Biodegradation of phthalate esters from synthetic wastewater in a batch operated internal loop airlift bioreactor

Abstract

In the present study, phthalate esters (PEs) (diethyl phthalate and dimethyl phthalate) containing wastewater was treated by aerobic bacterial strain isolated from soil contaminated with muncipal wastewater discharge site. The isolate was identified as Bacillus sp. on the basis of morphological, biochemical and molecular characteristics. An internal loop airlift bioreactor was designed and fabricated. Treatment of PEs containing synthetic wastewater by isolates was carried out for various initial concentrations in a batch mode. Growth kinetic study was performed by using various kinetic models and among them, Haldane model was found to fit well with the experimental data with coefficient of determination (R2) 0.95. Biokinetic constants indicated that the high concentrations of PEs inhibited the growth of bacteria. Dissolved oxygen was also measured during treatment and it was observed that the PEs biodegradation was oxygen limited. The isolated microbes of the present study are more potent in terms of tolerence and degradation efficiency than that reported in literature. The result of the study could be promising for the design and operation of airlift bioreactor in treating PEs containing muncipal wastewater.