Algae from Cr-containing infiltrate bioremediation for valorised chemical production - Seasonal availability, composition, and screening studies on hydrothermal conversion.

Integrating bioremediation of toxic wastewater with value-added production is increasing interest, but - due to some essential problems - it is hardly applied in industrial practice. The aim of the study was an annual observation of the taxonomic and biochemical composition of various Cr-resistant algal communities grown in the existing Cr-containing infiltrate treatment system, selection of the most suitable algal biomass for infiltrates bioremediation and chromium-loaded algae conversion under mild subcritical conditions. Considering continuous availability and relatively constant chemical composition, Cladophora sp. was selected for utilisation in the chromium bioremediation system, simultaneously as a waste biomass source suitable for hydrothermal conversion. Screening studies conducted in a continuous pilot plant confirmed the possibility of selective extraction of saccharides and their separation from the metals remaining in the solid residual. The negligible concentration of metals in the obtained sugar-rich aqueous phase is essential for its further use in biotechnological processes.

Unique biocenosis as a foundation to develop a phytobial consortium for effective bioremediation of Cr(VI)-polluted waters and sediments.

This paper analyzes a unique, aquatic phytobial biocenosis that has been forming naturally for over 20 years and operating as a filter for Cr(VI)-polluted groundwater. Our study presents a thorough taxonomic analysis of the biocenosis, including filamentous algae, vascular plants, and microbiome, together with the analysis of Cr accumulation levels, bioconcentration factors and other environmentally-significant parameters: siderophore production by bacteria, biomass growth of the plants or winter hardiness. Among 67 species identified in the investigated reservoir, 13 species were indicated as particularly useful in the bioremediation of Cr(VI)-polluted water and sediment. Moreover, three species of filamentous algae, Tribonema sp., and three easily culturable bacterial species were for the first time shown as resistant to Cr concentration up to 123 mg/dm3, i.e. 6150 times over the permissible level. The work presents a modern holistic phytobial consortium indispensable for the remediation of Cr(VI)-contaminated aquatic environment in temperate zones worldwide.