Screening & Filtration
Widely used in several industries, where separation of solids and liquids is required, this technique passes the suspension through a porous material (the filter) that retains the solids and allows the aqueous phase to pass. Only those algae which are larger than the pore size are captured and removed, while smaller species may pass through with the liquid.
In their substantial review of algal harvesting methods, (Uduman et al., 2010) explain that a reduction in pore sizes reduces the “flow-through” rate of the suspension. This results in increased costs of the filtration unit and limits its efficiency in polyculture environments, since it will only capture some of the species. Filtration requires a pressure difference across the membrane system, which may need to be induced by external energy input. Additionally, the concentration of algae in the source affects the long-term efficiency of the system as the screen may be fouled.
Technologies using submerged microfiltration membranes (Bilad et al., 2012) and ultrafiltration membranes (Zhang et al., 2010) have shown promising performances both in terms of capture efficiency and economic feasibility. However, the limiting factor for filtration as a sustainable harvesting tool continues to be its need for specific cell size and concentration levels, which are difficult to control in natural environments.
In their substantial review of algal harvesting methods, (Uduman et al., 2010) explain that a reduction in pore sizes reduces the “flow-through” rate of the suspension. This results in increased costs of the filtration unit and limits its efficiency in polyculture environments, since it will only capture some of the species. Filtration requires a pressure difference across the membrane system, which may need to be induced by external energy input. Additionally, the concentration of algae in the source affects the long-term efficiency of the system as the screen may be fouled.
Technologies using submerged microfiltration membranes (Bilad et al., 2012) and ultrafiltration membranes (Zhang et al., 2010) have shown promising performances both in terms of capture efficiency and economic feasibility. However, the limiting factor for filtration as a sustainable harvesting tool continues to be its need for specific cell size and concentration levels, which are difficult to control in natural environments.