*Review* **Diclofenac Biodegradation by Microorganisms and with Immobilised Systems—A Review**

**Danuta Wojcieszy ´nska , Karolina Łagoda and Urszula Guzik \***

Institute of Biology, Biotechnology and Environmental Protection, Faculty of Natural Science, University of Silesia in Katowice, Jagiello ´nska 28, 40-032 Katowice, Poland

**\*** Correspondence: urszula.guzik@us.edu.pl

**Abstract:** Diclofenac is one of the most popular non-steroidal anti-inflammatory drugs. Due to its over-the-counter availability and high consumption along with municipal and hospital wastewater, it enters the sewage treatment plant, where it is not completely degraded. This results in the appearance of diclofenac in the effluents from the treatment plant, and with them, it enters the surface waters. Due to its structure, it is characterised by its high resistance to degradation in the environment. At the same time, it shows documented acute and chronic toxicity to non-target organisms. For this reason, it is necessary to look for cheap solutions that enhance the degradation of diclofenac. The paper discusses both the pathways of microbiological degradation of this drug described so far, as well as modern systems of biocatalyst immobilisation, with a particular emphasis on laccases involved in the biotransformation of diclofenac.

**Keywords:** biodegradation; diclofenac; immobilization; toxicity; sewage treatment; laccase
