Efficacy of Bacillus subtilis BMT4i/Activated carbon composite for removal of diclofenac and carbamazepine from aqueous solution

Abstract

Pharmaceutical contaminants (PhACs) have become a worldwide concern in the present scenario. It is considered a group of emerging contaminants and is ubiquitously found in different water bodies in higher concentrations, leading to the deterioration of the water quality and causing ecotoxicity to several non-target organisms. This study extensively evaluates the efficacy of the bacterial strain Bacillus subtilis BMT4i for removing two emerging PhACs, diclofenac (DCF) and carbamazepine (CBZ), from an aqueous solution. A series of batch experiments were conducted by keeping parameters similar to wastewater effluent to investigate the biodegradation of B. subtilis BMT4i in removing PhACs in real scenarios. The study showed that around 67% and 50% of DCF and CBZ were removed within 72 hours when PhACs were supplied as the sole carbon source. Moreover, in co-metabolism with other carbon and nitrogen sources, the percentage removal was enhanced by 20-30%. Further, B. subtilis BMT4i were immobilized on two activated carbons (ACs) i.e., ACEco, and ACDarco prepared from coconut shells and coal so that the composite could directly be used as a bioreactor. The biofilm formation over ACs was confirmed by scanning electron microscopy and Fourier-transform infrared spectroscopy. The results obtained with batch experiment showed over 85-100% removal of both PhACs in a short duration of 2 hours. Moreover, the column studies revealed that around 60-77% of 1 mg/l PhACs were removed by passing over 2 liters of PhACs contaminated water. Overall, the current study confirms that the B. subtilis BMT4i/ACs composite shows promising performance for removing selected PhACs from water.