAEL and LOAEL with the BMDL01 and BMDL10

Although benchmark-dose methodology has existed for more than 20 years, benchmark doses (BMDs) still have not fully supplanted the no-observed-adverse-effect level (NOAEL) and lowest-observed-adverse-effect level (LOAEL) as points of departure from the experimental dose–response range for setting acceptable exposure levels of toxic substances. Among the issues involved in replacing the NOAEL (LOAEL) with a BMD are (1) which added risk level(s) above background risk should be targeted as benchmark responses (BMRs), (2) whether to apply the BMD methodology to both carcinogenic and noncarcinogenic toxic effects, and (3) how to model continuous health effects that aren’t observed in a natural risk-based context like dichotomous health effects. This paper addresses these issues and recommends specific BMDs to replace the NOAEL and LOAEL.

挥发酚和总氰化物在三种水质中测定方法的比对

本文采用连续流动注射法[1]和紫外分光光度法[2-3],分别对地表水、生活污水、工业废水三种水质中的挥发酚和总氰化物进行测定。实验结果表明:两种分析方法测定三种水质中的挥发酚和总氰化物结果基本一致,检出限、精密度、准确度、加标回收率均符合质量控制要求。连续流动注射法的自动化程度更高,操作更简便,可适用于多种水质挥发酚和总氰化物的分析。     

连续流动分析法测定水中总磷不确定度的评定

在实验室分析基础上对连续流动分析法测定水中总磷过程的不确定度进行评定。本文建立了数学模型,对不确定度来源进行了分析,并计算了不确定度分量、合成不确定度及扩展不确定度,最后给出了总磷测量结果的标准表示方法。     

连续流动分析-分光光度法测定水和废水中总氮

对连续流动分析-分光光度法测定水和废水中总氮进行方法适用性验证，6家验证单位验证数据表明：方法在0 mg/L～10．0 mg/L范围内线性良好，相关系数为0．9996～0．9999；方法检出限为0．04 mg/L，测定下限为0．16 mg/L；6家实验室测定总氮标准溶液 RSD为0．4％～9．6％，测定总氮有证标准物质的结果在允许范围内，实际水样的加标回收率为92．0％～111％。该方法与国标方法同时测定多种类型的水样，结果无显著差异。探讨了影响该方法测定的干扰因素和消除方法，并提出方法应用要点。     

The effects of different mixing intensities during anaerobic digestion of the organic fraction of municipal solid waste

Mixing inside an anaerobic digester is often continuous and is not actively controlled. The selected mixing regime can however affect both gas production and the energy efficiency of the biogas plant. This study aims to evaluate these effects and compare three different mixing regimes, 150 RPM and 25 RPM continuous mixing and minimally intermittent mixing for both digestion of fresh substrate and post-digestion of the organic fraction of municipal solid waste. The results show that a lower mixing intensity leads to a higher biogas production rate and higher total biogas production in both cases. 25 RPM continuous mixing and minimally intermittent mixing resulted in similar biogas production after process stabilization, while 150 RPM continuous mixing resulted in lower production throughout the experiment. The lower gas production at 150 RPM could not be explained by the inhibition of volatile fatty acids. Cumulative biogas production until day 31 was 295 ± 2.9, 317 ± 1.9 and 304 ± 2.8 N ml/g VS added during digestion of fresh feed and 113 ± 1.3, 134 ± 1.1 and 130 ± 2.3 N ml/g VS added during post digestion for the 150 RPM, 25 RPM and minimally mixed intensities respectively. As well as increasing gas production, optimal mixing can improve the energy efficiency of the anaerobic digestion process.     

爆炸性气体在连续拐弯管道中传播特性的实验研究

针对复杂燃气管网燃气爆炸致灾严重,传播规律复杂的问题,利用实验室加工成的连续拐弯管道,模拟研究了复杂燃气管网爆炸性气体通过连续拐弯管道时的火焰传播速度、爆炸波超压变化情况。研究结果表明,当整个管道内充满瓦斯气体时,通过连续拐弯后,火焰传播速度和爆炸波超压值产生显著变化,在连续拐弯管道拐弯处为一扰动源,诱导附加湍流,气流湍流度增大,管道拐弯增加了燃烧区的湍流度,火焰燃烧产生加速度,加速燃烧产生更大能量以推动加速传播。研究结果对指导现场如何防治复杂燃气管网气体爆炸,减轻爆炸的威力具有重要作用。     

连续流动分析法测定废水中的总氮

本文初步探讨了连续流动分析法测定废水中总氮的方法。通过将测量量程扩大至20mg/L,对混浊的废水进行过滤处理,实验结果表明,该方法的相关系数达0．9999,方法检出限为0．02mg/L,加标回收率在99．5％-108％之间,RSD为0．2％-0．6％,可适用于废水中总氮的分析。