Feasibility Study of Using Excess Sludge Fermentation Broth as a Co-Metabolic Carbon Source for 2,4,6-Trichlorophenol Degradation

Abstract

Excess sludge fermentation is a commonly employed method for carbon sources in wastewater treatment plants, but its use as a carbon source for chlorophenol removal has been relatively underexplored. In this study, a laboratory-scale sludge fermentation SBR (FSBR) was integrated with a 2,4,6-trichlorophenol (2,4,6-TCP) degradation SBR (DSBR), resulting in a stable removal of 2,4,6-TCP without the need for external carbon sources. In this coupled system, the concentrations of volatile fatty acids in FSBR remained constant, with acetic acid, propionic acid, butyric acid, and valeric acid concentrations reaching 322.04 mg COD/L, 225.98 mg COD/L, 274.76 mg COD/L, and 149.58 mg COD/L, respectively, and the acid production efficiency increased to 88.40%. Throughout the 110-day operational period, the activated sludge concentration in the DSBR was consistently maintained at 3021 ± 110 mg/L, and the sludge SVI remained stable at 70 mL/g. The maximum amount of 2,4,6-TCP removed reached 240.13 mg/L within a 12 h operating cycle. The use of excess sludge fermentation can completely replace commercial carbon sources for 2,4,6-TCP removal, leading to cost savings in chlorophenol treatment and broadening the applicability of this technology.