. Fig. 5 represents
the amount of CO2 in raw and purified biogas flowed through the activated
carbon filled U tube. Amount of CO2 removed is proportional
to the amount of activated carbon. The CO2 concentration in the raw
biogas varied between 24 to 38%, whereas the lowest CO2 concentration
(5%) after purification was possible to avail by using 10.0 g activated
carbon. The CO2 concentration decreased by the least rate for
treating with 8.0 to 10.0 g of activated carbon. The CH4 concentration
in raw and purified biogas is also depicted in