Valorization of Olive Mill Wastewater by Membrane Processes to Recover Natural Antioxidant Compounds for Cosmeceutical and Nutraceutical Applications or Functional Foods

Abstract

Olive oil boasts numerous health benefits due to the high content of the monounsaturated fatty acid (MUFA) and functional bioactives including tocopherols, carotenoids, phospholipids, and polyphenolics with multiple biological activities. Polyphenolic components present antioxidant properties by scavenging free radicals and eliminating metabolic byproducts of metabolism. The objective of this research project was to recover the biologically active components rich in polyphenols, which include treatment of olive oil mills wastewater, and, at the same time, to remove the pollutant waste component resulting from the olive oil manufacturing processes. With specific focus on using technologies based on the application of ultra and nanofiltration membranes, the polyphenols fraction was extracted after an initial flocculation step. The nano-filtration permeate showed a reduction of about 95% of the organic load. The polyphenols recovery after two filtration steps was about 65% w/v. The nanofiltration retentate, dried using the spray dryer technique, was tested for cell viability after oxidative stress induction on human keratinocytes model in vitro and an improved cell reparation in the presence of this polyphenolic compound was demonstrated in scratch assays assisted through time lapse video-microscopy. The polyphenols recovered from these treatments may be suitable ingredients in cosmeceuticals and possibly nutraceutical preparations or functional foods.

Keywords: cell culture; functional food; nano-filtration membranes; natural antioxidant; olive mill wastewaters; polyphenols; scratch assays; ultrafiltration membranes.

Figure 1

UF-NF (ultrafiltration-nano-filtration) system.

Figure 2

Block diagram of the process.

Figure 3

Transmembrane flux, corresponding transmembrane pressure (TMP), and inlet pressure during ultrafiltration treatment. The experiments were performed in triplicate.

Figure 4

Transmembrane flux, corresponding TMP, and inlet pressure during nano filtration treatment. The experiments were performed in triplicate.

Figure 5

Transmembrane flux, corresponding TMP, and inlet pressure during the ultrafiltration treatment. The experiments were performed in triplicate.

Figure 6

Transmembrane flux, corresponding TMP, and inlet pressure during the nano filtration treatment. The experiments were performed in triplicate.

Figure 7

Filters BECOPAD 550.

Figure 8

Transmembrane flux, corresponding TMP, and inlet pressure during the ultrafiltration treatment. The experiments were performed in triplicate.

Figure 9

Transmembrane flux, corresponding TMP, and inlet pressure during the nano filtration treatment. The experiments were performed in triplicate.

Figure 10

Chemical Oxygen Demand (COD) analyses in the initial wastewater and in the permeate of the nano filtration process. AV: vegetation water or wastewater.

Figure 11

MTT assay for each concentration of the NF concentrate after 24 h and 48 h of treatment.

Figure 12

(A) Representative panel of comparison of wound repair with and without NF concentrate 0.1 mg/mL w/v at different times. (B) Repair represented by wound area reduction with time [as (Area t₀ − Area t/Area t₀) × 100] for the control and in presence of 100 for the control and in presence of NF concentrate. The curves are averages of three independent experiments with standard deviation within 5% of the value. (C) Average time to achieve 80% wound repair in the presence of NF concentrate 1 mg/mL compared to the control.