Abstract

An emerging threat to membrane application is the seasonal proliferation of algae in water sources such as rivers, reservoirs and lakes. This study investigated the link between feed parameters and the membrane performance of a pilot-scale microfiltration (MF) plant for 7 months. The seasonal succession of algae in relation to temperature dynamics was monitored. Temperature-dependent seasonal patterns for algae species were observed. The water temperatures during the dominance of cyanobacteria, especially Microcystis, were relatively higher (over 25 °C) than those during the dominance of diatoms. Diatoms did not much affect membrane performance (less than 0.2 kgf/cm²), however, under the cyanobacterial dominance condition, especially Microcystis sp., transmembrane pressure (TMP) reached up to the limited level (0.4 kgf/cm²) within one month. Concurrently UV absorbance at 254 nm wavelength and dissolved organic carbon values increased significantly during the Microcystis bloom and the build-up rate of TMP increased up to 0.005 kgf/cm²/day. Membrane autopsy also showed that during the dominance of diatom, application of cleaning agents can fully remove foulants on the membrane surface. However, during the dominance of cyanobacteria, there is a lot of Al, Si and organic complex on the fouled membrane, indicating the formation of Al-organic complexes that contributed to the residual membrane fouling. It is suggested that the irrecoverable fouling layer still contained some Al, mostly in complex with organics. Thus, organic matter originated from cyanobacteria may cause a serious impact on membrane fouling by forming the complex with metal ions originated from coagulant.

摘要

膜应用的一个新威胁是藻类在河流、水库和湖泊等水源中的季节性增殖。该研究调查了进料参数与中试微滤 (MF) 工厂 7 个月的膜性能之间的联系。监测与温度动态相关的藻类的季节性演替。观察到藻类物种的温度依赖性季节性模式。蓝藻特别是微囊藻占优势期间的水温比硅藻占优势期间的水温相对较高（超过25℃）。硅藻对膜性能影响不大（小于 0.2 kgf/cm ²），但在蓝藻优势条件下，尤其是微囊藻sp.，跨膜压 (TMP ) 在 1 个月内达到极限水平 (0.4 kgf/cm ² )。同时，在微囊藻爆发期间，254 nm 波长处的紫外吸收和溶解的有机碳值显着增加，TMP 的累积速率增加至 0.005 kgf/cm ²/天。膜尸检还表明，在硅藻占优势的过程中，使用清洁剂可以充分去除膜表面的污垢。然而，在蓝藻占优势的过程中，污染的膜上有大量的铝、硅和有机络合物，表明形成了铝-有机络合物，导致了残留的膜污染。这表明不可恢复的污垢层仍然含有一些铝，主要与有机物复合。因此，源自蓝藻的有机物可能与源自混凝剂的金属离子形成络合物，从而对膜污染造成严重影响。