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来自甲烷发酵的厌氧污泥在反硝化条件下 ,可以对苯二甲酸 ( Terephthalic Acid,简称 TA)为唯一碳源快速驯化富集 TA厌氧降解菌 ,然后转换到甲烷发酵状态 ,到第 6周时 ,获得的 TA降解速度为 2 2 .6mg TA/g VSS· day,是对照实验的 2 .1倍。经过约 90天的驯化 ,原存在于种污泥中的发酵性细菌几乎全部消亡 ,新的培养物中取而代之的是 TA还原和开环菌 ,TA降解菌的驯化过程和富集过程是偶联的。MPN计数和滚管计数进一步证实了上述结果。 相似文献
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Acute toxicity of cadmium to fish Labeo rohita and copepod Diaptomus forbesi pre-exposed to CaO and KMnO4 总被引:5,自引:0,他引:5
96-h LC50 values of cadmium (Cd) to fish Labeo rohita and the copepod Diaptomus forbesi, determined by static bioassays, were, respectively, 89.5 and 10.2 mg/l. LC50 values increased significantly when fish pre-exposed to 100–350 mg/l CaO or 0.5–1.5 mg/l KMnO4 for 4 d and the copepod to 20–70 mg/l CaO or 0.25–1.0 mg/l KMnO4 for same period. The LC50 values also increased when the pre-exposure period of CaO was increased to 12 d at concentration 100 mg/l for fish and 20 mg/l for copepod. All fish died when pre-exposed to 1.5 mg/l KMnO4 for 8 d. But LC50 values of Cd to copepod increased when pre-exposure period of 0.5 mg/l KMnO4 was increased from 4 to 8 d. 相似文献
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物化-生化组合工艺在含高盐量、高氨氮量有机废水处理中的应用 总被引:4,自引:1,他引:4
采用双效蒸发浓缩器、蒸氨精馏塔等作为一级物化前处理技术;采用铁碳微电解-混凝作为二级物化处理技术;兼氧-好氧作为三级处理技术的工艺流程,成功地治理了含高盐量、高氨氮量的有机化工废水,经驯化污泥生化处理后,出水达到国家排放标准。 相似文献
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The cladoceran Daphnia magna was acclimated for seven generations to cadmium concentrations ranging from 0 (control) to 250 microg/l Cd (corresponding to a free ion activity of 4.60 nM Cd2+). Acute and chronic cadmium tolerance as well as cadmium accumulation were monitored as a function of acclimation time. After two to three generations of acclimation to concentrations ranging from 0.23 to 1.11 nM Cd2+ increases in acute tolerance were maximal (factor 7.2) and significant. Acclimation for seven generations to the same acclimation concentrations did result in an increased chronic cadmium tolerance (21 days EC50 values increased). Organisms acclimated to 1.93 nM Cd2+ were equally or more sensitive than non-acclimated daphnids in acute and chronic toxicity tests. Cadmium contents in D. magna increased significantly as a function of the acclimation concentration. Maximum body burdens of 236+/-30 microg Cd/g dry weight were measured in organisms exposed to 4.60 nM Cd2+, but detoxification mechanisms were only successful up to 82+/-20 microg Cd/g dry weight as this concentration did not cause major decreases in survival and reproduction in chronic toxicity tests. As the potential positive effect of acclimation on cadmium tolerance disappeared with successive acclimation generations and increasing acclimation concentrations, it is concluded that multi-generation acclimation studies are important for the evaluation of the long-term effects of environmental toxicants. 相似文献
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Upon exposure to altered levels of CO2, plants express a variety of acclimations to CO2 directly, over and above acclimations to indirect changes in temperature and water regimes. These acclimations commonly include increased photosynthetic CO2 assimilation and increased water-use efficiency with reduced N content and reduced stomatal conductance. The robust generic acclimations are explicable by combining simple models of carboxylation, stomatal control, energy balance, and functional balance. Species- or genotype-specific acclimations are overlaid on these generic acclimations. Several such specific acclimations that are often seen are readily incorporated in an extended model. These specific acclimations generate a great spread of values in key performance measures of photosynthesis, water- and N-use efficiencies, and rates of water and N use, even among C3 species that are the focus of this work. These performance measures contribute strongly to relative fitness and thus to evolving biogeographic distributions. The spread in fitness values is so large as to impend “chaotic” shifts in biogeography (and, ultimately, evolution) that are not understandable with models specific to species or functional groups; rather, a systematic study of key physiological and developmental parameters is merited. Also merited is a coherent extension of the model used here, or similar models, to include other phenomena, including mycorrhizal associations, transience in resource availability, etc. The composition of useful approximate fitness functions from physiological and allocational responses is a major challenge, with some leads originating from the model. In the search to extract patterns of responses, arguments based on the responses being close to optimal or adaptive will be misleading, in view of the absence of selection pressure to perform adaptively at high CO2 for over 20 million years. I offer suggestions for more useful research designs. 相似文献
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The dynamic change of microbial community during sludge acclimation from aerobic to anaerobic in a MBR for coking wastewater treatment was revealed by Illumina Miseq sequencing in this study. The diversity of both Bacteria and Archaea showed an increase–decrease trajectory during acclimation, and exhibited the highest at the domestication interim. Ignavibacteria changed from a tiny minority(less than 1%) to the dominant bacterial group(54.0%) along with acclimation. The relative abundance of Betaproteobacteria kept relatively steady, as in this class some species increased coupled with some other species decreased during acclimation. The dominant Archaea shifted from Halobacteria in initial aerobic sludge to Methanobacteria in the acclimated anaerobic sludge. The dominant bacterial and archaeal groups in different acclimation stages were indigenous microorganisms in the initial sludge, though some of them were very rare. This study supported that the species in"rare biosphere" might eventually become dominant in response to environmental change. 相似文献
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Immobilized pellets obtained by means of entrapping activated sludge in waterborne polyurethane were successfully adapted in ammonium(NH_4~+–N)synthetic wastewater.Its physicochemical characteristics were determined using scanning electron microscope,pyrosequencing,and microelectrodes,and its influence on the nitrification process in sequencing batch reactors(SBRs)at low temperatures was evaluated.A large number of rod-shaped bacteria were observed on the surface of the immobilized pellet,in which Rudaea spp.(Xanthomonadaceae family)was an important bacterial component(23.44% of the total bacteria).The oxygen uptake rate of immobilized pellets reached 240.83±15.59 mg O_2/(L·hr),and the oxygen was primarily consumed by the bacteria on the pellet surfaces(0–600μm).The dosing of the pellets(30 m L/L)into an SBR significantly improved the nitrification efficiency at low temperatures of 7–11°C,achieving an average NH_4~+–N removal of 84.09%,which is higher than the removal of 67.46% observed for the control group. 相似文献