Formaldehyde degradation by UV/TiO_2/O_3 process using continuous flow mode

The degradation of formaldehyde gas was studied using UV/TiO2/O3 process under the condition of continuous flow mode. The effects of humidity, initial formaldehyde concentration, residence time and ozone adding amount on degradation of formaldehyde gas were investigated. The experimental results indicated that the combination of ozonation with photocatalytic oxidation on the degradation of formaldehyde showed a synergetic action, e.g,, it could considerably increase decomposing of formaldehyde. The degradation efficiency of formaldehyde was between 73.6% and 79.4% while the initial concentration in the range of 1.84--24 mg/m^3 by O3/TiO2flJV process. The optimal humidity was about 50% in UV/TiO2/O3 processs and degradation of formaldehyde increases from 39.0% to 94.1% when the ozone content increased from 0 to 141 mg/m^3. Furthermore, the kinetics of formaldehyde degradation reaction could be described by Langmuir-Hinshelwood model. The rate constant k of 46.72 mg/（m^3.min） and Langmuir adsorption coefficient K of 0.0268 m^3/mg were obtained.

进水负荷对A^(2)/O连续流系统运行效能及微生物中功能菌群的影响

为深入探讨进水负荷对A^(2)/O系统的影响,本文采用A2/O连续流系统,对比研究了不同COD和磷负荷条件下系统对氮磷的去除效果,并通过检测胞外聚合物(extracellular polymeric substances,EPS)组分变化,追踪活性污泥菌群结构演替规律,揭示了不同负荷下活性污泥系统内在响应机制.结果表明:高浓度的进水COD和磷负荷更有利于优势菌群富集,该阶段优势菌属有Nitrospira、Dechloromonas和Ferruginibacter,更有利于实现更佳的脱氮除磷效果,当COD和磷负荷降低后,EPS产生菌Ferruginibacter、Terrimonas和Thauera的相对丰度明显减少,EPS的总量也减少,其中胞外聚合物中蛋白质(protein,PN)的含量增加,多糖(polysaccharide,PS)却减少.

内回流比对连续流改进A^2/O反应器性能的影响

以生活污水为原水,在常温(25～33℃)条件下采用连续流改进A2/O反应器进行脱氮除磷试验研究。结果表明,在反应器内能实现短泥龄细菌和硝化细菌的分相培养,有效降低了回流污泥中硝态氮的质量浓度,其值小于1mg·L-1。在进水COD在400～500mg·L-1,水力停留时间为13h,泥龄为5d的条件下,系统运行高效而稳定,当内回流比在100%～300%之间变化时,内回流比对TN、TP去除影响较大,对COD去除影响较小,NH4+-N的去除基本不受内回流比影响。但从整体上考虑,内回流比为200%时,系统整体除污效果最好,对COD、NH4+-N、TN、TP去除率分别为88%、97%、73.8%、65.1%。由于反应器存在一定程度的边界效应,时而造成泥区污泥分布不均,降低系统除磷效能。但通过修整反应器,消除或减小边界效应,可进一步提高系统除磷效果。