Anaerobic Digester Lining – The Leen, Leominster
THE PROBLEM – Anaerobic Digester Tank Lining – The Leen, Leominster
The biogas company had previosuly experienced issues with gas leaks when sealing/lining anaerobic digesters with HDPE liners. They required a solution that would both protect the concrete in the gas space and form a gas tight seal. An additional challenge was presented by the fact that the HDPE lining had already been cast in the outer tank wall.
THE SOLUTION – Anaerobic Digester Tank Lining – The Leen, Leominster
Initially all surfaces to be coated were prepared by method of high pressure water jetting to remove surface laitance and mould release. The waste wash water was pumped out and the tank heated to dry the concrete and ensure the correct climatic conditions.
The tank was then primed throughout using Remmers Epoxy MT100 applied by method of airless spray, as the first stage of the tank lining. This damp tolerant epoxy primer ensured excellent adhesion of the tank lining.
To form a gas tight seal between the sectional tank panels the gaps were first bridged using a foil de-bonding tape. All the wall to wall joints were sealed to the required height using a polyurethane jointing compound. These areas were then sealed by the spray application of Corrolastic pure polyurea. This highly elastomeric tank lining material can elongate in excess of 300% making it particularly suitable for areas where potential movement could occur.
To form a seal over the HDPE already cast in to the tank wall which is a extremely difficult surface to adhere to, the surrounding concrete areas of each panel were first primed using Remmers Epoxy MT100. This provided an excellently adhered perimeter for the subsequent polyurea tank lining to adhere to. Corrolastic polyurea was then applied to the entire area of HDPE, and affixed using shot fired mechanical fixings. These fixings were then encapsulated using the same polyurea material.
Once the gas tight seal had been constructed the tank was lined throughout using Remmers Epoxy Universal applied in two coats of contrasting colour. This tank lining material has over 20 years of case histories in the biogas market and can crack bridge to 0.2mm which is greater than the crack design width of this type of tank.
Finally the completed tank lining was spark tested to check for pin holing. Where found these were marked with chalk prior to touching by brush.
Another similar case study can be found here.