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141.
Li H Xin H Burns RT Roberts SA Li S Kliebenstein J Bregendahl K 《Journal of the Air & Waste Management Association (1995)》2012,62(2):160-169
Feed additives can change the microbiological environment of the animal digestive track, nutrient composition of feces, and its gaseous emissions. This 2-yr field study involving commercial laying-hen houses in central Iowa was conducted to assess the effects of feeding diets containing EcoCal and corn-dried distillers grain with solubles (DDGS) on ammonia (NH3), hydrogen sulfide (H2S), and greenhouse gas (CO2, CH4, and N2O) emissions. Three high-rise layer houses (256,600 W-36 hens per house) received standard industry diet (Control), a diet containing 7% EcoCal (EcoCal) or a diet containing 10% DDGS (DDGS). Gaseous emissions were continuously monitored during the period of December 2007 to December 2009, covering the full production cycle. The 24-month test results revealed that mean NH3 emission rates were 0.58 +/- 0.05, 0.82 +/- 0.04, and 0.96 +/- 0.05 g/hen/day for the EcoCal, DDGS, and Control diet, respectively. Namely, compared to the Control diet, the EcoCal and DDGS diets reduced NH3 emission by an average of 39.2% and 14.3%, respectively. The concurrent H2S emission rates were 5.39 +/- 0.46, 1.91 +/- 0.13, and 1.79 +/- 0.16 mg/ hen/day for the EcoCal, DDGS, and Control diet, respectively. CO2 emission rates were similar for the three diets, 87.3 +/- 1.37, 87.4 +/- 1.26, and 89.6 +/- 1.6 g/hen/day for EcoCal, DDGS, and Control, respectively (P = 0.45). The DDGS and EcoCal houses tended to emit less CH4 than the Control house (0.16 and 0.12 vs. 0.20 g/hen/day) during the monitored summer season. The efficacy of NH3 emission reduction by the EcoCal diet decreased with increasing outside temperature, varying from 72.2% in February 2009 to -7.10% in September 2008. Manure of the EcoCal diet contained 68% higher ammonia nitrogen (NH3-N) and 4.7 times higher sulfur content than that of the Control diet. Manure pH values were 8.0, 8.9, and 9.3 for EcoCal, DDGS, and Control diets, respectively. This extensive field study verifies that dietary manipulation provides a viable means to reduce NH3 emissions from modern laying-hen houses. 相似文献
142.
将大肠杆菌E.coli ATCC8739置于12.0 T超强静磁场(ultra-strong static magnetic field,SMF)中进行处理,获得了磁场处理0.5、1、2、4和8 h的菌株E.coli-SMFn(n=0.5、1、2、4、8)。在37℃、pH 7、静置的条件下,菌株对偶氮染料AR14(I.C.Acid Red 14)的脱色结果指出,当反应进行到4、6和8 h时,E.coli-SMF8的脱色效率分别为18%、55%和96%,远高于E.coli ATCC8739的3%、19%和50%,表明SMF作用显著地增强了菌株的脱色效率。基因组DNA提取、PCR扩增、分子克隆以及基因测序的实验结果进一步表明,全部6例E.coli ATCC8739菌株的偶氮还原酶基因(acpD)序列均与GenBank中报道的完全一致;而E.coli-SMF8菌株的acpD-SMF8核酸序列中缺失了第99位的胞嘧啶。该缺失突变不仅使acpD-SMF8的核酸序列与acpD的存在显著不同,同时得到了具新活性中心的偶氮还原酶AzoR-SMF8。这个新的活性中心具有更强的黄素(FMN)结合能力,因此使该酶与偶氮染料的亲和力大大增加,促进了脱色效率的提高。 相似文献
143.
Fe2O3-Cr2O3/TiO2系列催化剂的结构和脱硝性能 总被引:1,自引:0,他引:1
研究以纳米TiO2为载体,浸渍负载过渡金属氧化物,以CO为还原剂的脱硝催化剂的脱硝性能。实验中以计算量的Ni(NO3)2和Fe(NO3)3混合溶液浸渍纳米TiO2粉末,室温下搅拌30 min至混合均匀,放入旋转蒸发器中,70℃下至水分蒸干为止;所得粉末在550℃下、空气气氛中焙烧4 h即得所需催化剂。用以上方法分别制备2%Fe2O3-10%Cr2O3/TiO2、4%Fe2O3-8%Cr2O3/TiO2、6%Fe2O3-6%Cr2O3/TiO2、8%Fe2O3-4%Cr2O3/TiO2与10%Fe2O3-2%Cr2O3/TiO2等5种催化剂样品。实验结果表明,制备的催化剂具有较好的结构,分散较为均匀。对于CO+NO反应,Fe2O3-Cr2O3/TiO2系列催化剂具有较好的催化活性,NO的转化率都达到了100%。其中,10%Fe2O3-2%Cr2O3/TiO2样品具有最好的低温活性,H2-TPR结果表明,这是由于10%Fe2O3-2%Cr2O3/TiO2催化剂更易于被CO预还原。 相似文献
144.
垃圾渗滤液是公认的一种成分复杂且难以处理的高浓度有机废水,笔者在北京市海淀区六里屯垃圾填埋场通过2007—2010年垃圾渗滤液处理的工程实践,以COD和氨氮的去除率为指标,研究了不同的垃圾渗滤液处理工艺组合,以及不同运行参数条件下对垃圾渗滤液的处理效果。结果表明,在中温UASB和A/O的平均水力停留时间(HRT)缩短1/3的情况下,通过改进A/O段曝气方式,优化系统的pH、DO等运行参数,用MBR替代絮凝工艺,使整个组合工艺对COD的年平均去除率达到了94.3%,氨氮的去除率维持在99.5%以上,出水氨氮稳定在10 mg/L以内,而改造前的COD与氨氮的年平均去除率仅为82.2%与55.3%。与改造前的UASB+A/O+絮凝工艺组合相比,改造后的UASB+A/O+MBR工艺组合具有更高的污染物去除能力、更好的抗缓冲性和稳定性。 相似文献
145.
146.
Hongfang Lu Yu Bai Hai Ren Daniel E. Campbell 《Journal of environmental management》2010,91(12):2727-2735
China is the largest rice producing and consuming country in the world, but rice production has given way to the production of vegetables during the past twenty years. The government has been trying to stop this land-use conversion and increase the area in rice-vegetable rotation. Important questions that must be answered to determine what strategy is best for society are, “What is the reason behind this conversion?”; “Which system is more productive and which is more sustainable?”; and “How can economic policy be used to adjust the pattern of farmland use to attain sustainable development?” To answer these questions, a combined evaluation of these agricultural production systems was done using emergy, energy and economic methods. An economic analysis clearly showed that the reason for this conversion was simply that the economic output/input ratio and the benefit density of the vegetable production system were greater than that of rice. However, both energy and emergy evaluations showed that long-term rice was the best choice for sustainable development, followed by rotation systems. The current price of rice is lower than the em-value of rice produced from the long-term rice system, but higher than that of rice produced from the rotation system. Scenario analysis showed that if the government increases the price of rice to the em-value of rice produced from the long-term rice system, US$0.4/kg, and takes the value of soil organic matter into account, the economic output/input ratios of both the rice and rotation systems will be higher than that of the vegetable system. The three methods, energy, emergy and economics, are different but complementary, each revealing a different aspect of the same system. Their combined use shows not only the reasons behind a system’s current state or condition, but also the way to adjust these systems to move toward more sustainable states. 相似文献
147.
148.
着重研究了不同紫外灯光源和照射时间条件下,TiO2光催化(PCO)对微滤去除腐殖酸过程中的膜污染控制,并探讨了膜污染的控制机理。研究结果表明,TiO2光催化能有效提高微滤对腐殖酸的去除,同时降低膜通量的下降,起到有效控制膜污染的作用。进一步的实验分析表明,TiO2光催化控制膜污染的主要机理在于将腐殖酸降解为易于被TiO2吸附的小分子量物质,吸附腐殖酸降解产物后的TiO2聚合颗粒粒径增大,易于在膜表面形成更为松散的沉积层,并使膜污染从以膜孔堵塞和沉积层污染为主转化为以沉积层污染为主的可逆性污染。 相似文献
149.
Alexandre Joly Audrey Smargiassi Tom Kosatsky Michel Fournier Ewa Dabek-Zlotorzynska Valbona Celo David Mathieu René Servranckx Réal D'amours Alain Malo Jeffrey Brook 《Atmospheric environment (Oxford, England : 1994)》2010,44(34):4325-4329
Little is known about the level and content of exposure to fine particles (PM2.5) among persons who attend fireworks displays and those who live nearby. An evaluation of the levels of PM2.5 and their elemental content was carried out during the nine launches of the 2007 Montréal International Fireworks Competition. For each event, a prediction of the location of the firework plume was obtained from the Canadian Meteorological Centre (CMC) of the Meteorological Service of Canada. PM2.5 was measured continuously with a photometer (Sidepak?, TSI) within the predicted plume location (“predicted sites”), and integrated samples were collected using portable personal samplers. An additional sampler was located on a nearby roof (“fixed site”). The elemental composition of the collected PM2.5 samples from the “predicted sites” was determined using both a non-destructive energy dispersive ED-XRF method and an ICP-MS method with a near-total microwave-assisted acid digestion. The elemental composition of the “fixed site” samples was determined by the ICP-MS with the near-total digestion method. The highest PM2.5 levels reached nearly 10 000 μg m?3, roughly 1000 times background levels. Elements such as K, Cl, Al, Mg and Ti were markedly higher in plume-exposed filters. This study shows that 1) persons in the plume and in close proximity to the launch site may be exposed to extremely high levels of PM2.5 for the duration of the display and, 2) that the plume contains specific elements for which little is known of their acute cardio-respiratory toxicity. 相似文献
150.
Aziz Azri Galal Elmanfe René Olier Mireille Privat 《Atmospheric environment (Oxford, England : 1994)》2010,44(39):5211-5217
From a literature-based assessment of the current knowledge about both the toxic or salutary properties of copper, this study focused on the determination, at 25 °C, of the interfacial properties of CuCl2, either alone or in mixture with carbofuran used, here, as a model of organics and/or pesticide. The interfaces under study were: i) the air/solution interface and ii) the silica/solution interface. The former is considered as a path for volatilization, whereas the latter permits a modelling of physical adsorption upon solids, which is the first and unavoidable step in any adsorption process. One should note that it can also mimic adsorption on some sandy soils. Coadsorption was clearly identified as implicated in an enhancement of the surface content of both solutes at both interfaces. However, at the two interfaces under study, the way the surface became structured led to opposite adsorption mechanisms for the organic compounds and the salt. A rough theory about ionic adsorption is also proposed. 相似文献