Biosorption of Pb was evaluated for plants, Persicaria chinensis, Oenanthe javanica and Salvinia natans. The adsorption equilibrium was reached in about lhr for Pb and the highest adsorption capacity was 150㎎ Pb/g biomass at S. natans. Pb adsorption process showed a pseudo second order irreversible reaction. The highest initial adsorption rate was 2000㎎ Pb/g biomass/hr at O. javanica. In spite of pH variation, Pb adsorption capacity by P. chinensis was maintained uniformly. When light metals concentrations were increased in the solution, Pb was selectively adsorbed. The selectivity of mixture solution showed the adsorption order of Pb>Cu>Cr>Cd. The Pb adsorption capacity of P. chinensis pretreated with NaOH was increased by 30% in comparison with that of no treatment.

Pb2+ and Cr3+ uptake capacity by Sargassum horneri was 185.5㎎ Pb2+/g biomass and 102.6㎎ Cr3-/g biomass, respectively. An adsorption equilibria were reached within about 0.5 hr for Pb2+ and 1 hr for Cr3+. The adsorption parameters for Pb2+ and Cr3+, were determined according to Langmuir and Freundlich model. With an increase in pH values of 2 to 5, Pb2+ uptake was increased, however Cr3+ uptake was constant. The selectivity of mixture solution showed the uptake order of Pb2+>Cu2+>Cr3+>Cd2+. Pb2+ and Cr3+ adsorbed by S. horneri could be recovered from 0.1M HCl, 0.1M HNO3 and 0.1M EDTA by desorption process, and the efficiency of Pb2+ desorption was above 98%, whereas the efficiency of Cr3+ desorption was below 34%.

The feasibility of foam separation to remove protein in aquacultural recirculating water was investigated. From the results of batch foam separation on protein removal, superficial air velocity and initial protein concentration in bulk solution were found to be important operational factors in determining removal rates of protein. The protein removal rate by batch foam separation was proportionally increased with the superficial air velocity. Performance characteristics of continous foam separator were highly dependent upon the operating parameters of superficial air velocity, hydraulic retention time(HR) and foam height. Removal efficiency of protein increases with increasing superficial air velocity and HRT, and independent on foam height. As DO concentration was increased with superficial air velocity, foam separator is also used for oxygen addition. It could be confirmed that foam separator might offer better perspective for protein removal in aquacultural recirculating water