Biodegradation of PAHs by The Mixed Cultures of Diesel Degradation Bacteria

Abstract

Polycyclic aromatic hydrocarbons or polyaromatic hydrocarbons (PAHs) is an organic compound in hydrocarbon group. This structure is two or more aromatic rings without heteroatoms. The most abundant groups of aromatic compounds occurring in diesel fuels are naphthalene. Three strains of diesel-degrading bacteria including Achromobacter insolitus, Candida spp and Xanthobactor polyaromatici yorans was proved as high capability to degrade diesel. Thus, this study was aims to determine the optimal condition for growth up of diesel-degrading bacteria and diesel degradation efficiency. The experiment was conduct in batch experiment with the varied ratio of synthetic wastewater as nutrient and diesel concentration with surfactants (N:D) at 100:0, 80:20, 60:40, 40:60, 20:80 and 0:100. Then the optimal ratio of N:D was used to determine the effect of initial naphthalene concentration on naphthalene degradation. The different initial concentration of naphthalene was varied in the range of 0 to 100 mg/L. The results showed that the highest percent COD removal (100%) was found at N:D ratio 60:40 and 0:100 followed by N:D ratio 40:60 at 96.7% and N:D ratio 80:20 and 20:80 at 97.4%, respectively. The different of nutrient added was affected the growth of biomass. The highest biomass yield was found in N:D ratio 20:80. The growth of biomass depended not only diesel but also glucose in nutrient. Glucose play as a cometabolism for growth up bacteria. The initial concentration naphthalene was affected the growing of biomass and the efficiency of naphthalene degradation. The highest naphthalene degradation efficiency (99.8%) was found at initial napthalene concentration at 20 mg/L.