STRIPPING AND DISSIPATION TECHNIQUES FOR THE REMOVAL OF DISSOLVED GASES FROM ANAEROBIC EFFLUENTS

UASB reactors are a common technology for wastewater treatment. However, certain disadvantages must be considered. One of the disadvantages relates to the presence of dissolved gases, hydrogen sulfide and methane, in the effluent, which can potentially be released into the atmosphere. This can cause malodours and contribute to the greenhouse effect. In this perspective, this work investigated alternative techniques to minimize these disadvantages: air stripping inside the settling compartment; and a dissipation chamber immediately after the reactor outlet. Results achieved with the air stripping technique showed low removal efficiencies for methane, around 30%, and in the range of 40 to 60% for hydrogen sulfide. On the other hand, the removal efficiencies obtained with the dissipation chamber technique were much higher, consistently reaching 60% or more for both gases, plus a relatively lower exhaust flow. For the best operational condition tested, median removal efficiencies of 73 and 97% were observed for dissolved methane and dissolved sulfide, respectively.