Influence of pH and concentration on the growth of bacteria - fungus and benzo[a]pyrene degradation

Abstract

The bioremediation method has been widely used in wastewater treatment. The fungi and bacteria have been recognized as useful bioremediation agents. Benzo[a]pyrene, the polycyclic aromatic hydrocarbons (PAHs), was used in this study, degraded by Sphingobacterium spiritivorum and Aspergillus brasiliensis. Here, the batch culture experiment has been executed to evaluate the optimum condition of pH and benzo[a]pyrene concentration towards the bacteria and fungus growth. Later, the statistical method of response surface methodology (RSM) was performed to fit the experimental results with the study’s parameters. From the experimental results, the optimum conditions were found to be at pH 6 and 40 mg/L benzo[a]pyrene concentration, which yields the maximum growth of 4.37E+07 CFU/ml bacteria and 0.254 g/l fungi growth, respectively. The percentage removal of benzo[a]pyrene in the batch experiment was 38.98% under bacteria consumption and 44.14% by the fungi bioremediation process. In comparing with RSM, the optimum conditions evaluated from the model were found to be at pH 6.41 and 38.8 mg/L benzo[a]pyrene concentration, which the maximum growth of 4.46E+07 CFU/ml bacteria and 0.242 g/l fungi, accordingly. To fit the model, the percentage of removal obtained was 41.9% benzo[a]pyrene degradation by bacteria and 42.34% of benzo[a]pyrene removal done by fungi. It has been denoted that the experimental and statistical models’ results were parallel and acceptable. Therefore, the ANOVA for all the results obtained was significant, which showed the reliability of the results. It can be deduced that the fungi exhibited a better removal percentage of benzo[a]pyrene than the bacteria in the wastewater.