Evaluation of chemical flocculation-electro flocculation for harvesting of halotolerant microalgae

摘要

Microalgae are a large diverse group of autotrophic organisms ranging from unicellular to multicellular forms which do not require arable land for their growth. Their small size and low concentration in the culture medium, pose a great challenge in harvesting the microalgae. Many methods like centrifugation, precipitation, flocculation, etc., were used to harvest the algal biomass. Flocculation is one among such efficient methods to separate the algal cells. We evaluated the potentials of ferric alum flocculation and electroflocculation methods for harvesting microalgae using the jar experiment. These two experiments were conducted to compare the efficiency of harvesting the algal biomass. Ferric alum was an efficient flocculent for halotolerant algae. As the concentration of the ferric alum is increased from 20 to 160 mg/l, the separation efficiency of algal cells also increased.? Similarly, in electro flocculation, when the voltage is increased the separation of the cells was increasing marginally. In addition, the influence of pH on harvesting was also measured. This study revealed that the micro algal biomass concentration, calcium/magnesium precipitation and initial pH could influence the efficiency of flocculation. These results demonstrated that the electro flocculation at 5 V for 30 min. is very much effective for 90% algal recovery. thereby providing the way to the production of biodiesel and biofuel from algae.