Zeng Taotao

Nitrogen removal efficiency and microbial community analysis of ANAMMOX biofilter at ambient temperature

An upflow anaerobic biofilter (AF) was developed to investigate anaerobic ammonium-oxidizing (ANAMMOX) efficiency in treating low-strength wastewater at ambient temperature (15.3-23.2 °C). Denaturing gradient gel electrophoresis (DGGE) and fluorescence in situ hybridization were used to investigate treatment effects on the microbial community. Stepwise decreases in influent ammonia concentration could help ANAMMOX bacteria selectively acclimate to low-ammonia conditions. With an influent ammonia concentration of 46.5 mg/L, the AF reactor obtained an average nitrogen removal rate of 2.26 kg/(m³ day), and a removal efficiency of 75.9%. polymerase chain reaction-DGGE results showed that microbial diversity in the low matrix was greater than in the high matrix. Microbial community structures changed when the influent ammonia concentration decreased. The genus of functional ANAMMOX bacteria was Candidatus Kuenenia stuttgartiensis, which remained stationary across study phases. Visual observation revealed that the relative proportions of ANAMMOX bacteria decreased from 41.6 to 36.3% across three study phases. The AF bioreactor successfully maintained high activity due to the ANAMMOX bacteria adaptation to low temperature and substrate conditions.

羟基铁插层膨润土的制备及其对铀（VI）的吸附特性与机制1

通过羟基铁对钠基膨润土插层改性制备了羟基铁插层膨润土（OH-Fe-Bent），用于去除废水中的U（Ⅵ）。实验考察了pH值、U（Ⅵ）初始浓度、温度和吸附时间对OH-Fe-Bent吸附U（Ⅵ）效果的影响，并进行吸附动力学和热力学分析。采用FTIR、SEM、XRD等手段分析相关吸附机制。实验结果表明：OH-Fe-Bent吸附U（Ⅵ）的最佳pH为4，在温度为15℃，投加量为0.8 g/L，U（Ⅵ）初始浓度为10 mg/L时，OH-Fe-Bent对U（Ⅵ）的去除率达到99.55%，吸附平衡时间为90 min。Langmuir等温吸附模型和准二级动力学模型（相关系数的平方约为1）均可较好地拟合其吸附过程，理论饱和吸附量可达97.09 mg/g，OH-Fe-Bent对U（Ⅵ）是单分子层吸附。FTIR、SEM分析表明OH-Fe-Bent吸附U（Ⅵ）后自身结构没有改变，XRD分析表明羟基铁已经成功插入膨润土层间。