Biogas purification to produce quality and environmentally friendly biogas

Biogas produced by anaerobic bioreactors from processing liquid organic waste contains several types of gases, including methane gas (CH4) with the largest percentage of around 50-75%, H2S gas (corrosive) around 0-1%, CO2 gas (causes the greenhouse effect and acid rain if biogas is burned) around 25-50% and other pollutant gases such as N2 gas, H2 gas and NH3 gas. Biogas also contains water vapor, where water vapor can reduce the calorific value of biogas, so that biogas is of good quality and environmentally friendly, biogas produced by anaerobic bioreactors must be purified first before being used so that the impurity gas content meets the standards (for example, H2S gas content in biogas is below 100-200 ppm (parts per million), CO2 gas content in biogas is below 50% and water content in biogas is below 0.02% (200 ppm) or around 20 mg/m3). So in this paper, a biogas purification technique will be presented using the method of immersing biogas in water to remove H2S and CO2 gas content, followed by filtering the water content in the biogas using silica gel to increase the quality of the heat produced through a serial filtering process. The biogas produced from serial filtering showed a decrease in the content of impurity gases (H2S gas content from 1,126.7 ppm to 2 ppm and CO2 gas content from 99.15% to 19.51%), and increased quality due to the decrease in water content in the biogas (from 87.1% to 11.1%). This paper also proves that there is an increase in the quality of biogas (methane CH4 gas content from the calculation results (methane CH4 gas content in biogas coming out of the serial filter is 71.1%)) and the water content in the biogas has decreased (before entering the serial filter and after leaving the serial filter), so that the color of the flame from the combustion of biogas after being filtered using a serial filter is blue while the color of the flame from the combustion of biogas before being filtered is yellowish.