Evaluation of different air dosing strategies to enhance H₂S removal in microaerobic systems treating low-strength wastewaters

Abstract

This study aimed to evaluate different air dosing strategies such as microaeration flow rates and air dosing points to enhance HS removal in microaerobic systems treating low-strength wastewaters. Efficiency and stability of the reactors, as well as biogas quality, were assessed, and microbial community changes were evaluated using the PCR-DGGE technique. The results showed that the air dosing point affected the HS concentration and that air dosing at the headspace promoted the highest HS removal efficiency. The airflow rate also affected the process, since HS concentration in the biogas was higher at 0.1 mL air.min than at 0.3 mL air.min. The methane concentration in the biogas was also affected by both air dosing point and flow rate, since the lowest value was observed at the highest airflow rate of the headspace dosing point, due to dilution by the N influx applied to the system. The highest productivity and operational efficiency were observed at this air dosing point, with this airflow (HD), which corroborates with the operational results and the ecological parameters, since the microaeration at this stage promoted high bacterial and archaeal species richness and diversity, optimum functional organization, high COD and HS removal efficiencies.