Back to Home Page of CD3WD Project or Back to list of CD3WD Publications

		The Purification of Biogas (GTZ, 1985, 33 p.)
			(introduction...)
			0. Introduction
			1. Properties of hydrogen sulphide
			2. The origins of hydrogen sulphide in biogas plants
			3. The effect of hydrogen sulphide on the biogas plant and the gas-utilization equipment
			4. Determination of the hydrogen sulphide content of biogas
			5. Methods for removing hydrogen sulphide from biogas
			6. Purifying absorbent
			7. Requirements on the absorbent
			8. The desulphurizing apparatus
			9. Operation procedures for gas desulphurization
			10. Summary
			Appendix

2. The origins of hydrogen sulphide in biogas plants

Formation

Hydrogen sulphide is formed in the biogas plant by the transformation of sulphur-ontaining protein. This can be protein from plants and fodder residues. However, when animal and human faeces are used, bacteria excreted in the intestines is the main source of protein. Inorganic sulphur, particularly sulphates, can also be biochemically converted to H2s in the fermentation chamber.

Amounts

Plant material introduces little H2S into biogas. On the other hand, poultry droppings introduce, on average, up to 0.5 vol. % H2S, cattle and pig manure about 0.3 vol. % H2S.

Protein-rich waste (e.g. swill, molasses etc.) can produce large amounts of hydrogen sulphide (up to 3 vol. %). Inorganic sulphates (from salty, stall rinse water or diluting water) also produce considerable H2S.