Therefore, it is urgent to find a kind of low cost, nontoxic and more efficient flocculant for controlling
HABs in seawater. With the characteristics of nontoxic and biodegradable, the so-called “green
flocculants” such as starch [21], amylopectin [22], alginic acid [23], guar gum [24] have been applied into
the wastewater treatment and mineral processing industries. The natural corncob powder (CP), mainly
composed of cellulose, lignose and pentosan, has abundant output in China. Composed of much hydroxyl
groups, CP can be grafted by cationic polymers and perform efficient flocculation characteristics. In view
of several authors’ earlier findings, CP was chosen as the basic polymer grafted by a quaternary
ammonium compound [25,26] for the wastewater treatment. However, it has not been reported as
flocculating agent for removing harmful microalgae.