Effects of hydraulic retention time, co-substrate and nitrogen source on laundry wastewater anionic surfactant degradation in fluidized bed reactors

The aim of this study was to evaluate the influence of hydraulic retention time (HRT) on linear alkylbenzene sulfonate (LAS) removal in fluidized bed reactors (FBRs). FBR1 (HRT of 8 h) and FBR2 (HRT of 12 h) were fed laundry wastewater with 18.6 ± 4.1 to 27.1 ± 5.6 mg/L of LAS in the following conditions: ethanol and nitrate addition (Phases I, II and III), nitrate (Phase IV), ethanol (Phase V) and laundry wastewater (Phase VI). LAS removal was 93 ± 12% (FBR1) and 99 ± 2% (FBR2). In FBR1, nitrate influenced significantly on LAS removal (99 ± 3% - Phase IV) compared to the phase without nitrate (90 ± 15% - Phase V). In FBR1 the absence of ethanol was more favourable for LAS removal (99 ± 3% - Phase IV) compared to ethanol addition (87 ± 16% - Phase II). In FBR2, 99 ± 2% LAS removal was found up to 436 days. By microbial characterization were identified bacteria as Acinetobacter, Dechloromonas, Pseudomonas and Zoogloea.