November 8th 2018

Nine eager Wombles arrived promptly at the Renewi site at Hespin Wood, Rockcliff, to discover the process that all waste in private household black bins undergo. This site also takes waste from the County Council such as park bins and road sweepings and according to Allerdale Borough Council also the red top bins from holiday homes, businesses and catering establishments too. Joanna Crone and Paul, the site manager provided us with a great presentation as to who Renewi were and then the process involved in transforming waste into a useful commodity. No longer are they a waste management company but one that uses the resource of waste to fulfil needs within different industries, waste processed by them no longer goes to landfill.


The Wombles eagerly awaiting the presentation

Renewi currently have a 25-year contract with the County Council to process 150,000 tonnes of waste per year from within the county, with 75,000 tonnes being processed at the Hespin Wood plant, the remaining 75,000 tonnes are processed at the South Lakes site in Barrow. Hespin Wood has been functioning for the past 8 years. The government has set councils a target to recycle 60% of all waste – be that from homes, businesses or household recycle sites. If this target is not met the council suffers heavy fines from central Government, so it is in their best interests to insure as much waste as possible undergoes recycling in one form or another. Before 2009 that target was missed consistently, costing millions of pounds in fines, 56% (255,342 tonnes) of waste was going to landfill. At Flusco Household Waste Recycling Centre there is a board at the exit stating the amount of waste that has been recycled the previous month, this figure has been steadily increasing since Renewi took on the contract with the council.

The process of transforming waste used at Renewi is known as Mechanical Biological Treatment (MBT). The operation is continuous for 24 hours a day, 5 days a week. Everything is mechanised and controlled from a central control room. The day shift is covered by 7 members of staff, the night shift is overseen by 3 members of staff.


The central control room

Waste is delivered into the main reception pit where it is then transferred into a shredder using a very large grabber. Material is then shredded and moved once again by a large grabber into the bio-hall. The bio-hall has a capacity to hold 3,450 tonnes of waste. Here the waste is left for 14 days to start the organic decomposition and shrink in volume by 33% as the moisture is removed.




The Bio-hall containing waste from half of the county



Air is drawn through the material to speed up the decomposition process and moisture reduction. The air is then filtered through natural wood chippings – biofiltered - to remove bad odours and particulates before being released into the atmosphere. The leachate (juices from decomposing rubbish) is drained off and collected in a tanker under the bio-hall. It is then removed from site and processed elsewhere to clean it up. All surface water from around the site is collected in ponds on site and passed through a reed bed to clean it, after which it is discharged into the river.

Air from the bio-hall being processed through the bio-filters. Reed beds are in the background.



Once the waste has rested for 14 days the treatment process continues. It is then transferred into a ‘trommel’. This is a very large cylinder with holes that tumbles the waste. This sorts the waste into different categories. The ‘compostable fraction’ of waste consists of food waste, small particles of textile, paper and plastic. This is then used as a composting/topper ‘soil’ in sites such as quarries, slag heaps or landfills which are being restored, but will not be used for grazing within 10 years.

‘Heavy’ items such as glass and stone as well as non-ferrous metals, drop to the bottom and fall through holes. The glass and stone are sent away for further treatment where they are then used in tarmac. Ferrous metal is collected on large magnets. Both ferrous and non-ferrous metals are sold as scrap metal to be used again after further processing.

‘Light’ materials consist of textiles, plastics and paper which are separated by air blown through the trommel. A second magnet is at the collection point to retain as much metal as possible. The ‘lights’ are then put through another shredder to reduced the size to 80mm and then compacted. This is then known as Solid Recoverable fuel (SRF).

The giant compactor



‘Fines’ material consists mainly of dust from the whole process. This is currently the only part of the process that goes to landfill, approximately 0.02% of the total amount of waste processed. Renewi are looking into ways in which to eliminate this completely so nothing goes to landfill.

Solid Recoverable Fuel (SRF) is transported to a cement factory where they burn the waste to power the cement kiln. SRF comprises of ‘light’ materials, approximately

58% paper

20% plastic

15% textiles

5% wood

2% miscellaneous


Refuse Derived Fuel (RDF) consists of hard plastics such as toys which cannot be shredded. These are removed after trommelling and are transferred to another company where they are broken down further to a size of 30mm and reused in other industries, mainly burnt as a fuel.

All of this process takes place within a large warehouse. No waste is left outside to await processing and no lorry is loaded in the open air, all is done behind closed shutters ensuring no rubbish escapes. No bad smells come from the plant and very few sea gulls are around. Litter is not blown into the surrounding area. The site is very clean and tidy, unlike the classic landfill rubbish dump.


Renewi site, Carlisle


The challenge for the company in the near future is that the number of houses within the county is growing with huge developments happening on the outskirts of Carlisle as well as further south. This means more rubbish will be coming their way, except that they have a capped capacity of 75,000 tonnes per year, meaning their licence will not allow them to take any more waste. Thus, it is of paramount importance that the black bin is used correctly and that everything that can be recycled and correctly sorted by the household is done so accordingly. Very little should be going into these bins. Paper, card, tins, metals and plastics can all be recycled, if not on the doorstep then at local Household Waste Recycling Centres. Batteries, wood, florescent lights, textiles, electrical goods, car oil and furniture can all be processed at these centres too. It is however still unclear as to where and how the ‘red top’ bins from holiday properties are processed and disposed of. Conflicting information is coming from Allerdale Borough Council and Renewi, however Renewi are looking into the matter and will hopefully be able to shed some light on it for us in the not so distant future.