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排序方式: 共有123条查询结果,搜索用时 31 毫秒
81.
为探究氨氮浓度对鸡粪中高温甲烷发酵的影响,采用固定水力停留时间(HRT,20d),提高进料总固体浓度(TS,5%、7.5%和10%)的方式增加氨氮浓度,通过265d的长期甲烷发酵试验,比较了不同氨氮浓度条件下鸡粪中高温甲烷发酵效果和污泥的比产甲烷活性.结果显示,TS由5%增至10%,中高温反应器中氨氮浓度由2.1~2.5g/L增至6.1~6.5g/L,对应的比产甲烷活性分别降低了44%和100%,中温反应器中挥发性脂肪酸由0.4g/L增至7.6g/L,甲烷产率由253mL/gTS降至203mL/gTS;高温反应器中挥发性脂肪酸由0.4g/L增至26.1g/L,甲烷产率由181mL/gTS降至18mL/gTS.氨氮浓度对高温甲烷发酵系统的抑制作用更加明显. 相似文献
82.
Yu HY Shen RL Liang Y Cheng H Zeng EY 《Environmental pollution (Barking, Essex : 1987)》2011,159(12):3700-3705
Existing evidence indicated that dichlorodiphenyltrichloroethane (DDT)-containing antifouling paints were an important source of DDT residues to mariculture zones. However, the magnitude of the impact on aquafarming environment has remained largely unknown. In the present study, the concentrations of DDT and its metabolites (designated as DDXs) were determined in harbor sediment and antifouling paint samples collected from a typical mariculture zone in South China. Compositional and concentration correlation analyses implicated the DDT-containing antifouling paints for fishing boat maintenance as an important source of DDT in the mariculture zone. The annual emission of DDXs to the study region was estimated at 0.58 tons/yr. Furthermore, a comparison of the expected DDT loadings in pelagic fish and field measurements indicated that fish feed especially trash fish was a major source of DDTs in the fish body. Nevertheless, the use of DDT-containing antifouling paints should be limited to prevent further deterioration in aquafarming environment. 相似文献
83.
84.
As result of a study to control feedstuff, analyses were carried out to evaluate the contamination caused by PCDDs and PCDFs in different animal feed ingredients. Thirty two samples were selected, including ingredients of animal and mineral origin. For samples of mineral origin, some additives widely employed as binder and anticaking agents, such as bentonite, damoline, kaolin, magnesite, sepiolite and zeolite were selected. And, for ingredients of animal origin, samples of hemoglobin, animal fat, fish oil, fish meal and meat and bone meal were analyzed. The levels ranged from 0.52 to 9.08 pg WHO-TEQ/g fat for samples of animal origin, and from 0.05 to 460.59 pg WHO-TEQ/g for samples of mineral origin. The higher concentrations were observed for the kaolin samples that presented high levels of dioxin contamination. 相似文献
85.
Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were determined in some additives widely employed as binder and anti-caking agents in feedstuffs, such as kaolin, bentonite, zeolite, etc. with an special attention on sepiolite samples. Owing to their physico-chemical properties, the little information of these materials reported in the literature, the variability of PCDDs/PCDFs found in a preliminary evaluation and the absence of reference materials highlighted further research needed. Therefore, an extensive study on the analytical procedures based on the classical methods was performed with sepiolite samples. The study includes evaluation of reproducibility and repeatibility. To this end, a series of intra-day and nine inter-day analysis were made. The methodolgy was also assessed against the sample size and series of 12.5, 25, 37.5 and 50 g were analyzed. In all cases, the results confirmed good correlation with the parameters evaluated. 相似文献
86.
Zbigniew Engel Wiktor M. Zawieska 《International journal of occupational safety and ergonomics》2013,19(2):183-194
The article presents proposals for an indexical evaluation of exposure of hand tool operators to vibrations. The presented indices have been developed on the basis of the results of laboratory tests. The examinations studied the effect of pressure force and grip force exerted by an operator on a hand tool as well as the amplitudes and frequencies of an exciting signal on vibrations transmitted in the hand-tool handle system. 相似文献
87.
洞庭湖区芦苇和荻的饲用潜力及开发利用 总被引:11,自引:0,他引:11
洞庭湖区拥有丰富的芦苇和荻资源。两者鲜嫩时的化学与营养成分接近优良牧草黑麦草,适于饲喂牛。若于拨节中期收获2~4次,则可年产干草4.5~7.5×105t,可为8.22~20.55×104个黄牛单位提供全年用优质饲草;若再与湖区丰富的农副产品相配合,发展集约化商品性的养牛业是切实可行的。收获的牧草可通过青饲、青贮、调制干草、加工成草粉或颗粒配方饲料的方式加以利用。为保障秋季其他用途的收获及第二年的正常生长发育,必须要采取一系列行之有效的措施,其中人工促进再生复壮和加强宏观调控是最关键的环节。 相似文献
88.
有机碳源对同时硝化/反硝化(SND)过程的影响 总被引:27,自引:1,他引:27
究了同时硝化 反硝化 (SimultaneousNitrificationandDenitrification ,SND)体系中有机碳源对氨氮去除的影响。实验结果表明 ,在氨氮初始浓度为 35mg L时 ,存在使氨氮降解率达到 99 5 %以上的有机碳源浓度区间 ,其CODCr浓度为40 0mg L~ 10 0 0mg L ;为保证反应后期体系中C N维持在微生物所需的水平 ,提出了补料的方式 ,使得氨氮降解不会出现停滞阶段 ,可以达到较好的去除效果 ;在周期为 8h的连续序批式 (SBR)操作中 ,采用较高的有机碳源初始进料值 ,并在反应过程中进行补料 ,可以很好的将出水氨氮的浓度维持在较低值 (<5mg L) 相似文献
89.
90.
Firdevs Mor 《毒物与环境化学》2013,95(3):329-334
The cadmium and lead contents in cattle manure taken from four agricultural areas exposed to different degrees of environmental pollution and in the livestock feeds grown in those places were measured by Atomic Absorption Spectrophotometer (AAS). The levels of cadmium and lead contamination in the manures of the cattle, which were fed in the areas far from industries, traffic or urbanization, were less than those that were closer to heavy traffic and industrial activities. The highest heavy metal content was found in cattle manure collected from the region with heavy traffic, followed by the industrial region and the rural region. Among the live stock feeds used in the present study, the highest levels of lead were found in grass; and the lowest levels were obtained from the samples of straw. 相似文献