Removal of odorous compounds in wastewater by using activated carbon, ozonation and aerated biofilter

Abstract

Activated carbon, ozonation and aerated biofilters were applied to eliminate odor-causing compounds that occur in wastewater and effluents from the activated sludge process. Odorous organics used in this experiment were sulfur containing odorous compounds which include carbon disulfide, methyl mercaptan, dimethyl sulfide and dimethyl disulfide, and nitrogen containing compounds such as ammonia, trimethylamine, dimethylamine and n-propylamine. The removal of sulfur containing odorous compounds by activated carbon, was very effective compared to nitrogen containing compounds under the same experimental conditions. Sulfur containing substances were oxidized with ozone rapidly, while the reaction of low aliphatic amines with ozone occurred slowly. Methane sulfonic acid was converted from methyl mercaptan through dimethyl disulfide by ozonation. Ammonia and trimethylamine was converted to nitrate and nitromethane by ozonation, respectively. More than 80% of the sulfur and nitrogen containing malodorants were removed by acclimated microorganisms in an aerated biofilter at about 30 min of hydraulic retention time. Neither carbon disulfide nor dimethyl disulfide were removed at all in the biofilter without aeration. Conclusively, the aerated biofilter was the most acceptable process for eliminating sulfur and nitrogen containing odorous compounds in wastewater as it produced none of the oxidized organics noticed with ozonation, and it had an equally high removal efficiency for both sulfur and nitrogen containing odorous compounds.