This project is designed to treat 40,000 tpa of source separated domestic bio-waste containing both food & green waste and 3,000 tpa of commercial food waste (former food stuffs). The process utilizes a combination of batch dry fermentation and in-vessel composting (IVC) to maximize the energy production from the bio-waste without compromising on the compost quality.
Anaerobic Digestions Process & Residence Time:
Feedstock is a mixture of food & green waste. The feedstocks are delivered to the enclosed reception building & tipped into the food reception pit. These materials are loaded into the 14 fermenters where it is digested for periods of 28 days, with an average hydraulic retention time of 40 days. The biogas is collected in the head space of the fermenters and stored in a gas bag prior to feeding a battery of CHP engines. The electricity will be exported to the electrical grid with the renewable heat being used in a district heating system servicing Dunfermline. The solid digestrate is transferred to aerated bays for conditioning prior to ABPR pasteurisation in tunnels. The Plant produces a marketable compost. There will also be future capacity of gas scrubbing to allow for reinjecting upgraded gas back to the grid.
The Lochhead dry anaerobic digestion facility is unique in being able to process both green waste in addition to food waste thus greatly increasing the biogas yield from domestic deliveries while removing the requirement to seperately collect the food and green waste. The facility is designed to generate up to 1.5 MW of renewable electricity and 1.6 MW of renewable heat. The plant is connected to a district heating sytem thus providing for a very high efficiency of energy use. As a dry AD system linked to an IVC system, the facility primarily generates an ABPR compliant marketable compost as opposed to a liquid digestate. This gives significant flexibility in the marketing of the product. The Lochhead facility represents the future
of anaerobic digestion of bio-waste.