Review: recent advances in biogas purifying technologies

Biomethane production through biogas upgrading is a promising renewable energy for some industries which could be part of the equilibrium needed with fossil fuels consumption to achieve a sustainable society. This paper presents a comprehensive list of biogas upgrading technologies focused on carbon dioxide removal as well as recent advances reported by researcher with wide expertise in this topic. Additionally, an extensive costs–performance comparison among the technologies studied is discussed. Among the different alternatives, chemical scrubbing stood out to achieve high biomethane purities while cryogenic technologies proved to be effective against methane losses. Regarding the different costs, water scrubbing and membrane separation seem to be the most affordable techniques.     

可张孔曝气器曝气能耗试验研究

通过试验研究，总结出可张孔曝气阻力损失的影响因素，以优化产品的结构设计参数，降低产品在工程应用中的能耗，获取更好的经济效益。     

Analysis of the Trend and Seasonal Cycle of Carbon Monoxide Concentrations in an Urban Area (4 pp)

Background, Aim and Scope Air quality is an field of major concern in large cities. This problem has led administrations to introduce plans and regulations to reduce pollutant emissions. The analysis of variations in the concentration of pollutants is useful when evaluating the effectiveness of these plans. However, such an analysis cannot be undertaken using standard statistical techniques, due to the fact that concentrations of atmospheric pollutants often exhibit a lack of normality and are autocorrelated. On the other hand, if long-term trends of any pollutant’s emissions are to be detected, meteorological effects must be removed from the time series analysed, due to their strong masking effects. Materials and Methods The application of statistical methods to analyse temporal variations is illustrated using monthly carbon monoxide (CO) concentrations observed at an urban site. The sampling site is located at a street intersection in central Valencia (Spain) with a high traffic density. Valencia is the third largest city in Spain. It is a typical Mediterranean city in terms of its urban structure and climatology. The sampling site started operation in January 1994 and monitored CO ground level concentrations until February 2002. Its geographic coordinates are W0°22′52″ N39°28′05″ and its altitude is 11 m. Two nonparametric trend tests are applied. One of these is robust against serial correlation with regards to the false rejection rate, when observations have a strong persistence or when the sample size per month is small. A nonparametric analysis of the homogeneity of trends between seasons is also discussed. A multiple linear regression model is used with the transformed data, including the effect of meteorological variables. The method of generalized least squares is applied to estimate the model parameters to take into account the serial dependence of the residuals of this model. This study also assesses temporal changes using the Kolmogorov-Zurbenko (KZ) filter. The KZ filter has been shown to be an effective way to remove the influence of meteorological conditions on O₃ and PM to examine underlying trends. Results The nonparametric tests indicate a decreasing, significant trend in the sampled site. The application of the linear model yields a significant decrease every twelve months of 15.8% for the average monthly CO concentration. The 95% confidence interval for the trend ranges from 13.9% to 17.7%. The seasonal cycle also provides significant results. There are no differences in trends throughout the months. The percentage of CO variance explained by the linear model is 90.3%. The KZ filter separates out long, short-term and seasonal variations in the CO series. The estimated, significant, long-term trend every year results in 10.3% with this method. The 95% confidence interval ranges from 8.8% to 11.9%. This approach explains 89.9% of the CO temporal variations. Discussion The differences between the linear model and KZ filter trend estimations are due to the fact that the KZ filter performs the analysis on the smoothed data rather than the original data. In the KZ filter trend estimation, the effect of meteorological conditions has been removed. The CO short-term componentis attributable to weather and short-term fluctuations in emissions. There is a significant seasonal cycle. This component is a result of changes in the traffic, the yearly meteorological cycle and the interactions between these two factors. There are peaks during the autumn and winter months, which have more traffic density in the sampled site. There is a minimum during the month of August, reflecting the very low level of vehicle emissions which is a direct consequence of the holiday period. Conclusions The significant, decreasing trend implies to a certain extent that the urban environment in the area is improving. This trend results from changes in overall emissions, pollutant transport, climate, policy and economics. It is also due to the effect of introducing reformulated gasoline. The additives enable vehicles to burn fuel with a higher air/fuel ratio, thereby lowering the emission of CO. The KZ filter has been the most effective method to separate the CO series components and to obtain an estimate of the long-term trend due to changes in emissions, removing the effect of meteorological conditions. Recommendations and Perspectives Air quality managers and policy-makers must understand the link between climate and pollutants to select optimal pollutant reduction strategies and avoid exceeding emission directives. This paper analyses eight years of ambient CO data at a site with a high traffic density, and provides results that are useful for decision-making. The assessment of long-term changes in air pollutants to evaluate reduction strategies has to be done while taking into account meteorological variability     

臭氧耦合陶瓷膜过滤对膜性能及出水消毒副产物的影响

利用臭氧（O₃）-陶瓷膜过滤（CMF）处理常规工艺出水,研究了不同O₃-CMF耦合方式对膜性能和消毒副产物（DBPs）的影响.结果表明,与单独CMF相比,异位O₃-CMF和原位O₃-CMF均可以有效缓解膜污染,原位O₃-CMF控制效果最佳.异位O₃-CMF对进水（常规工艺出水） DOC去除率（26.25%）略高于原位O₃-CMF（22.31%）,但是其SUVA去除率（83.91%）明显低于原位O₃-CMF（93.10%）.羟基自由基（·OH）生成特征表明原位O₃-CMF可促进O₃产生更多的·OH.在O₃、·OH氧化和陶瓷膜截留协同作用下,异位O₃-CMF和原位O₃-CMF出水中总荧光响应强度和相对分子质量大于0.3×10³,有机物含量降低,进而使得出水中含碳消毒副产物（C-DBPs）生成量分别降低了21.86%和32.35%,含氮消毒副产物（N-DBPs）生成量分别降低了16.16%和19.13%.但O₃和·OH氧化后生成的小分子有机物因难以被CM截留导致其在出水中含量增加,进而增加了卤代酮（HKs）、水合氯醛（CH）和三卤硝基甲烷（THNMs）的产生.本研究对于不同O₃-CMF方式下O₃与CM的协同机制的探讨,改善膜性能和提升DBPs前体物的去除具有一定指导意义.     

滤纸法测定悬浮物的干扰及其消除

提出了滤纸法测定悬浮物时，水样的酸碱度，取样量的多少对悬浮物测定有直接的影响。通过实验验证，对于偏酸，偏碱的水样用酸碱中和后再过滤即可消除影响，取样量应根据悬浮物的不同而定。     

Determination of organophosphorus pesticides and related compounds in water samples by membrane extraction and gas chromatography

A membrane extraction-gas chromatography method was developed fordetermination of organophosphorus pesticides and related compounds including methamidophos, DDVP, dimethoate, methyl parathion, parathion, thiophosphoric acid trimethyl ester, and thiophosphoramidic acid dimethyl ester in water samples. In thismethod, surface-modified acetic cellulose membranes were used to extract the target analytes in water samples, the extracted analytes were back-extracted into a small amount of methanol, andgas chromatography with pulsed flame photometric detector (GC-PFPD) was used to determine the concentrations of targetanalytes in the extracts. The recoveries obtained for thetarget analytes spiked into the water samples ranged from 66to 94%. The method detection limit for each target analyte was 0.05 g L^-1. The method developed in this study had shown the advantages of being cheap, simple, fast, and reliable. It had been used successfully to determine the concentrations of target analytes in river water samples.     

Large pore size polyacrylonitrile membrane for ultrafiltration

ＩｎｔｒｏｄｕｃｔｉｏｎＩｎｒｅｃｅｎｔｙｅａｒｓ,ｔｈｅｔｅｃｈｎｉｑｕｅｆｏｒｕｌｔｒａｆｉｌｔｒａｔｉｏｎｈａｓｇａｉｎｅｄｒａｐｉｄｄｅｖｅｌｏｐｍｅｎｔ.Ｍｏｒｅａｎｄｍｏｒｅｋｉｎｄｓｏｆｍｅｍｂｒａｎｅｓａｒｅｓｔｕｄｉｅｄａｎｄｍａｎｕｆａｃｔｕｒｅｄ ,ａｎｄａｌａｒｇｅ ｓｃａｌｅｉｎｄｕｓｔｒｉａｌａｐｐｌｉｃａｔｉｏｎｈａｓｂｅｅｎｇｒｏｗｎ .ＰＡＮｐｏｌｙｍｅｒｉｓｅｘｔｅｎｓｉｖｅｌｙｕｓｅｄｔｏｐｒｅｐａｒｅＵＦｍｅｍｂｒａｎｅｓ(Ｓｔｏｉｋｏ,1 991 ) .Ｉｔｓｈｙｄｒｏｐ…     

BOD微生物膜的再利用研究初探

对失去大部分活性的微生物膜进行再培养,以研究膜再利用的可能性。试验结果初部表明:在1/2MS培养基中加入一定量的植物激素,不仅可以使膜的电位值(I0)显著升高,且活性强,稳定性好,可使膜重复利用。     

湖州市北污水处理厂污泥处理运行管理

重点介绍湖州市北污水处理厂采用带式压滤机进行污泥脱水处理的应用情况及运行管理,并进行了小结。     

Improvement of the antifouling characteristics in a bioreactor of polypropylene microporous membrane by the adsorption of Tween 20

Surface modification by physical adsorption of Tween 20 was accomplished on polypropylene microporous membranes (PPMMs). Attenuated total reflection-Fourier transform infrared spectroscopy (ATR/FT-IR) and scanning electron microscope (SEM) were used to characterize the chemical and morphological changes on the membrane surfaces. Water contact angles and relative pure water fluxes were measured. The data showed that the hydrophilic performance for the modified membranes increased with the increase in the adsorption amount of Tween 20 onto the surface or into the pores of polypropylene microporous membranes. To test the antifouling property of the membranes by the adsorption of Tween 20 in a membrane bioreactor (MBR), filtration for active sludge was performed using synthetic wastewater. With the help of the data of water fluxes and the FE-SEM photos of the modified PPMMs before or after operating in a MBR for about 12 d, the PPMMs with monolayer adsorption of Tween 20 showed higher remained flux and stronger antifouling ability than unmodified membrane and other modification membranes studied.