Improving Biogas Quality through Circulated Water Scrubbing Method

Abstract

The dependence of human being on fossil fuels has decreased significantly the conventional energy resources. To overcome this problem it is required alternative substitute fuels which are cheap and accessible which biogas is one of the fuels. Nevertheless, the use of biogas has not yet been maximized because of the low calorific value which is produced from the process without purification. The circulated water absorption method is one mean of effective biogas purification. Under this method it is expected to increase the level of methane (CH4) and to reduce both the level of carbon dioxide (CO2) and hydrogen sulfide (H2S). In order to obtain the aim, the research was carried out under variations of water and biogas volumetric flow rate. The results show that the highest quality of biogas produced was under the variation of water volumetric flow rate of 15 lt/min with biogas volumetric flow rate of 1 lt/min which increased the level of methane (CH4) from 59.36 % to 62.8 % and decreased the carbon dioxide (CO2) content from 33.53 % to 26.8 %, and hydrogen sulfide (H2S) from 208.33 to 86 ppm. Lower biogas and water volumetric rates allowed longer contact between biogas molecule and absorbent. This resulted in an opportunity for absorbent more active to dissolve carbon dioxide and hydrogen sulfide in biogas. These compounds then flowed outward of the scrubbing unit along with the absorbent. The research proved that the raw biogas purification by circulated water scrubbing method was an effective mean in enhancing the quality of biogas.

Optimization of Water Scrubbing Method for Enhancement of Biogas Quality through Base Solutions Addition

“…However, by the time the composition of purified biogas was nearly similar to the raw biogas. The main reason for this result was a decreasing on pH of absorbent [6].…”

Mitigation of nitrogen in the poultry litter to enhance biomethane production

“…The gas after scrubbing CO 2 is passed through a unit filled with steel wool to make the H 2 S deposit on the wool. The resulting gas is passed through silica gel to remove moisture present in the gas [19]. The mono fermentation mixture of about 8 litres of substrate is loaded in each digester in two batches containing raw poultry litter (Batch 1) with total solids of 17%, ASPL (Batch 2) with TS of 20%.…”

Removal of CO2 and H2S from raw biogas using activated natural zeolite

“…The production of biogas using water and cow dung ratio of 1 : 1. From previous research, it was found that the higher biogas volume production was achieved in the ratio under shorter period of anaerobic process [1]. The produced biogas is then flowed to a receiving-station before directed to biogas scrubbing unit.…”

“…CH4, CO2 was measured by dual wavelength infrared cell with reference channel, O2 by internal electrochemical cell and H2S by optional external gas pod. A digital pH meter with accuracy of 0.1 was used to measure the adsorbent acidity [1]. The surface morphology of zeolite was analyzed using electron scanning micrographs and then recorded by JEOL JSM-6510LA scanning electron microscope.…”

“…However, the production of biogas not only produces methane but also hydrogen sulfide and carbon dioxide. The last two substances should be removed in order to avoid corrosion while improve the energy content of biogas [1].…”