Li Tinggang, Bai Renbi, Ohandja Dieudonné-Guy, Liu Junxin
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, People's Republic of China.
Biodegradation. 2009 Jul;20(4):569-80. doi: 10.1007/s10532-008-9246-7. Epub 2009 Jan 11.
A membrane-aerated biofilm reactor (MABR) was developed to degrade acetonitrile (ACN) in aqueous solutions. The reactor was seeded with an adapted activated sludge consortium as the inoculum and operated under step increases in ACN loading rate through increasing ACN concentrations in the influent. Initially, the MABR started at a moderate selection pressure, with a hydraulic retention time of 16 h, a recirculation rate of 8 cm/s and a starting ACN concentration of 250 mg/l to boost the growth of the biofilm mass on the membrane and to avoid its loss by hydraulic washout. The step increase in the influent ACN concentration was implemented once ACN concentration in the effluent showed almost complete removal in each stage. The specific ACN degradation rate achieved the highest at the loading rate of 101.1 mg ACN/g-VSS h (VSS, volatile suspended solids) and then declined with the further increases in the influent ACN concentration, attributed to the substrate inhibition effect. The adapted membrane-aerated biofilm was capable of completely removing ACN at the removal capacity of up to 21.1 g ACN/m(2) day, and generated negligible amount of suspended sludge in the effluent. Batch incubation experiments also demonstrated that the ACN-degrading biofilm can degrade other organonitriles, such as acrylonitrile and benzonitrile as well. Denaturing gradient gel electrophoresis studies showed that the ACN-degrading biofilms contained a stable microbial population with a low diversity of sequence of community 16S rRNA gene fragments. Specific oxygen utilization rates were found to increase with the increases in the biofilm thickness, suggesting that the biofilm formation process can enhance the metabolic degradation efficiency towards ACN in the MABR. The study contributes to a better understanding in microbial adaptation in a MABR for biodegradation of ACN. It also highlights the potential benefits in using MABRs for biodegradation of organonitrile contaminants in industrial wastewater.
开发了一种膜曝气生物膜反应器（MABR）来降解水溶液中的乙腈（ACN）。该反应器接种了经过驯化的活性污泥菌群作为接种物，并通过提高进水ACN浓度逐步提高ACN负荷率进行运行。最初，MABR在中等选择压力下启动，水力停留时间为16小时，循环速率为8厘米/秒，起始ACN浓度为250毫克/升，以促进膜上生物膜的生长并避免其因水力冲刷而损失。一旦每个阶段的出水ACN浓度显示几乎完全去除，就会逐步提高进水ACN浓度。在101.1毫克ACN/克挥发性悬浮固体（VSS）·小时的负荷率下，ACN的比降解率达到最高，然后随着进水ACN浓度的进一步增加而下降，这归因于底物抑制作用。经过驯化的膜曝气生物膜能够以高达21.1克ACN/平方米·天的去除能力完全去除ACN，并且在出水中产生的悬浮污泥量可忽略不计。批次培养实验还表明，降解ACN的生物膜也能降解其他有机腈，如丙烯腈和苯甲腈。变性梯度凝胶电泳研究表明，降解ACN的生物膜包含一个稳定的微生物群落，其16S rRNA基因片段的群落序列多样性较低。发现特定氧利用率随着生物膜厚度的增加而增加，这表明生物膜形成过程可以提高MABR中对ACN的代谢降解效率。该研究有助于更好地理解MABR中微生物对ACN生物降解的适应性。它还突出了使用MABR对工业废水中有机腈污染物进行生物降解的潜在益处。
