Extracellular organic matters of Chlorella pyrenoidosa: Characteristics, flocculation and self-flocculation enhancement

Extracellular organic matters (EOMs) of algae widely threaten public health and ecological environment. Herein, the relationship between the characteristics of EOMs and their flocculation in water treatment is discussed. Two kinds of EOMs, dissolved extracellular organic matter (dEOM) and bound extracellular organic matter (bEOM), extracted from Chlorella pyrenoidosa owned the similar characteristics. Hydrophobic organic matters were dominant in them. The hydrophobic organic matters were basically the aromatic-like substances and humic-like substances. The dEOM and bEOM possessed small molecule organic matters and multifarious functional groups. Hydrophobic property and functional groups of dEOM and bEOM contributed to their bridging and adsorption in flocculation of colloidal particles in water. And the flocs formed by polyaluminum chloride (PAC) assisted with EOMs were larger than those yielded by individual PAC. In situ self-polymerization of diallyldimethylammonium chloride (DMDAAC) and copolymerization of DMDAAC and EOMs improved the self-flocculation of algae in the simulated wastewater.