Microalgal removal with natural coagulants

Abstract:

Algal removal capacity via coagulation–flocculation with natural products was investigated in the laboratory using the jar-test technique. Traditional chemical coagulants such as aluminium sulphate may have negative impacts on human health. For this reason, a natural coagulant, Tanfloc, was tested for algal (Chlorella, Microcystis, Oocystis, Scenedesmus) removal from surface water. The jar-test method was used to identify the best Tanfloc conditions, including operating parameters such as coagulant dosage (1–25 mg·l⁻¹), initial algal concentration (original – 75 μg·l⁻¹), pH (5–9) or agitation time (10–60 min). Removal capacity was verified for water with high algal contamination, and pH was not an important factor in the removal efficiency for pH values less than 8. Up to 95% of all algae were removed from aqueous solutions. The water sources did not have a considerable influence on the process. Coagulation–flocculation equilibrium data can be represented by the Langmuir and Freundlich models.

Key Words::

• Algae
• Coagulation–flocculation
• Freshwater
• Tanfloc
• Tannin coagulant agents

ACKNOWLEDGEMENTS

This investigation has been supported by the Comisión Interministerial de Ciencia y Tecnología CTM 2013-41354-R Project and Fundación Fernando Valhondo Calaff.