Development of a novel filter-incubation system encompassing oil palm empty fruit bunch biosorbent and antartic microalgae for diesel removal

Diesel is commonly used as a fuel in Antarctica to enable human activities. However, the increasing demand for diesel raises the risk of oil contamination due to accidental events, which can threaten the Antarctic environment. Through the provisions of the Antarctic Treaty, the environment in Antarctica is protected by the implementation of steps to combat and minimise fuel pollution, as required under the Protocol on Environmental Protection to the Antarctic Treaty. Across the continent of Antarctica, chronically low temperatures can reduce the rate of hydrocarbon attenuation, making pollution management challenging in isolated and extreme regions. The current oil remediation technologies have the potential to generate secondary pollution as they are unable to make use of the biomass. New bioremediation approaches adopted for removal of diesel in Antarctic that are environmentally friendly are required. Therefore, there has been increasing interest in the potential for using agricultural waste as a biosorbent. The empty fruit bunch (EFB) produced from oil palms, a cost-effective material, contains cellulose-related materials that have shown good results in trial pollution treatments. In parallel, studies of the potential for remediation of diesel pollution in the Antarctic using indigenous microalgae remain limited to date, while the optimised conditions required are yet to be determined. This study’s central goal was to combine evaluation of the diesel-sorption capabilities of EFB and diesel-degrading capabilities of native Antarctic microalgae in a filter-incubation system designed to remove diesel and contribute to potential bioremediation efforts in Antarctica. In this study, EFB was screened using conventional analysis, one-factor-at-a-time (OFAT) and statistical analysis, response surface methodology (RSM), whereby the effects of EFB on diesel biosorption were characterised. The optimum conditions for EFB diesel biosorption were determined to be 172ºC with 19.4 min heating time, 0.096 g/cm3 packing density and 10% initial diesel concentration. The predicted model was highly significant (R2 = 0.9987) and four interactions, between temperature and packing density, temperature and diesel concentration, time and packing density, and packing density and diesel concentration, were confirmed to significantly affect the diesel biosorption. Using pre-heat treated EFB, 25.33 mL of oil was successfully absorbed from an initial volume of 40 mL. The EFB sample was subjected to morphological and chemical content analysis relating to diesel biosorption. For bioremediation of diesel hydrocarbons, an Antarctic microalgal (strain WCY_AQ5_2) was screened, identified and characterised using conventional OFAT and statistical RSM analysis. The optimal degradation conditions were 1% diesel concentration, 11.17 mg/L NaCl concentration, pH 6.22, 0.415 g/L NaNO3 and photoperiod of 12:12 h L/D. The predicted model was highly significant (R2 = 0.9848) and confirmed that the parameters of salinity and pH significantly influenced diesel biodegradation. Diesel biodegradation of 66.08% was achieved within 7 d incubation period. Morphological and molecular examination supported that strain WCY_AQ5_2 represents the species Chlorella vulgaris. The effect of heavy metal contamination (Ag, Al, As, Cd, Co, Cr, Cu, Ni, Pb and Zn) on the degradation of diesel was further assessed and analysed by assessing their half-maximal inhibition concentration (IC50). The findings demonstrated that Cr, Cu and Ag inhibited the degradation of diesel by more than 50%, with IC50 values of 3.165, 3.371 and 4.205 ppm, respectively. These findings were then integrated into the development of a filter-incubation system that uses EFB as the sorbent with optimum packing density (0.1 g/cm3) in the filter press machine in combination with the native Antarctic microalgal strain WCY_AQ5_2 in a light incubation tank illuminated with optimum red light that boosted the alga’s ability to degrade diesel to 70.7%. The novelty of this study is the used of the bioremediatory agents, EFB as biosorbent and native Antarctic microalgal as diesel degrader integrated in a novel filter-incubation system for diesel removal. The findings of this study help advance the diesel biosorption and bioremediation techniques currently available in Antarctica.

Text 122749.pdf Download (1MB) Official URL or Download Paper: http://ethesis.upm.edu.my/id/eprint/18651

Actions (login required)

View Item