Part B: Advances in gas emission control techniques for anaerobic-based STPs Technical Note 3 - Recovery dissolved gases in effluents from anaerobic reactors by means of vacuum degasification

During anaerobic sewage treatment, it is estimated that 30% to 40% of the total CH4 produced is dissolved in the liquid phase, being ultimately released to the atmosphere if control measures are not used. In addition, part of the hydrogen sulfide (H2 S) generated in the process also remains dissolved in the sewage, being easily released and causing routine problems with bad odors and corrosion. Different technologies have been explored in the literature for the removal of dissolved gases, as detailed in this Collection of Technical Notes (TN). This TN aims to present the use of vacuum degasification reactors for recovery of CH4 and H2 S dissolved in effluents from anaerobically treated municipal wastewater. The following content is presented: (i) fundamentals of the process; (ii) dimensioning example; (iii) a case study of a system at pilot scale.