A lot of our work in recent years has involved exploring options around food waste collections, or working with Councils that already separately collect food waste or comingle organics. We therefore have a strong track-record in analysing:

1. Separate food waste collection systems as part of multi-stream collections (e.g. West of England councils, St Helens Council).
2. Systems where food waste is collected on separate vehicles (e.g. Stroud) or on podded vehicles (e.g. Peterborough).
3. Comingled collections of organics (garden & food combined e.g. most of Greater Manchester & Warwickshire).

We have modelled each of the above and there are merits of different approaches.

Which approach is best?

This is one of those sub-headings where you know at the outset that there isn’t a clear answer, the factors which govern the ‘best’ alternative will ultimately depend on the priorities of the Council in question. In general terms, as regards collection costs, comingling organics has the lowest additional cost, but this is balanced by the lowest yield of food waste, typically between 0.4 – 0.75kg/hh/wk for a fortnightly organics collection in a wheeled bin. Furthermore, the treatment cost of processing all the organics (garden and food) in an in-vessel composting plant is an additional cost burden not faced by Councils with separate collections. Moreover, the carbon impact, whilst lower in the collection operation is higher for the treatment operation (compared to Anaerobic Digestion which is primarily used for separate food waste collections, whereby the food waste is converted to biomethane for bioenergy purposes).

It should also be recognised that when comparing separate food waste collections with comingled organics collections there are several variables that come into play. Firstly, separate food waste collections are delivered weekly (rather than typically fortnightly for comingled collections). Secondly, and to an extent related, the anticipated food waste yield from a separate collection of food waste will generally be in the region of 0.8 – 1.8kg/hh/week (two or three times that from comingled collections). The yield is influenced by socio-demographic factors, as demonstrated by WRAP. Indeed, WRAP developed a ‘ready reckoner’ for food waste yields for weekly separate collections based around this, which estimates a ‘low’, ‘medium’ and ‘high’ yield of food waste for any given Council. It is our experience that the ‘low’ projection is most realistic in practice. However, if a residual waste restriction exists (e.g. 90 litres of residual waste capacity available to households per week or less), then the yield shifts closer to the ‘medium’ band.

The cost differential between collection systems varies widely between Councils that (1) collect food waste in a compartment on a multi stream collection vehicle, or (2) adopt small (7.5t) dedicated food waste vehicles, or (3) utilise a pod on an RCV. Again, in general terms, the pods are the least favoured approach. The additional capital costs and some operational limitations (e.g., size of vehicle / reduced waste capacity for the main body) has meant these are less common in the UK. One operational issue that impacts on efficiency of all food waste collections is the low amount of waste collected in volume terms. This means that some vehicles run over two typical rounds per day and are still not getting a full load. There is a balance here regarding good participation in the service and not wishing that households generate a lot of food waste…

What are the key issues?

Key issues for food waste collections may be summed up in seven areas:

1. Cost – there is undoubtedly a significant additional net cost to establishing a food waste collection. This can be modelled in advance of implementing a collection, and Government has committed (and budgeted) to cover any net new cost burden.
2. Participation – it can be challenging conveying key food waste collection messages and dispelling any myths (most commonly regarding vermin and disamenity) or previous unsuccessful trials. However, there are good communications examples and PR campaigns to apply.
3. Carbon – the greatest detrimental carbon impact is from the additional collection activity; this is usually outweighed (in systems using Anaerobic Digestion) by a combination of (1) reduced emissions from disposal and (2) energy recovery benefits from AD. As collection fleets decarbonise this should improve further.
4. Policy – the Government is likely to require separate food waste collection, there may be mitigations in areas under existing contract with Mechanical Biological Treatment facilities or in long term arrangements with In-Vessel Composters for Councils with comingled organics collections (we await clarity on both aspects).
5. Prevention – food waste in itself should be tackled through education and campaigns around behaviour change, such as the Love Food Hate Waste and also to a degree, home composting initiatives. The best result is no food waste at all.
6. Treatment – adequate planning for and procuring of suitable anaerobic digestion capacity is essential, for processing the food waste with good quality outlets for the digestate and biomethane produced.
7. Operations – suitable containers and liners, this is another blog in itself, but liners should align to the treatment system above and containers cater for different types of housing stock.

Frith Resource Management have worked with over 60 Councils on collection and treatment options and provide collection modelling and communications support for implementing food waste collections. For further information contact paul@frithrm.com or call 01746 552423.