2.3.3 Balloon-Type Digester

Biogas Sanitation 2 Digestion Technologies and Types 2.3.3 Balloon-Type Digester

*Left Cross-Section View of Balloon-Type Digesters (FAO, 1996), Right: Installed Balloon Type Digester (Energypedia, 2010)*

A balloon biogas digester is a weather-resistant plastic or rubber bag with a long shape. It serves the dual purpose of functioning as a digester and a biogas holder, storing the gas in the balloon’s upper portion. The inlet and outlet connections are directly attached to the balloon’s surface. This digester effectively prevents short-circuiting, allowing the digestate to flow through the reactor in a plug-flow manner.

To increase gas pressure, weight must be placed on the top of the balloon. Notably, balloon-type biogas solution offers a cost-effective approach and is suitable for areas with high groundwater tables or rocky ground because of shallow below-ground installation. To enhance longevity and reduce vulnerability to mechanical damage, it is advisable to consider utilising UV-resistant and reinforced plastic balloons. These reinforced balloons have the potential to last up to 10 years, providing a more durable and reliable solution.

The table highlights the pros and cons of balloon-type digesters.

Pros	Cons
Easy to understand and operate	Relative short lifespan
Prefabricated and low-cost	Susceptibility to mechanical damage
Increased digester temperature in a warm climate	Susceptibility to temperature fluctuations
Easy to transport and install	Special knowledge and expertise might be required to repair a balloon digester
Uncomplicated emptying and maintenance	Low gas pressure requires extra weight or a gas pump
Suitable for areas with high groundwater tables and/or rocky ground	Requires space
The system is moveable, especially suitable in the context where permanent construction is not permitted
Adopted from: (Vögeli Y., 2014), (GTZ )

Pros & Cons of Balloon Type Digesters

For further information, please click on the Materials tab at the top of the page.

Further reading:

Low-Cost Polyethylene Tube Digesters (Link)

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