title: Sludge exchange process on two serial CSTRs anaerobic digestions: process failure and recovery.
abstract: The sludge exchange process using two anaerobic digesters (CSTRs) in series was investigated under the mesophilic condition (36-38°C). At first, the digesting sludge of the CSTRs in series with different TVFA/alkalinity ratios was tested in the laboratory by mixing the digesting sludge of two CSTRs from 6.5% to 50% based on volume. The sludge exchange test was then performed using the same CSTRs under batch and continuous processes. The change in the TVFA/alkalinity ratio was found to be linear with the digesting sludge exchange volume. The CSTR of TVFA/alkalinity ratio 1.970 recovered completely failed within 11 days for the batch process and the CSTR of TVFA/alkalinity ratio 1.514 within 3 weeks for the continuous feeding process at a sludge exchange volume of 13%. The reactor operation was stable when the TVFA/alkalinity ratio was less than 1.0 and when the TVFA concentration was lower than 10,000 mg L(-1).
authors.affiliation: Department of Biosystems Engineering, Kangwon National University, Chuncheon, Kangwon-do, Republic of Korea. gopikafle@yahoo.com
authors.forename: Gopi Krishna
authors.initials: GK
authors.lastname: Kafle
authors.forename: Sang Hun
authors.initials: SH
authors.lastname: Kim
mesh_terms: D000468:Alkalies / Q000032:analysis; D000693:Anaerobiosis; D056804:Biofuels / Q000032:analysis; D019149:Bioreactors; D001709:Biotechnology / Q000295:instrumentation* / Q000379:methods*; D005232:Fatty Acids, Volatile / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D008697:Methane / Q000032:analysis; D012722:Sewage / Q000032:analysis*
chemical_list: D000468:Alkalies; D056804:Biofuels; D005232:Fatty Acids, Volatile; D012722:Sewage; D008697:Methane