Removal and reuse of phosphorus from aquaculture water using activated carbon-based CaO<inf>2</inf> nanoparticles

Abstract

Excessive amounts of phosphate entering freshwater from aquaculture farming have serious environmental impacts. Adsorption is the most promising technique for phosphate reduction in water. A continuous adsorption study in a fixed-bed column was conducted using activated carbon containing CaO2 nanoparticles (nCaO 2-AC) to investigate the removal of phosphate from aquaculture water. The effects of the operating parameters on the removal of phosphorus in deionized water confirmed that the adsorption capacity increased as bed height increased but decreased as the flow rate decreased. The interaction of the adsorption sites with phosphate ions was confirmed based on the FTIR spectra. The highest bed capacity of 11.38 mg/g was obtained using a flow rate of 15 mL/minutes, an inlet phosphate concentration of 100 mg/L, and a bed height of 5 cm. When using this column to treat phosphate in aquaculture wastewater, the results showed that the adsorption capacity decreased slightly to 9.01 mg/g. Additionally, the plant growth test using French marigold revealed that the application of phosphorus-adsorbed nCaO 2-AC (P-nCaO 2-AC) significantly affected plant height, number of leaves per plant, number of branches, number of flowers, and flower fresh weight; however, flower diameter was not significantly affected at 35 DAT. The experiment revealed that P-nCaO 2-AC at 15 g/kg produced good quantity and quality features for French marigolds. These results suggest that nCaO 2-AC has the potential for use in the removal and reuse of phosphate from aquaculture water.