Treatment of wastewater containing NH₄⁺-N and Cu²⁺ in copper mining area

In view of the characteristics of wastewater sewage containing low-concentration NH₄⁺-N and Cu²⁺ in copper mining areas, amethod combined adsorption with biological aerated filter (BAF) processes was applied to for this kind of sewage treatment. The adsorption and removal of Cu²⁺ in simulated sewage by modified copper slag-based ceramsite were explored. And the removal efficiency of BAF filled with the ceramsites on NH₄⁺-N in simulated wastewater after copper removed by adsorption process was investigated under different operating conditions. The results showed that under the optimum conditions of the initial concentration of Cu²⁺ in sewage being 50 mg/L, the initial pH value about 5.00, the ceramsite addition of 20 g/L, the temperature of 35 ℃, and the adsorption time 120 min, the modified ceramsite had a good adsorption effect on Cu²⁺with the equilibrium adsorption capacity reaching about 0.936 mg/g.Under the conditions of the initial concentrations of Cu²⁺and NH₄⁺-N in simulated wastewater 20 and 100 mg/L, respectively, adding content of ceramsite 40 g/L, temperature 35 ℃, the removal rate of Cu²⁺adsorbed by the modified ceramsite reached 80% with the rest Cu²⁺ concentration being only 4.0 mg/L, while the removal effect of the ceramsite on NH₄⁺-N was not obvious. When the simulated wastewater was treated by BAF after Cu²⁺ in it was removed by the modified ceramsite, under the optimum conditions of hydraulic residence time HRT=6 h, carbon-nitrogen ratio m(C/N)=4/1, pH=8.00 and aeration rate of 1.2 L/min, the removal rate of NH₄⁺-N reached 96%. The combined process of adsorption and biological aerated filter (BAF) technique could effectively treat the wastewater containing low concentration of NH₄⁺-N and Cu²⁺ in copper mine area, and the rest concentrations of Cu²⁺ and NH₄⁺-N in the wastewater both met the requirements of national emission standards.