Surfactant removal from commercial laundry wastewater in co-digestion with domestic sewage using a pilot scale anaerobic reactor

Author(s)

Alana Gandra Lima de Moura

• Document type: Master's Dissertation
• Press: São Carlos.
• Institution: Universidade de São Paulo (USP). Escola de Engenharia de São Carlos (EESC/SBD)
• Defense date: 2017-09-22

Examining board members

Maria Bernadete Amancio Varesche Silva; Nelma Regina Segnini Bossolan; Lorena de Oliveira Pires

• Advisor: Maria Bernadete Amâncio Varesche

Abstract

Classified as an emergent contaminant, Alkylbenzene Linear Sulfonate (LAS) is an anionic surfactant of high priority given its environmental risk. Previous studies reported LAS anaerobic degradation from laundry wastewater in co-digestion with synthetic substrates (such as methanol, ethanol and yeast extract). However, studies with more economic viable substrates as domestic sewage still lacking. This study assessed LAS removal from laundry wastewater diluted in domestic sewage, using an Expanded Bed Granular Sludge (EGSB) pilot scale reactor. The reactor was kept in mesophilic temperature, with 62,0 L total volume and it was operated with a hydraulic retention time (HRT) of 40 h. The inoculum was 12,0 L of sludge from an UASB used on a poultry slaughterhouse wastewater treatment plant. On the first stage, of adaptation, the reactor was fed only with domestic sewage for 60 days. Then, commercial laundry wastewater was diluted in domestic sewage to obtain LAS affluent concentrations of 5 ± 4; 19 ± 10 and 36 ± 19 mg L-1, on stages II, III and IV, respectively. These stages lasted for 60, 270 and 90 days. The increase of commercial laundry wastewater proportion on fed resulted in lower organic matter removal efficiencies. These parameter decreased from 73 ± 23% on adaptation, to 61 ± 25%, 50 ± 15% and 39 ± 23% on following stages. As well as LAS removal efficiencies that dropped from 73 ± 31% to 55 ± 29% and 44 ± 15 % on three last stages. Sulphide production enhanced from stage II (8 ± 2 mg L-1) to stage III (29 ± 12 mg L-1) and remained 31 ± 5 mg L-1 on stage IV. Taxonomic characterization of granular sludge biomass in the end of each stage was performed and genders similar to Bellinea (Bacteria domain) and Methanosaeta (Archae domain) were the ones with higher relative abundance in all stages. The technology applied was suitable for anaerobic surfactant removal with LAS affluent concentration of 20 mg L-1. Acclimation of microbial biomass was observed after long exposure of microbial community to recalcitrant compounds from laundry wastewater. (AU)

• FAPESP's process: 16/11948-3 - Effect of las loading rate on its removal efficiency by co-digestion of commercial laundry wastewater and domestic sewage in a pilot scale EGSB reactor
• Grantee: Alana Gandra Lima de Moura
• Support Opportunities: Scholarships in Brazil - Master