The relation of ultrafiltration membrane fouling caused by algae to algal growth phase

S. Laksono*, A. Kouchaki Shalmani, J. Jansen, S. Panglisch, University of Duisburg-Essen, Germany

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.

During a typical algal growth phase in source water including lag phase, exponential phase, stationary phase and death phase, various types of algal organic matter (AOM) can be present in the source water causing different fouling behaviour in UF membrane applications.

Hence three different types of algae cell samples were prepared for further UF experiments:

  1. “intact-living” (mostly present in exponential phase),
  2. “intact-dead” (present in all phases, but in minor number) and
  3. “lysed” (mostly present in death phase).

Chemical deaden of algae cells by using Copper (II) sulphate and combined chemical-mechanical disruption by using Copper(II) sulphate and ultra-high shear mixer were the applied methods for preparing “intact-dead” and “lysed” algae cell samples. Prepared samples were analysed by evaluating the results of chlorophyll-a concentration, particle size distribution, and dissolved organic carbon (DOC) concentration. Presence of chlorophyll-a in the samples was always indicator for the “intact” cell samples while absence of chlorophyll-a indicator for “intact-dead” or “lysed” cells. Particle size distribution comparison of algae cells samples showed that when the algae cells are “lysed”, the total volume of particles in a certain particle size range were lower compared to “intact-living” and “intact-dead” cells. Additionally, DOC measurement results showed that “lysed” algae cells samples have higher concentration of dissolved organics compared to “intact” algae cells. Mechanical disruption of the algae cells is likely to increase the release rate of intracellular organic matter which gives rise to dissolved organic carbon concentration.

The research work so far focused on the fouling potential of Chlorella Sorokiniana, a single cell green microalga which is frequently present in fresh water sources, and its correlation to algae characteristics. A comprehensive comparison between the three cell samples in terms of membrane fouling potential and backwash-ability has been performed. UF capillary Multibore® membranes made from polyethersulfone (PES) with a pore size of approximately 0.02 µm and active surface area of 0.051 m2 were used for this series of experiments.

The results showed that...

Session: M8 - Separation of Bio-Products
Day: 15 March 2018
Time: 14:45 - 16:00 h

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