Reducing COD level on oily effluent by utilizing biosurfactant-producing bacteria

ABSTRACT

Two bacteria isolated from crude oil contaminated soil, Pantoea agglomerans and Planococcus citreus, produced biosurfactants utilizing 1.5 percent of kerosene and olive oil as the sole carbon sources, respectively. The bacteria and the biosurfactants produced were introduced to oily effluent, arising from margarine and soap industry. Emulsification activities were determined by increases in the absorbance of the oil-in-water emulsions at 610 nm, whereas the water-in-oil emulsions were expressed as the height (cm) of the emulsion layers formed. The 72 h incubation experiment resulted in a COD (Chemical Oxygen Demand) reduction of 76 percent with Planococcus citreus strain and 70 percent with Pantoea agglomerans.The COD reduction with bacterial biosurfactants was over 50 percent in 24 h of incubation. The COD reduction showed that these strains and the surfactants produced could be used in bioremediation processes.

RESUMO

Duas bactérias isoladas de solo contaminado com derivados de petróleo, Pantoea agglomerans e Planococcus citreus, produzem biosurfactantes utilizando respectivamente 1.5 por cento de querosene e óleo de oliva como únicas fontes de carbono. As bactérias e os biosurfactantes produzidos foram adicionados a um efluente oleoso obtido de uma indústria nacional de sabão e margarina. As atividades de emulsificação foram determinadas pelo aumento da absorbância das emulsões óleo em água a 610 nm, enquanto que as emulsões do tipo água em óleo foram expressas em centímetros, pela altura do halo de espumas formado. A redução da demanda química de oxigênio (COD) mostra que as linhagens e os biosurfactantes produzidos podem ser utilizados em processos de biorremediação.