Stability and performance of anaerobic fixed‐bed reactor packed with a saddle‐shaped slag biocarrier

Abstract A saddle‐shaped biocarrier, which was made of slag discharged from blast furnaces, was packed in an anaerobic fixed‐bed reactor. Reactor performance was evaluated by using a synthetic wastewater composed of glucose and corn‐steep‐liquor. Mesophilic anaerobic bacteria from the seed sludge tank were attached to the biocarrier (which has a specific surface area of 335 m2m‐3) by circulating seed sludge up through the fixed‐bed reactor. During the experiment, the effluent from the top of the reactor was reintroduced into the bottom of the reactor (flow rate, 16 cm3min‐1) and mixed with the influent from the feed tank (flow rate, 0.4 to 2.4 cm3min‐1). The recycle ratios changed from 40: 1 to 7: 1 through the experiment, and the linear velocity in the reactor was 1.1 to 1.2 cm.min‐1. When the influent COD was increased from 4 to 20 gdm‐3 at a hydraulic residence time (HRT) of 48 hours (corresponding to COD loading rates of 2 to 10 gdm‐3day‐1), the COD removal was more than 95%. For variations of HRT fro...