Influences of Aeration and Biological Treatment on the Fates of Aromatic VOCs in Wastewater Treatment Processes

Abstract

In this study, a lab-scale bioreactor experiment was conducted to investigate the fates of three aromatic hydrocarbons (benzene, toluene, and xylenes) in wastewater treatment processes, with respect to the differences among the species, together with the effects of aeration and the presence of activated sludge. The concentrations of the volatile organic compounds (VOCs) in the phases of air, water, and activated sludge in the bioreactor were analyzed to determine the respective chemical activities and to predict the possible transferring potentials of the VOCs among the three phases. Given appreciable levels of the VOCs being absorbed from the wastewater treatment plants (WWTPs) and their volatility, the directions of the transfers for these VOCs were from activated sludge to water and from water to air, indicating the importance of volatilization for the fates of VOCs in this reactor. The presence of activated sludge in the bioreactor had a positive effect on the transfers of the VOCs from air to water and from water to sludge, particularly for those VOCs with large octanol-water partition coefficients (K OW ). The effect of aeration on the fates of the VOCs was affected by factors including the Henry's law coefficients and K OW values of the VOCs, and the presence of activated sludge in the system. For the VOCs with large Henry's law coefficients and small K OW values, aeration reduced the concentration of the VOCs in the air and water phases more significantly, resulting in positive and negative impacts on the volatilization and biosorption/biodegradation of the VOCs in WWTPs, respectively, which was unexpected based on the design of the WWTPs for VOC removal.

Source Identification of VOCs in a Petrochemical Complex by Applying Open-Path Fourier Transform Infrared Spectrometry

“…The odor problems related to petrochemical plants are often caused by VOCs emitted from stacks, leakages from pipelines and tanks, production processes and wastewater treatment (Kalabokas et al, 2001;Huang et al, 2012;Chen et al, 2013). People living near a petrochemical complex can thus suffer from direct and indirect exposure to unpleasant odors.…”

Source Apportionment of Air Pollution and Characteristics of Volatile Organic Compounds in a Municipal Wastewater Treatment Plant, North Taiwan

“…VOCs are organic chemicals mainly composed of carbon atoms that are readily emitted to the atmosphere as gases due to the high vapor pressures resulting from their low boiling points (Chen et al, 2013). VOCs are also crucial precursors to secondary organic aerosols (SOAs) (Zheng et al, 2017).…”

Dissolved Oxygen Control in Activated Sludge Process Using a Neural Network-Based Adaptive PID Algorithm

“…In a large-scale wastewater treatment plant, intermittent aeration can reduce only a fraction of aeration energy. However, continuous aeration can effectively reduce the emissions of volatile organic compounds (VOCs) from a wastewater treatment plant, which has been proven as a factor for the increase of haze in some Chinese cities [39].…”