Composting and Anaerobic Digestion (AD)

EPA waste data release 27 November 2023. Latest reference year 2021. (Data subject to Eurostat validation).

The quantity of Irish waste accepted for treatment at composting and anaerobic digestion (AD) facilities decreased sightly from 597,000 in 2020 to 590,000 in 2021.

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 has decreased slightly from 597,000 in 2020 to 590,000 in 2021.
Municipal biowaste (kitchen and canteen food waste, garden and park green waste, edible oils and fats) made up 56% of the waste accepted for composting/anaerobic digestion in 2021 up from 50% in 2020 (Figure 1).
Wastes from agriculture, horticulture, aquaculture, forestry, hunting and fishing, and food preparation/processing contributed 27%, while 12% came from waste management facilities and water/waste water treatment plants.
Of the 590,000 tonnes of waste accepted for composting/anaerobic digestion in 2021:

For the second year in a row AD has exceeded composting, with 51% of waste was treated by anaerobic digestion while 49% underwent composting. There has been a marked increase in the share of waste treated by AD in recent years up from 30% in 2017 to 52% in 2020 and 51% in 2021.
Seventy-two per cent was composted/AD at facilities in Ireland while 28% was transferred to facilities in Northern Ireland in 2021 (up from 27% in 2020).
Forty-two per cent of Ireland’s municipal biowaste (140,128 tonnes) was transferred to facilities in Northern Ireland for treatment in 2021 .

Products of composting and anaerobic digestion are used in horticulture, landscaping and agriculture.
The treatment of wastes by biostabilisation at composting plants increased significantly in 2021, up from 196,000 tonnes in 2020 to 267,000 in 2021. These biostabilised wastes (post treatment) were disposed at landfill or went for further treatment. Ideally, all biowaste should be segregated at source and collected separately so it can be treated by composting or anaerobic digestion rather than biostabilisation and disposal at landfill.

Figure 1 excludes wastes accepted for biostabilisation.

Municipal Biowaste

There was a 10% increase in the quantity of municipal biowaste sent for composting and anaerobic digestion in 2021, up from 302,000 tonnes in 2020 to 332,000 tonnes in 2021 (see Figure 3).

The latest EPA Household Waste data indicates that 69% of Irish householders with a bin service had access to a brown bin in 2021 (percentage includes bin sharing). The same level of waste collection service needs to be provided to all householders.

The 2022 EPA Waste Characterisation Report found that one-third of commercial general bin waste from non-household sources (including restaurants, hotels, offices etc.) was in the wrong bin.

Twenty-one per cent of the general household waste bin still contains food and garden waste. This should be correctly segregated into the organic waste bin.

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 targeted awareness raising and education activities as well as enforcement to ensure better segregation levels are achieved. New EU waste legislation^[1]means that the separate collection of biowaste will be mandatory from the end of 2023.

While this waste is suitable for composting/AD, more needs to be done to prevent food waste through initiatives such as Stop Food Waste.

The quantity of municipal biowaste exported to Northern Ireland for composting/anaerobic digestion increased by 46% from 96,054 tonnes in 2020 to 140,128 tonnes in 2021. Overall, 42% of Ireland’s municipal biowaste was exported to Northern Ireland for treatment in 2021. Of the waste exported, some 56% was sent for composting.

Biostabilised Waste

In 2020, eight composting facilities in Ireland accepted organic fines and other mixed waste for biostabilisation. Most of 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 152,000 tonnes in 2019 and 196,000 in 2020 to 267,000 tonnes in 2021. 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 along with other mixed wastes undergo stabilisation to reduce their biological activity to an EPA-approved standard. The biostabilised waste can then be disposed of at landfill or sent for further treatment. Ideally all biowaste should be segregated at source and collected separately so it can be treated by composting or anaerobic digestion rather than biostabilisation and disposal at landfill.

List of Waste entry chapter sub-heading	Waste types accepted for composting and anaerobic digestion	Qty 2018	Qty 2019	Qty 2020	Qty 2021
02 01	Wastes from agriculture, horticulture, aquaculture, forestry, hunting and fishing	5,380	5,037	5,844	9,911
02 02	Wastes from the preparation and processing of meat, fish and other foods of animal origin	56,511	47,217	87,550	47,758
02 03	Wastes from fruit, vegetables, cereals, edible oils, cocoa, coffee, tea and tobacco preparation and processing; conserve production; yeast and yeast extract production, molasses preparation and fermentation.	2,549	10,435	13,626	11,601
02 04	Wastes from sugar processing	0	15	0	0
02 05	Wastes from the dairy products industry	20,618	44,730	76,421	43,523
02 06	Wastes from the baking and confectionery industry	1,923	448	199	1,142
02 07	Wastes from the production of alcoholic and non-alcoholic beverages (except, coffee, tea and cocoa)	23,714	27,375	35,384	42,545
03 01	Waste from wood processing and the production of panels of furniture	0	729	0	0
03 03	Wastes from pulp, paper and cardboard production and processing	24	0	0	35
04 02	Wastes from the textile industry	114	140	127	125
06 05	Sludges from onsite effluent treatment	0	21	18	0
06 10	Wastes from the manufacture, formulation, supply and use (MFSU) of nitrogen chemicals, nitrogen chemical processes and fertiliser manufacture	1,026	1,267	1,441	1,570
07 01	Wastes from the manufacture, formulation, supply and use (MFSU) of basic organic chemicals	0	1,783	3,869	0
07 05	Wastes from MFSU of pharmaceuticals	2,427	4,204	4,217	4,591
07 06	Wastes from the MFSU of fats, grease, soaps, detergents, disinfectants and cosmetics	63	7	22	26
10 01	Wastes from power stations and other combustion plants	801	936	1,132	971
10 13	Waste from manufacture of cement, lime and plaster and articles and products made from them	0	0	0	0
15 01	Packaging (including separately collected municipal packaging wastes)	0	30	0	400
16 03	Off-specification batches and unused products	235	354	519	376
16 10	Aqueous liquid waste	2,692	303	4,254	9,634
17 02	Construction and demolition waste wood	127	880	0	1,000
17 08	Gypsum waste		0	0	0
19 05	Wastes from aerobic treatment of waste	216	0	66	0
19 07	Landfill leachate	63	284	0	158
19 08	Wastes from waste water treatment plants not otherwise specified	54,779	64,622	42,846	55,112
19 09	Wastes from the preparation of water intended for human consumption or water for industrial use	3,475	4,311	6,590	6,933
19 12	Wastes from mechanical treatment of waste (wood waste)	3,822	8,036	4,540	9,583
20 01	Municipal wastes (separately collected fractions) except 15 01	210,805	248,538	247,942	270,737
20 02	Garden and park wastes (including cemetery waste)	46,290	45,988	54,167	60,164
20 03 (Note 1)	Other municipal wastes	7,686	10,389	6,418	12,099
	Total	445,341	528,080	597,192	589,994
Note 1: Includes List of Waste entries 20 03 04 (septic tank sludge) and 20 03 06 (waste from sewage cleaning) which are excluded from municipal waste reporting as per Eurostat guidance.

Open in Excel: Table 1 2021 (XLS 12KB)

Open in CSV : Table 1 2021 (CSV 3KB)

Home Composting

The quantity of waste for home composting in Ireland for 2021 was 155,847 tonnes . A Household Guide to Composting provides an introduction to home composting and also gives details of what types of composters are available and how to select a system that is suitable for your household.

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).

(Photo from EnviroGrind Ltd website)

Yellow industrial tractor unloading organic waste for composting