Removal of recalcitrant compounds using iron-reducing bacteria

• Main Author: Lim, Wan Fen.
• Other Authors: Volodymyr Ivanov
• Format: Final Year Project
• Language: English
• Published: 2010
• Subjects: DRNTU::Engineering::Environmental engineering::Water treatment
• Online Access: http://hdl.handle.net/10356/38925
• Institution: Nanyang Technological University

Recalcitrant compounds are hard to degrade in the natural environment and may cause harm to the environment if left to accumulate. Current wastewater treatment technologies may be too costly or not effective enough to remove these compounds. The aim of this research was to study the conventional wastewater treatment and improve with innovative methods to increase the efficiency and effectiveness of the removal of recalcitrant compounds. The method uses anaerobic bacteria in the anoxic treatment of wastewater from soft drink production. The recalcitrant compound used was sucralose, an artificial sweetener that has increasing usage in food industries. Removal of recalcitrant compounds can be done through microbial-mediated oxidation or reduction under aerobic or anaerobic conditions. Natural iron ore was used as the iron source and model wastewater polluted with sucralose was used as the medium. Adsorption tests were also carried out to determine the adsorption capacity of iron ore as compared to granulated activated carbon (GAC). Adsorption was also carried out at various pH. Lastly, aerobic cultures were carried out on wastewater heated for different durations to test the effects of heat on removal of total organic carbon (TOC). TOC concentration, pH, TOC, total ferrous production and true color were used as parameters for analysis. Based on the studies, treatment of wastewater under anaerobic conditions were unsuccessful. In the adsorption tests, using GAC for the adsorption of TOC is more effective and more economical than using natural iron ore. The optimum pH for adsorption using iron ore was found to be pH 6 to 10. For the experiment to test the effects of heat on biodegradation TOC was removed under aerobic conditions. Further tests using the bacteria isolated shows that the bacteria was ineffective for removing TOC, hence TOC may decrease due to the degradation of other compounds apart from the recalcitrant compounds.