Comparison of the sensitivities of fish, Microtox and Daphnia-magna bioassays to amoxycillin in anaerobic/aerobic sequential reactor systems

In this study the anaerobic treatability of amoxycillin (AMX) was investigated in a laboratory-scale anaerobic multi-chamber bed reactor (AMCBR)/aerobic continuously stirred tank reactor (CSTR) system. The chemical oxygen demand (COD) and AMX removal efficiencies were around 94% in the AMCBR reactor at hydraulic retention times (HRTs) between 2.25 and 5.5 days. Decreasing the HRT appeared not to have a significant effect on the performance of the AMCBR up to a HRT of 1.13 days. The maximum methane production rate and methane percentage were around 1,100-1,200 mL/day and 55%, respectively, at HRTs between 2.25 and 5.5 days. The decrease in HRT to 1.5 days decreased slightly the gas productions (1,000 mL/day and 500 mL for total and methane gases) and methane percentage (45%). The AMCBR recovered back to its baseline performance within a couple of days. The acute toxicity of 150 mg/L AMX was monitored with Daphnia magna, Lepistes sp., and Vibrio fischeri acute toxicity tests. The acute toxicity removals were 98, 96 and 96% for V. fischeri, D. magna and Lepistes sp. in the effluent of the sequential system treating 150 mg/L AMX at HRTs of 2.25-5.5 days. Among the trophic organisms used in the acute toxicity tests the most sensitive organism was found to be bacteria (V. fischeri) while the most resistant organism was found to be fish (Lepistes sp.).     

Study on the removal efficiency of UF membranes using bacteriophages in bench-scale and semi-technical scale

To determine the removal efficiency of ultrafiltration (UF) membranes for nano-particles in the size range of viruses the state of the art uses challenge tests with virus-spiked water. This work focuses on bench-scale and semi-technical scale experiments. Different experimental parameters influencing the removal efficiency of the tested UF membrane modules were analyzed and evaluated for bench- and semi-technical scale experiments. Organic matter in the water matrix highly influenced the removal of the tested bacteriophages MS2 and phiX174. Less membrane fouling (low ΔTMP) led to a reduced phage reduction. Increased flux positively affected phage removal in natural waters. The tested bacteriophages MS2 and phiX174 revealed different removal properties. MS2, which is widely used as a model organism to determine virus removal efficiencies of membranes, mostly showed a better removal than phiX174 for the natural water qualities tested. It seems that MS2 is possibly a less conservative surrogate for human enteric virus removal than phiX174. In bench-scale experiments log removal values (LRV) for MS2 of 2.5-6.0 and of 2.5-4.5 for phiX174 were obtained for the examined range of parameters. Phage removal obtained with differently fabricated semi-technical modules was quite variable for comparable parameter settings, indicating that module fabrication can lead to differing results. Potting temperature and module size were identified as influencing factors. In conclusion, careful attention has to be paid to the choice of experimental settings and module potting when using bench-scale or semi-technical scale experiments for UF membrane challenge tests.     

Influence of photoperiod on carbon dioxide and methane emissions from two pilot-scale stabilization ponds

Greenhouse gas (GHG) emissions (CO(2), CH(4)) from pilot-scale algal and duckweed-based ponds (ABP and DBP) were measured using the static chamber methodology. Daylight and nocturnal variations of GHG and wastewater characteristics (e.g. chemical oxygen demand (COD), pH) were determined via sampling campaigns during midday (12:30-15:30) and midnight (00:30-03:30) periods. The results showed that under daylight conditions in ABP median emissions were -232 mg CO(2) m(-2) d(-1) and 9.9 mg CH(4) m(-2) d(-1), and in DBP median emissions were -1,654.5 mg CO(2) m(-2) d(-1) and 71.4 mg CH(4) m(-2) d(-1), respectively. During nocturnal conditions ABP median emissions were 3,949.9 mg CO(2) m(-2) d(-1), 12.7 mg CH(4) m(-2) d(-1), and DBP median emissions were 5,116 mg CO(2) m(-2) d(-1), 195.2 mg CH(4) m(-2) d(-1), respectively. Once data measured during daylight were averaged together with nocturnal data the median emissions for ABP were 1,566.8 mg CO(2) m(-2) d(-1) and 72.1 mg CH(4) m(-2) d(-1), whilst for DBP they were 3,016.9 mg CO(2) m(-2) d(-) and 178.9 mg CH(4) m(-2) d(-1), respectively. These figures suggest that there were significant differences between CO(2) emissions measured during daylight and nocturnal periods (p < 0.05). This shows a sink-like behaviour for both ABP and DBP in the presence of solar light, which indicates the influence of photosynthesis in CO(2) emissions. On the other hand, the fluxes of CH(4) indicated that DBP and ABP behave as net sources of CH(4) during day and night, although higher emissions were observed from DBP. Overall, according to the compound average (daylight and nocturnal emissions) both ABP and DBP systems might be considered as net sources of GHG.     

锦屏二级水电站转子组装技术改进

结合锦屏二级水电站发电机转子安装过程中出现的技术问题,着重探讨了转子支架加强板改造中的焊接变形控制、转子磁轭的高度、圆度、半径及垂直度的控制措施及转子静平衡影响的因数等三个技术难点。     

“招待卡”议

“招待卡”议张志强《中州审计》第８８期刊登了临颖县繁城镇实行《村来客招待卡》一文，文章虽短，颇党新鲜。读后，在为繁城镇审计站叫好之余，顿生一些感想。我国作为发展中国家，人民的生活水平是否真正达到了可以经常上饭馆、酒店的水平固然值得商榷。然而近年来，高...     

法学本科毕业生就业难的原因与对策分析

法律院校大学毕业生的就业问题已经成为人们非常关注的问题,解决大学生的就业问题,是社会稳定发展以及实现社会价值和自我价值的需要,直接关系着社会、家庭和个人的切身利益.如何指导法律院校大学生顺利就业,探索法律院校毕业生就业的新途径是一个很有现实意义的重要问题.     

中国宏观经济模型对比估计

一、前言联立方程计量经济学模式是相对于单方程计量经济学而言,它以经济系统为研究对象,以揭示经济系统中各部分、各因素之间的数量关系和系统的数量特征为目的,用于经济系统的预测、分析和评价。单方程计量经济学模型,是用单一方程描述某一经济变量与影响该变量变化的诸因素之间的数量关系。但对于经济现象复杂,诸因素是相互依存、互为因果的情况下,单一方程就不再适用了。本文以联立方程为研究对象,用不同的方法对3方程     

浅谈行政事业单位固定资产管理存在的问题及对策

行政事业单位的固定资产是一般指使用期限在一定的年限以上、单位价值在规定的标准范围，并且在使用过程中基本上保存原有物质形态的资产。行政事业单位的固定资产是行政事业单位开展各项业务以及经营活动的物质基础，也是行政事业单位赖以生存与发展的重要资源之一，并且行政事业单位的固定资产占单位的资产总额比例较大，那么如何管理好这些国有资产，提高其运转效率、确保国有资产的增值保证作用值得我们这些管理者去思考，目前笔者在实际工作中看到行政事业单位固定资产管理存在诸多问题，这些问题的存在已经严重地影响了行政事业单位的经济运行，那么分析问题的存在原因，找出解决问题的对策为更好地配合国家最新颁布的行政事业单位内部控制管理，促进国有资产的有效循环有着十分重要的意义。下面就谈些我个人的看法。     

全球经济将加剧“分化”

如果新兴经济体能够推进各自的结构性改革，它们将提高各自在全球经济中的相对和绝对地位。