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

Fares Almomani,Rahul R Bhosale,María C Veiga,Eldon R Rene,Christian Kennes

doi:10.1016/j.jhazmat.2020.123735

Abstract

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 (Qgas), inlet DCM concentration ([DCM]i), residence time (τ), photocatalyst loading (PH-CL) and % relative humidity (% RH) on the AOPs performance and the removal of DCM (%DCMr) were studied and optimized. The UV process exhibited %DCMr ≤ 12.5 % for tests conducted at a [DCM]i ≤ 0.45 g/m3, Qgas 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 %DCMr ≥ 71 ± 1.5 % at Qgas of 0.06 m3/h, [DCM]i of 0.45 g/m3, τ of 55.2 s, PH-CL 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 %DCMr 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.

Highlights

Volatile organic compounds (VOCs) are present in industrial waste gases (IWGs) and it has a direct impact on human health and the envi ronment (Beauchet et al, 2007; Chen et al, 2016; Chlala et al, 2016; Kasperczyk et al, 2019; Zhong et al, 2017)
Accord ingly, this study investigates the use of destruction processes (UV and UV-TiO2), biological treatment (BT), and their combination (AOPs-BT) for the treatment of a WG stream contaminated with DCM
The SEM images of the TiO2-film presented in Fig. 2a clearly show the formation of a relatively rough TiO2 film deposited on the inner side of the annular photo-reactor (APHR)

Summary

Introduction

Volatile organic compounds (VOCs) are present in industrial waste gases (IWGs) and it has a direct impact on human health and the envi ronment (Beauchet et al, 2007; Chen et al, 2016; Chlala et al, 2016; Kasperczyk et al, 2019; Zhong et al, 2017). Health problems including sensory irritation symp toms, allergies, asthma, neurological and liver toxicity, and cancer were related to the exposure and inhalation of VOCs (Matejovaet al., 2013). Dichloromethane (DCM; CH2Cl2) was listed by the United States Envi ronmental Protection Agency (US EPA) and the European Environment Agency (EEA) as an extremely dangerous and toxic waste gas (WG) with a high environmental risk that requires well-organized treatment and control technologies (Directive, 2013; Ribeiro et al, 2015). DCM is regularly used in various industries including aerosol paint, urethane, plastic manufacturing, foam industries, and in elec tronic applications (electroplating, circuit boards, and metal degreasing) (Almomani et al, 2018; Bailon et al, 2009; Ribeiro et al, 2015)

Methods

Results

Conclusion