Vast majority of cells were between 2 and 8 μm in diameter.
•
Major carbohydrate fraction consisted of molecules weighing less than 10 kDa.
•
Caked Microalgae were effectively removed by backwashing at 90 kPa for 5 s.
•
Membrane could concentrate Coccomyxa by 30-fold under optimized conditions.
•
Total OPEX and CAPEX were estimated at $0.25/kg-algae.
Abstract
We challenged to introduce macroporous membrane for algae harvesting with a permeate flux of 166 L m−2 d−1 to achieve significant reduction of harvesting cost. Analysis of the dissolved organic matter in the supernatant of cultures of the green alga, Coccomyxa sp. strain Obi, detected a scarce amount of hydrophilic macromolecules, which can be membrane fouling agents. The continuous filtration with a macroporous membrane achieved a 30-fold concentration of algal cells from 800 mg biomass/L to 24,000 mg biomass/L with a harvesting efficiency of 100%. Most of previous studies on the membrane filtration for harvesting microalgae merely utilized microfiltration membranes developed for wastewater treatment. However, the use of a membrane of the largest pore size that microalgal cells cannot seep through will result in slower fouling, higher flux, and a great reduction of harvesting cost.
