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501.
以附着在固体表面的生物膜为材料,实验研究了渔药漂白粉和敌百虫对其菌类数量及活性的影响。通过分析生化需氧量(BOD5)的曲线,测定实验前后细菌、放线菌、真菌的数量和水中化学需氧量(CODMn)、铵氮(NH+4-N)的质量浓度,并用电子显微镜观察。结果表明:ρ(漂白粉)小于6 17mg L,生物膜的活性能够恢复;ρ(漂白粉)为0 7mg L时,15d后生物膜的活性可恢复80%以上。在实验浓度范围内,虽然敌百虫对生物膜的活性和水质净化能力影响不明显,但也应谨慎使用以防止污染环境。 相似文献
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Lysine is an essential amino acid for human body, and lysine sulfates are at risk of fire and explosion during the production and processing. However, there is no public report on the lysine sulfate powder explosion hazard research. In this paper, the effects of moisture, mass concentration and particle size on the flame propagation behaviors of L-lysine sulfate powder were studied in a vertical pipe. The results showed that the flame propagation could be divided into 3 stages: free propagation, acceleration and attenuation, in which the acceleration was owed to the positive feedback of combustion reaction, gas expansion and turbulence. Moisture content could promote the flame propagation of L-lysine sulfate powder to a certain extent, but it had a strong inhibitory effect on the explosion when the moisture content was too large. The flame propagation velocity increased with the decrease of the average particle size of powder,.With the increase of the particle concentration, the flame propagation velocity of powder explosion increased first and then decreased, that was, there was an optimal concentration of powder explosion, and the powder was more sensitive to the change of concentration in the range of low concentration. 相似文献
504.
杨尚军 《中国安全生产科学技术》2018,14(11):144-148
为了探究石墨粉 (GP) 与聚磷酸铵 (APP) 膨胀阻燃体系对硅橡胶复合材料的阻燃及抑烟特性的影响,采用锥形量热仪 (CCT)、热重分析仪 (TG) 及极限氧指数测试仪 (LOI) 对阻燃硅橡胶复合材料进行表征。研究结果表明:与单独添加膨胀阻燃剂APP的阻燃硅橡胶相比,添加GP/APP膨胀阻燃体系可有效提升燃烧过程中形成的膨胀碳层的致密度,降低阻燃硅橡胶复合材料的热释放速率及总烟释放量,提高阻燃硅橡胶复合材料高温阶段的热稳定性,提升阻燃硅橡胶复合材料的燃烧成炭率和质量保持率; 使阻燃硅橡胶复合材料的氧指数值增大。 相似文献
505.
提出了一种新的绿矾综合利用的途径,即绿矾经碳酸盐转化,然后采用无烟煤作还原剂,CaCO3为添加剂,进行高温还原焙烧制取还原铁粉.先将绿矾用水溶解,用理论量1.2倍的(NH4)2CO3将FeSO4转化为FeCO3,FeCO3焙烧的最佳条件是FeCO3∶无烟煤∶CaCO3为100∶60∶8,焙烧温度为1000℃,焙烧时间为4.5 h.粗还原铁粉化学成分除C含量较高外,符合国家有关标准,900℃左右经氢气精还原1 h所得精还原铁粉化学成分的各项指标,均达到或优于国家有关标准的要求. 相似文献
506.
Zeolite powder addition to improve the performance of submerged gravitation-filtration membrane bioreactor 总被引:4,自引:0,他引:4
In this study, the effect of zeolite powder addition on submerged membrane bioreactor (SMBR) on membrane permeability, and the removals for COD, NH3-N, TN were investigated. Through the parallel operation of control and test systems, it was found that the zeolite powder addition could alleviate the ultra-filtration membrane fouling and enhance the membrane permeability. On the basis of experimental investigations, a concept of "protection coating layer" was proposed to illustrate the phenomenon of UF membrane fouling. In addition, the removal for COD in test system was more stable, a little higher compared to the control system. Due to the combination of nitrification and ion exchange, a more excellent removal for NH3-N in test system was obtained regardless of influent NH3-N loading rate. It was also found that a mean 25% higher TN removal took place in the test system, and ion exchange and simultaneous nitrification and de-nitrification were analyzed to be main factors. During the stable operation period, the SOURs of test zeolite powder added sludge and control activated sludge were measured to be 75 mgO2/(gMLVSS, h) and 24 mgO2/(gMLVSS, h) respectively, it meant that the zeolite powder addition could enhance the microorganism activity significantly. 相似文献
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以废铝易拉罐为原料,通过除漆、研磨等制得废铝易拉罐粉末(SAlCP)。利用SAlCP处理含U(VI)废水,优化处理工艺条件,采用SEM和XPS技术对SAlCP进行表征,并探讨了SAlCP去除U(Ⅵ)的机理。实验结果表明:在反应温度为30℃、溶液初始pH为5.0、U(Ⅵ)初始质量浓度为10 mg/L、SAlCP投加量为4 g/L、反应时间为120 min的优选条件下,U(Ⅵ)的去除率达98.2%。SAlCP去除U(Ⅵ)的反应过程可用拟一级动力学模型和Langmuir-Hinshelwood模型能较好地拟合。SAlCP的作用机理是还原沉淀-吸附共沉,且还原作用是SAlCP去除U(Ⅵ)的主要途径。 相似文献
510.
The main risk factors from methane explosion are the associated shock waves, flames, and harmful gases. Inert gases and inhibiting powders are commonly used to prevent and mitigate the damage caused by an explosion. In this study, three inhibitors (inert gas with 8.0 vol% CO2, 0.25 g/L Mg(OH)2 particles, and 0.25 g/L NH4H2PO4 particles) were prepared. Their inhibiting effects on methane explosions with various concentrations of methane were tested in a nearly spherical 20-L explosion vessel. Both single-component inhibitors and gas–particle mixtures can substantially suppress methane explosions with varying degrees of success. However, various inhibitors exhibited distinct reaction mechanisms for methane gas, which indicated that their inhibiting effects for methane explosion varied. To alleviate amplitude, the ranking of single-component inhibitors for both explosion pressure (Pex) and the rate of explosion pressure rise [(dP/dt)ex] was as follows: CO2, NH4H2PO4 particles, and Mg(OH)2 particles. In order of decreasing amplitude, the ranking of gas‒particle mixtures for both Pex and (dP/dt)ex was as follows: CO2–NH4H2PO4 mixture, CO2‒Mg(OH)2 mixture, and pure CO2. Overall, the optimal suppression effect was observed in the system with the CO2–NH4H2PO4 mixture, which exhibited an eminent synergistic effect on methane explosions. The amplitudes of Pex with methane concentrations of 7.0, 9.5, and 11.0 vol% decreased by 37.1%, 42.5%, and 98.6%, respectively, when using the CO2–NH4H2PO4 mixture. In addition, an antagonistic effect was observed with CO2‒Mg(OH)2 mixtures because MgO, which was generated by the thermal decomposition of Mg(OH)2, can chemically react with water vapor and CO2 to produce basic magnesium carbonate (xMgCO3·yMg(OH)2·zH2O), thereby reducing the CO2 concentration in a reaction system. This research revealed the inhibiting effects of gas‒particle mixtures (including CO2, Mg(OH)2 particles, and NH4H2PO4 particles) on methane explosions and provided primary experimental data. 相似文献