Aerobic Bioremediation of Fischer-Tropsch Effluent – Short Chain Alcohols and Volatile Fatty Acids

Aerobic degradation was used as a treatment method to reduce the high chemical oxygen demand (COD) found in Fischer-Tropsch (FT) wastewater. The compounds investigated were short chain alcohols (SCA) and volatile fatty acids (VFAs), they contribute up to 87.4%. When released into the environment, such high strength COD can cause detrimental effect to the environment. Synthetic FT wastewater were prepared in a mineral salt solution comprising of only SCAs and VFAs and a COD of 67.9 gCOD/L. Parameters investigated were temperature and substrate concentration (COD). A gas-chromatograph revealed that VFAs were degraded faster than SCAs. Bacteria found in natural wetland situated east of Gauteng province in South Africa and FT wastewater plant, were collected, studied and used in this study. It was observed that degradation was favoured at 35 °C with 90% COD removal within three days. At substrate concentrations of 0.13, 0.73 and 1.5%, the highest COD reduction was 91, 49 and 24% respectively. The isolates were sent for 16S rRNA sequence analysis which revealed that Bacillus sp. was the dominant species for degrading these compounds.