EXPERIMENTAL STUDY ON SUPER HIGH-SOLIDS ANAEROBIC DIGESTION OF SEWAGE SLUDGE —INFLUENT SOLIDS CONTENT OF 17-21%

Abstract

 This study examined super high-solids anaerobic digestion (35°C and 30 days HRT) treating TS 17-21% of sewage sludge. Once a week, ammonia stripping of digested sludge (80°C, initial pH 9 and 3 hours, 120% of the influent) was applied to the digested sludge for reducing ammonia inhibition. The average performance obtained was VS reduction of 53.8% and gas production of 0.470 NL/gVS at the loading rate of 5.20 gVS/L-day, which is almost equivalent to the standard anaerobic digestion of sewage sludge. The ammonia removal efficiency of ammonia stripping was about 75%, maintaining the ammonia concentration at around 3,300 mgN/L in the digester. Although the super high-solids anaerobic digestion can be operated with the ammonia control, there are disadvantages in the viscousity and dewaterability of digested sludge, posing severe problems with subsequent transport and handling processes of the digested sludge.