Characteristics of lipid fractions recovered from municipal wastewater as a raw material for the production of bio-polyols

The presence of fats in municipal wastewater is a significant problem, primarily due to their propensity to cause clogging of installations and failure of treatment systems. However, these fats also can serve as a valuable raw material for the production of bio-polyols that can be further used in e.g. polymer technology. This paper presents a novel approach for the separation of fats from wastewater, and evaluates their potential for use in the production of bio-polyols. The study included a comprehensive characterization of the fat fraction, including infrared spectroscopy (FTIR) analysis, an examination of fat content, an elemental analysis of fats, and an assessment of the calorific value of fats through determination of calorific value and heat of combustion. Moreover, thermal analysis investigations have been performed using TG and DSC methods, as well as decomposition behaviour using pyrolysis coupled with gas chromatography-mass spectrometry (Py-GC/MS) has been studied. The results show that the recovered fat fraction contains up to 60% fats. The results further indicate that fats from sewage sludge contain a mixture of fatty acids, esters and hydrocarbons, which are key components for the synthesis of bio-polyols. The use of fat fraction from wastewater can significantly contribute to the reduction of waste and the development of sustainable technologies in the chemical industry. Furthermore, fats can serve as an alternative feedstock for the production of bio-polyols, thereby replacing conventional vegetable oils. This approach facilitates the more sustainable and value-added utilisation of lipid-based raw materials.