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Anaerobic Digester Covers


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 digester converts the full pond or reservoir to an anaerobic digester. This helps to keep out light and oxygen, which can interfere with the process of producing biogas.

Discover The Many Anaerobic Digester Cover Options Available

The process of anaerobic digestion requires an environment devoid completely of oxygen in order for the bacteria to do their work. IEC Covers offers world-class anaerobic digester covers that keep the bacteria temperature stable and eliminate odor by containment of methane. IEC Covers designs, fabricates and installs floating covers for digesters for many industries including farms, food processing plants, paper mills and other facilities that produce organic waste.

IEC Covers’ anaerobic digester covers are perfect for new and retrofit installations. Our custom anaerobic covers are expertly designed by certified IEC Covers technicians and engineers with decades of experience meeting customer specifications for biogas and odor containment. We integrate the latest structural standards to ensure complete customer satisfaction. Our floating cover for digesters can be designed into fixed or floating/buoyant configurations. We have some of the most versatile anaerobic covers available in the market today. Our tank mount design can provide you with an innovative and cost-effective solution for 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

Dual Membrane Digester Covers

Dual membrane covers offer the most versatile solution as the tank mount design offers an innovative and cost-effective answer for new and replacement covers.

Benefits include:

  • Offer variable liquid level capabilities
  • Significant gas storage capabilities
  • Low installation cost
  • Complete odor containment

Slide Guides for Gasholder and Buoyant Anaerobic Covers

The function of the slide guides permits the cover to travel above the wall of the tank thereby increasing gas storage at high liquid levels. IEC Covers uses ultra-high molecular weight polyethylene slide plates on three sides of the structural steel tube in order to stop anaerobic covers from tipping and binding as they move vertically within the tank itself. They feature strong resistance against wind, seismic and unbalanced loads in both the radial and tangential directions. Our versatile, low-friction ultra-high molecular weight polyethylene slide plate surfaces also remove the need for lubrication, thereby allowing for convenient maintenance-free operation.

About our slide guides:

  • Retrofits and upgrades with existing covers in place
  • Elimination of tipping and binding of the anaerobic digester covers
  • Corrosion proof
  • No need for lubrication
  • Loads re-distributed over several guides
  • Completely adjustable for convenient installation and alignment
  • Very minimal wear and tear
  • Gasholder Covers may also be fabricated using radial beams, trusses or engineered textiles.

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