Guide for biogas capture, storage & combustion (appendix 3)

Biogas is the product of anaerobic biological breakdown of organic substances. Anaerobic ponds or lagoons (the terms are interchangeable) are a common treatment step of wastewater produced from the meat industry. The technology is simple and inexpensive to operate while significantly reducing the wastewater organic loading. The by-product, biogas, is both a valuable fuel and a greenhouse gas (contributing towards carbon emissions). Captured biogas can be used to fuel a boiler or for co-generation. The burning of the biogas also significantly reduces carbon emissions. Hence, the covering of the anaerobic ponds has recently become popular.

The collection and handling of biogas in covered anaerobic lagoons (CAL) from the bacterial degradation of meat processing wastewater is accompanied by a number of hazards, the most significant of which include:

• The formation of hydrogen sulphide gas (H2S), which is toxic
• The flammability of biogas when mixed with air in the appropriate proportions
• Suffocation due to the exclusion of air from especially confined spaces.