Investigation of TNT red wastewater treatment technology using the combination of advanced oxidation processes.

Different types of advanced oxidation processes and their combinations such as O3/H2O2/UV, O3/Fenton/UV, O3/TiO2/UV, Fenton/H2O2/UV, Fenton/TiO2/UV, TiO2/H2O2/UV, TiO2/H2O2/O3/UV, TiO2/O3/Fenton/UV, TiO2/H2O2/Fenton/UV and O3/H2O2/Fenton/UV were studied for the treatment of undiluted red wastewater from Z113 Factory. The treatment efficiency was evaluated by analyzing chemical oxygen demand (COD) reduction, % degradation of α-TNT, 2,4-DNT, 2,6-DNT, 2,4-DNT-3-SO3Na and 2,4-DNT-5-SO3Na. Among studied processes Fenton/TiO2/O3/UV was the most effective technology to treat red wastewater. It allows to reduce >99% of COD, α-TNT, 2,4-DNT, 2,6-DNT, 2,4-DNT-3-SO3Na and 2,4-DNT-5-SO3Na after 30 h of treatment with optimum operating conditions: rotation speed of 600 rpm, pH of 4 and temperature of 40 °C. According to the chromatograms obtained by gas chromatograph/mass spectrometer (GC/MS), intermediates of the decomposition of pollutants in red wastewater were identified. GC/MS, HPLC, UV-vis and Bacterial Toxicity test were used to assess effluent quality changes before and after treatment. By economic analysis, the studied process had the potential to apply in practice to treat real wastewater at the Z113 Factory.