Insights into the Physicochemical Parameters, Microbial Community Structure, and Functional Variations in Biodegradation of N-Alkane Derivatives from Fischer–Tropsch Wastewater

Abstract

This study provides a theoretical baseline on the application of chemical and microbiological indicators as rapid system performance monitoring tools that will allow for timely corrective measures to maintain and improve the bioremediation performance of the Fischer–Tropsch wastewater (FTWW) treatment plants. Microorganisms isolated from the sediments and water samples collected from site 1 of Blesbokspruit wetland exhibited the highest biodegradation efficiency of up to 98.04% and 92.85%, respectively, in 96 h reaction time using batch culture media spiked with 300 ppm short chain n-alkane derivatives. The highest COD reduction rate was observed during the first 24 h of biodegradation, and it steadily declined thereafter. The decline in pH from 7.0 to 6.3 was observed in the 96 h reaction time and was attributed to the production of acidic secondary metabolites and the entrapment of the produced CO2 within the batch media. The ORP also declined from the aerobic zone to the anaerobic zone within 24 h (day 1) reaction time. The EC and TDS results were also indicative of the rate of consumption of essential nutrients during the biodegradation process, which could be related to biochemical reactions involved in biodegradation of n-alkane derivatives. Proteobacteria and Firmicutes were the prevalent phyla during the biodegradation of the n-alkane derivatives. Enterococcus and Escherichia genera were more dominant on most days of biodegradation, therefore, indicating that these genera were actively involved in the biodegradation process of the n-alkane derivatives. These genera displayed a positive correlation with EC, ORP, pH and TDS in the four days of biodegradation for batch cultures inoculated with microorganisms from the water and sediments samples collected from the Blesbokspruit wetland. The results obtained demonstrated that physicochemical and microbiological indices can be used to infer the biodegradation rates, patterns and system operations in FTWW bioremediation.