Application of a low-cost biosurfactant in heavy metal remediation processes

The industrial interest in microbial surfactants has intensified in recent years due to the characteristics of these compounds, such as biodegradability, low toxicity, and effectiveness in removing heavy metals and hydrophobic organic compounds from soil and water. This paper describes the productio...

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Bibliographic Details
Published in:	Biodegradation (Dordrecht) Vol. 30; no. 4; pp. 215 - 233
Main Authors:	da Rocha Junior, Rivaldo B., Meira, Hugo M., Almeida, Darne G., Rufino, Raquel D., Luna, Juliana M., Santos, Valdemir A., Sarubbo, Leonie A.
Format:	Journal Article
Language:	English
Published:	Dordrecht Springer Netherlands 01-08-2019 Springer Springer Nature B.V
Subjects:	Anions Aquatic crustaceans Aquatic Pollution Biodegradability Biodegradation Biomedical and Life Sciences Bioreactors Biosurfactants Contaminants Contamination Copper Corn Distilled water Economic analysis Electrical conductivity Electrical resistivity Emulsification Ethylenediaminetetraacetic acid Frying Geochemistry Heavy metals Hydrophobicity Kinetics Lead Life Sciences Manganese Metals Microbiology Microorganisms Molasses NMR Nuclear magnetic resonance Oil Organic chemistry Organic compounds Organic soils Original Paper Packed columns Pollutants Production processes Reaction kinetics Remediation Removal Saline water Seeds Sodium chloride Soil Soil pollution Soil remediation Soil Science & Conservation Solutions Stability Surface active agents Surface tension Surfactants Tension Terrestrial Pollution Toxicity Waste Management/Waste Technology Waste Water Technology Water Management Water pollution Water Pollution Control Yeast Yeasts Zinc Biosurfactant Environmental contamination Heavy metals Industrial residues Candida tropicalis
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Summary:	The industrial interest in microbial surfactants has intensified in recent years due to the characteristics of these compounds, such as biodegradability, low toxicity, and effectiveness in removing heavy metals and hydrophobic organic compounds from soil and water. This paper describes the production of a biosurfactant by the yeast Candida tropicalis grown in distilled water with 2.5% molasses, 2.5% frying oil and 4% corn steep liquor. The production of the biosurfactant reached 27 g/l in a 50-l bioreactor with a surface tension of 30 mN/m. Surface tension and engine oil emulsification assays demonstrated the stability of biosurfactant under extreme conditions of temperature and pH as well as in the presence of NaCl. Chemical structures of the biosurfactant were identified using GC–MS and NMR. The isolated biosurfactant was characterised as an anionic molecule capable of reducing the surface tension of water from 70 to 30 mN/m at 0.5% of the critical micelle concentration, with no toxic effects on plant seeds or brine shrimp. In tests involving both the crude and isolated biosurfactant for the removal of heavy metals from contaminated sand under dynamic conditions, the removal rates for Zn and Cu ranged from 30 to 80%, while the best removal rate for Pb was 15%. Tests in packed columns also confirmed the ability of biosurfactant to remove Cu and Zn at rates ranging from 45 to 65%. However, lead was not removed under static conditions. The removal kinetics demonstrated that 30 min was sufficient for the removal of metals and a single washing with the biosurfactant achieved greater removal efficiency. The use of the biosurfactant led to a significant reduction in the electrical conductivity of solutions containing heavy metals. The present findings as well as a brief economic analysis suggest the great potential of this agent for industrial remediation processes of soil and water polluted with inorganic contaminants.
ISSN:	0923-9820 1572-9729
DOI:	10.1007/s10532-018-9833-1