Biodegradation of linear alkylbenzene sulfonate in commercial laundry wastewater by an anaerobic fluidized bed reactor

Abstract

The biodegradation of linear alkylbenzene sulfonate (LAS) from commercial laundry wastewater was evaluated in an anaerobic fluidized bed reactor (FBR) fed with synthetic substrate (598 mg L⁻¹ to 723 mg L⁻¹ of organic matter) supplemented with 9.5 ± 3.1 mg L⁻¹ to 27.9 ± 9.6 mg L⁻¹ of LAS. The average chemical oxygen demand (COD) removal efficiency was 89% and the biodegradation of LAS was 57% during the 489 days of anaerobic FBR. Higher levels of volatile fatty acids (VFA) were observed in the effluent at the stage with the best LAS removal performance. Increasing the surfactant concentration did not increase the VFA production in the effluent. The predominant VFAs after the addition of LAS were as follows: isovaleric acid and valeric acid, followed by propionic acid, caproic acid and formic acid. The similarities of 64% and 45% to Archaea and Bacteria domains were observed in the samples taken in the operating period of anaerobic FBR fed with 23.6 ± 10 mg L⁻¹ and 27.9 ± 10 mg L⁻¹ of LAS. During the operation stages in the reactor, Gemmatimonas, Desulfobulbus and Zoogloea were determined as the most abundant genera related to surfactant degradation using 454-Pyrosequencing.

Keywords:

• Anionic surfactant
• co-substrate
• LAS
• microbial diversity
• sucrose pyrosequencing

Funding

The authors gratefully acknowledge the Laboratório de Processos Biológicos – LPB/EESC/USP, Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) process number 2010/11531-9 and the Conselho Nacional Desenvolvimento Científico e Tecnológico (CNPq) for their financial support.