*Article* **Development of Electrospun Films from Wastewater Treatment Plant Sludge**

**Gregor Lavriˇc 1, Aleksandra Mileti´c 2, Branka Pili´c 2, Daša Medvešˇcek 1, Saša Nastran 3 and Urška Vrabiˇc-Brodnjak 4,\***


**Abstract:** Electrospinning is a versatile method for producing continuous polymer nanofibers, including from wastewater treatment plant sludge (WTPS). In this context, purified WTPS was successfully used to produce electrospun fibers. The main objective of our research was to produce new, local, circular, renewable and environmentally friendly packaging material. The aim of the research was to purify and treat WTPS to make it suitable for the electrospinning process, thus producing a new material and chemically characterizing it in the first step. One of the major advantages of our process was that the electrospinning process could be carried out with water and ethylenediaminetetraacetic acid. The optimal viscosity was determined to be 20,000 mPas in order to produce sufficient nanofibers. Analyses such as Fourier-Transform Infrared Spectroscopy (FTIR) and 1H-NMR (proton nuclear magnetic resonance) were used to determine the substances of unpurified and purified WTPS. The tensile properties, contact angle, surface properties and differential scanning calorimetry of the final material were determined and used. The 1H-NMR analysis confirmed the presence of a small quantity of polyhydroxyalkanoates in the samples. Based on the properties, the final material was brittle and less stretchable compared to electrospun packaging films available in the market.

**Keywords:** wastewater treatment; electrospinning; differential scanning calorimetry; tensile properties; proton nuclear magnetic resonance spectroscopy; packaging
