Production of Polyhydroxyalkanoates using Volatile Fatty Acids from Municipal Wastewater Treatment Plant Sludge

Abstract

The massive and global use of plastic elements causes serious environmental, economic and social problems for aquatic fauna, fishery, and tourism. This makes it necessary to consider alternatives to replace conventional plastics for easily biodegradable bioplastics made from renewable raw materials. However, the cost of production of so-called green plastics is high compared to the conventional plastics industry, causing the implementation and development of this type of material to be limited. This work aims to develop a sustainable process for the production of polyhydroxyalkanoates (PHAs) using as carbon source volatile fatty acids (VFAs) from sludge from wastewater treatment plants of WWTP El Salitre. The concentrations to complete the 1 g/L VFAs condition were: acetic acid 0.722 g/L; propionic acid 0.208 g/L and butyric acid 0.098 g/L; for 0.7 g/L VFAs: acetic acid 0. 505 g/L; propionic acid 0.145 g/L and butyric acid 0.068 g/L and 0.5 g/L VFAs: acetic acid 0.361 g/L; propionic acid 0.104 g/L and butyric acid 0.049 g/L. The percentages used in each mixture were: 69% acetic acid, 21% propionic acid, and 10% butyric acid respectively. The fermentations were carried out in a shaker incubator at 30°C. The tests were carried out at a flask scale and the biomass and PHA concentration were determined. The best percentage of polyhydroxyalkanoates accumulation concerning the Pseudomonas Burkholderia cepacia 2G-57 Biomass was 91%, using 0.7 g/L of volatile fatty acids as a carbon source, and using mixed cultures from the WWTP was 86% with the same concentration of VFAs. Copyright © 2023, AIDIC Servizi S.r.l.