Sedimentation
Flocculation is another major process used in wastewater treatment, where solid particles accumulate and form flocs, usually encouraged by adding chemicals called flocculants. There is extensive research being carried out investigating the applicability and efficiencies of conventional flocculants (such as alum, ferric chloride and chitosan) with mixed results.
As before, flocculation alone is unlikely to be sufficient for harvesting economically, this process would need to be combined with (for example) sedimentation which benefits from the larger particles.
Divakaran and Sivasankara Pillai (2002) investigated flocculation of three freshwater algae using chitosan. They found it to be effective but very sensitive to the pH and concentration levels. A question to explore is the effect of chitosan as a flocculant on anaerobic digestion.
A major drawback in the sustainability of flocculation is the costs of recovery are increased downstream. Post-processing is affected: especially for anaerobic digestion for biogas as the bacteria cannot feed with the presence of most flocculants used today.
As before, flocculation alone is unlikely to be sufficient for harvesting economically, this process would need to be combined with (for example) sedimentation which benefits from the larger particles.
Divakaran and Sivasankara Pillai (2002) investigated flocculation of three freshwater algae using chitosan. They found it to be effective but very sensitive to the pH and concentration levels. A question to explore is the effect of chitosan as a flocculant on anaerobic digestion.
A major drawback in the sustainability of flocculation is the costs of recovery are increased downstream. Post-processing is affected: especially for anaerobic digestion for biogas as the bacteria cannot feed with the presence of most flocculants used today.
