We have two facilities at our South Lanarkshire site where we create quality compost. Firstly, we recycle combined or “co-mingled” green and food waste in an in-vessel composting system (IVC) and secondly we process pure green waste, both producing high grade compost certified to British Standard PAS100.
Our green waste and food derived compost is produced in an in-vessel composting (IVC) system with an additional maturation stage. This four-stage organic process can take up to 12 weeks and is carefully managed to ensure nutrient retention.
Combined food waste and garden waste is collected and delivered by truck to our reception shed. The co-mingled material is then screened to remove fine particles before progressing over a picking station to remove typical contaminants which are non-compostable such as plastic bags, plastic bottles, food wrapping and packaging. The material is then fed into a high-speed shredder to reduce the product down to 40 mm after which it is transferred to one of the 18 vessels on site.
Shredded material is then loaded into an empty vessel and once full the cover is drawn over and the door secured.
Fans introduce air through the bottom of the vessel and extract through pipes in the roof, accelerating the natural composting process. Heat is generated naturally in the process which kills any harmful bacteria, allowing the material to break down to produce compost, there are no additives to this natural process.
The temperature is continuously monitored in each vessel for quality control to ensure that only good bacteria remain which is key to the nutritious content of the compost. At timed intervals, the compost is then moved to another vessel and the process is repeated.
At the third stage the material is then moved to the maturation area and placed into rows called windrows. The windrows are turned regularly to aerate the compost to ensure that heat is evenly spread throughout. The sequence takes 6 to 8 weeks and each windrow is batch numbered for traceability. During the maturation process any contaminants and rubbish from the material continue are removed.
Once the material has been through the maturation process it is moved to the screening area for the final stage of the process, 20mm and 10mm compost.
All other larger particles of mainly wood are taken out at this time and material has its final clean-up of plastic and rubbish by a wind surfer machine.