Application of Immobilized Biocatalysts in the Biotransformation of Non-Steroidal Anti-Inflammatory Drugs

Featured Application Given the new EU Water Directive, wastewater treatment plants are interested in increasing the efficiency of wastewater treatment in terms of pharmaceuticals. Diclofenac is one of the most common pollutants indicated in the above directive. In connection with the above, the developed preparation, after passing tests on a semi-technical scale, can be used as a factor supporting the work of the sewage treatment plant to remove non-steroidal anti-inflammatory drugs. Among the micropollutants identified in the environment, non-steroidal anti-inflammatory drugs (NSAIDs) dominate more and more often. This is due to both the high consumption and low efficiency of biological wastewater treatment plants, where the initial transformation of NSAIDs most often takes place. The solution to the problem may be using preparations supporting activated sludge in sewage treatment plants in the biodegradation of NSAIDs. Therefore, the research aimed to develop a biopreparation stimulating the activated sludge of the sewage treatment plant to decompose paracetamol and selected NSAIDs. This biopreparation is based on strains of Stenotrophomonas maltophilia KB2, Planococcus sp. S5, Bacillus thuringiensis B1(2015b), and Pseudomonas moorei KB4 immobilized on a plant sponge. As a result of the tests, it was shown that the optimal species composition of the proposed preparation includes all tested strains immobilized on a carrier with a mass of 1.2 g/L. The system optimization showed that the optimal amount of strains on the carrier was 17 mg/g of the carrier, 15 mg/g of the carrier, 18 mg/g of the carrier, and 20 mg/g of the carrier for KB4, B1(2015b), KB2, and S5, respectively. The presence of phenol stimulated the degradation of the tested drugs, and this effect deepened with increasing phenol concentration. At the same time, the degradation rate of the mixture of NSAIDs in the presence of phenol did not depend on the amount of biomass. The lack of inhibition in the presence of an additional co-contaminant, i.e., phenol, indicates that the preparation constructed in this way has a chance of being used in sewage treatment plant systems, where introduced strains are exposed to various aromatic compounds.