The general experimental procedure followed can be summarized
as follows: in the batch experiment 8 g of rice husks and
250mL of 0.9% NaCl solution are mixed in 250mL Erlenmayer
flasks under anaerobic conditions. Samples are taken from the
flasks every two days and then they are scanned with Perkin
Elmer Lambda 35 UV/VIS spectrophotometer. In the continuous
systems the reactors are filled with rice husks. The connection tubes
between the reactors and feed bottles are washed with ethanol for
Fig. 1.