Co-metabolic degradation of iomeprol by a Pseudomonas sp. and its application in biological aerated filter systems

ABSTRACT

The non-ionic water-soluble X-ray contrast agent iomeprol (IOM) enters the water supply through sewage treatment plants, which can cause considerable environmental harm. In this study, Pseudomonas sp. I-24 (I-24) was tested for its ability to remove IOM from water via co-metabolic pathways. The optimum removal rate of IOM by I-24 was 38.43% ± 3.70% when starch served as the source of external carbon, and its co-metabolism of IOM conformed to the first-order kinetics. The highest activity of intracellular enzyme (degrading enzyme) extracted from I-24 was 0.143 ± 0.005 mU in starch condition. The Michaelis constant of the degrading enzyme was found to be 91.08 μmol L⁻¹. However, glucose and maltose showed the best promotive effects on the growth and electron transport activity of I-24, indicating that overgrowth may result in competitive inhibition and a reduced degradation rate of IOM. Adding I-24 and degrading enzymes to biological aerated filters increased IOM removal rates without affecting COD_Mn removal.

KEYWORDS:

• Iomeprol
• non-ionic X-ray contrast agent
• co-metabolism
• trace organic pollutant removal
• degrading enzymes
• biological aerated filter

Funding

This study was supported by the Natural Science Foundation of Jiangxi Province (No. 20151BAB213018, 20161BAB214152), the National Natural Science Foundation of China (No. 21767013, 51562016, 31660205) and the Foundation of the Key Laboratory of Yangtze River Water Environment, Ministry of Education (Tongji University), China (No.YRWEF201502).