The ETS activity in the AD reactor was tested methodically using INT (2-(p-iodophenyl)-3-(pnitrophenyl)-5-phenyl tetrazolium chloride) method (Hou et al., 2022). Microbial enzyme activities (β-glucosidase, dehydrogenase (DHA), coenzyme F420) were measured using kits, which were purchased from Shanghai Hengyuan Biotechnology Co.
