Treatment of waste gas contaminated with dichloromethane using photocatalytic oxidation, biodegradation and their combinations

The treatment of waste gas (WG) containing dichloromethane (DCM) using advanced oxidation processes (AOPs) [UV and UV-TiO2], biological treatment (BT), and their combination (AOPs-BT) was tested. AOP tests were performed in an annular photo-reactor (APHR), while BT was conducted in a continuous stirred tank bioreactor (CSTBR). The effects of gas flow rate (Q_gas), inlet DCM concentration ([DCM]_i), residence time (τ), photocatalyst loading (PH-C_L) and % relative humidity (% RH) on the AOPs performance and the removal of DCM (�M_r) were studied and optimized. The UV process exhibited �M_r ≤ 12.5 % for tests conducted at a [DCM]_i ≤ 0.45 g/m³, Q_gas of 0.12 m³/h and τ of 27.6 s, respectively, and < 4 % when the [DCM]_i ≥ 4.2 g/m³. The UV-TiO₂ achieved a �M_r ≥ 71 ± 1.5 % at Q_gas of 0.06 m³/h, [DCM]_i of 0.45 g/m³, τ of 55.2 s, PH-C_L of 10 g/m², and %RH of 50, respectively. The BT process removed ∼97.6 % of DCM with an elimination capacity (EC) of 234.0 g/m³·h. Besides, the high �M_r of ∼98.5 % in the UV-BT and 99.7 % in the UV-TiO₂-BT processes confirms AOPs-BT as a promising technology for the treatment of recalcitrant compounds present in WG.

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Published in: Journal of Hazardous Materials
License: http://creativecommons.org/licenses/by/4.0/
See article on publisher's website: https://dx.doi.org/10.1016/j.jhazmat.2020.123735