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Agroindustry factory's such as the table olive industry etc. that gain importance in the economies of Mediterranean countries. Conventional treatment methods are not effective for treating table olive processing wastewater due to its unique composition. Ultrasound/Ultraviolet light (US/UV) oxidation was used to treat wastewater of table olive industry to improve hydroxyl radicals and enhance organic compound removals. A statistical experimental design was used on table olive processing wastewater to examine the effects of the UV/US oxidation process. The highest removal efficiency for chemical oxygen demand, total organic carbon, color, suspended solids and phenol were obtained as 64 %, 52 % 60 %, 87.5 % and 22.3 %, respectively. These results were obtained under optimal conditions of 20 min reaction time for ultrasound process, intensity of 50 W/cm2, and 20 min reaction time for ultraviolet process in the US/UV process. The study also showed that the ultrasound/ultraviolet oxidation process resulted in small reaction time and low chemical requirements. Sludge production and operational cost decreased at best experimental conditions due to small reaction time and low chemical requirement.

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In this study, we systematically developed the long-term photoaging behavior of different-sized polypropylene (PP) floating plastic wastes in a coastal seawater environment. After 68 d of laboratory accelerated UV irradiation, the PP plastic particle size decreased by 99.3 ± 0.15%, and nanoplastics (average size: 435 ± 250 nm) were produced with a maximum yield of 57.9%, evidencing that natural sunlight irradiation-induced long-term photoaging ultimately converts floating plastic waste in marine environments into micro- and nanoplastics. Subsequently, when comparing the photoaging rate of different sized PP plastics in coastal seawater, we discovered that large sized PP plastics (1000-2000 and 5000-7000 µm) showed a lower photoaging rate than that of small sized PP plastic debris (0-150 and 300-500 µm), with the decrease rate of plastic crystallinity as follow: 0-150 µm (2.01 d-1) > 300-500 µm (1.25 d-1) > 1000-2000 µm (0.780 d-1) and 5000-7000 µm (0.900 d-1). This result can be attributed to the small size PP plastics producing more reactive oxygen species (ROS) species, with the formation capacity of hydroxyl radical •OH as follows: 0-150 µm (6.46 × 10-15 M) > 300-500 µm (4.87 × 10-15 M) > 500-1000 (3.61 × 10-15 M) and 5000-7000 µm (3.73 × 10-15 M). The findings obtained in this study offer a new perspective on the formation and ecological risks of PP nanoplastics in current coastal seawater environments.

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Propolis is a resinous compound made by bees with well-known biological activity. However, comparisons between encapsulated and non-encapsulated propolis are lacking. Therefore, the antibacterial activity, effect on the phase transition of lipids, and inhibition of UV-induced lipid oxidation of the two forms of propolis were compared. The results showed that non-encapsulated propolis produces quicker effects, thus being better suited when more immediate effects are required (e.g., antibacterial activity). In order to gain an in-depth introspective on these effects, we further studied the synergistic effect of propolis compounds on the integrity of lipid membranes. The knowledge of component synergism is important for the understanding of effective propolis pathways and for the perspective of modes of action of synergism between different polyphenols in various extracts. Thus, five representative molecules, all previously isolated from propolis (chrysin, quercetin, trans-ferulic acid, caffeic acid, (-)-epigallocatechin-3-gallate) were mixed, and their synergistic effects on lipid bilayers were investigated, mainly using DSC. The results showed that some compounds (quercetin, chrysin) exhibit synergism, whereas others (caffeic acid, t-ferulic acid) do not show any such effects. The results also showed that the synergistic effects of mixtures composed from several different compounds are extremely complex to study, and that their prediction requires further modeling approaches.

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According to extensive in situ investigations, the microplastics (MPs) determined in current wastewater treatment plants (WWTPs) are mostly aged, with roughened surfaces and varied types of oxygen-containing functional groups (i.e., carbonyl and hydroxyl). However, the formation mechanism of aged MPs in WWTPs is still unclear. This paper systematically reviewed MP fragmentation and generation mechanisms in WWTPs at different treatment stages. The results highlight that MPs are prone to undergo physical abrasion, biofouling, and chemical oxidation-associated weathering in WWTPs at different treatment stages and can be further decomposed into smaller secondary MPs, including in nanoplastics (less than 1000 nm or 100 nm in size), suggesting that WWTPs can act as a formation source for MPs in aquatic environments. Sand associated mechanical crashes in the primary stage, microbes in active sewage sludge-related biodegradation in the secondary stage, and oxidant-relevant chemical oxidation processes (light photons, Cl2, and O3) in the tertiary stage are the dominant causes of MP formation in WWTPs. For MP formation mechanisms in WWTPs, external environmental forces (shear and stress forces, UV radiation, and biodegradation) can first induce plastic chain scission, destroy the plastic molecular arrangement, and create abundant pores and cracks on the MP surface. Then, the physicochemical properties (modulus of elasticity, tensile strength and elongation at break) of MPs shift consequently and finally breakdown into smaller secondary MPs or nanoscale plastics. Overall, this review provides new insights to better understand the formation mechanism, occurrence, fate, and adverse effects of aged microplastics/nanoplastics in current WWTPs.

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