How To Reduce Hospital Food Waste Disposal Costs

Hospitals are one of the largest producers of food waste in the UK. The 1297 NHS hospitals and the 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.

However, these figures are only estimates according to the NHS Digital, Estates Returns Information Collection England, 2018-19, as 81% of NHS trusts did not file returns for their food waste. One of the main reasons was that food waste in the majority of hospitals is disposed of into the drain system and was therefore not measured.

While a focus on reducing overproduction of food and encouraging the use of food banks as an alternative to disposal are reasonable proposals (made in the 2020 Independent Review of Hospital Food), it is inevitable that a significant proportion of hospital food will always have to be thrown away. There is a statutory obligation to provide every patient with nutritious food but many patients are too ill to finish meals, or miss meals through being asleep or by being at other procedures like X-rays.

The focus then is how to dispose of the food waste when it returns to the kitchen and how to reduce the cost of that disposal. The Environment Act 2021 places a further obligation on hospitals as it mandates all food waste to be presented separately for collection. The commencement date for this aspect of the legislation is expected to be later in 2023, when it will be 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

This is the simplest option 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 its own problems such as the attraction of vermin and pests, particularly in summer and 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. It reduces the volume and weight of food waste by enzymes instead of a carbon source in a standard composting unit, which are added to the food waste and turn it in a warm air stream (around 50-60°C). Enzymes are a substance that speeds up chemical reactions in cells, in this case in the decomposition of food, in which large nutrient molecules (such as proteins, carbohydrates, and fats) are broken down into smaller molecules. The food waste with the added enzymes is gradually turned over, exposing the waste to oxygen in the warm air and the process ‘digests’ the food waste, effectively speeding up the decomposition, 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 load them whenever you have food waste. 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 rapid composters. Every time the loading door is opened, the smell of decomposing food waste escapes. For this reason many hospitals that have opted for aerobic digesters have either had them removed because of the smell or placed them in a location away from the kitchen. Or you could:

4. Use a Food Waste Dryer

A food waste dryer 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. 


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.

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