Part B: Advances in gas emission control techniques for anaerobic-based STPs Technical Note 6 – Energetic use and burning of waste gas

Abstract

The techniques for controlling gaseous emissions in anaerobic-based STPs studied in this collection of Technical Notes (TNs) are based on the desorption principle of dissolved gases (e.g. CH4 and H2 S) in anaerobic effuent, through their transfer to a waste gas. The waste gas must be properly managed, for example through its degradation/ oxidation in biofilters (TN 5). This TN considers other approaches to manage the waste gas: (i) its energetic use mixed with biogas; and (ii) its use as a comburent in the burning of biogas. Through mathematical models, the operating conditions of the desorption systems required for both options were established. For option (i), values of the gas / liquid ratio (QG /QL in the desorption system) in the range of 0.03-0.10 are necessary, leading to an increase in the energetic potential in the range of 18 to 58%. For option (ii), it was determined that favourable conditions of biogas production are necessary, along with QG /QL values of less than 2.5.