Influence of Magnetic Nanoparticles and Organic Loading Rates (OLRs) on the Behavior of Continuous Stir Tank Reactor (CSTR)

Abstract ABSTRACT In this study, the biocompatibility of iron oxide nanoparticles (Fe3O4 NPs) with a concentration of 75 mg/L was experimentally investigated with different organic loading rates (OLRs) in Continuous Stir Tank Reactors (CSTRs). The OLRs were started from the lowest concentration of 0.3 gVS/Ld to the highest at 1.3 gVS/Ld with an intermediate of 0.8 gVS/Ld. During this experimentation, the behavior of other parameters like pH, soluble chemical oxygen demand (sCOD), total volatile fatty acids (TVFAs) generation and degradation, total solids (TS) and VS removal were monitored along with CH4 generation. It was observed that the NPs efficiency was higher at the lowest OLR. The CH4 yield was optimal at 0.3 gVS/Ld, which was 725.9 mL/gVS and reduced to 652.02 mL/gVS in R1 (with NPs additives). However, R2 (without NPs) showed much-stabilized behavior and get increasing from 372.8 to 424.4 mL/gVS at 0.3 to 1.3 gVS/Ld of OLR, respectively. Moreover, the higher removal of sCOD, TVFAs, and TV/VS were archived in R1 at the shortest hydraulic retention time (HRT).