Methanogenic and nonmethanogenic activity of granulated sludge in anaerobic baffled reactor

The methanogenic and nonmethanogenic activities of sludge from anaerobic baffled reactor (ABR) were investigated. The lab-scale ABR treated synthetic wastewater containing starch and peptone. The activities were measured at two values of organic loading rate (OLR) - 3.5 kg m(-3) d(-1) and 10 kg m(-3) d(-1) (as COD - Chemical Oxygen Demand). The performance of ABR. was compared with the performance of a UASB (Upflow Anaerabic Sludge Bed) reactor operated under the same conditions. For the kinetic tests corresponding substrates were used: the starch for hydrolytic activity, the glucose for acidogenic activity, and the sodium acetate for methanogenic activity. NaHCO3 was added to each test with the aim to keep pH in a normal range of operation. For ABR the maximal measured specific hydrolytic activity was 36.8 kg kg(-1) d(-1), maximal specific acidogenic activity 38.1 kg kg(-1) d(-1), and maximal specific methanogenic activity 1.51 kg kg(-1) d(-1) (at OLR. 10 kg m(-3) d(-1)). The activities of the anaerobic sludge from UASB reactor at OLR 10 kg m(-3) d(-1) were as follows: hydrolysis 3.52 kg kg(-1) d(-1), acidogenesis 1.12 kg kg(-1) d(-1), and methanogenesis 0.66 kg kg(-1) d(-1). The measurements have shown that the rate-limiting step of anaerobic degradation for the used system substrate-reactor was the methanogenic phase.