The Glenmorangie Distillery Ltd, based in Tain, Scotland, produces 5–6 million litres of whisky annually. Production main co-products are draff, grain slurry remaining after the mashing step, pot ale, the liquid residue from the first distillation step, and spent lees from subsequent distillations.
Draff is utilized as feed for cattle by surrounding farms.
Liquid co-products, such as pot ale and lees is led to anaerobic digestion plant, which produces biogas which is used as is energy source for distilling process. Treated effluent from the digestion plant is discharged to the Dornoch Firth. The firm has also led a project to restore endangered oyster reefs in the Firth. Reefs will improve biodiversity and filter the remaining organic matter from water released by the distillery.
Reject is used as nutrient rich soil enhancer for the barley fields.
Generated biogas from the plant is burnt is a biogas boiler and gasses produced from the treatment process are scrubbed to minimize potential odour sources. Biogas from digestion plant reduced fossil fuel use by 15 per cent.
Some facts about the process capacity.
Peak capacity of the plant
Designed COD load
2,500 kg/h (F+A)
Anaerobic membrane bioreactor – AnMBR LETM system.
The AnMBR LE™ system combines a low rate completely mixed anaerobic reactor with low energy UF membrane separation system. This combination results in a number of advantages in circumstances which favour anaerobic treatment with a focus on very high COD removal rates and biogas recovery.
The membrane separation stage provides complete solids retention thus uncoupling the hydraulic and solids retention times allowing for optimised long sludge ages which maximises COD reduction and provides higher biogas yields. The process is more tolerant to TSS (Total Suspended Solids) and FOG (Fats, Oils and Greases) than granular anaerobic systems and thus provides simplified pre-treatment requirements.