Depuration Performance of Aerated Tanks Simulating Lagoons to Treat Olive Oil Mill Wastewater under Different Airflow Rates, and Concentrations of Polyphenols and Nitrogen

The uncontrolled disposal of olive oil mill wastewater (OMW) is hazardous for the health of water and soil, since this wastewater shows low pH and high contents of organic matter and polyphenols (PP). Lagooning is one of the most common treatment systems for agro-industrial wastewater (such as OMW), due to its low cost and easy management. Aeration allows reducing the low depuration time, which is a constraint for this system. Despite this potential feasibility, literature about OMW lagooning is not abundant. Moreover, the effects of the aeration rates, concentration of polyphenols and nitrogen shortage on depuration performance of lagoons treating OMW have not been properly explored. This study analyzes the removal rates of COD and PP, and variations of pH in OMW treated in aerated tanks at the laboratory scale simulating lagooning systems. Compared to the non-aerated tanks, aeration of OMW increased the removal rates from 61% to 90% (for COD) and from 52% to 64% (for PP). Permanent aeration was more advisable compared to intermittent flow rates. Increasing concentrations of PP noticeably reduced the COD removal rates, which were halved at a 4-fold PP concentration. In contrast, the PP removal rate was constant at every concentration experimented. Compared to the COD:N value suggested by literature for aerobic processes (100:5), a shortage in nitrogen availability reduced both COD (by about 20–25%) and PP removal rates (by 25%), the latter only when COD:N was higher 400:5. The pH was less influenced by the variations in aeration rates, PP concentration and COD:N ratio compared to COD and PP removal. This investigation provides indications about the most suitable operation parameters (airflow rates, inhibiting PP concentration, and optimal COD:N) in aerated lagooning of OMW towards environmentally sound treatments of highly polluting wastewater.

Phenolic compounds and biological activities of phenolic extract of olive oil mill wastewater issue from the cold extraction of olive oil from Khenchela (Algeria)

This study aimed to the determination of antioxidant, anti-inflammatory, and anticoagulant activities of phenolic compounds present in olive oil mill wastewater (OMW) issue from the cold extraction of olive oil from Khenchela eastern of Algeria.After polyphenols extraction, a quantity and quality analysis by LC-MS was made. The LC-MS (liquid chromatography–mass spectrometry)results were revealed the presence of 20 phenolic compounds in theextract of OMW which were: (quinic acid, gallic acid, protocatechuic acid, caffeic acid, p-coumaric acid, rutin, transfrolic acid, hyperoside (quercetin-3-o-galactoside), luteolin-7-o-glucoside, naringin, 4.5-di-caffeoyquinic acid, quercetrin(quercetin-3-o-rhamonosid), apegenin-7-o-glucoside, salviolinic acid, kampherol, quercetin, naringenin, apegenin,cirsiliol, and cirsilineol). The results of antioxidant activity with DPPH(2,2-diphenyl-1-picrylhydrazyl), ABTS+ (2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid), and FRAP (ferric reducing ability of plasma)showed that the IC50(half-maximal inhibitory concentration) were(9.62 ± 0.28µg/mL, 7.10 ± 0.11µg/mL and 3.59 ± 0.24µg/mL)respectively. The extract of OMW was found to exhibit the highestinhibitory effectanti-inflammatory activity usinginhibition of protein denaturation(IPD) and membrane stabilizing potential (MSP) tests (80.46 ± 3.81; 87.43 ± 0.66 µg/mL) more than the standard used. In addition, the extract had the best anticoagulation activity in the endogenous and exogenous pathways (44.77 ± 0.25s; 15.84 ± 0.12s). Based on these results, it is right to conclude that OMW is an important source of natural phenolic compounds that have important antioxidant, anti-inflammatory, and anticoagulant activities.