Valentina Cabbai

Environmental Engineer, Ph.D.


PhD Thesis



The PhD project was focused on the creation of an applicative protocol to optimize the WWTP anaerobic digesters upgrade and the project of new ones, basing the design on biochemical process equations rather than on classical empirical methods. To reach this purpose, a complete analysis of the whole anaerobic digestion process is designed, scaling up from micro to macro parameters. The research work was divided in the following four steps:

Organic substrates characterization (measuring classic chemical-physical parameters and AD key macromolecular compounds such as carbohydrates, proteins, lipids and VFA);

  • Biochemical methane potential (BMP) tests (to test organic substrates methane yields with a standard method);
  • Pilot plant test (to investigate in a CSTR, the interaction between the substrates with increasing organic loading rates);
  • Anaerobic Digestion Model (ADM) no°1 (Batstone et al., 2006) implementation.

The actual case study regarded the up-grade, of an existing anaerobic digestion within WWTP of the city of Udine (Italy), to lead to sewage sludge codigestion with organic fraction of municipal solid wastes. Different OFMSW streams, coming from an appropriate waste collection basin, were characterized as a perspective of the AD unit upgrade to AcoD. The waste collection basin was set considering an essential OFMSW management, built on the most productive and clean material streams reaching anaerobic digester. The organic substrates characterization was accomplished basing on traditional physicochemical parameters (commonly used in past to design anaerobic digesters), elemental analysis and macromolecular compounds. In BMP tests SwS together with the more representative substrates for AD unit process, within the waste collection basin, were analysed. Further BMP tests on different SwS and SS-OFMSW mixing ratio were carried out to compare codigestion methane yields. Pilot plant test were performed at 2.3 m3 reactor, after start-up procedure, experimental loading cycles were applied to understand biomass behavior in codigestion regime.

The ADM no°1 model was used to simulate the process in both bench-top and pilot plant tests with the aim of create a calibrated and validated model to optimize the AD unit up-grade. A feasibility study complete the PhD project: basing on results obtained in the experimental phase: two upgrade scenarios on results obtained in the experimental phase: two upgrade scenarios were defined considering the local substrates availability.

  • V. Cabbai, M. Simonetti, D. Goi, “La co-digestione anaerobica dei fanghi di depurazione e Forsu”, Rassegna Tecnica del FVG, (2010), 3/2010: 24-26.
  • M. Simonetti, G. Rossi, V. Cabbai, D.Goi. “Experimental tests of ultrasonic pretreatment on organic fractions for anaerobic co-digestion”. Proceedings of 3rd International Simposium on Energy from Biomass  and Waste, 8-11 November 2010, VENICE, Poster nr. 174 and Paper n. PA05. ISBN 978-88-6265-008-3.
  • V. Cabbai, M. Simonetti, D. Goi, “Digjestion anaerobiche dal pantan dal depurator cu la FORSU (Anaerobic co-digestion of sewage sludge with OFMSW)”, Gjornâl Furlan des Siencis (Friulian Journal of Science), (2011), 15:33-40.
  • E. Aneggi, V. Cabbai, A. Trovarelli, D. Goi, “Ceria-based catalysts potential for the oxidation of landfill leachate by heterogeneous Fenton process” Special Issue on "Advanced Oxidation Processes for Wastewater Treatment", Int. J. Photoenergy (2012), Volume 2012, Article ID 694721, 8 pages. doi:10.1155/2012/694721.
  • V. Cabbai, M. Ballico, D. Goi “Anaerobic digestion of sewage sludge: macromolecular composition and IWA ADM1 application” . In: L. Bonomo, R. Canziani, F. Malpei, M. Grosso, S. Saponaro. Book of Abstracts, (2012) SIDISA 2012. Milano, 26-29/06/2012, vol. ID: 949, Milano:L. Bonomo, ISBN: 978-88-903557-2-1.
  • V. Cabbai, M. Ballico, E. Aneggi, D. Goi. “BMP tests of source selected OFMSW to evaluate anaerobic codigestion with sewage sludge” Waste Manage., (2013), 33, 1626-1632.
  • M. Simonetti, G. Rossi, V. Cabbai, D. Goi, “Tests on the effect of ultrasonic treatment on two different activated sludge waste” Environ. Prot. Eng., (2014), 40(1): 23-34.
  • V. Cabbai, N. De Bortoli, D. Goi, "Pilot plant experience on anaerobic codigestion of source selected OFMSW and sewage sludge” Waste Manage., (2016), 49: 47-54. 
  • M. Mainardis, G. Rossi, V. Cabbai, D. Goi, “Characterization of high-loaded organic substrates and suitability as a potential feed for high-velocity anaerobic UASB reactors”. In: M.R. Boni, P. Sirini, A. Chiavola, A. Polettini, R. Pomi, P. Viotti, A. Rossi. Book of Abstracts, (2016), X International Symposium on Sanitary and Environmental Engineering, SIDISA 2016. Rome, 19-23/06/2016, P/20, ISBN: 978-88-496-391-1.
  • M. Mainardis, V. Cabbai, G. Zannier, D. Visintini, D. Goi, “Characterization and BMP tests of liquid substrates for highrate anaerobic digestion”. Chem. Biochem. Eng. Q., (2017), 31(4).