The InnoVa project, funded by the German Federal Ministry of Education and Research under the grant number 01DG20005, aimed to develop a holistic valorisation pathway for olive mill wastewater (OMW). The research was carried out by the Technical University of Berlin in collaboration with the Centre de Biotechnologie de Sfax, Delta Umwelttechnik, the start‑up giaiatech, and an industry partner from the food sector. The project ran from 1 June 2020 to 31 May 2022, with a neutral extension until 31 December 2022. The German Aerospace Center provided supervisory support, while the University of Berlin’s Faculty III, Institute for Technical Environmental Protection, led the scientific work.
Technically, the core achievement was the construction and operation of a 300 L fixed‑bed anaerobic reactor that was run continuously for 120 days. During this period approximately 3 t of OMW treated with the InnoVa process were fed into the reactor. The feed was a carefully balanced mixture of membrane concentrate, sediment, and the floating layer from the pre‑tank, together with depolyphenolised OMW. The pilot plant operated without major incidents and was successfully integrated into the research centre in Sfax, Tunisia. Optimised commissioning, maintenance and operating protocols were developed, and potential scale‑up improvements were identified in close coordination with Delta Umwelttechnik.
The process produced a polyphenol concentrate with a hydroxytyrosol mass fraction of about 20 %, placing it within the commercial range of 100–900 €/kg. From 1 t of raw OMW, using 200 kWh of electrical energy and 80 L of pure ethanol (partly recycled), the system yielded 12 L of polyphenol concentrate and 850 L of biogas‑rich substrate. Anaerobic digestion of the residue generated roughly 22 Nm³ of biogas with a methane content of 65 %. A combined heat and power unit could convert this into approximately 18 kWh of electrical and thermal energy, demonstrating the energy recovery potential of the scheme.
Analytical work was performed for every experimental run, which caused delays in data availability. Nevertheless, the results were sufficient to support a planned publication in August 2023, which will describe the process without revealing market‑sensitive details. The pilot plant also served an educational purpose: several student groups visited the site, and a team of three female students operated the plant for several months in Sfax to collect data for their master theses. Two additional student trips were organised under DAAD exchanges to provide practical exposure to the technology.
Future work will focus on product applications for the polyphenol concentrate. A follow‑up project is planned with a small‑medium enterprise in applied chemistry to investigate different purification routes and process optimisations for various end‑uses. The InnoVa team also engaged with the start‑up giaiatech, which is developing a market‑oriented process for OMW raw materials, and held two meetings with its management to discuss shared challenges and opportunities.
The project faced several external constraints. In April 2021 a hacker attack shut down the entire IT system at TU Berlin, causing a multi‑month interruption of IT services and delaying project progress. Supply chain bottlenecks for essential components, especially in measurement, control, and automation, postponed the pilot plant construction until 2022. Legal and regulatory hurdles included dual‑use export approvals, compliance with safety, environmental, and explosion protection regulations in Tunisia, and the procurement and storage of pure ethanol. Despite these challenges, the InnoVa project successfully demonstrated a scalable, environmentally friendly route to recover valuable antioxidants and renewable energy from olive mill wastewater.