The effect of heterotrophic sewage bacteria of Mashhad on the removal of mercury from fluorescent lamp used in Mashhad

Abstract

Background and Aim: Today, fluorescent lamps are the most common light source in the world and Iran. Mercury in these lamps may enter the environment and cause harmful effects. The aim of the present study was to investigate the effect of heterotrophic wastewater bacteria on the mercury removal from fluorescent lamps. Materials and Methods: In this study, different components of lamps were separated using a crushing machine and then mercury was separated from phosphorus powder by acid washing. Bacteria isolated from wastewater were exposed to mercury from acid wash and the mercury content in the lamps was measured by atomic absorption spectrophotometer. The highest concentrations of mercury extracted from lamps was 86.03 ppb in the ratio of 4 HCL: 1 HNO3, and the lowest mercury concentration was14.03 ppb in the 1HCL: 1HNO3 ratio. Results: The results of this study showed that heterotrophic bacteria can reduce mercury levels to less than 5 µg / L. 19 bacteria purified from wastewater were resistant to mercury chloride at concentrations of 5 and 10 mg. Also, 10 bacteria were able to reduce mercury. The highest rate of mercury reduction (92.24%) was related to Pseudomonas marginalis and the lowest rate (62.47%) was related to Pseudomonas simiae. Conclusion: This study showed that heterotrophic sewage bacteria can be used as an efficient, low-cost, and environmentally friendly method for detoxification of mercury from out-of-date fluorescent lamps.

Keywords

• fluorescent lamp
• mercury
• biosorption
• heterotrophic wastewater bacteria