Removal of Chlorella Pyrenoidosa by copper-chitosan algaecide

A copper-containing algaecide(CCA) was prepared by using chitosan as the carrier material and then we investigated its effect on the removal of Chlorella pyrenoidosa.The results showed that the CCA could clearly suppress the growth of Chlorella pyrenoidosa.The optimal application time of algaecide was during the lag phase of Chlorella pyrenoidosa,and the algae removal increased with increasing CCA dosage.The 96h-EC50 of CCA was 13.2 mg · L-1 for Chlorella pyrenoidosa and an effective dosage of 10~30 mg · L-1 is recommended for eutrophied water bodies.The rate of algae removal could reach over 80% two days after application of the recommended dosage of CCA,while the residual Cu2+ concentration was decreased to 0.38 mg · L-1.The release of Cu2+ and change in water pH associated with CCA application were the main algae removal mechanisms.The first-order and Elovich-second-order equation could be used to describe the release dynamics of Cu2+ from CCA for the initial 24 hrs and the subsequent period,respectively.The effective duration of CCA application was over 15 d.