Method and apparatus for treating biogas

A system for separating carbon dioxide from a biogas stream, the system comprising:

• a first pipe having a first end and a second end;
• a second pipe extending within the first pipe, the second pipe having a first end and a second end, wherein the first end of the second pipe is proximate the first end of the first pipe;
• a first inlet at the first end of the second pipe to deliver the biogas stream into the second pipe;
• a second inlet at the first end of the first pipe to deliver a liquid absorbent into the first pipe, wherein:
• the biogas stream is dispensed from the second pipe to an interior of the first pipe, and
• the biogas stream mixes with the liquid absorbent within the first pipe to separate the carbon dioxide from the biogas stream resulting in a purified biogas stream and a mixed liquid absorbent stream, wherein the purified biogas stream rises to a top of the first pipe;
• a first outlet in fluid communication with the first pipe to deliver the purified biogas stream from the top of the first pipe;
• a third pipe extending into the first pipe, the third pipe having a first end and a second end, wherein the first end of the third pipe extends from the first pipe and the second end of the third pipe extends through the purified biogas stream into the mixed liquid absorbent stream within the first pipe;
• and
• a second outlet in fluid communication with the first end of the third pipe to deliver the mixed liquid absorbent stream from the top of the first pipe.