The increase in recycling rates achieved by local authorities over recent years has been impressive. But it has also resulted in the creation of different collection systems with many local variations. So far, there has been little objective evidence about their cost and effectiveness.

To address this, WRAP recently conducted a study into kerbside recycling, looking at the indicative costs and performance of the different systems. The resulting report, Kerbside recycling: indicative costs and performance, identifies the characteristics of a good practice approach to the main recycling options. It then models the relative cost of these approaches and their effectiveness.

Service variations

The study focused on the three main kerbside collection systems: kerbside sort; single-stream co-mingled; and two-stream partially co-mingled. It also examined a number of the main service variations in each category within two different local contexts – urban and rural.

About 44% of schemes are kerbside sort, 35% are single- stream co-mingled and 11% are two-stream partially co-mingled. The costs and performance achieved by a scheme varies depending on the system type, its design and operation, and where it is operated.

The advantage of kerbside sorting is that contamination can be identified and left in the container. If the reasons for this are explained, residents are provided with feedback on the correct use of the service. This sorting also ensures a high quality material for the market – typically the level of contamination is less than 0.5%.

A comparison of kerbsider and stillage vehicles for kerbside sort was undertaken.

While stillage vehicles are generally cheaper to buy and maintenance costs are low, they tend to have smaller capacities and slower unloading times. They also have limited space for promoting recycling services on the side of the vehicle. There are also concerns with loaders sorting on the vehicle, dual-side entry and inappropriate loading heights.

But a kerbsider can be less flexible in the type and range of materials that can be collected. For example, food waste cannot be added due to the unloading operation. There is also the potential for cross-contamination with other materials. The maximum number of compartments is generally five, so it can be difficult to add new materials to existing rounds without mixing materials.

If the kerbsider volume is increased from 28m2 to 33m2, in most cases the collection costs associated with this are marginally higher – around 5-20p in the net cost per household per year. The only case where there is a saving in this net cost is where refuse is collected weekly, recycling is fortnightly, and plastic bottles are collected. If textiles can be added to a scheme using stillage vehicles, the net cost per household can reduce by 70p.

Couting the cost of frequency

When it comes to collection frequency, fortnightly recycling collections are less expensive than weekly, although the yield is higher from a weekly service. The difference in net cost per household between fortnightly and weekly ranges from £3 to £5.60 a year in the urban authority, and from £7.40 to £8.80 in the rural authority.

When assessing the cost of single-stream co-mingled systems, consideration should be given to all cost elements. The collection-only costs are lower than similar kerbside sort options due to larger round sizes resulting from quicker collections. But the net costs are higher once MRF gate fees and the cost of handling contamination are accounted for.

While the impact of a higher or lower gate fee on the cost per tonne can be easily observed, the impact on the net cost per household may be less apparent. For the systems modelled, a variation in the gate fee of plus or minus £15 per tonne has the effect of increasing or decreasing the net cost per household of between £1.75 and £3.50 a year.

In some cases, revenue sharing mechanisms are in place so that the risk and reward of material markets is shared between the council and the MRF provider. But the benefits to an authority will depend on the contractual/income-sharing arrangements in place. Good practice for co-mingled collections indicates materials should not be over-compacted during collection as this can impact on material quality.

Collecting glass via co-mingled schemes were examined. Currently UK MRFs accepting glass cannot sort it to the standard required for remelt applications. The increase in yield resulting from collecting glass has the effect of reducing the net cost per tonne of targeted materials, despite the fact that a higher MRF gate fee has been assumed. Collecting glass can increase yields in a rural area by 42kg to 51kg per household per year, and in urban areas by 31 to 37 units accordingly. This can result in a reduction in the net cost of collection by about £11 per tonne in urban areas, and £14-£22 in rural areas.

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