Recirculation Aquaculture Effluent Treatment by Using Clinoptiloite and Bentonite Modified by Cationic Surfactant

Nitrogenous compounds are the main anionic pollutants in recirculating aquaculture systems. Ion exchangers are vastly applied in waste water industry. Negative surface charge? of the zeolites and clays enable them for cation absorptions, however, they do not have any tendency for absorbing anion absorptions. Meanwhile, by modifying surface structure??, they can absorb anions. In the present study, modifications of superficial and layered structures of clays were carried out using the organic compound, tetradecyltrimethylammonium and heat treatment to enable the ion exchangers to absorb the nitrogenous anions from rearing system. Three different ambient temperatures (10, 15 and 20 °C) and different pHs (6, 6.5, 7, 7.5 and 8) were used. Results showed that environmental conditions influenced anionic adsorption. Nitrate and nitrite absorption from aquaculture effluent and nitrate from standard solution by two absorbent had significant effect by ambient temperature (P< 0.05). In aquaculture effluent, pH did not show any regular effect on nitrite absorption. It was inferred that environmental factors such as temperature, pH, anion concentration, presence of other ions and counter ions are effective on absorptive capability of a given ion. Results showed that modified ion exchangers might be useful for harmful anion absorption from recirculating aquaculture system.