UPFLOW ANAEROBIC SLUDGE-DIGESTION IN A PHASE-SEPARATION SYSTEM

This paper aims to expand the knowledge about methods for improving th e rate of solids hydrolysis, volatile acid formation and methane gas p roduction. It studies the effects of phase separation and operational modes on the performance of the process. Two systems were investigated . The two-phase system consisted of a CSTR acid-phase digester and an upflow methane-phase digester, the one-phase system comprised of an up flow anaerobic digester. In order to provide optimal contact condition s and recycle liberated indigenous enzymes or cell biomass fractions, continuous recycling of the effluent sludges to the sludge bed of the reactor was used. In general, the nonbiodegradable portion of the subs trates contained in the mixed sludges was found to be about 45% on the basis of TVS. The TVS reduction of the two-phase system was 53%, this is higher than in the one-phase system. Methane production rate and m ethane content were 0.351 Ug TVS added and 66.6%, respectively.