Advanced Biofuels Production from Waste Olive Pomace of Olive Oil Industries

Project Information

OliPFUEL

Grant agreement ID: 101062601

DOI

10.3030/101062601

Project closed

EC signature date 13 July 2022

Start date 5 September 2022

End date 4 September 2024

Funded under

• Marie Skłodowska-Curie Actions (MSCA)

Total cost

No data

EU contribution

€ 165 312,96

Coordinated by

UNIVERSIDAD DE JAEN
Spain

Periodic Reporting for period 1 - OliPFUEL (Advanced Biofuels Production from Waste Olive Pomace of Olive Oil Industries)

Reporting period: 2022-09-05 to 2024-09-04

Summary of the context and overall objectives of the project

Global biofuel demand is anticipated to surge by 30% between 2023 and 2028 (International Energy Agency, 2024). This would reduce fossil fuel consumption, protect the environment, inhibit climate change, and safeguard public health. Several initiatives of the European Union (EU), such as the Renewable Energy Directive, the European Green Deal, and the European Bioeconomy Strategy, have been operational to promote the utilization of biofuels and bio-based products. These initiatives recommended the production of bioproducts through greener technologies from locally available and non-edible waste biomass.
Olive pomace (olive pulp and seeds) is an abundantly available waste biomass in the EU. It is generated during the production of olive oil by the olive oil industry. The valorization of olive pomace is tough due to its high moisture content (about 70%) and phytotoxic phenolic compounds. The conventional processes that could be used for the conversion of olive pomace into bioproducts include acid hydrolysis, enzymatic hydrolysis, pyrolysis (400–800 °C), and gasification (800–1000 °C). These processes have several limitations, such as the use of corrosive acids, expensive enzymes, and high energy consumption. To innovate an alternative, more environmentally friendly process, the main objectives of the OliPFUEL project are:
1. Investigate an integrated process comprised of hydrothermal treatment and non-conventional yeast-based fermentation technology to convert olive pomace into hydrochar (solid biofuel) and bioethanol.
2. Identify suitable process conditions for the production of hydrochar with high calorific value and to achieve a higher bioethanol yield.

The olive oil industry could adopt the OliPFUEL process for in-situ conversion of olive pomace slurry into bio-based products, which would provide them with economic benefits by saving waste management costs and marketing the bioproducts. This would protect the environment and public health from the negative impact of improper disposal of olive pomace waste and create new employment opportunities to handle the production of bioproducts. Furthermore, this would ultimately improve the social and economic conditions of the public, specifically the people employed in the olive sector.
The OliPFUEL would contribute to promoting the bioeconomy, achieving the EU net zero targets, and several UN sustainable development goals (waste resource recycling, clean environment, and renewable energy).

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The hydrothermal process coproduced a solid fraction called hydrochar and a liquid fraction known as hydrolysate. The sugars and inhibitors were found in varied concentrations in hydrolysate. The oil fractions extracted from the hydrochar are used for biodiesel production through transesterification. The wild-type strain of H. polymorpha (DSM70277) and its modified strains prepared through the adaptive evolution method using liquid hydrolysate produced by hydrolysis was studied for fermentation under varied process conditions for the production of bioethanol, xylitol, and butanol. The inoculum concentration, time and temperature mpacted the bioethanol production, but there was no significant impact on xylitol production. The formation of butanol was not detected in the fermentation samples, which indicated that the H. polymorpha was not suitable for butanol production.The major outcomes
of this project are as follows:
The conventional and microwave-assisted water hydrolysis and hydrothermal carbonisation processes co-produced olive pomace hydrochar with enriched calorific value and hydrolysate with varied sugar and inhibitory content.
Both conventional and microwave (1000 W) hydrothermal carbonisation at relatively high temperature (250 °C) and time (30 min) and autogenic pressure (50 bar to 70 bar)
produced hydrochar with a higher calorific value.
The microwave hydrolysis (120°C and 30 min) produced hydrolysate with relatively higher sugar (glucose) and lesser inhibitory contents than the hydrothermal carbonisation process. Thus, microwave hydrolysate was found suitable to be used as a feedstock for
bioethanol production.
The oil fraction extracted from the hydrochar generated by microwave hydrothermal carbonisation at 180°C for 30 min produced more biodiesel.
The 0.64 g/L inoculum concentration and 25 h time was found as optimal fermentation cconditionsto achieve the ethanol yield of 0.57 g/L. Whereas, 20 h time was found suitable for xylitol co-production.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The OliPFUEL project has developed an integrated process comprised of hydrothermal treatment and fermentation processes for the conversion of olive pomace slurry into hydrochar, biodiesel, glycerol, ethanol, and xylitol. The main innovation in the case of hydrothermal treatment was the use of microwave technology and the inherent water
content present in the olive pomace slurry in place of distilled water and acids to produce hydrochar and sugar-rich hydrolysate. Furthermore, the oil fractions retained in hydrochar were used for the production of biodiesel and glycerol. In the case of fermentation, an adapted strain of non-conventional Hansenula polymorpha yeast prepared using hydrolysate produced the ethanol and xylitol. Therefore, the OliPFUEL process advanced the research on olive-pomace-based biorefinery, microwave-based hydrothermal processes, biodiesel production from oil-rich hydrochar, and H. polymorpha yeast used for fermentation. Currently, the olive pomace slurry is used for the production of pomace oil and exhausted olive pomace pellets (for energy applications). This involved the transportation of olive pomace slurry from the olive oil industry to olive pomace mills, which is a very challenging process. The OliPFUEL process is an alternative to the above approach in which the olive pomace slurry can be hydrothermally treated onsite to produce various bioproducts. This will economically benefit the olive sector and also help to reduce the consumption of environmentally harmful fossil-based products.