Impact of temperature and biomass augmentation on biosulfur-driven autotrophic denitrification in membrane bioreactors treating real nitrate-contaminated groundwater

• Published in: The Science of the total environment 2022-12, Vol.853, p.158470-158470, Article 158470
• Main Authors: Demir, Özlem, Atasoy, Ayşe Dilek, Çalış, Bedia, Çakmak, Yakup, Di Capua, Francesco, Sahinkaya, Erkan, Uçar, Deniz
• Format: Article
• Language: English
• Subjects: Autotrophic denitrification; Biogenic sulfur; Groundwater treatment; Membrane bioreactor; Nitrate; Temperature
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2022.158470

Nitrate (NO3−) contamination of groundwater is a major health concern worldwide as it can lead to serious illnesses such as methemoglobinemia and cancer. Autotrophic denitrification is a smart approach for treating groundwater, being typically organic-deficient. Lately, biogenic sulfur (S0bio) has emerged as a sustainable, free, and high-efficiency substrate to fuel membrane bioreactors (MBRs) treating contaminated groundwater. However, the effects of moderate temperature and biomass concentration on the performance and fouling of the S0bio-fed MBR were not investigated previously. This study shows that biomass levels of ~1 g MLVSS/L limit membrane fouling but also denitrification efficiency. Biomass augmentation up to 3 g MLVSS/L enhanced denitrification but worsened fouling due to increase of extracellular polymeric substance (EPS) levels in the bulk liquid. Temperature decrease from 30 °C to 20 °C halved denitrification efficiency, which could be partially recovered through bioaugmentation. The mechanisms affected by temperature decrease, practical applications, and future research needs were discussed. [Display omitted] •Membrane bioreactor with biosulfur was run at varying temperatures and biomass level.•Increasing biomass levels from 1 to 3 g cells/L enhanced nitrogen removal by >20 %.•Biomass augmentation increased transmembrane pressure and microbial product levels.•Temperature decrease from 30 to 20 °C reduced denitrification efficiency.•Biomass augmentation at 20 °C could effectively recover denitrification efficiency.