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In China, over 1.43×107 tons of dewatered sewage sludge, with 80% water content, were generated from wastewater treatment plants in 2007. About 60% of the COD removed during the wastewater treatment process becomes concentrated as sludge. Traditional disposal methods used by municipal solid waste treatment facilities, such as landfills, composting, or incineration, are unsuitable for sludge disposal because of its high water content. Disposal of sludge has therefore become a major focus of current environmental protection policies. The present status of sludge treatment and disposal methodology is introduced in this paper. Decreasing the energy consumption of sludge dewatering from 80% to 50% has been a key issue for safe and economic sludge disposal. In an analysis of sludge water distribution, thermal drying and hydrothermal conditioning processes are compared. Although thermal drying could result in an almost dry sludge, the energy consumption needed for this process is extremely high. In comparison, hydrothermal technology could achieve dewatered sewage sludge with a 50%–60% water content, which is suitable for composting, incineration, or landfill. The energy consumption of hydrothermal technology is lower than that required for thermal drying. 相似文献
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一种新型高效复合絮凝剂的研制 总被引:2,自引:0,他引:2
以本地产红黄土壤,经焙烧活化后,再用工业废酸浸渍,取出浸出液,在一定的条件下,加入适量活性硅酸,制备成聚硅酸氯化铝铁,其最佳活化工艺条件为烧焙温度700℃,焙烧时间2小时。 相似文献
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A New Approach for the Flocculation Mechanism of Chitosan 总被引:2,自引:0,他引:2
A peak III/I ratio (peak) in pyrene-fluorescence spectrum was used to measure the polarity of microenvironment of chitosan adsorbing pyrene molecules. The authors detected the pyrene-fluorescence spectrum of chitosan with different degrees of deacetylation (DD) and determined the relationship between the flocculation of bentonite colloid and the peak of chitosan with a different molecular weight (MW) and DD. It can be concluded that MW rather than DD plays a key role in the flocculation and that bond bridging rather than charge neutralization dominates the flocculation with chitosan from a microenvironmental structure of view. 相似文献
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Honey bees, Apis mellifera L., bred for hygienic behavior uncap and remove diseased and mite-infested brood. We hypothesized that within a colony bred for hygienic behavior, there would be differences in olfactory sensitivity among bees of the same age. We predicted that bees that initiate the behavior by perforating and uncapping brood would have greater olfactory sensitivity to the odor of the diseased brood, and would be better able to discriminate between odors of healthy and diseased brood, compared to bees that complete the behavior by removing the uncapped brood from the cells. Electroantennogram recordings of 15- to 21-day-old bees from three colonies demonstrated that bees collected while uncapping dead brood had significantly greater olfactory sensitivity to all concentrations of diseased brood odor compared to bees collected while removing brood. Proboscis-extension reflex discrimination conditioning demonstrated that 15- to 21-day-old bees collected while uncapping discriminated significantly better and generalized significantly less between the odors of diseased and healthy brood compared to bees collected while removing, when the odor of diseased brood was rewarded, but not when the odor of healthy brood was rewarded. Bees collected while uncapping brood that had been pierced with a pin had significantly less olfactory sensitivity than bees collected while uncapping freeze-killed brood, most likely because the pierced brood had greater stimulus intensity. Initiation of hygienic behavior depends on the olfactory sensitivity of the bee and stimulus intensity of the abnormal brood. Differential olfactory sensitivity and responsiveness among hygienic bees could lead to the apparent partitioning of the behavior into uncapping and removing components.Communicated by R.F.A. Moritz 相似文献
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一株海洋假单胞菌产生物絮凝剂去除赤潮生物的实验研究 总被引:1,自引:0,他引:1
利用一株假单胞菌(Pseudomonas sp.)的发酵液研究了该细菌产絮凝剂对东海原甲藻和裸甲藻的絮凝去除作用.结果表明,该生物絮凝剂可有效絮凝去除实验所选用两种赤潮生物,并且随絮凝剂用量的增加以及作用时间的延长,去除效果逐渐增加至最大然后基本保持恒定.有效絮凝去除赤潮生物的体积浓度为4.0%~10.0%.有效絮凝作用时间为1.5 h左右,絮凝效率与体系的pH值密切相关,pH在8.0左右絮凝效率较高.不同浓度的Ca2+、Mg2+对该絮凝剂絮凝除藻作用有一定的增效作用, Ca2+、Mg2+的最佳助凝离子浓度分别为2.0 mmol/L及4.0 mmol/L. 相似文献