Abstract
Coagulation foam separation with dispersed air using milk casein as a collector and a frother is an effective method to remove suspended substances in water. Harmful algae, which proliferate as outbreaks in many lakes and ponds, are considered suspended organic substances. Hence, the applicability of this method for algal removal is promising. In this study, removal of algae by coagulation and foam using polyaluminum chloride (PAC) and casein was examined.
Highly effective processing was achieved within 10 min by adjusting pH and dosages of PAC and casein. The most important consideration in the foam separation process is adding the proper amount of casein, which functions as both collector and frother. The removal efficiency of Microcystis aeruginosa, Selenastram capriornutum, and Chlorella pyreniodosa was over 97% when PAC and casein were added at a dosage of 3 mg-Al·l-1 and 15 mg·l-1, respectively at pH 7-8. The percentage of liquid volume of collapsed foam in the total amount of algal suspension was about 2%. Approximately 100% of the added PAC and casein were recovered from the treated water. These results prove that this novel method has a high efficiency and applicability in removing algae from aquatic blooms.
