Composting and Anaerobic Digestion (AD)

EPA waste data release November 2021. Latest reference year 2019. Data subject to Eurostat validation.

The quantity of Irish waste accepted for treatment at composting and anaerobic digestion facilities increased considerably from 445,000 tonnes1 in 2018 to 528,000 tonnes in 2019; an overall increase of 19 per cent. 

These figures exclude (i) home composting estimates, (ii) facilities which only treated their own waste, (iii) waste imported to Ireland for treatment, and (iv) organic fines accepted for biostabilisation, which are reported separately (see below). 

Key findings

  • The largest increases were seen in:
    • municipal biowaste (up 15 per cent from 257,0002 to 295,000 tonnes);
    • wastes from the dairy products industry which more than doubled (from 20,618 tonnes to 44,730 tonnes), and
    • wastes from waste water treatment plants (up 18 per cent from 54,779 to 64,622 tonnes) (Table 1).
  • Municipal biowaste (kitchen and canteen food waste, garden and park green waste, edible oils and fats) made up 56 per cent of the waste accepted for composting/anaerobic digestion in 2019 (Figure 1).
  • Wastes from agriculture, horticulture, aquaculture, forestry, hunting and fishing, and food preparation/processing contributed 26 per cent, while 14 per cent came from waste management facilities and water/waste water treatment plants.
  • Of the 528,000 tonnes of waste accepted for composting/anaerobic digestion in 2019:
    • 80 per cent was composted/digested at facilities in Ireland (down from 83 per cent in 2018) while 20 per cent was transferred to facilities in Northern Ireland in 2019 (up from 17 per cent in 2018).
    • Almost one-third of Ireland’s municipal biowaste (89,642 tonnes) was transferred to facilities in Northern Ireland for treatment in 2019. More favourable gate fees in Northern Ireland are attributed as the main driver for this trend.
    • Fifty-five per cent of waste underwent composting while 45 per cent was treated by anaerobic digestion. There has been a marked increase in the share of waste treated by AD in recent years up from 30 per cent in 2017 to 40 per cent in 2018 and 45 per cent in 2019 (Figure 2).
  • Products of composting and anaerobic digestion are used in horticulture, landscaping and agriculture.
  • There has been a notable rise in the treatment of organic fines accepted for biostabilisation at composting plants, up from around 50,000 tonnes in 2013 to 152,000 tonnes in 2019. This reflects that most residual waste is now pre-treated mechanically at waste facilities. The biostabilised fines are used as landfill cover or disposed at landfill. 

Note: Figure 1 excludes organic fines accepted for biostabilisation.

Municipal Biowaste

There was a marked 15 per cent increase in the quantity of municipal biowaste sent for composting and anaerobic digestion, up from 257,000 in 2018 to 295,000 in 2019 (see Figure 3). The implementation of the Food Waste Regulations since 2010 and the associated roll out of brown bins to commercial and household premises, along with associated awareness raising activities to promote better segregation, have contributed to an upward trend in the quantity of municipal biowaste being treated by composting/anaerobic digestion. However, despite improved brown bin services and use, the latest EPA Household Waste data indicates that still only 48 per cent of Irish households had access to a brown bin in 2019 (up from 43 per cent in 2018 and 41 per cent in 2017).

The 2018 EPA Waste Characterisation Report found that one-third of residual (black bin) waste from non-household sources (including restaurants, hotels, offices etc.) is suitable for composting/anaerobic digestion. To boost our recycling rates and foster Ireland’s move to a circular economy, more biowaste from both commercial and household sources needs to be diverted to brown bins and composted. EU waste legislation3 requires the mandatory separate collection of biowaste from 2024 on. Ireland’s Waste Action Plan for a Circular Economy, published in September 2020, includes a commitment to make the provision of an organic waste bin mandatory as part of waste collection services for all households in Ireland. This should lead to a further sustained increases in the quantity of municipal biowaste separately collected and recycled in Ireland in the years ahead.

The quantity of municipal biowaste exported to Northern Ireland for composting/anaerobic digestion increased by 39 per cent from 64,362 in 2018 to 89,642 in 2019. Of the waste exported, some 62 per cent was sent for anaerobic digestion. Overall, almost one-third of Ireland’s municipal biowaste was exported to Northern Ireland for treatment in 2019. More favourable gate fees in Northern Ireland are attributed as the main driver for this trend.

 

Biostabilised Organic Fines

In 2019, five composting facilities in Ireland accepted organic fines for biostabilisation. Organic fines arise from the mechanical treatment of residual waste. There has been a notable rise in the treatment of organic fines at composting plants in Ireland, up from around 50,000 tonnes in 2013 to 138,000 tonnes in 2018 and 152,000 tonnes in 2019. This reflects the fact that most residual waste in Ireland is now pre-treated mechanically at waste facilities, for example by trommelling, before it is sent for recovery or disposal. The organic fines arising from this pre-treatment process undergo biostabilisation to reduce their biological activity to an EPA-approved standard. The biostabilised fines can then be used as landfill cover or disposed of at landfill without giving rise to odour and greenhouse gas emissions.

Notes:

1Revised 2018 Data Published Nov. 2021 - In validating and compiling the 2019 composting/anaerobic digestion data, it was identified 19,000 tonnes of waste had been omitted by a waste operator in 2018 reporting and LoW code 02 01 06 (animal faeces, urine and manure effluent including spoiled straw) was counted in error in 2018. These amendments resulted in a net increase in the quantity of waste composted/anaerobically digested in 2018 from 436,000 tonnes to 445,000 tonnes.

2Revised 2018 Data Published Nov. 2021 - In validating and compiling the 2019 data, an error was identified in the 2018 data.  Some 11,500 tonnes of waste had been misreported by a waste operator as food processing waste instead of municipal food waste.  This resulted in an amendment to municipal biowaste figure for 2018 from 245,000 tonnes to 257,000 tonnes.

3Revised Waste Framework Directive (Directive (EU)2018/851)

  • Table 1. Waste types accepted for composting & anaerobic digestion in 2018 and 2019.

    Open in Excel: Compost Table 1 2018 & 2019 (XLS 12KB)

Data collection

The EPA compiles information on composting and anaerobic digestion using data reported by waste facilities, data provided by the National Transfrontier Shipment Office and data collected from facilities in Northern Ireland.

From Envirogrind Ltd a compost image

Photo courtesy of Envirogrind Ltd.