The aim of this study is investigating and analyzing the water scrubbing, cryogenic separation, amine scrubbing and caustic wash biogas upgrading processes. In order to comparing the upgrading processes, input condition is supposed to be fixed for all of the processes. The results of this study indicate that although amine scrubbing process consumes less power but the required hot utility is higher than other upgrading methods. In the cryogenic process, high pressure operating condition needs high compression power. This process also needs low temperature refrigeration system. Water wash process is a simple and economic method which has acceptable separation efficiency, but caustic wash is more efficient than other methods and its energy consumption is reasonable. (C) 2018 Elsevier Ltd. All rights reserved.