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191.
Biosorption of silver ions onto Bacillus cereus biomass was investigated. Overall kinetic experiments were performed for the
determination of the necessary contact time for the attainment of equilibrium. It was found that the overall biosorption process was
best described by pseudo second-order kinetic model. The crystals detected by scanning electron microscope and X-ray photoelectron
spectroscopy suggested the precipitation was a possible mechanism of biosorption. The molecular genetics of silver resistance of B.
cereus biomass was also detected and illustrated by a whole cell sensor tool. 相似文献
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曝气强度对膜生物反应器处理石化废水工艺运行特征的影响 总被引:1,自引:0,他引:1
采用膜生物反应器(Membrane Bioreactor,MBR)处理石化废水,研究曝气强度分别为1.50,3.00 m3/(m2·h)的条件下,MBR对石化废水中主要污染物的去除特征、跨膜压差(Trans Membrane Pressure,TMP)和混合液性质的变化特征。结果表明:在两种曝气强度条件下MBR对COD、NH+4-N及挥发酚等污染物的平均去除率分别为80.74%、80.23%、96.79%和97.55%、99.34%、98.84%,即在不同曝气条件下,曝气强度的变化对MBR的污染物去除性能无显著影响。但随着曝气强度由1.50 m3/(m2·h)增加到3.00 m3/(m2·h),MBR达到设定的最大跨膜压差(TMPMax=25k Pa)的运行时间由11.8 d增加到31.4 d,TMP上升速率降低。通过活性污泥颗粒粒径分析发现:增加曝气强度后,对膜污染影响显著的活性污泥颗粒粒径范围(0~2μm)所占体积比由2.10%减小到1.78%;并且混合液中溶解性微生物产物(soluble microbial product,SMP)和胞外聚合物(extracellular polymeric substance,EPS)质量浓度分别由24.07 mg/L和15.66 mg/g减小到15.14 mg/L和9.81 mg/g,从而降低了膜污染速率。 相似文献
197.
The brominated products, formed in chlorination treatment of benzophenone-4 in the presence of bromide ions, were identified, and the formation pathways were proposed.Under disinfection conditions, benzophenone-4 would undertake electrophilic substitution generating mono- or di-halogenated products, which would be oxidized to esters and further hydrolyzed to phenol derivatives. The generated catechol intermediate would be transformed into furan-like heterocyclic product. The product species were p H-dependent,while benzophenone-4 elimination was chlorine dose-dependent. When the chlorination treatment was performed on ambient water spiked with benzophenone-4 and bromide ions, most of brominated byproducts could be detected, and the acute toxicity significantly increased as well. 相似文献
198.
Mengnjo J. Wirmvem Takeshi Oh Wilson Y. Fantong Samuel N. Ayonghe Jonathan N. Hogarh Justice Y. Suil Asobo Nkengmatia E. Asaah Seigo Ooki Gregory Tanyileke Joseph V. Hell 《环境科学学报(英文版)》2014,26(4):801-809
Rainwater characteristics can reveal emissions from various anthropogenic and natural sources into the atmosphere. The physico-chemical characteristics of 44 monthly rainfall events (collected between January and December 2012) from 4 weather stations (Bamenda, Ndop plain, Ndawara and Kumbo) in the Bamenda Highlands (BH) were investigated. The purpose was to determine the sources of chemical species, their seasonal inputs and suitability of the rainwater for drinking. The mean pH of 5 indicated the slightly acidic nature of the rainwater. Average total dissolved solids (TDS) were low (6.7 mg/L), characteristic of unpolluted atmospheric moisture/air. Major ion concentrations (mg/L) were low and in the order K+ 〉 Ca2+ 〉 Mg2~ 〉 Na+ for cations and NO3 〉〉 HCO3 〉 SO] 〉 CI- 〉 PO3- 〉 F- for anions. The average rainwater in the area was mixed Ca-Mg-SO4-CI water type. The CI-/Na+ ratio (1.04) was comparable to that of seawater (1.16), an indication that N a+ and CI originated mainly from marine (Atlantic Ocean) aerosols. High enrichments of Ca2+, Mg2+ and SO2- to Na+ ratios relative to seawater ratios (constituting 44% of the total ions) demonstrated their terrigenous origin, mainly from Saharan and Sahelian arid dusts. The K+/Na+ ratio (2.24), which was similar to tropical vegetation ash (2.38), and NO3 was essentially from biomass burning. Light (〈 100 mm) pre-monsoon and post-monsoon convective rains were enriched in major ions than the heavy (〉 100 mm) monsoon rains, indicating a high contribution of major ions during the low convective showers. Despite the acidic nature, the TDS and major ion concentrations classified the rainwater as potable based on the WHO guidelines. 相似文献
199.
制备了3种乙酰胺-无机盐类低共熔离子液体,测定了其物理性质并将其应用于SO2气体的吸收。结果表明,这些低共熔离子液体具有和传统离子液体相似的性质,例如熔点低、粘度低、密度高、电导率高以及较宽的液态范围。此类离子液体对SO2气体有较好的吸收能力,而且吸收量和温度的关系满足二次多项式方程。红外光谱结果表明吸收是可逆的,回收的离子液体可高效重复使用至少5次。乙酰胺-硫氰酸钠(3∶1)对SO2的质量分数吸收量为0.554 g/g(20℃,1 atm),具有吸收量高、成本低和易回收的优势,是一个很有前景的SO2吸收剂。 相似文献
200.
通过序批实验的方法,直接接种厌氧氨氧污泥,研究了Zn2+对厌氧氨氧化(Anammox)脱氮效能的影响。研究结果表明,当进水Zn2+质量浓度小于2 mg/L时,对厌氧氨氧化生物活性有促进作用,可增强微生物的脱氮效能;当进水Zn2+质量浓度在2 mg/L和4 mg/L之间时,脱氮效能无明显变化,说明对厌氧氨氧化微生物活性无明显影响;当进水Zn2+质量浓度大于4 mg/L,对厌氧氨氧化反应有抑制作用,Zn2+浓度越高,抑制作用越明显。 Zn2+对厌氧氨氧化的半抑制质量浓度(CI,50)为32.3 mg/L,NO2--N与NH4+-N转化比的平均值为1.28。 相似文献