利用死端式膜截留藻菌共生系统中微藻的研究

Study on Interception of Microalgae from Algal-bacterial Symbiotic System by Dead-end Membrane Process

采用死端式膜法对藻菌共生系统中的微藻进行截留,通过调节反应器内藻类的停留时间和繁殖时间的关系,从4种膜组件中优选出膜组件及其工况,并考察了利用死端式膜法对藻菌共生系统中微藻的截留效果,并进行了浓差极化及反冲洗实验。结果表明,4种膜组件对微藻的截留率均可达到100%,且截留后藻类的生长活性保持率在85.7%以上。0.4μm聚乙烯中空纤维膜以膜通量大、能耗低和膜污染速率慢等性能被确定为死端式膜法微藻截留的最优膜组件,其优化工况点:曝气量30 m^3/(m^3·h),蠕动泵的输出功率8 W/m^3。死端过滤时,膜通量下降主要是膜表面滤饼层作用的结果,而影响出水流量下降的主要因素是曝气量的大小,通过反冲洗和40 k Hz超声波震动能够有效控制膜污染,其中超声开停时间分别为5、10 min、功率为7.5 W/L时膜污染的控制效果为佳。

The dead-end membrane process was used to intercept microalgae in algal-bacterial symbiotic system（ABSS）. By adjusting the retention time and reproduction time of algal in reactor, the optimum membrane module and operation conditions was selected from four types of membrane modules.Microalgae interception effect by dead-end membrane process in ABSS was investigated, and concentration polarization and backwash experiment were carried out. The results showed that, the algae interception rate by four types of membrane modules could reach 100%, and the growth activity of microalgae after interception was above 87.5%. The 0.4 μm PE hollow fiber membrane was determined as the optimal membrane module for dead-end membrane microalgae interception, due to its high membrane flux, low energy consumption, and low membrane fouling rate. The optimal operating conditions were as follow, the aeration volume was 30 m3/（m3·h） and the output power of peristaltic pump was 80 W/m3. During the dead-end filtration, the decrease of membrane flux and effluent flow was mainly due to the cake layer on the membrane surface and aeration rate, respectively. The membrane fouling could be effectively controlled by backwashing and 40 k Hz ultrasonic vibration, when the open and stop time of ultrasonic vibration was 5 min and 10 min respectively, and ultrasonic power was 7.5 W/L, the membrane fouling control effect was optimal.