Digester systems that convert waste material into biogas are becoming more prevalent throughout the world. Rural farmers now have a means to produce good quality fertilizer and biogas from waste materials like manure in a cheap renewable way.
The problem is that this biogas produced is roughly 60% methane and 29% Co2 with trace elements of H2S, and is not up to the quality of 99% pure methane natural gas if the owner was planning on selling this gas or using it as fuel gas for machinery. The corrosive nature of H2S alone is enough to destroy the internals of expensive plants.You can also use h2s removal from natural gas.
The solution is the implementation of a biogas upgrading or purification system. Biogas upgrading is a series of processes where the gas is first cleaned from contaminants and then dried, so that what is left at the end of the process is 98%+ methane fuel gas.
Manufacturers that produce biogas purification systems each have their own different processes and technology that they employ to produce the sales quality gas. A few of them are detailed below.
This is the most common method of purifying biogas. Here raw biogas from the digester is compressed and fed into the scrubber vessel where passing water streams adsorb the gas contaminants leaving near pure methane. The gas is then dried by dessicant in the drier columns and exit the system as 98%+ pure natural gas.