Stratified ecology techniques in the startup of an anaerobic downflow fixed film percolating reactor.
A two-column pilot scale downflow percolating fixed film (DPFF) anaerobic reactor treating deproteinized cheese whey (DPW) was used in this study. The system was operated at one-third of the maximum working volume in an attempt to avoid mass transfer limitations of the gas products (since two-thirds of the immobilized microbial culture was unsubmerged), as well as to minimize the effects of localized high volatile fatty acids (VFA) levels and low pH on its methanogenic activity. A new method to shorten the start-up period was used by growing methanogenic and acetogenic (H(2)-producers) bacteria on a synthetic medium until reaching a stable methane production rate and then switching the reactor over to DPW and allowing acidogenic growth. The start-up period was reduced to 35 days as a result of this operational mode. The reactor was able to handle 8 kg COD/ m(3).d after 35 days of operation.
Canovas-Diaz
M
M
Department of Chemical Engineering, University College of Swansea, Swansea, SA2 8PP, United Kingdom.
Howell
J A
JA