Degradation of olive mill wastewater by different methods and antioxidant activity of olive mill wastewater extraction

Abstract

Olive wastewater (OMW) is an important environmental problem due to the high phenol level and contains organic substances such as sugars, organic acids, polyalcohols, pectins, colloids, tannins, and lipids. Removing OMW is difficult because of the high concentrations of chemical oxygen demand (COD), biochemical oxygen demand, and phenolic compounds. In this study, we concentrated on the degradation of OMW to solve this problem. The degradation of OMW at high pressure and temperature (with H 2 O 2 and without H 2 O 2), at room temperature and atmospheric pressure with H 2 O 2 , at room temperature and atmospheric pressure with O 3 , and with ultrasound-assisted ozonation, was investigated by means of COD, phenolic compounds, and sulfur analyses. The results showed that the method of high pressure and temperature with H 2 O 2 was the most successful. H 2 O 2 at high pressure (O 2) and temperature removed 89.2% of COD, 91.5% of phenolic compounds, and color of OMW. With this result, we showed that the use of O 2 atmosphere instead of N 2 is important for degradation and also especially for color removing. In addition, the antioxidant property of OMW was also examined. Fourier-transform infrared spectroscopy of the extracts revealed vibration bands corresponding to acid, alcohol, and ketone groups. The results showed that high pressure and temperature treatment is very effective for removing phenolic compounds from olive oil wastewater. In addition, 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging potential of OMW in the Çukurova area of Turkey was studied and the IC 50 value of OMW was determined to be 118 µg/mL.

Bioactive Compounds in Waste By-Products from Olive Oil Production: Applications and Structural Characterization by Mass Spectrometry Techniques

“…For example, Hafidi et al studied the aerobic digestion of OMWW under various medium conditions to determine the best treatment of residue stabilisation; FTIR and 13 C NMR spectroscopies were used to compare results showing that treatment of OMWW by soil micro-flora with pH neutralization by phosphate could be considered the best one, allowing good stabilisation of organic matter and high preservation of nitrogen in the humic form [154]. More recently, the degradation of OMWW by different methods was studied by FTIR: results showed that treatment with H 2 O 2 under high pressure and temperature removed 89.2% of COD, 91.5% of phenolic compounds, and the colour of OMWW; the comparison of NMR spectra confirmed that all phenolic compounds and the majority of other compounds were abated [155].…”

Impact of Storage Duration on Polyphenolic Composition, Biological Activities, and Biodegradation of Olive Mill Wastewater

“…Mean squares of the analysis of variance of the storage effect of OMW on antioxidant activity. DPPH test of OMW was discussed in the literature; (Evci et al, 2019) found a value of (118 µg / mL) for OMW from olive oil mill located in Mersin, Turkey. A recent study of (Romeo et al, 2020) showed the result (114.37 ± 151.87 mmol TE / 100 mL) for OMW from a three-phase centrifugation process from Ottobratica olive cultivar, Calabrian region, Italy.…”

Olive vegetation waters (OVWs): characteristics, treatments and environmental problems

“…The values of COD (Chemical Oxigen Demand) and BOD5 (Biological Oxygen Demand), are always very high, they are much higher for vegetation waters deriving from traditional processes. During storage, the OVWs can undergo fermentation phenomena due to the action of aerobic and anaerobic microorganisms with consequent increase in pH, decrease in BOD5 [31]. The microbial population is mainly made up of bacteria such as Cellulosolytics, Pseudomonas, while nitrifying agents are absent.…”