Material Balance for Stepwise Extraction of Freshwater Algae Biomass with Heavy Metal Sequestration

Abstract

During our studies concerning the isolation of sulfated polysaccharides (SPs) from freshwater algae species widespread in Poland, an improved overall extraction methodology has been developed. This new, multi-step procedure allows for obtainment of several fractions that could find use in cosmetic and food industries, with the final one containing the valuable SPs, important both from economic and scientific perspective. Moreover, the process allows for easy use of typical chelating agents to remove harmful heavy metal ions without important losses in natural compounds of interest. Furthermore, a material balance has been established for said process, allowing for its easier implementation on bigger scales, and highlighting the areas which could still be improved to positively affect the final time-cost ratio of the methodology. Combined with previously published information concerning the detailed composition of obtained fractions, we aim to provide a robust and informative outlook on the potential of native freshwater algae species as cheap, raw and easily purifiable resource, usable in a number of important industries. According to the mass balance, nearly 5 % of dry mass of Cladophora glomerata is extractable with ethanol and this fraction consists mostly of fatty acids, phenolics and pigments. Another 5 % of mass can be isolated as pure SPs from aqueous fraction. Additionally, calcium from natural incrustations on the surface of C. glomerata amounts to 17 % of dry material weight and can be reclaimed from acidic wash by simple precipitation; such calcium salts have garnered significant interest as nutritional supplements.

Comparison of the Antioxidant Properties of Green Macroalgae from Diverse European Water Habitats by Use of Several Semi-Quantitative Assays

“…The active compounds extracted from algal thalli may depend on the type of algae material, site and time of collection (which determines growth parameters, such as temperature, sunlight exposure, water pH and salinity) [36]. Moreover, the yield of extraction (per dry mass) depends also on the presence of encrustations, mainly calcium carbonate [37], and epiphytes-other algae species, mainly microalgae [25,38]. Although a comparison of biomass growth of green algae from different water habitats was not the main aim of this study, it is worth noting how many different factors have a significant impact on the yield of extractions.…”

“…carbonate [37], and epiphytes-other algae species, mainly microalgae [25,38]. Although a comparison of biomass growth of green algae from different water habitats was not the main aim of this study, it is worth noting how many different factors have a significant impact on the yield of extractions.…”

“…In order to explain the low yield of Cladophora glomerata (CA) extraction, a sample of this algae was subjected to de-incrustation. The weighted sample of the algae was carefully washed with a solution of acetic acid, dried and weighted again (the procedure is described in detail in [37]). After elimination of incrusts, composed mainly of calcium carbonate, the dry material lost nearly 45% of its weight.…”