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781.
I. K. P. Tan E. S. Stuart R. W. Lenz R. C. Fuller 《Journal of Polymers and the Environment》1998,6(2):67-71
It is well known that Pseudomonas oleovorans can utilize sodium octanoate for both cell growth and the synthesis of polyhydroxyalkanoates (PHAs), but it can utilize sodium butyrate only for limited cell growth and not for the polyester formation when this substrate is the sole carbon source. Therefore, these two substrates were evaluated as cofeeds for the possible incorporation of 3-hydroxybutyryl groups in the resulting PHA. When sodium butyrate and sodium octanoate were fed to P. oleovorans as cosubstrates in various proportions, the resultant cell density and polymer content were proportional to the amount of sodium octanoate in the feed. The PHA extracted from cells grown in all combinations of these cosubstrates had similar unit compositions of approximately 8 mole % 3-hydroxyhexanoate, 91 mole % 3-hydroxyoctanoate and 1 mole % 3-hydroxydecanoate. 3-Hydroxybutyrate units were not detected in any of the PHAs isolated, indicating that these units could not be incorporated in the copolymer synthesized by P. oleovorans either because the cell did not synthesize that monomer or, if it did, the PHA synthase could not copolymerize it with the longer chain monomers. 相似文献
782.
Franois Oehler Paul Bordenave Patrick Durand 《Agriculture, ecosystems & environment》2007,120(2-4):313-324
We measured denitrification at 15 sites during 1 year in a agricultural catchment in Brittany, France. Our objective was to assess the relative importance of heterotrophic denitrification on the fate of excess nitrogen at the catchment scale, and to quantify the relative importance of riparian areas on the N2O emissions. Using the C2H2 inhibition technique, denitrification rate on soil core and denitrifying enzyme activity (DEA) were each determined, for samples taken from two soil layers: 0–20 and 20–40 cm. Denitrification rates, ranging from 0 to 417 mg N m−2 d−1, were significantly higher in riparian areas than for hillslopes (median of 24.87 against 10.38 mg N m−2 d−1). However, since denitrification rates are significant in the hillslope and given that hillslope surface area is much greater (79% of catchment surface), this domain could be responsible for half of the overall denitrified nitrogen (N). Also, the 20–40 cm deep soil layer was found to account for more than 46% of the denitrification. The DEA indicates the potential for denitrifying activity by the soil under non-limiting conditions, measured values ranged from 76.48 to 530.63 ng N g−1 dry soil h−1. The ratio N2O/(N2O + N2) was about 60% with no clear spatial or temporal trends. Soil moisture appeared to be the main limiting factor for denitrification at the field scale. The results suggest that, for this catchment, denitrification is a major route for nitrogen removal, but a significant proportion of this removal occurs as N2O. 相似文献
783.
屠宰废水是一种常见的食品加工废水,废水中有机污染物浓度较高,且含有脂肪、蛋白质等大分子有机物和毛发、动物内脏等杂物.絮凝气浮 CASS组合工艺在铁岭某肉鸡屠宰公司废水处理工程应用中,取得了较为显著的效果,CODcr去除率98%,BOD5去除率98%,SS去除率98%,氨氮去除率58%,动植物油去除率91%;出水水质均满足GB13457-92<肉类加工工业水污染物排放标准>要求.该工艺具有投资少、操作简单、处理效果好、便于管理的特点,易于在同类食品加工废水处理中推广应用. 相似文献
784.
半干法烟道气脱硫影响因素的理论分析 总被引:1,自引:0,他引:1
建立了半干法烟气脱硫的理论模型,分析了各种影响因素,以反应时间和液滴干燥时间为基础数据,优化出液滴在脱硫干燥塔内的停留时间,由停留时间确定脱硫塔高度,由处理的烟气流量确定塔径. 相似文献
785.
786.
787.
788.
废气治理的低温等离子体-催化协同净化技术 总被引:2,自引:0,他引:2
低温等离子体 催化协同净化技术具有能耗低、投资少、处理效率高、不产生二次污染等显著优点备受人们的关注。从挥发性有机化合物 (VOC)的转化、氮氧化合物的脱除、汽车尾气净化等不同废气治理的角度 ,概括了目前国内外在这方面的研究进展 ,最后提出了该项技术在环境保护领域的应用前景及研究方向 相似文献
789.
Virus retention and transport through Al-oxide coated sand columns: effects of ionic strength and composition 总被引:11,自引:0,他引:11
Knowledge of the factors that influence the fate and transport of viruses in porous media is very important for accurately determining groundwater vulnerability and for developing protective regulations. In this study, six saturated sand column experiments were performed to examine the effects of a positively charged Al-oxide, which was coated on sand particles, on the retention and transport of viruses (phiX174 and MS-2) in background solutions of different ionic strength and composition. We found that the Al-oxide coating on sand significantly removed viruses during their transport in a phosphate buffered saline (PBS) solution. Mass balance calculations showed that 34% of the input MS-2 was inactivated/irreversibly sorbed on the surface of Al-oxide coated sand whereas 100% of phiX174 was recovered. Results from this study also indicated that higher ionic strength facilitated the transport of both phiX174 and MS-2 through the Al-oxide coated sand. This was attributed to the effect of ion shielding, which at higher ionic strength decreased the electrostatic attraction between the viral particles and the sand surface and consequently decreased virus sorption. Strong effect of the ionic strength indicates that an outer-sphere complexation mechanism was responsible for the virus sorption on the Al-oxide coated sand. Ion composition of the background solutions was also found to be a significant factor in influencing virus retention and transport. Virus transport was enhanced in the presence of phosphate (HPO(4)(2-)) as compared to bicarbonate (HCO(3)(-)), and the effect of HPO(4)(2-) was more significant on MS-2 than on phiX174. The presence of bivalent cations (Ca(2+) and Mg(2+)) increased virus transport because the cations partially screened the negative charges on the viruses therefore decreased the electrostatic attraction between the positively charged sand surface and the negatively charged viruses. Mass recovery data indicated that bivalent cations gave rise to a certain degree of inactivation/irreversibly sorption of phiX174 on the surface of Al-oxide coated sand. On the contrary, the bivalent cations appeared to have protected MS-2 from inactivation/irreversibly sorption. This study provides some insights into the mechanisms responsible for virus retention and transport in porous media. 相似文献
790.
炭素焙烧炉沥青烟净化处理 总被引:1,自引:0,他引:1
采用干式静电除尘技术,对炭素焙烧炉排放的含有烟尘、沥青烟的工业废气进行处理,达到既能高效净化有害气体,又能降低资金投入。处理后的各项指标为:烟尘排放浓度=20.0mg/m3,沥青烟排放浓度=14.2mg/m3,苯并(a)芘排放浓度=0.054×10-3mg/m3,所有污染物均达到排放标准。 相似文献