Biopolymers recovery from municipal sewage sludge: sustainability assessment in large wastewater treatment plants

The main scope of this work is feasibility studies in real urban wastewater treatment plants for Volatile fatty acids (VFA) recovery and Polyhydroxyalkanoates production (PHA.) A critical review of scientific literature on VFA and PHA recovery has been carried out in order to obtain an overall view of VFA Yield and PHA production. The feasibility studies have been carried out in three different plants located in different regions in Italy: Castelfranco Salvatronda WWTP (Veneto region), Modena Canale Navigli WWTP (Emilia Romagna region) and Castiglione WWTP (Piemonte region). The work is part of a project carried out in collaboration with the companies Hera, Ireti, Smat and A2A and the University of Verona. Further, the life cycle assessment has been performed with the support of the Umberto software in order to evaluate the environmental impact of different scenarios. The LCA has been conducted in Castelfranco Salvatronda WWTP to support decision making for the new configuration plant and sludge valorization centre in order to recover Phosphorus and PHA from sludge. Moreover, feasibility study for PHA recovery have been made for Modena and Castiglione WWTPs using literature yield and production, and in order to evaluate the impacts of the rejected water from the sludge line on the water line, some models simulations have been implemented. Finally, the experimental activity has included laboratory tests on the sludge samples from two WWTPs in order to compare literature VFA yield with experimental results. The tests were done at 5, 7 and 9 days of fermentation in order to control the variation of yields over time.