Anaerobic Digester Covers

WHY USE AN ANAEROBIC DIGESTER COVER?

Many people believe that anaerobic digestion only works in a laboratory setting. However, this is not the case. Anaerobic conditions, without the presence of oxygen, allow the microbes that produce biogas to develop and thrive. When storage basins are left open with no cover, they can be influenced by sunlight and wind. The introduction of oxygen is non-conducive for anaerobic microbial activity in the top 3 to 4 feet of any lagoon, pond, or reservoir.

Adding a floating cover for the digester, such as a double membrane cover, converts the full pond or reservoir into an effective anaerobic digester. A double membrane cover not only helps to keep out light and oxygen but also provides enhanced insulation and structural integrity, supporting consistent biogas production even in varying environmental conditions.

Discover The Many Anaerobic Digester Cover Options Available

The process of anaerobic digestion requires an environment completely devoid of oxygen for bacteria to do their work effectively. IEC Covers offers world-class anaerobic digester covers, including the double membrane cover, which helps maintain stable temperatures for microbial activity and eliminates odors by containing methane. Our covers are designed, fabricated, and installed for a wide range of industries, including farms, food processing plants, paper mills, and other facilities that produce organic waste.

IEC Covers’ anaerobic digester covers, such as the double membrane cover, are perfect for both new and retrofit installations. These covers are expertly engineered by certified IEC Covers technicians and engineers with decades of experience in meeting customer specifications for biogas production and odor control. The double membrane design enhances insulation, provides additional structural stability, and allows for internal gas pressure regulation—making it ideal for efficient and long-term biogas containment.

We integrate the latest structural standards to ensure complete customer satisfaction. Our floating covers for digesters can be designed in fixed or buoyant configurations, and the double membrane cover is one of the most versatile and high-performing options available on the market today. Our tank mount designs also offer innovative and cost-effective solutions for both new and replacement anaerobic digester covers.

Key Features of Our Anaerobic Covers

Effectively keeps oxygen out of anaerobic environments
Prevents biogas odors from escaping to the atmosphere
Reduces the possibility of explosion hazards due to CH4 biogas
Effectively insulates the top of the digester

Structural Designs

Steel Truss and Radial Beam Covers

Radial beam covers are the most cost-effective anaerobic digester covers as they do not feature any ceiling plates and also require 50% less weld length compared to a truss cover. Steel truss covers make use of welded plates on both the top and bottom of the trusses in order to create attic space that safeguards the structural members from the effects of corrosion and also insulates the sludge.

Our steel truss and radial beam anaerobic digester covers come in several options for different process requirements and come in varying sizes to meet your specifications.

Advantages include:

Prefabricated beam roof sections for quicker field installation
Custom-designed for a wide variety of different applications
More affordable than other options
Ideal for biogas and odor containment

Double Membrane Digester Covers

A double membrane cover, also known as a dual membrane cover, offers one of the most versatile solutions for anaerobic digestion systems. The tank mount design provides an innovative and cost-effective answer for both new and replacement covers.

Benefits include:

Variable liquid level capabilities
Significant gas storage capabilities
Low installation cost
Complete odor containment

Slide Guides for Double Membrane and Buoyant Anaerobic Covers

The function of the slide guides permits the double membrane cover to travel above the wall of the tank, thereby increasing gas storage capacity at high liquid levels. IEC Covers uses ultra-high molecular weight polyethylene slide plates on three sides of the structural steel tube to prevent double membrane covers from tipping and binding as they move vertically within the tank. These slide guides feature strong resistance against wind, seismic, and unbalanced loads in both radial and tangential directions.

Our versatile, low-friction ultra-high molecular weight polyethylene slide plate surfaces eliminate the need for lubrication, enabling convenient, maintenance-free operation.

About our slide guides:

Retrofits and upgrades with existing covers in place
Elimination of tipping and binding of anaerobic digester covers
Corrosion proof
No need for lubrication
Loads redistributed over several guides
Completely adjustable for convenient installation and alignment
Very minimal wear and tear

Fixed Anaerobic Digester Covers

Innovative cover designs integrate a water launder or a more sophisticated seal that can overcome the liquid level variation limits. They feature an annular seal design that makes use of side sheets submerged in the sludge in order to achieve a pressure seal that can stop odors from escaping outside to the environment. Our fixed anaerobic covers may be used in digesters with no variation in total volume and is often used on the primary digester for a two-stage system. The sludge volume may vary but only by fluctuating the gas volume at the same time will you be able to keep the total volume constant. If pressurized gas is required, a companion floating cover connected by gas lines is necessary. The fixed anaerobic covers may be anchored to the top of the digester tank where you can normally find a constant or static sludge level. Therefore, the rim plate only needs to be as deep as the tank freeboard plus the tank operating pressure and the right seal depth to contain the gas. The fixed cover features a single steel membrane over the structural framework. This design presents one of the most cost-effective solutions for your needs.

Benefits of Fixed Covers

Complete gas and odor containment
No movement as it is connected to the tank
Economical
Quick Installation
Perfect for small liquid level variations

Floating Anaerobic Digester Covers

Our buoyant floating anaerobic covers come in contact with the sludge, which minimizes the exposed liquid surface area and also prevents the formation of a large scum blanket. Floating covers for digesters float directly on top of the sludge which allows for changing sludge levels. The floating cover provides for the submergence of scum and is again applied on the primary digester in a two-stage system. Floating anaerobic covers float on the liquid surface and feature a minimum rim plate depth since they float directly on the sludge itself. The cover embodies both a ceiling plate as well as a roof plate, creating an attic space, in which are the trusses. Rollers are then mounted on the cover to provide for movement. Advantages of this type of cover include: excellent scum suppression, superior insulation due to attic space, support trusses are quite resistant to the digester corrosive products and is reliably stable.

Benefits of Buoyant Covers

State-of-the-art Truss Design
Covers float on the surface of the liquid
Features an attic space
The best option for high liquid level variability
Innovative truss design increases cover stability
Natural thermal insulation properties