Research Of The Removal Of Phaeocystis Globosa Red Tide By The Chemical Means

In order to find out an effective method to remove the Phaeocystis globosa red tide, a batch of experiments are studied at our laboratory.Phaeocystis globosa (Hong Kong) was examined under laboratory conditions with batch culture method. The growth cycle of Phaeocystis globosa takes about 20~ 30 days in batch culture.To investigate the relationship between optical density (OD) and the biomass of Phaeocystis globosa. P. globosa was used under laboratory conditions to study the relationship between the cell density and its related OD. Meanwhile, the optical absorption coefficient, namely the slope of the liner graph which showed the relationship between cell density and OD, was utilized to estimate the P. globosa biomass. The regression analysis results showed the liner function: N( X 104Cell/ml)=644.63OD-1.73, (R=0.9985). This is a useful and rapid method to measure the biomass of P. globosa.In the experiment of searching the agent for removal of Phaeocystis globosa, Six organic biocides were studied on their effect of removal of Phaeocystis globosa. Then isothiazolone biocide, glutaric dialdehyde and benzalkonium bromide were selected to apply to remove P. globosa red tide. Their minimum use levels are 1 .Omg/L, 1.4mg/L, 0.6mg/L respectively, and the efficiencies of removal are above 80%. All the results showed that using these three organic algaecides to remove and control P. globosa red tide is not only effective but also convenient. It is the appropriate time to add the organic algaecides at the prophase of logarithmic phase. What' s more isothiazolone biocide and glutaric dialdehyde have good inhibitory effect on P. globosa.Flocculation and removal of P. globosa red tide by inorganic aluminum flocculating agents were discussed. The results showed that Flocculation is compatible to meet the emergency removal P. globosa red tide. It is a method effective and quick. Besides, it has a good efficiency using PVP-I to remove P. globosa red tide at the prophase of logarithmic phase.