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.

Note: Figure 1 excludes wastes accepted for biostabilisation.

Municipal Biowaste

There was a two per cent increase in the quantity of municipal biowaste sent for composting and anaerobic digestion, up from 295,000 tonnes in 2019 to 302,000 tonnes in 2020 (see Figure 3), and the per capita amount increased from 60 kg per capita in 2019 to 61 kg per capita in 2020.

The latest EPA Household Waste data indicates that 64 per cent of Irish households with a bin service had access to a brown bin in 2020. Despite the continued rollout of brown bins the quantities of organic waste materials captured separately is progressing slowly. In 2020 significant quantities of organic waste remain uncaptured and are collected as part of the residual bin collection. This material is mechanically treated to produce a biostabilised ouput which goes for disposal at landfill.

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. The EPA is currently undertaking a new municipal household waste characterisation study which will be published in 2023. This study will provide an insight into how householders waste segregation practices have changed since the last characterisation study was carried in 2018.

The implementation of the current Food Waste Regulations and associated roll out of brown bins to commercial and household premises needs to be implemented without delay supported by awareness raising and education activities as well as enforcement to ensure better segregation levels are achieved.

EU waste legislation[1] 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 bins mandatory as part of waste collection services for all households in Ireland. This requierment needs to be progressed urgently.

The quantity of municipal biowaste exported to Northern Ireland for composting/anaerobic digestion increased by seven per cent from 89,642 tonnes in 2019 to 96,054 tonnes in 2020. Overall, one-third of Ireland’s municipal biowaste was exported to Northern Ireland for treatment in 2020. Of the waste exported, some 57 per cent was sent for composting. More favourable gate fees in Northern Ireland are attributed as the main driver for this trend. 

 

 

 

Biostabilised Waste

In 2020, six composting facilities in Ireland accepted organic fines and other mixed waste for biostabilisation. This waste arises from the mechanical treatment of residual waste. There has been a notable rise in the treatment of organic fines and other mixed waste at composting plants in Ireland in recent years, up from around 50,000 tonnes in 2013 to 138,000 tonnes in 2018, 152,000 tonnes in 2019 and 196,000 in 2020. 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 disposal. The wastes arising from this pre-treatment process undergo stabilisation to reduce their biological activity to an EPA-approved standard. The biostabilised waste can then be disposed of 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. 

  • Table 1. Waste types accepted for composting & anaerobic digestion from 2018 to 2020.

    Open in Excel: Table 1 2020 (XLS 12KB)

    Open in CSV : Table 1 2020 (CSV 2KB)

Data collection

The EPA uses multiple data sources to compile the information on composting and anaerobic digestion, including data reported by waste treatment facilities and collectors in Ireland and data collected from facilities in Northern Ireland.

Please note composting/AD sludge data is now consistently reported as wet masses in line with EU Waste Statistic reporting requirements. Dry masses are therefore converted to wet where relevant.

Further information on food waste and biodegradable municipal waste sent to landfill can be found on our Waste Statistics webpages

 [1] Revised Waste Framework Directive (Directive (EU) 2018/851)

From Envirogrind Ltd a compost image

Photo courtesy of Envirogrind Ltd.