Remediation of soil contaminated with copper using Rhamnolipids produced from Pseudomonas aeruginosa MTCC 2297 using waste frying rice bran oil

Abstract

Rhamnolipids production by Pseudomonas aeruginosa MTCC 2297 was studied, using waste frying rice bran oil as carbon substrate. Response surface methodology was employed to arrive at the optimum production condition. Maximum rhamnolipids production (7.6 g/l) was attained with waste frying rice bran oil at 34.8 g/l, with sodium nitrate at 3.9 g/l. Optimum temperature and initial pH were found to be 34°C and 7.4. Batch washing experiments were used to evaluate the efficiency of rhamnolipids on remediating copper-contaminated soils. Synthesized rhamnolipids were used at different concentrations from 0.5 to 2% with and without 1% sodium hydroxide at a fixed ratio of 4:1. It was found out that 2% rhamnolipids removed 71% and 74% of copper from soil with initial concentrations 474 and 4,484 ppm, respectively. The use of waste frying oil in the production of rhamnolipids which was used in the bioremediation of copper-contaminated soil results in an environmentally friendly, cost-effective, and specific alternative to various physical and chemical methods of remediating polluted soil.