PMC

Rolling tank experiments to generate aggregate formation. (A) Rolling tanks containing shrimp pond water with molasses (brown) and without molasses (green); (B) aggregates without molasses in cylindrical tanks; (C) collection of aggregates; (D) collected aggregates based on their sizes which are smaller than 3 mm and in size of 3 mm to 5 mm.

Time course of biomass production, lipid yield and lipid content by R. kratochvilovae SY89 using molasses as a substrate in stirred tank bioreactor. Error bars in the figures represent standard deviation

Overview of the various biotechnological processes (BSer process, UASB reactor, ABMet, and MBfR) used to remove SeO₄²⁻, SeO₃²⁻, and heavy metals from wastewater or process water. In the BSer process, SeO₄²⁻ and SeO₃²⁻ are reduced to elemental selenium by biofilms of propriety microorganisms, using molasses as the carbon source and electron donor (). In the UASB reactor, carbon (i.e., adipic acid, acetic acid, ethanol, or formic acid) and phosphorus sources are added to facilitate microbial growth and reduction of Se oxyanions to elemental selenium. ABMet consists of a biofilter tank, backwash effluent tank, wash waste tank, and nutrient dosage tank. SeO₄²⁻ and SeO₃²⁻ are reduced to insoluble Se⁰ in a biofilter, and a backwash is performed to remove elemental selenium from the biofilter. Molasses-based nutrients were added to self-sustain biofilm growth and microbial reduction of Se oxyanions (, ). In MBfRs, selenium oxyanions are bioreduced to elemental selenium by the autotrophic biofilm, using H₂ as the electron donor ().

Analysis of microbial communities of bio-oxidation reactors (40 °C): (a)—total number of microbial cells (10⁷ cells/mL); results of molecular biological analysis of microbial populations: (b)—reactor 1 (CO₂); (c)—reactor 2 (molasses); (d)—reactor 3 (control).