High-throughput microrespirometric characterization of activated sludge inhibition by silver nanoparticles. Issue 5 (13th April 2018)

• Record Type: Journal Article
• Authors: Hernández-Martínez, Gabriel R.; Zepeda, Alejandro; Ordaz, Alberto; Sánchez-Catzin, Luis A.; Estrada-Díaz, Zaira D.; Thalasso, Frederic
• Is Part Of: Environmental science. Volume 4:Issue 5(2018)
• Page Start: 721
• Page End: 730
• Publication Date: 2018-04-13
• Subjects: Water-supply -- Periodicals; Water security -- Periodicals; Water resources development -- Periodicals; Water chemistry -- Periodicals; 553.705
• DOI: 10.1039/c7ew00563f
• Languages: English
• ISSNs: 2053-1400

Abstract

Abstract : This study present for first time the application of microrespirometric method to evaluate the effect of nanomaterial on biological process. Abstract : Silver nanoparticles (AgNPs) are widely used in a high number of industrial applications and are becoming prevalent in wastewater effluents. It is known that AgNPs exert a toxic effect on activated sludge processes, but to what extent and under which conditions are still largely unknown. The inhibitory effect of AgNPs on a synthetic wastewater treatment process was tested using pulse microrespirometry ( i.e., a pulse of substrate is injected into a microreactor system). Several conditions were tested, including AgNP concentration, substrate to biomass ratio ( S 0 / X 0 ) and exposure time. The inhibitory effects were quantified through the percentage of inhibition of the exogenous and endogenous respiration rates as well as through determination of the half saturation constant ( K S ), inhibition constant ( K I ) and maximum oxygen uptake rate (OURmax ). The results indicated that AgNPs exert uncompetitive inhibition and the concentration that caused a 50% of inhibition (IC50 ) of the exogenous respiration rate was 3.32 ± 0.16 mg L −1 . The inhibitory effect of AgNPs on the endogenous respiration was relatively lower, with an IC50 of 7.12 ± 0.11 mg L −1 . Overall, it was observed that an increase in the S 0 / X 0 ratio resulted in higher inhibition and that the inhibitory effects of AgNPs decreased with exposure time.