Abstract: Nano-SnO₂ photocatalyst was obtained by the chemical precipitation method with SnCl₄·5H₂O as the raw material. The particle size of powders, object and morphology have been characterized using the X-ray diffraction and electron microscope. The photocatalytic degradation of ammonia nitrogen in aquaculture wastewater was investigated by using our home-made nano-SnO₂. The effects of different degradation variables on the degradation efficiency were investigated, and the results show that nano-SnO₂ catalyst dosage, the initial mass concentration of ammonia-N in wastewater, pH value, the mass concentration of H₂O₂ are the main effect factors. The optimum reaction conditions are as follows: nano-SnO₂ catalyst dosage is 1.2 g/L, the initial concentration of ammonia-N is 20 mg/L, pH value is 8.0, reaction time is 2 hours and H₂O₂ concentration is 1.0 g/L. Under such condition, the removal rate of ammonia-N can nearly reach 72%.

Key words: aquaculture wastewater, nano-SnO₂, photocatalytic oxidation, ammonia nitrogen