Medidas de control de olores para un tanque homogeneizador de una planta de tratamiento de aguas residuales en Costa Rica

[Objective] This study aimed to evaluate the short-term response of four different odor control measures in a homogenization tank of a university Wastewater Treatment Plant (WWTP). [Methodology] The following were implemented: aeration, adding lime, adding iron sulfate, and adding the commercial product BiOWiSH® Odor over four hydraulic retention times. The effluent and the unit were monitored during each period, using a baseline to compare the measures. Hydrogen potential, oxidation-reduction potential, dissolved oxygen, and dissolved sulfide concentration were measured in triplicate every 30 minutes. An odor perception survey was administered to WWTP visitors to evaluate intensity, offensiveness, and character (15 surveys per monitoring period). Differences were determined between control measures and the baseline using Student’s t-tests (quantitative data) and Mood’s median tests (qualitative data). Minitab 2019 was used with a 95% confidence level. [Results] All control measures significantly reduced the dissolved sulfide concentration in the unit. Aeration prevented oxygen depletion, reductive regime, and acid fermentation, which favored the oxidation of odorants. Aeration was also the only studied control measure that reduced odor intensity and offensiveness. [Conclusions] Applying aeration changed unit behavior and odor perception, which confirms its effectiveness, while adding iron sulfate, lime, and BiOWiSH® did not significantly change odor perception.