The four new anaerobic digesters required a gas tight tank lining solution that would also protect the concrete from biogenic sulphuric acid which is created when the hydrogen sulphide that is produced during the anaerobic digestion process is digested by aerobic bacteria within the gas space.
We quoted for the application of our proven digester tank lining system. Initially all surfaces were prepared by method of high pressure washing using a 5,000psi washer to remove mould release and surface laitance from the concrete to ensure excellent adhesion of the tank lining.
Following completion of the washing all water was pumped out and heating and dehumidification introduced to dry out the tank and ensure the correct climatic conditions for tank lining application. This was tested and recorded throughout the tank lining application as part of our standard quality assurance.
All joints were primed 100mm either side using Remmers Epoxy MT100 damp tolerant epoxy primer applied by method of brush and roller.
All vertical panel joints were sealed using a polyurethane jointing compound and the horizontal soffit joints bridges using a foil tape. This serves two purposes, the first of which is to provide a ‘scaffold’ for the polyurea coating to be applied to. The second is that due to the smooth surface of the tape it serves as a bond breaker to allow the polyurea membrane to move freely and maximise its elastic potential.
All joints were then gas sealed using Speciality Products Incorporated Corrolastic UB polyurea to a thickness of 2mm.
The first coat of Remmers Epoxy Universal tank lining was then applied by method of airless spray, followed by back rolling to ensure the coating filled all pores in the high quality pre cast concrete.
As per best tank lining practice the second coat of Remmers Epoxy Universal tank lining was applied in a contrasting colour to aid identification of areas applied.
As of our standard tank lining quality assurance the completed lining was checked for pin holing using a DC holiday spark tester. A single pin hole in a tank lining within an aggressive environment such as an anaerobic digester will allow degradation of the concrete to commence and if in the wrong location allow gas to leak.
All pin holes found were marked prior to touching in using the same material applied by brush.
