EVALUATE Pb2+ TOXIN REMOVAL EFFICIENCY IN WATER OF COW DUNG DERIVED BIOCHAR: TOXICITY TEST ON FISH (O. niloticus)

Abstract

Heavy metal Pb2+ in water is toxic to organisms, especially, O.niloticus, a common species in the Southeast region of Vietnam. The adsorption method by cow dung derived biochar were used to remove Pb2+ toxin in water has been implemented. A series of acute toxicity tests were conducted to determine the LC50 (96 hours) of lead (Pb2+) that ranged from 0 to 10.0 mg/L on O. niloticus fingerling and to evaluate Pb2+ treatment efficiency of biochar. The research results showed that the maximum adsorption capacity of Pb2+ of biochar, qm = 76.9 mg/g, time to reach equilibrium state of 60 minutes. The isothermal models of Langmuir and Freundlich, second order pseudo kinetic models are suitable to explain the mechanism of Pb2+ adsorption onto biochar. Toxic test result for LC50 is 1.3 mg/L (96 hours). The application of biochar has significantly reduced the mortality of fish from 87% to 7% when adding biochar
to Pb2+ 5.6 mg/L solution with dose range 0.07-0.16 g/L. Research results show that it is possible to use biochar derived from cow manure to reduce the toxicity of Pb2+ in water to O. niloticus.