Bio-Methane Enrichment by Water Scrubbing Technique /

Abstract

The scrubber is equipment, used for the purification of Biogas produced by the anaerobic digestion of animal manures or agricultural waste. This digestion can be mono-digestion or co-digestion. Anaerobic Digestion (AD) is a process in which microorganism of biodegradable materials like animal manure or agricultural waste is broken down to produce biogas in the absence of oxygen. Biogas is now widely produced and used domestically especially in rural areas where it the source of energy generation and also for domestic use. Biogas is generated by the decomposition of wastes and it contains a lot of impurities like Hydrogen sulfide (H2S), carbon dioxide (CO2), and some other impurities which should be removed to get pure gas and for that scrubbing, techniques should be observed. In experimentation, a three-step scrubbing technique (H2S scrubber, Packed Column Water Scrubber (PCWS), and Charcoal Scrubber (CS)) based compact scrubber was designed and up to 95% H2S reduction was achieved along with enriched methane contents ranged (75 – 97) %. In PCWS, 20 different scrubbing experiments were executed. In which four methods were based on flowing water (water/gas (w/g) flow rate of 1:1, 2:1, 3:1, and 4:1) while the other 16 were based on static water in the scrubbing column with different water level heights of (0.55m, 0.85, 1.15m) and time contact of (0sec, 30sec, 45sec, and 60sec). For flowing water; the average methane refinement ranged from (87-97) %, and maximum methane refinement was observed at a flow rate of 2:1. Whereas for the static water column, the average methane refinement ranged from (75-97) %, with maximum recorded methane refinement at 0.85m with time contact of 30sec. Both processes showed a good impact on methane enhancement but the flowing process is more practical because CO2 is more soluble in flowing water as compared to static water after some period.