Simultaneous Denitrification and Sodium Dodecyl Sulfate (SDS) Biodegradation by Pseudomonas citronellolis L11

Abstract

Sodium dodecyl sulfate (SDS) and nitrate (NO₃⁻) are prevalent contaminants in industrial wastewater that pose significant environmental threats to aquatic ecosystems. Strain L1 was isolated from anaerobic SDS-degrading denitrifying sludge and identified as Pseudomonas citronellolis based on the 16S rRNA gene sequence. This study investigated the capacity of strain L1 to biodegrade both contaminants simultaneously under three distinct oxygen conditions (anaerobic, anoxic, and aerobic environments). Strain L1 was a facultative bacterium capable of degrading NO₃⁻ and SDS simultaneously. At initial concentration of 100 mg/L NO₃⁻ and 200 mg/L SDS, NO₃⁻ removal efficiencies after 24 h were highest at 96.9% under anaerobic, followed by 56.6% under anoxic, and 10.8% under aerobic conditions. Additionally, SDS removal efficiencies were 76.4%, 99.8%, and 99.9% under anaerobic, anoxic, and aerobic conditions, respectively. Strain L1 also showed adaptation to SDS concentrations of 200-1000 mg/L and NO₃⁻ concentrations of 100-500 mg/L. After 24 h, the highest SDS degradation rate reached 29.37 mg/L/h at SDS of 1000 mg/L, while the maximum NO₃⁻ removal rate was 4.28 mgN/L/h at NO₃⁻ of 150 mg/L. These findings indicate the potential of strain L1 for biological treatment of wastewater contaminated with nitrogen compounds and anionic surfactants.