It is known that bioflocculation is successfully used for harvesting
microalgae in facilities where microalgae are used in wastewater
treatment. Some microalgal species flocculate more readily
than others and such naturally bioflocculating microalgae can be
mixed with other species to induce flocculation. In many
researches have been shown that some bacteria and fungi have
ability to induce efficient bioflocculation of microalgae (Zhang and Hu, 2012; Surendhiran and Vijay, 2013; Talukder et al., 2014).
Also it was proposed new effective method for harvesting of
microalgae by bioflocculation of a non-flocculating microalga with
another autoflocculating microalga (Salim et al., 2011). The advantage
of this method in comparison with other applied flocculating
microorganisms (such as bacteria or fungi) is that it does not
require different cultivation conditions and therefore avoids additional
costs and prevents undesired contaminations.
In this study the flocculation efficiency of commercial PEO compared
with PAA and coagulant (i.e., ferric chloride) on harvesting
Chlorella vulgaris. The technology of simultaneously employing
coagulant and flocculant for drinking water purification and sewage
treatment was used for harvesting of microalgae. The flocculated
biomass was used as ballast agent for harvesting of
microalgae (Fig. 1). Also the supernatant after flocculated biomass
separation was reused for microalgae cultivation.