Expanded granular sludge bed reactor technology feasibility for removal of nonylphenol ethoxylate in co-digestion of domestic sewage and commercial laundry wastewater: Taxonomic characterization and biogas production

Abstract

Nonylphenol Ethoxylate (NPEO) is a non-ionic surfactant used worldwide in the formulation of cleaning products. Removal of these compounds from domestic sewage is difficult to achieve. In this study, the degradation of NPEO from the co-digestion of domestic sewage (DS) and commercial laundry wastewater (CLW) was evaluated using a pilot-scale expanded granular sludge bed (EGSB) reactor operated for 637 days. In phase I, the reactor was fed with synthetic substrate (SS) – without NPEO, phases II and III with SS plus 3.5 ± 1.0 mgNPEO L−1 and 7.6 ± 2.1 mgNPEO L−1, respectively. Phase IV with SS plus CLW containing 4.0 ± 1.1 mgNPEO L−1, phase V with DS plus CLW and 3.7 ± 1.3 mgNPEO L−1. Nearly 60% of NPEO was biodegraded and chemical oxygen demand (COD) removal varied from 90 ± 5% to 97 ± 2% (for up to 573.8 ± 130.1 mgCOD L−1). Spirochaetacea exhibit the greatest relative abundance (from 65.3% to 90.7%) throughout the operation. NPEO addition negatively affected methanogenic activity, such that CH4 yield decreased 91% even at high COD removal. Surprisingly, after 549 days of operation, a CH4 yield of 0.30 ± 0.14 LCH4 gCOD−1 removed was observed.