title: Construction and evaluation of a modular biofilm-forming chamber for microbial recovery of neodymium and semi-continuous biofilm preparation. Tolerance of Serratia sp.N14 on acidic conditions and neutralized aqua regia.
abstract: Recovery of neodymium from liquid metallic wastes and scrap leachates is a crucial step for its recycling, which can take place through the immobilized biofilms of Serratia sp. N14. These biofilms are produced in a fermentor vessel with a turnaround time of 10-14 days, which is unacceptable from an economic point of view for an industrial process. This study proposes the construction and evaluation of a modular system, whereby a biofilm-forming chamber is inserted into the continuous biomass outflow of the main chemostat vessel, for an alternative semi-continuous and economic production of biofilm. The activity of the biofilm from the outflow chamber was found to be the same as the one from the main chamber, which was stored in a cold room (4°C), for 9-12 months, depending on a 24 h nucleation step.Moreover, the ability of the biofilm to function in the presence of a leaching agent (aqua regia) or in acidic conditions was also evaluated. The biofilm of the main chamber can remain active even at 50% neutralized aqua regia (pH 3.0), while at acidic conditions, phosphate release of the cells is reduced to 50%. This strain proves to be very tolerant in low pH or high salt concentration solutions. The biofilm produced from the outflow of the main fermentor vessel is of acceptable activity, rather than being disposed.
authors.affiliation: a Unit of Functional Bionanomaterials, Institute of Microbiology and Infection, School of Biosciences , University of Birmingham , Edgbaston, Birmingham , UK.
authors.forename: Dimitrios A
authors.initials: DA
authors.lastname: Vavlekas
mesh_terms: D018441:Biofilms; D019149:Bioreactors; D006851:Hydrochloric Acid; D006863:Hydrogen-Ion Concentration; D009354:Neodymium / Q000378:metabolism*; D017942:Nitric Acid; D010710:Phosphates / Q000378:metabolism*; D012705:Serratia / Q000254:growth & development / Q000378:metabolism*
chemical_list: D010710:Phosphates; D009354:Neodymium; D017942:Nitric Acid; D006851:Hydrochloric Acid; C022102:aqua regia
keywords: Neodymium; REEs; Serratia sp. N14; aqua regia; fermentor outflow; leachates