An aerobic sequencing batch reactor for 2,4,6-trinitrophenol (picric acid) biodegradation

Area of Science:

• Environmental microbiology
• Wastewater treatment engineering
• Bioremediation

Background:

• 2,4,6-trinitrophenol (TNP), also known as picric acid, is a hazardous explosive compound contaminating water sources.
• Effective and sustainable methods are needed to remove TNP from industrial wastewater and groundwater.

Purpose of the Study:

• To design and evaluate a bench-scale sequencing batch reactor (SBR) for the degradation of TNP.
• To assess the performance of the SBR under various temperature and influent concentration conditions.
• To determine the efficiency of TNP removal and the development of a stable biomass.

Main Methods:

• A sequencing batch reactor (SBR) was operated at bench scale.
• The SBR was seeded with Rhodococcus opacus strain JW01, a known nitroaromatic degrader.
• Experiments were conducted at temperatures of 25, 15, and 10 degrees C with TNP influent concentrations ranging from 40-200 mg/L.
• Kinetic growth modeling was performed to determine micro(max) and K(s) values.

Main Results:

• A stable biomass capable of degrading TNP was successfully developed.
• The SBR consistently achieved TNP removal efficiencies greater than 99.9% over 2000 hours of operation.
• TNP was degraded to levels below the regulatory drinking water limit of 0.057 mg/L.
• Kinetic modeling indicated micro(max) values of 0.14, 0.08, and 0.04 d(-1) at 25, 15, and 10 degrees C, respectively.
• Modeled K(s) values were 0.68, 1.11, and 1.24 mg/L at the tested temperatures.

Conclusions:

• The developed SBR is highly effective for the bioremediation of TNP-contaminated wastewater and groundwater.
• The system demonstrates robust performance across a range of temperatures and influent concentrations.
• The process achieves significant TNP removal, low residual dissolved carbon, and nitrogen release, meeting stringent environmental standards.