Nanofiltration and reverse osmosis as a platform for production of natural botanic extracts: the case study of carob by-products

Carob kibbles are a low-cost and renewable source of economically relevant phenolic compounds (high value catechin and its derivatives and gallic acid) and abundant in small sugars. This work aims at producing two distinct natural extracts from carob kibbles, one extract enriched in catechin and its derivatives for the nutraceuticals market and an extract enriched in sugars for the food industry. This valorisation strategy involves an integrated process based on membrane technology that fulfils the zero discharge principle and may be applied to other agro-industrial by-products. Different aqueous extraction schemes were considered (a one-step process and a two-steps approach). The aqueous extracts obtained were fractionated by diananofiltration and the fractions obtained were evaluated in terms of their content in target products. An integrated scheme for production of fractionated extracts is proposed based on the experimental work developed assuring, simultaneously, a minimal use of resources and emission of waste

Cellulose membranes in the treatment of spent deep eutectic solvent used in the recovery of lignin from lignocellulosic biomass

Ultrafiltration was employed in the purification of spent Deep Eutectic Solvent (DES, a mixture of choline chloride and lactic acid, 1:10, respectively) used in the extraction of lignin from lignocellulosic biomass. The aim of this was to recover different lignin fractions and to purify spent solvent. The results revealed that the commercial regenerated cellulose membranes—RC70PP and Ultracel 5 kDa UF membranes—could be used in the treatment of the spent DES. The addition of cosolvent (ethanol) to the spent DES decreased solvent’s viscosity, which enabled filtration. With two-pass ultrafiltration process with 10 kDa and 5 kDa membranes about 95% of the dissolved polymeric compounds (lignin and hemicelluloses) were removed from the spent DES. The utilized membranes also showed the capability to fractionate polymeric compounds into two fractions—above and under 10,000 Da. Moreover, the 10 kDa cellulose-based membrane showed good stability during a continuous period of three weeks exposure to the solution of DES and ethanol. Its pure water permeability decreased only by 3%. The results presented here demonstrate the possibility to utilize cellulose membranes in the treatment of spent DES to purify the solvent and recover the interesting compounds

Treatment options for nanofiltration and reverse osmosis concentrates from municipal wastewater treatment: A review

© 2019, © 2019 Taylor & Francis Group, LLC. Conventionally treated municipal wastewaters create environmental challenges due to eutrophication of effluent receiving waters and significant concentrations of micropollutants and other harmful impurities. To enhance purification, different tertiary membrane filtration technologies are utilized. The concentrate produced in membrane filtration is a voluminous waste stream, which further treatment is challenging. Also the valuable components in the concentrate remain typically unutilized. This review identifies potential treatment strategies for membrane concentrates originating from municipal wastewater treatment and evaluates approaches for value component recovery and waste minimization. Various technologies were examined as possible options for advanced concentrate treatment. Study concluded that electrodialysis processes or shear enhanced nanofiltration or reverse osmosis could be promising approaches to concentrate the valuable components, mainly nutrients, in concentrate. Few technologies were seen potential for value component recovery. These included ammonium recovery or struvite recovery with electrodialysis combined with crystallization or with struvite crystallization as well as calcium phosphate recovery with EPR process or with combined process of electrodialysis and crystallization. The concentrate recirculation back to the biological treatment can be enabled by concentrate oxidation which increases biodegradability. Combining these unit processes appropriately, an efficient strategy of membrane concentrate management can be implemented and even zero wastewater discharge achieved.status: publishe

Comparative evaluation of various lignin determination methods on hemicellulose-rich fractions of spruce and birch obtained by pressurized hot-water extraction (PHWE) and subsequent ultrafiltration (UF)

Abstract Various lignin determination methods have been applied to hemicellulose-rich wood extracts obtained after pressurized hot-water extraction (PHWE) and membrane ultrafiltration (UF). In focus were the chlorine number (Cl no.) method, the acetyl bromide method, and the four modifications of the Klason lignin determination, such as the KCL, TAPPI, LAP, and Goldschmid methods. The furfural (F) and hydroxymethylfurfural (HMF) concentrations in the acid hydrolysates were also determined. The mass balances of the fraction were calculated with respect to the contents of dry solids and lignin, including the acid-soluble lignin. The reliability of the methods was evaluated based on the lignin mass balances and the gross chemical composition of the extracts. Although the results were dependent on the method applied, the lignin mass balance calculations yielded similar results in general.</jats:p

Selective recovery of phenolic compounds and carbohydrates from carob kibbles using water-based extraction

Carob kibbles are an important renewable source of valuable compounds, such as fermentable sugars and phenolic compounds. However, the selective recovery of these compounds is not a trivial task. In this work, a strategy was developed to enable the recovery of both classes of compounds by means of awater-based extraction.One-step extraction recovered only approximately 20% of the phenolic compounds, corresponding to an extraction yield of 0.6 g Gallic acid equivalents (GAE)/100 g dry mass of carob kibbles. The obtained extract contained a significant amount of carbohydrates (110 g/L). The alternative two-step extraction developed enabled higher compound selectivity together with an increase in the yield of the phenolic compounds to about 70%, corresponding to 1.9 gGAE/100 g carob dry matter.The two-step extraction was easily scaled-up and is an effective method to obtain significantly sepa-rated carbohydrates and polyphenol-rich streams that can be further processed, e.g., in biorefineries orfood industries, respectively