Water scrubbing involves the physical absorption of CO2 and H2S in water at high pressures and regeneration takes place by release in pressure with very little change in temperature.
It is simple method involving use of pressurized water as an absorbent. The raw biogas is compressed and fed into a packed bed absorption column from bottom and pressurized water is sprayed from top. The absorption process is, thus a counter-current one.
This dissolves CO2 as well as H2S in water, which are collected at the bottom of the tower [9 and 11].
The design of water scrubbing system depends on the solubility of carbon dioxide in water as solubility is governed by pressure
and temperature as given in Table 3.2 [11]. It is clear from table that as the pressure increases solubility of CO2 in water increases but
decreases as temperature increases.