Bimodal platform encompassing cogon grass and Antarctic bacterial consortium for diesel removal in marine water systems

Cogon grass (Imperata cylindrica) is a resilient and invasive species that thrives in harsh conditions such as drought, salinity and waterlogging. Despite its abundance, cogon grass is often under-utilised and discarded as waste due to a perceived lack of economic value. This study explored the use of cogon grass to help address diesel pollution in cold marine environments where hydrocarbons persist longer due to low temperatures and harsh environmental conditions. Its high cellulose and hemicellulose content makes it an effective sorbent for hydrocarbons. The study aimed to synergistically enhance diesel removal efficiency by integrating cogon grass with a native Antarctic bacterial consortium, combining their strengths through establishing a novel bimodal system for diesel removal from marine environments. The study optimised the ability of cogon grass ability to absorb diesel by varying temperature, exposure time, packing density and oil concentration using established one factor at a time (OFAT) and response surface methodology (RSM) approaches. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analyses were carried out to confirmed hydrocarbon absorption. The RSM validation achieved 93.54% efficiency, absorbing 22.45 mL of oil at 128°C with a 36% oil concentration, a constant packing density of 0.20 g/cm3 and heating time of 30 min. After treatment and oil absorption, FTIR confirmed the absorption of hydrocarbons by identifying new functional groups (O-H, CH, C=C), while SEM analysis showed morphological changes in the cogon grass, including a roughened texture due to heat treatment, enhancing its effectiveness for oil absorption. The ability of the Antarctic bacterial consortium to remove diesel was also optimised, resulting in the following optimal parameters: 3% (v/v) inoculum size, 30 ppt salinity, 10°C temperature, pH 7.5, NH4NO3 concentration of 1 g/L, and initial diesel concentration of 3% (v/v). The RSM statistical model highlighted the significant impact of inoculum size, nitrogen concentration and diesel concentration on diesel degradation, achieving 79.63% removal within a 7 d incubation. Metagenomic analysis revealed Psychrobacter as the predominant bacterial genus present in the consortium post-diesel exposure, crucial for understanding its role in diesel degradation in polluted environments. Evaluation of the combined impact of heavy metal exposure revealed a 50% inhibition of diesel degradation, with IC50 values of 0.114 ppm for Co and 0.219 ppm for Ag, indicating substantial thresholds. Finally, kinetic studies validated the Aiba-Edwards model as providing the mathematically best description of microbial degradation kinetics. This study demonstrates the potential effectiveness and utility of combining cogon grass with Antarctic bacterial consortia to reduce diesel pollution in cold marine environments. This novel bimodal platform could provide an important advance in environmental cleanup, particularly in Antarctica's challenging conditions.

Text 125065 fulltext.pdf Download (1MB) Official URL or Download Paper: https://ethesis.upm.edu.my/id/eprint/18798

Actions (login required)

View Item