REMOVAL OF HEAVY METALS FROM HOSPITAL WASTEWATER BY BACILLUS SUBTILIS AND PSEUDOMONAS AERUGINOSA: A COMPARATIVE STUDY ACROSS TREATMENT PERIODS
Keywords:
Hospital wastewater, Bioremediation, Bacillus subtilis, Pseudomonas aeruginosa; Heavy metalsAbstract
Background: Hospitals continuously emit pollutants through their medical and laboratory-related activities, making them a key source of heavy metal pollution. This study aim to investigate the in-vitro efficiency of Bacillus subtilis and Pseudomonas aeruginosa at removing cadmium, lead, and copper from hospital wastewater.
Methods: For the bioremediation study reported here, we collected wastewater samples from Al-Hilla Surgical Teaching Hospital in Babylon Province, Iraq. The target pollutants were three heavy metals: cadmium (Cd), copper (Cu), and lead (Pb). We selected two bacterial strains, B. subtilis and P. aeruginosa, to conduct remediation tests. We carried out a 9-day laboratory batch bioremediation experiment, used atomic absorption spectrophotometry to monitor heavy metal concentrations on days 0, 3, 6, and 9, and processed all data with principal component analysis (PCA).
Results: It showed that all heavy metal concentrations in the treatment groups were significantly lower than those in the control group (P≤0.05). B. subtilis produced a slightly better remediation effect than P. aeruginosa in most time periods. After 9 days of treatment, the removal rates of the three heavy metals by Bacillus subtilis were 95.51%, 100%, and 100% respectively, while the corresponding rates for P. aeruginosa were 94.23%, 95.87%, and 100%. The order of heavy metal removal efficiency was Cu≥Pb>Cd. PCA results showed that treatment duration had a stronger impact on remediation effect than strain type, and samples were mainly clustered by incubation time. Both strains are effective, low-cost, and environmentally sustainable remediation agents. Further optimization of treatment duration is required to maximize remediation efficiency.
Conclusion: under laboratory conditions that B. subtilis and P. aeruginosa can effectively reduce the concentrations of cadmium, lead, and copper in hospital wastewater.
