Degradation performance and microencapsulation of hydrolytic bacterial consortium formulated as bioremediation agent of liquid biomedical waste

Abstract

This study aimed to develop bioremediation agent with bacterial cells as components for the treatment of biomedical wastes from two hospitals in Semarang City (Central Java), i.e. Roemani Muhammadiyah (coded R1) and Wongsonegoro (coded R2). Single isolates and consortium of indigenous hydrolytic bacteria characterized as multiple hydrolytic enzyme producers with low-to non-pathogenic properties obtained from previous study were tested for their degradation performance. The degradation performance test is necessary to formulate components of bacterial consortium as bioremediation agent. The tests were conducted on the selected bacteria as single isolate and as consortium. The six bacteria tested as single colonies and as consortium were Bacillus velezensis R1.3, B. amyloliquefaciens R1.6, B. amyloliquefaciens R1.14, B. velezensis R1.16, B. licheniformis R2.5, and B. amyloliquefaciens R2.9. Degradation performance on biomedical waste mainly containing organic matters was assessed based on water pollution parameters on 4.0-L samples. They included a control, 6 samples treated with bacteria as single colonies, a sample treated with bacteria as indigenous consortium and a sample treated with bacteria as mixed consortium. Parameters of wastewater pollution measured included COD (Chemical Oxygen Demand), BOD (Biological Oxygen Demand), TSS (Total Soluble Solid), NH3, and PO4. Next, encapsulation of a bacterial consortium as the best condition for degradation was also carried out using maltodextrin to allow storage and preservation of the bioremediation agent for longer period. The encapsulated product was visualized in SEM images to evaluate its quality. The results showed that a consortium comprising 4 indigenous bacterial isolates from R1 hospital could decrease BOD of biomedical wastewater by 85% and TSS by 43%. Those from R2 showed performance in reducing PO4 by 21%. This study demonstrated that compared to single isolates and mixed bacterial consortium tested, the indigenous hydrolytic bacterial consortium showed better ability in improving BOD and TSS of liquid biomedical waste of R1 hospital.