Optimizing Ammonia Nitrogen Removal from Hospital Effluent Using a Bacteria-Algae Consortium

The discharge of medical institution effluent into a water body can result in eutrophication, primarily due to the presence of ammonia nitrogen in the effluent. Therefore, it is essential to thoroughly treat the effluent to effectively eliminate ammonia nitrogen. This study aimed to to investigate the effectiveness of co-cultures of different bacteria and algae in removing ammonia nitrogen, while also identifying the most effective combination of bacteria and algae. Response surface methodology (RSM) was employed to investigate the interaction effects of “light intensity”, “irradiation time”, and “bacterial inoculation ratio” on the removal efficiency of ammonia nitrogen. The optimal parameter combination was proposed and validated through experiments. The results indicated that among different combinations of bacteria and algae, Chlorella pyrenoidosa and Bacillus licheniformis demonstrated a more effective removal of ammonia nitrogen. Furthermore, the response surface model and variance analysis revealed that light intensity had a significant influence (P = 0.0397< 0.05) as compared to irradiation time and bacterial inoculation ratio. Under optimal conditions, light intensity at 4792lux, irradiation time at 12.8h, and bacterial inoculation ratio at 7.1%, it was predicted that the removal efficiency for ammonia nitrogen reach 88.66%. Subsequent experimental verification under similar conditions - light intensity at 4800lux, irradiation time at 13h, and bacterial inoculation ratio at 7% - yielded an actual value for ammonia nitrogen removal efficiency at 88.15%, consistent with the predicted value. These findings establish a theoretical foundation for the practical implementation of bacteriaalgae symbiosis systems in wastewater treatment processes.