Adsorptive fouling of inorganic membranes during microfiltration of vegetable oils

Concentrations of Beetroot (Beta vulgaris L.) Peel and Flesh Extracts by Reverse Osmosis Membrane

The objective of this investigation was to concentrate betalains, phenolics, and antioxidants from the extract of peel and flesh of beetroot (Beta vulgaris L.). Thin-film composite reverse osmosis (RO) membrane composed of the thick polyamide barrier layer, microporous polysulfone interlayer, and polyester support web was used in membrane module. In a later exercise, thermo-instability of betalain color compounds was investigated with different temperatures. After the filtration of the aqueous extract of flesh, betacyanins, betaxanthins, and total betalains were increased by 5.2, 6.1, and 5.5 times, respectively. Likewise, the mentioned bioactive compounds were increased by 3.7, 4.9, and 4.2 times after filtration of the aqueous extract of peel. The amounts of total betalains measured in the final flesh extract were two times lower (14.33 ± 0.15 mg·g−1 dm) compared to the peel concentrate (30.02 ± 0.28 mg·g−1 dm). The superior amount of phenolic was shown in the final flesh extract (34.47 ± 0.19 mg GAE·g−1 dm) compared to peel extract (12.74 ± 0.42 mg GAE·g−1 dm). The antioxidant activity in final beetroot peel extract and flesh extract were 24.65 ± 1.42 mg ASE·g−1 dm and 11.6 ± 0.1 mg ASE·g−1 dm, respectively. The recovery of thermo-sensitive bio-colorants was achieved by membrane filtration with the least thermal degradation.

Performance of nanofiltration process during concentration of strawberry juice

The aim of this study was to evaluate the microfiltration and nanofiltration of strawberry juice. Processes performance was evaluated in terms of resistances-in-series, flux decline modeling and extract quality (maintenance of the phenolic compounds). The results obtained showed that concentration polarization is the main resistance to permeate flux in nanofiltration process, representing around 95% of the total resistance. Microfiltration process suffered more influence of the concentration polarization and fouling, next to 47% for both resistances. For all the processes, Hermia's pore blocking models presented good fitting, with R² over 0.85. The same behavior was observed for a conjugated model which provided a realistic description (R² > 0.76). Also, nanofiltration process allowed phenolic compounds maintenance, demonstrating the efficiency of this process for strawberry juice concentration.

Membrane-based zero-sludge palm oil mill plant

The palm oil industry is one of the most important agro-industries for tropical countries because of the unique properties and wide range of uses of palm oil for various end products. In a palm oil extraction process, a large quantity of water is required, of which half the quantity will end up as effluent. This palm oil mill effluent (POME) has an extremely high content of organic matter, which can cause severe pollution of waterways and other environmental problems. Disposal of this highly polluting effluent has become a major problem for the palm oil mills. Therefore, several methods have been proposed either to treat the POME so it could comply with environmental regulation while discharged or to recover water and other valuable components from the effluent. Membrane technology has emerged as a feasible alternative to conventional treatment in vegetable oil processing because of its attractive features such as low energy consumption, reduction in the number of processing steps, high separation efficiency, and improvement of the final product quality. In the case of POME treatment, an integrated membrane-based process promises efficient water recycling and total solid recovery from the effluent, thus eliminating the environmental problem. Recently, a novel concept combining oil–oil extraction and continuous filtration using a superhydrophobic membrane has been proposed to achieve a zero-sludge palm oil mill. In this concept, the huge wastewater effluent generated from the conventional process can be eliminated and the palm oil milling process simplified. Furthermore, the superhydrophobic membrane enables the production of high-purity palm oil. In this paper, we review the prospect of a zero-sludge palm oil mill concept and strategies to achieve the proposed concept. In addition, we also highlight the development of the superhydrophobic membrane and phytonutrient recovery.