Enhancing efficiency of biological contact oxidation reactors through filaments optimization of basalt fibers bio-carriers: Insights from a pilot-scale study

Abstract

There has been significant interest in using Modified basalt fibers (MBF) based bio-carriers in biological contact oxidation reactors to enhance biological remediation while minimizing secondary pollution and carbon footprints. These MBF filaments form a unique spherical structure called “bio-nest,” which supports diverse microbial communities and facilitates various biogeochemical processes. However, impact of different structural alignments of the filaments within the bio-nest on system performance has not been fully understood. To address this question, this study investigated the variable spatial structures of MBF filaments using response surface methodology. The MBF carrier media were retrofitted in a pilot-scale bio-contact oxidation reactor (R-MBF) under multiple runs, and optimal parameters for the spatial distribution were identified. The optimal parameters were identified as 17.27 cm for horizontal spacing, 15.04 cm for vertical spacing, and 62.51 % for filling ratio at 6 h of HRT. R-MBF demonstrated successful treatment performance, achieving a total nitrogen removal rate of 0.231 kg/m3/d simulated by the modified Stover-Kincannon model. Denitrifying and decarboxylating bacteria, heterotrophic nitrifying-aerobic denitrifying bacteria, ammonia-oxidizing bacteria, and nitrite-oxidizing bacteria were likely involved in pollutants transformation. The findings of the study emphasize the significance of filament optimization prior to installation as it may improve the efficiency of system's performance.