Removal of volatile organic compounds (VOCs) emitted from a textile dyeing wastewater treatment plant and the attenuation of respiratory health risks using a pilot-scale biofilter

Abstract

The textile dyeing is a significant worldwide economic pillar of the industry mainstay of the region’s industrial economy. Therefore, significant attention should be paid to its emitted volatile organic compounds (VOCs) regarding their potential adverse effects on ecosystems and human health. In this study, a spray tower (ST) (preferential elimination of hydrosoluble VOCs) and biofilter (primary removal of particle-free VOCs) were used in combination. Three techniques, including gas chromatography-mass spectrometer (GC-MS), e-nose, and Proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS) were used to accurately identify the associated VOCs profile. In total, 50 types of VOCs, with total concentrations ranging from 1.26 to 2.79 mg m−3, were detected from the outlet of the TDWTP over a 90-day treatment period. The highest level occurred for nitrogen- and oxygen-containing compounds (NAOCCs), followed by aliphatic hydrocarbons (AIHs), aromatic hydrocarbons (AHs), and halogenated hydrocarbons (HHs). Average removal efficiencies (REs) of the four studied VOC groups (NAOCCs, AIHs, AHs, and HHs) were 66.7%, 67.9%, 11.7%, and 52.1%, respectively. Proteobacteria dominated the biofilter, followed by Actinobacteria, Firmicutes, and Bacteroidetes. A positive correlation was observed between the relative abundance of Proteobacteria and the RE of NAOCCs, with RE significantly increased from 38.1% (day 1) to 83.2% (day 90). The degradation of these organic pollutants, such as NAOCCs, may be mainly performed by the dominant genus, such as Acidithiobacillus and Metallibacterium, as predicted by PICRUSt. A respiratory health risk evaluation demonstrated that the cancer and non-cancer risks of typical VOCs were dramatically reduced after the above-mentioned purification. The combined results indicate that the ST-biofilter is an efficient approach for the end-of-pipe treatment of exhausted gas in TDWTP and helps attenuate human health risk.