The relation of ultrafiltration membrane fouling caused by algae to algal growth phase
In water treatment industry, ultrafiltration (UF) membrane technology is receiving more and more attention in treatment of algae laden eutrophic source waters. However, fouling of the membrane due to accumulation of algal organic matter on the membrane surface or in membrane pores is the main obstacle to the smooth operation of membrane filtration plants. This drawback is mainly due to the presence of the algae-rich and the algae-derived substances which are well known as algae organic matter (AOM). Membrane fouling behavior can varry as a result of different amount of AOM being produced by algae at different phases (lag phase, exponential phase, stationary phase, and death phase). A series of comprehensive membrane filtration experiments were performed in order to compare the two algae cell conditions, “intact” (mostly present in exponential phase) and “lysed” (mostly present in death phase), in terms of membrane fouling potential and membrane cleaning. Three types of marine algae were used as model water for filtration process: Chlorella Sorokiniana (CS), Arthrospira Platensis (AP), and Thalassiosira Rotula (TR). The results showed that the differences in size and shape of algae in “intact” condition resulting in the different filterability by the membrane. Additionally, moderate and severe fouling was observed in TR and CS in “lysed” condition compared to “intact” condition. In contrast, in case of AP, ”lysed” condition was slightly better in term of filterability. A chemical cleaning procedure close to usual chemical enhanced backwash was applied with which about 85 to 90% of the initial permeability could be recovered for all types of algae in both “intact” and “lysed” condition.