Composting and Anaerobic Digestion (AD)

EPA waste data release 27 October 2022. Latest reference year 2020. (Data subject to Eurostat validation).

The quantity of Irish waste accepted for treatment at composting and anaerobic digestion facilities increased considerably from increased from 528,000 in 2019 to 597,000 in 2020; an overall increase of 13 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 and other mixed waste accepted for biostabilisation, which are reported separately (see below). 

Key findings

• The quantity of Irish waste accepted for composting and anaerobic digestion increased considerably from 528,000 in 2019 to 597,000 in 2020; an overall increase of 13 per cent. This increase can be partially explained by a change in the reporting methododology for 2020 data (detailed below),
• Municipal biowaste (kitchen and canteen food waste, garden and park green waste, edible oils and fats) made up 50 per cent of the waste accepted for composting/anaerobic digestion in 2020 (Figure 1).
• Wastes from agriculture, horticulture, aquaculture, forestry, hunting and fishing, and food preparation/processing contributed 37 per cent, while 9 per cent came from waste management facilities and water/waste water treatment plants.
• Of the 597,000 tonnes of waste accepted for composting/anaerobic digestion in 2020:
  • 73 per cent was composted/digested at facilites in Ireland (down from 80 per cent in 2019) while 27 per cent was transferred to facilities in Northern Ireland in 2020 (up from 20 per cent in 2019).
  • One-third of Ireland’s municipal biowaste (96,054 tonnes) was transferred to facilities in Northern Ireland for treatment in 2020. More favourable gate fees in Northern Ireland are attributed as the main driver for this trend
  • Fifty two per cent of waste was treated by anaerobic digestion while 48 per cent underwent composting. 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 52 per cent in 2020. This is the first year that AD has exceeded composting (Figure 2)
  • The large increase from 2019 to 2020 (evident in Table 1)  is mainly attributable to a change in reporting methododology: in order to align with European reporting,  any tonnages given as dry mass for 2020 were converted to their wet mass equivalent. This change mainly affected:
• The large increase from 2019 to 2020 (evident in Table 1)  is mainly attributable to a change in reporting methododology: in order to align with European reporting,  any tonnages given as dry mass for 2020 were converted to their wet mass equivalent. This change mainly affected:
  • Waste from the preparation and processing of meat, fish and other foods of animal origin (which almost doubled from 47,217 tonnes in 2019 to 87,550 tonnes in 2020);
  • wastes from the dairy products industry (which increased from 44,730 tonnes in 2019 to 76,421 in 2020), and
  • wastes from the production of alocholic and non-alocholic beverages (which rose  from 27,375 tonnes in 2019 to 35,385 tonnes in 2020).
• Products of composting and anaerobic digestion are used in horticulture, landscaping and agriculture.
• The treatment of wastes by biostabilisation at composting plants increased by 29% in 2020, up from around 152,000 tonnes in 2019 to 196,000 tonnes in 2020. These biostabilised wastes (post treatment) were disposed at landfill. Ideally all organic waste should be segregated at source and collected seperately so it can be treated by composting or anerobic digestion rather than biostabilisation and disposal at landfill.