Biorecovery of Metals from a Stainless Steel Industrial Effluent through Denitrification Performed in a Novel Anaerobic Swirling Fluidized Membrane Bioreactor (ASFMBR)

Abstract

"A novel technology was developed for the treatment of a stainless steel wastewater, which contains high nitrate concentration (6.8 g N-NO3–/L), acidic pH (pH 3.3), and high concentration of metals. Denitrification was performed in an anaerobic swirling fluidized-bed membrane bioreactor (ASFMBR) with synthetic and real wastewater. The treatment concept was also integrated by a precipitation column in which high recirculation of the alkalinity produced from denitrification was introduced to drive the precipitation and recovery of metals present in the wastewater. The novel reactor configuration achieved high nitrate removal (>94%), and the acidic pH was efficiently neutralized in the reactor by recycling the alkalinity produced from denitrification. More than 40% of the metals present in the industrial wastewater was recovered. Membrane fouling was avoided by the hydrodynamic regime established in the ASFMBR. The treatment concept is promising to achieve an efficient removal of nitrate and recovery of metals from metallurgic wastewater."