Re-use of partially purified iron color fixation solutions using electro-coagulation and ozonation in ripe table olive processing and packaging

Reuse of KOH Solutions during Black Ripe Olive Processing, Effect on the Quality of the Final Product and Valorization of Wastewaters as Possible Fertilizer Product

A high volume of water is needed to produce black ripe olives, which also entails a significant volume of wastewater with a high organic and inorganic contaminant charge. To reduce this problem, the reuse of KOH solutions (lyes) in a new process was studied. Once the lyes were removed from the tanks, KOH was then added for a new darkening process. Reusing the lyes up to four times gave rise to a product with similar physico–chemical and organoleptic characteristics as obtained with fresh solutions. The application of this process reduced coadjutant consumption by 32% and water by 20%, while global wastewater presented a high K content whose concentration could be valorized as a fertilizer by replacing commercial potassium nitrate.

Simultaneous and sequential combination of electrocoagulation and ozonation by Al and Fe electrodes for DirectBlue71 treatment in a new reactor: Synergistic effect and kinetics study

In this study, the simultaneous combination of electrocoagulation and ozonation (EC-O₃) was optimized in a new reactor for Direct Blue 71 treatment and compared to electrocoagulation (EC), ozonation (O₃), and their sequential combination (EC→O₃) by considering the performance criteria (dye and naphthalene ring removal efficiency), economic assessment (energy and anode consumption), chemical degradability, mineralization rate, and kinetic study. Applying a middle wall in the reactor improved coagulation under ozone-induced rapid mixing on the first side and flocculation under flow-induced slow mixing on the other side which reduced the floc breakage at high ozone dosages. Dye, COD, and TOC removal rate was in the following order: EC(Al)-O₃>EC(Fe)-O₃>EC(Al)→O₃>EC(Fe)→O₃>EC(Al)>EC(Fe)>O₃. The synergistic effect of simultaneous combined process on dye, COD, and TOC removal were obtained 1.97, 1.42, and 1.69 for EC(Al)-O₃ and 1.37, 1.14, and 1.26 for EC(Fe)-O₃, respectively, which showed more ozone activation in the presence of Al ions compared to Fe ions. Also, ozone-induced corrosion for Al electrode was less than Fe electrode, which reduced anode consumption and operation cost. Finally, EC(Al)-O₃ due to best performance and EC(Fe)→O₃ due to optimal use of EC for decolorization and O₃ for oxidation, with dye, COD, and TOC removal efficiency, energy and anode consumption, and operation cost equal to 99, 51, and 62%, 18.6 kWh m^-3, 0.05 kg m^-3 and 0.21 $ m^-3, respectively, for EC(Al)-O₃ and 99, 44.5, and 51%, 6.7 kWh m^-3, 0.2 kg m^-3 and 0.14 $ m^-3, respectively, for EC(Fe)→O₃, are suggested as suitable options for dye wastewater treatment.

Effect of ozone treatment on the physical, microbiological and sensorial properties of Spanish-style table olives

Ozone has been widely used in the food industry as an effective antimicrobial agent. In this study the possibilities of using ozone in table olive preservation was investigated for the first time. For this purpose, the Domat variety of table olives was processed according to the Spanish style and treated with aqueous ozone for 5, 10, and 20 minutes at 0.5, 1, 2 and 4 ppm. The effects of ozonation on the microbiological, physical and sensory characteristics of the table olives were evaluated during the storage period (up to 180 days). The pH, color and firmness of the ozone treated table olives showed higher stability. Statistically significant reductions in the total bacteria and yeast/mould counts were obtained (p < 0.05). Enterobacteriaceae and Escherichia coli were not found in the samples. After 60 days of storage the control samples (ozone untreated olives) obtained low values for sensory analysis, and did not meet market requirements. The results indicate that treating green table olive with ozon (1 ppm concentration) for 10 min in aqueous form reduces the microbial population without any negative effects on the firmness, color (L*, a* b*) or sensory attributes of the table olives.