APLICACIÓN DEL RAMNOLÍPIDO PRODUCIDO POR PSEUDOMONAS AERUGINOSA, EN EL LAVADO Y BIODEGRADACIÓN DE COMPUESTOS PRESENTES EN SUELOS CONTAMINADOS CON HIDROCARBUROS DEL PETRÓLEO

Abstract

The soil washing or supplemented with rhamnolipids biostimulation have been recent alternative to remediate contaminated soils because rhamnolipids are biodegradable, nontoxic and stable temperature, pH and salinity extremes, despite their separation and purification costs are high so has been proposed that non-purified rhamnolipids remediation. In the present study were produced 100 mg/L of rhamnolipids by P. aeruginosa in olive oil as carbon source and by drying the culture broth at 75 °C for 96 h generated a powder containing 0.19% (w / w), rhamnolipid also measured the effect on its CMC in water two levels of purity (filtered with 0.45 μm membrane and direct) in the presence of 0.5 to 2 mM Ca2+ or Fe3+ and pH 4 to 10, finding that the CMCs were similar to those reported in literature for pure rhamnolipids. Then, rhamnolipids were used for washing soil contaminated with 6500 mg/kg of TPH and another with As, Cu and Zn with 130, 41458 and 151 mg/kg, respectively. With less than 176 mg/L of rhamnolipids was removed HTP 80% compared with the removal of SDS (75.3%) and tween 80 (69.4%) at a concentration of 1250 mg/L, showing greater efficiency at low concentrations and removal evaluated TPH 0.074 to 7.9 times the CMC of rhamnolipid, suggested that hydrocarbons are removed by mobilization. On the other hand, the rhamnolipids evaluated from 17.6 to 1760 mg/L removed As, Cu and Zn at low concentrations due to acid soil pH affected the complexation, whereas the removal was correlated with the properties of metals as follows: atomic radius<atomic number<atomic weight<radius ionic< covalent radius<< density<<affinity constant first <ionization potential, the correlations were obtained with Excel in Office. It has been studied the kinetics of biodegradation of TPH, it was observed that the constants of the biodegradation rate increased from 0.72 to 1.64 week-1 in the presence of 0.155 mg/L of rhamnolipids, but decreased to 1.21 week-1 with 0.775 mg/L, also this value was similar to that obtained with tween 80 at the same concentration (1.42 week-1). In parallel, we applied three types of rhamnolipids (different value of CMC) in the biodegradation of TPH by biostimulation, based on 3-dose and 3 different temperatures, finding that removal is affected according to the following equation: removal (%) = 76.75 + 0.223 (CMC) - 6.16 (Servings) - 0.39 (temperature).