Toxicity and biodegradation of 2,4-dinitrophenol and 3-nitrophenol in anaerobic systems

Anaerobic toxicity, biodegradability and kinetics of 2,4-dinitrophenol (2,4-DNP) and 3-nitrophenol (3-NP) were investigated. In an anaerobic toxicity assay (ATA), glucose and volatile fatty acids (VFA) were used as co-substrates. The test was operated at the temperature of 35 ± 1 °C. Accumulative methane production was used to judge the inhibition level of nitrophenols (NPs) on methanogenic bacteria. No obvious inhibitory effects were detected for 2,4-DNP and 3-NP at concentrations <25 and <5 mg l−1. About 10–74% of 2,4-DNP and 60–80% of 3-NP can be removed. Anaerobic treatment is an effective method for removal of 3-NP. The degradation kinetics experiments were conducted in batch mode. The data were analyzed by nonlinear regression to estimate parameters in the Haldane inhibition equation. Parameter values estimated for 2,4-DNP and 3-NP, were 65.0 and 426.8 mg/gVSS d for maximum degradation rates; 475.9 and 7445.7 mg l−1 for saturation coefficients, and 16.3 and 25.6 mg l−1 for inhibition coefficients, respectively.