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451.
研究了人工土模拟柱对污水中氮去除的主要机制。试验结果表明,在脱氮的各种机制中,生物硝化-反硝化起着较重要的作用,对全N的相对去除率为50%,对NH^+4-N的相对转化去除率为69%;对SS的物理截留也起了一定的作用。 相似文献
452.
实验研究了氧化铝陶瓷膜处理高浊度水时膜通量衰减变化规律,发现运行初期膜通量衷减很快,后期衰减趋于平缓,总体成线性下降。对0.8μm、0.2μm、50nm 3种不同孔径的氧化铝陶瓷膜性能进行了比较,发现50nm氧化铝陶瓷纳滤膜处理高浊度水膜通量明显大于0.8μm和0.2μm氧化铝陶瓷超滤膜,而浊度和污染指数也较两者小。 相似文献
453.
Daojun Zhang Ziran M Baodong Wang Tao Zhu Duan Weng Xiaodong Wu Hongyan Wang Ge Li Jiali Zhou 《环境科学学报(英文版)》2020,32(2):145-154
A series of vanadium based catalysts(VxMn(4-x)Mo3Ce3/Ti) with different vanadium(x wt.%) and manganese((4-x) wt.%) contents have been prepared by the wet impregnation method and investigated for selective catalytic reduction(SCR) of NO_x by NH_3 in the presence of 8 vol.% H_2O and 500 ppm V SO_2.The physicochemical characteristics of the catalysts were thoroughly characterized.The SCR of NO_x by NH_3(NH_3-SCR) activity, especially the low-temperature activity, significantly increased with increasing V_2O_5 content in the catalyst until the V_2O_5 content reached 1.5 wt.%, which corresponds well with the redox properties of the catalyst.All of the metal oxides were well dispersed and strongly interacted with each other on the catalyst surface.V mainly exists in the V~(5+)state in the catalysts.The strong synergistic effect between the vanadium and cerium species led to formation of more Ce~(3+)species, and that between the vanadium and manganese species contributed to formation of more manganese species with low valences.All of the catalysts exhibited strong acidity, while the redox properties determined the NH_3-SCR activity, especially the low-temperature activity.H_2O and SO_2 had severe inhibiting effects on the activity of V1.5Mn2.5Mo3Ce3/Ti.However, good H_2O and SO_2 resistance and high NO_x conversion by V1.5Mn2.5Mo3Ce3/Ti could be achieved in the presence of SO_2 and almost no decline was observed in a long-term test at 275℃ for 168 hr in the presence of SO_2 and H_2O, which can be attributed to the sulfate species formed on the catalyst surface. 相似文献
454.
Shuting Luo Xiaodong Wu Baofang Jin Shuang Liu Rui Ran Zhichun Si Duan Weng 《环境科学学报(英文版)》2020,32(8):64-71
Pt/Al2O3 catalysts with mean Pt particle size ranged from 2.7 to 7.1 nm were synthesized by chemical reduction method, and the sulfated counterparts were prepared by impregnation of sulfuric acid. The turnover frequency of platinum for soot oxidation under loose contact conditions in a feed flow containing NO and O2 are positively correlated with the size of platinum. The sulfated Pt/Al2O3 exhibits higher catalytic activity for soot oxidation in the presence of NO despite their reduced ability for NO2 production. Such a contradiction is more significant for those catalysts with smaller platinum particles. Herein, the catalysts were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), transmission electron microscopy (TEM), inductive coupled plasma (ICP) emission spectrometry, CO chemisorption, thermogravimetric analysis (TGA), NH3 temperature-programmed desorption (NH3-TPD), NO temperature-programmed oxidation (TPO) and NOx temperature-programmed desorption (TPD). Possible effect of Pt particle size for the catalytic oxidation of soot in the presence of NO was presented based primarily on the promoted NO2 transfer efficiency onto the soot pushed by the acidic catalysts. 相似文献
455.
Hongbo Duan Gupeng Zhang Shouyang Wang Ying Fan 《Mitigation and Adaptation Strategies for Global Change》2018,23(3):387-403
In this study, we incorporate a three-reservoir climate module into our energy-economy-environmental integrated (3E-integrated) system model, in order to estimate the effect of China’s contribution of unilateral emissions on global warming and to weigh the macro-mitigation cost against the risk of damage, and we also explore the role of adaptation in reducing climate change risk. Our results suggest that China’s unilateral emission-control action plays a relatively limited role in mitigating global warming and is not particularly cost-effective, given that the macro-reduction cost is much larger than the benefit in the corresponding climate damage mitigation. Adaptation plays a large role in curbing China’s climate damages and improving the economics of China’s unilateral emission-control actions, and it is little affected by the introduction and option mitigation strategies. To prevent global warming from exceeding critical thresholds, more international collaborations and cooperative efforts are therefore anxiously needed; as for China, bolstering a low-carbon economy and installing an effective mechanism for improving the adaptation level are two feasible options for controlling climate damage risks, given the great uncertainty on the present situation of international cooperation mitigation. 相似文献
456.
457.
458.
随着中国养殖业的迅速发展,禽畜粪便的排放数量逐年增加。据统计,禽畜粪尿排放量每头牛为55kg/d~65 kg/d,每头猪为3.5 kg/d~11.0 kg/d,每只鸡为0.10 kg/d~0.15 kg/d,每只羊为2.66 kg/d。大量的禽畜粪便不经处理而排入环境,将会对地表水、地下水、土壤和空气造成严重的污染,并危及禽畜本身及人体健康。因此,实现禽畜粪便的减量化、无害化及资源化,防止和消除养殖场粪便的污染及其利用问题的研究,对于生态环境的保护、实施可持续发展战略都具有十分重要的意义。本试验利用日本JST赠送的生态厕所反应装置为试验设备,分别以木屑和木屑与秸秆混合物为微生物载体,对牛粪便进行减量化处理技术研究。旨在为研究中国农业的玉米作物秸秆是否可以替代木屑作为反应过程中的调理剂,达到对禽畜养殖业粪便良好的减量化处理效果,减轻对环境的污染,同时也为中国大量的农作物秸秆寻找另一条资源化利用途径。 相似文献
459.
Yao Chen Jinhui Li Huabo Duan Zhishi Wang 《Frontiers of Environmental Science & Engineering in China》2011,5(2):167-174
Mechanical waste-processing methods, which combine crushing and separation processes for the recovery of valuable materials,
have been widely applied in waste printed wiring board (PWB) treatment. However, both the high impact toughness and the tensile
and flexural strengths of whole PWB with a laminated structure result in great energy consumption and severe abrasion of the
cutters during multi-level crushing. In addition, the high temperatures occurring in continual crushing probably cause the
decomposition of the polymer matrix. A thermal-crack method using residual steam as the heating medium has been developed
to pre-treat waste PWBs. This treatment reduces the mechanical strength in order to improve the recovery rate of valuable
materials in subsequent mechanical recycling. The changes of the PWBs’ macro-mechanical properties were studied to evaluate
thermal expansion impacts associated with changes in temperature, and the dynamic dislocation micro-structures were observed
to identify the fracture mechanism. The results showed that thermal cracking with steam at the temperature of 500 K can effectively
attenuate the mechanical properties of waste PWBs, by reducing the impact, tensile and flexural strengths respectively, by
59.2%, 49.3% and 51.4%, compared to untreated PWB. Thermal expansion can also facilitate the separation of copper from glass
fiber by reducing peel resistance by 95.4% at 500 K. It was revealed that the flexural fracture was a transverse cracking
caused by concentrated stress when the heating temperature was less than 500 K, and shifted to a vertical cracking after exceeding
500 K. 相似文献
460.
Arsenic (As) is a pervasive and ubiquitous environmental toxin that has created catastrophic human health problems world-wide.
Chlamydomonas reinhardtii is a unicellular green alga, which exists ubiquitously in freshwater aquatic systems. Arsenic metabolism
processes of this alga through arsenate reduction and sequent store and efflux were investigated. When supplied with 10 mol/L arsenate,
arsenic speciation analysis showed that arsenite concentration increased from 5.7 to 15.7 mg/kg dry weight during a 7-day period,
accounting for 18%–24% of the total As in alga. When treated with different levels of arsenate (10, 20, 30, 40, 50 mol/L) for 7 days,
the arsenite concentration increased with increasing external arsenate concentrations, the proportion of arsenite was up to 23%–28%
of the total As in alga. In efflux experiments, both arsenate and arsenite could be found in the efflux solutions. Additionally, the efflux
of arsenate was more than that of arsenite. Furthermore, two arsenate reductase genes of C. reinhardtii (CrACR2s) were cloned and
expressed in Escherichia coli strain WC3110 (ΔarsC) for the first time. The abilities of both CrACR2s genes to complement the arsenatesensitive
strain were examined. CrACR2.1 restored arsenate resistance at 0.8 mmol/L. However, CrACR2.2 showed much less ability
to complement. The gene products were demonstrated to reduce arsenate to arsenite in vivo. In agreement with the complementation
results, CrACR2.1 showed higher reduction ability than CrACR2.2, when treated with 0.4 mmol/L arsenate for 16 hr incubation. 相似文献