Integrated advanced technologies for olive mill wastewater treatment: a biorefinery approach

Towards the Integral Valorization of Olive Pomace‐Derived Biomasses through Biorefinery Strategies

“…Microwave-assisted extraction (MAE) is based on the use of microwaves with frequencies between 0.3 and 30 GHz, making it possible to heat a matrix externally and internally [111]. In MAE, the solvent should be able to absorb and transfer microwave energy, while UAE requires solvents with low viscosity [8]. Although ultrasound can reach temperatures of 75 °C at the end of the process, caused by the ultrasonic waves themselves, the process temperature required is lower than using MAE or conventional extraction.…”

“…This type of solvent is based on the use of a hydrogen bond acceptor (e.g., choline chloride) and hydrogen bond donors (e.g., organic acids) that form an eutectic mixture. A recent review suggests that NADES have the potential to be used for the sustainable recovery of bioactive compounds from biomass due to their natural origin and compatibility with food, pharmaceutical, and cosmetic uses [8]. Nonetheless, to really be ''green'', the sustainable and competitive production of this type of solvent from renewable sources should be warranted.…”

“…2a). The paste is placed on pressing disks, where water (320–600 L/ton) is added 8. The main driving force for separation is pressure, generating a liquid fraction composed of water and oil and another solid fraction known as olive pomace 31.…”

“…2a). In the three‐ and two‐phase extraction systems, a horizontal decanter is used to separate the oily phase in continuous mode through centrifugal action at about 3000 rpm 13. In the former case, 350–700 L/ton of water are added to the paste 8. Subsequently, it is centrifuged, thus obtaining olive oil, vegetable water (or alpechin) (80–130 kg per 100 kg olives), and olive pomace (40–57 kg/100 kg olives) (Fig.…”

“…While Spain mainly uses the two‐phase system (∼ 99 %), most of the top‐producing countries use the three‐phase system. The two‐phase system emerged to reduce water consumption and therefore diminish the wastewater generated in the overall process 8. This has resulted in more sustainable processes with CO 2 savings while providing good‐quality extra virgin olive oil 6.…”