The Environment Act 2021 is already enforcing huge changes in hospital food waste management systems and equipment .in England. The sections of the act covering food waste management come into force later in 2023 or early 2024.
The 1297 NHS hospitals and 515 private hospitals produce 12% of the total food waste generated in the UK. That’s 1.1 million tonnes of the total of 9.5 million tonnes. (2018-19 figures from WRAP). The cost of hospital food waste is estimated as £230m per annum. WRAP estimate that around 18% of all food prepared goes to waste, equivalent to one meal in six.
These figures are only estimates according to the NHS Digital, as 81% of NHS trusts did not file returns for their food waste in the survey. Also, most hospitals still use macerators to dispose of food waste into the drain system and was therefore not measured.
The Environment Act 2021 places a further obligation on hospitals (and other food waste producers) to present all food waste separately for collection. It also makes it illegal to put food waste into drains using macerators or liquidizing digesters (which turn food waste into a slurry with enzymes and hot water before flushing into the sewers).
To comply with the legislation there are four options:
1. Dispose of food waste in wheelie bins
Many hospitals are already doing this. This will be compliant but if you have been using a macerator, you will now have the additional cost of food waste disposal. Food waste is removed by a waste contractor or food waste contractor, typically in 240L or 120L wheelie bins. They will charge by the bin (between £8 and £20 per bin depending on the contractor and where you are in the country).
This option brings not only results in a disposal cost but bring other problems such as the attraction of vermin and pests, particularly in summer. Many hospitals are facing huge increases in pest control costs as a result of moving to bins. Wheelie bins full of wet food waste can also be a manual handling risk for kitchen staff due to the weight (around 70-100kg). To reduce the cost you could consider:
2. On-site composting
A typical composting unit will turn wet food waste into compost in around 6 weeks, although there are models that claim to be able to speed that up to around two weeks. Composters use a carbon source (woodchip) which is added to the food waste when it is loaded at one end of the machine. The screw mechanism slowly turns the mixture over and pushes it along the length of the machine. Bacteria in the food waste break it down and turn it into a material which can be spread on gardens and grounds (except in Scotland where commercial food waste must go to a recognised composting facility). This will reduce food waste disposal costs significantly.
The major drawback with composters is the smell. You can't have them in the kitchen as they are full of decomposing food waste and every time the loading door is opened, the smell escapes. Apart from that, they are very large as they need to be able to hold several weeks' of food waste. You would need to find an outside location with a roof to protect it from the elements. An alternative might be:
3. Use an Aerobic Digester
‘Aerobic’ means ‘with oxygen’. An aerobic digester is essentially a type of rapid composter and uses added enzymes (instead of woodchip in a standard composting unit). The enzymes and food waste are turned in a warm air stream (around 50-60°C). Enzymes speed up chemical reactions in cells during decomposition of food to break down protein and fat cells into smaller molecules. The process ‘digests’ the food waste, removing the water content and turning the food waste into a dryish mulch which is about 20-30% of the original weight of food waste.
Using an aerobic digester will reduce food waste disposal costs by 60-80% but there are some important operational considerations. They are 'continuous loaders' which means that they are on 24/7 and you can add food waste at any time during the process. But that also means:
- the processing time is difficult to calculate: only some of the food waste will be processed in a 24 hour period, the majority will take up to 72 hours. The profile of food waste will vary from day to day and therefore the processing time. This can become an operational headache.
- it is therefore difficult to work out the capacity of machine you might.
- smells are also a problem because these are essentially composting units. Every time the loading door is opened, the smell of decomposing food waste escapes. Consequently, many hospitals have had their digester removed because of the smell. Or you could:
4. Use a Food Waste Dryer
A food waste dryer solves many of the problems of aerobic digesters and bins . It uses applied heat to evaporate the water content of food waste (average 80% by weight). The food waste is turned over in this higher temperature (70-85°C) and the water content rises as steam within the closed unit and is recirculated through a condenser which turns the steam back into water which is discharged to a normal drain. The solid matter is reduced to a sterile, dry powder which is typically 15-20% of the original weight of food waste.
Food waste dryers are ‘batch loaders’ which means you fill them up and turn them on to start the drying cycle. You cannot add any other food waste until the cycle has finished which is typically 12 – 16 hours later, depending on how full it is filled.
This is quicker than aerobic digesters. 100% of the food waste is processed in this time which makes it easier to manage.
There are no smells because a food waste dryer is a closed unit and no smells from drying food waste escape. When the discharge door is opened 12-16 hours later to empty the machine, the dried powder is virtually odourless. This means they can be sited in kitchens where the food waste is generated.
As a food waste dryer sterilizes food waste as it is heated to 70-80°C for several hours, they are a hygienic solution when compared to aerobic digesters.
As of 2023, NHS Greater Glasgow & Clyde have 15 Eco-Smart Food Waste Dryers in service across their estate. Queen Elizabeth University Hospital recently installed four of the ES500 units (350kg per day) to replace their defunct aerobic digester. The hospital is the largest hospital in Scotland with over 1800 beds. Prior to installing the dryers, they had been forced to put wet food waste in wheelie bins and their food waste disposal cost was as large as all the other hospitals in Glasgow put together. The dried residue goes to anaerobic digestion through food waste contractor Olleco.
Mid-Yorkshire NHS Hospitals Trust have three Eco-Smart Food Waste Dryers. There are two ES80 (50kg per day) units at Dewsbury District Hospital (200 in-patient beds) and one ES300 unit (200kg per day) at Pinderfields Hospital, Wakefield (730 beds). The dryers have replaced their macerator units.
Following a long period when the macerator had broken down and had not been able to be repaired, Walsall Healthcare installed an ES300 (200kg) Eco-Smart Food Waste Dryer and were able to reduce the number of wheelie bins by 80%., a significant operational and financial improvement aswell as contributing towards their Net Zero agenda.
For more information about the Eco-Smart Food Waste Dryer, how it can reduce your disposal costs, improve your food waste processing and ensure a hygienic operation, go to this page on our website or contact us for a no-obligation discussion.
