Composting and Anaerobic Digestion (AD)

EPA waste data release 25 November 2024. Latest reference year 2022. (Data subject to Eurostat validation).

The quantity of Irish waste accepted for treatment at composting and AD facilities in 2022 was 735,000 tonnes. Wet sludges are a component of this waste, when wet sludges were converted to dry sludges, the total waste accepted for treatment reduced to 510,000 tonnes. The sludge conversion was carried out in line with Waste Statistics Regulation.¹

These figures exclude home composting, facilities that treat their own waste on site, and waste imported to Ireland for treatment. Organic fines and other mixed waste treated by biostabilisation, are reported separately (see below).

Key Findings

The quantity of Irish waste accepted for treatment at composting and AD facilities in 2022 was 510,000.
In 2022 an improved calculation method was implemented. This included the conversion of wet sludges to dry sludges in line with the requirements of the Waste Statistics Regulation1.
Municipal waste made up 66% of the waste accepted for composting/AD in 2022 up from 56% in 2021 (Figure 1).
Wastes from agriculture, horticulture, aquaculture, forestry, hunting, fishing, food preparation and food processing contributed 20%. An additional 10% came from waste management facilities, water/wastewater treatment plants and 4% from other sources.
Data in the 510,0001 tonnes of waste accepted for composting and AD in 2022 show that:

AD has exceeded composting in the treatment of biodegradable waste and sludges, with 51% of waste 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 and 2022.
Sixty-seven per cent of this waste was treated at composting/AD facilities in Ireland while 33% was transferred to facilities in Northern Ireland in 2022.
There was a slight increase in the quantity of separately collected municipal bio-waste² sent for composting and AD in 2022, up from 332,000 tonnes in 2021 to 334,000 in 2022 (see Figure 3). Forty-two per cent of this municipal bio-waste (138,620 tonnes) was transferred to facilities in Northern Ireland for treatment in 2022. This is similar to 2021 figure of 140,128 tonnes.

Products of composting and AD are used in horticulture, landscaping and agriculture.
The treatment of wastes by bio-stabilisation at composting plants increased in 2022 to 273,000, up from 196,000 tonnes in 2020 to 267,000 in 2021. These biostabilised wastes (post treatment) were disposed of at landfill or went for further treatment.
Ideally, all bio-waste should be segregated at source and collected separately so it can be treated by composting or AD rather than by bio-stabilisation and disposal at landfill.

Figure 2. Compost compared to anaerobic digestion 2017-2022

The year 2022 is presented twice in this barchart, 2022A shows data prior to conversion of sludges to dry weight, this is the approach that has been used in previous years. Data used in 2022B shows totals after conversion from wet to dry.

Municipal Bio-waste

There was a slight increase in the quantity of municipal waste sent for composting and AD in 2022, up from 332,000 tonnes in 2021 to 334,000 in 2022 (see Figure 3).

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 latest EPA Household Waste data indicates that 66% of Irish householders with a bin service had access to a brown bin in 2022 (percentage includes bin sharing). The same level of waste collection service needs to be provided to all householders.

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 legislation³ means that the separate collection of bio-waste must be offered to all customers from January 2024.

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 bio-waste exported to Northern Ireland for composting/anaerobic digestion was similar at 138,620 in 2022 from to 140,128 tonnes in 2021. Overall, 42% of Ireland’s municipal bio-waste was exported to Northern Ireland for treatment in 2022. Of the municipal waste exported, some 59% was sent for anaerobic digestion.

Biostabilised Waste

In 2022, nine composting facilities in Ireland accepted organic fines and other mixed waste for bio-stabilisation. 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 196,000 in 2020, to 267,000 tonnes in 2021 and 273,000 in 2022. 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 bio-waste 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	Qty 2022
02 01	Wastes from agriculture, horticulture, aquaculture, forestry, hunting and fishing	5,380	5,037	5,844	9,911	5,090
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	31,148	*
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	10,968
02 04	Wastes from sugar processing	0	15	0	0	0
02 05	Wastes from the dairy products industry	20,618	44,730	76,421	43,523	21,058	*
02 06	Wastes from the baking and confectionery industry	1,923	448	199	1,142	955
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	34,043	*
03 01	Waste from wood processing and the production of panels of furniture	0	729	0	0	432
03 03	Wastes from pulp, paper and cardboard production and processing	24	0	0	35	26	*
04 02	Wastes from the textile industry	114	140	127	125	24	*
06 05	Sludges from onsite effluent treatment	0	21	18	0	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	1,734
07 01	Wastes from the manufacture, formulation, supply and use (MFSU) of basic organic chemicals	0	1,783	3,869	0	73
07 05	Wastes from MFSU of pharmaceuticals	2,427	4,204	4,217	4,591	5,302	*
07 06	Wastes from the MFSU of fats, grease, soaps, detergents, disinfectants and cosmetics	63	7	22	26	4
10 01	Wastes from power stations and other combustion plants	801	936	1,132	971	516
10 13	Waste from manufacture of cement, lime and plaster and articles and products made from them	0	0	0	0	0
15 01	Packaging (including separately collected municipal packaging wastes)	0	30	0	400	2,129
16 03	Off-specification batches and unused products	235	354	519	376	0
16 10	Aqueous liquid waste	2,692	303	4,254	9,634	5,625	*
17 02	Construction and demolition waste wood	127	880	0	1,000	866
17 08	Gypsum waste		0	0	0	727
19 05	Wastes from aerobic treatment of waste	216	0	66	0	0
19 07	Landfill leachate	63	284	0	158	5	*
19 08	Wastes from waste water treatment plants not otherwise specified	54,779	64,622	42,846	55,112	32,914	*
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	1,777	*
19 12	Wastes from mechanical treatment of waste (wood waste)	3,822	8,036	4,540	9,583	15,836
20 01	Municipal wastes (separately collected fractions) except 15 01	210,805	248,538	247,942	270,737	278,529
20 02	Garden and park wastes (including cemetery waste)	46,290	45,988	54,167	60,164	54,331
20 03 (Note 1)	Other municipal wastes	7,686	10,389	6,418	12,099	5,347	*
	Total	445,341	528,080	597,192	589,994	509,459
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.
* Chapters effected by converting Wet to Dry sludges

Open in Excel: Table 1 2022 (XLS 13KB)

Open in CSV : Table 1 2022 (CSV 3KB)

Home Composting

The quantity of waste for home composting in Ireland for 2022 was estimated at 146,000 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. Please note composting/AD sludge data is now consistently reported as DRY masses in line with EU Waste Statistic reporting requirements.

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

(Photo from EnviroGrind Ltd website)

Yellow industrial tractor unloading organic waste for composting

To see data from previous years see: Compost and Anaerobic Digestion Data Archive | Environmental Protection Agency (epa.ie)

_{1. The reporting unit to be used for all waste categories is 1 tonne of (normal) wet waste except for the waste categories ‘industrial effluent sludges’, ‘common sludges’, ‘sludges and liquid waste from waste treatment’ and ‘dredging spoils’ were the reporting unit is 1 tonne of dry matter. https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=celex%3A32010R0849}

_{2. Bio-waste is defined as biodegradable garden and park waste, food and kitchen waste from households, restaurants, caterers and retail premises, and comparable waste from food processing plants. It does not include forestry or agricultural residues, manure, sewage sludge, or other biodegradable waste such as natural textiles, paper or processed wood. It also excludes those by-products of food production that never become waste. https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32008L0098}

_{3. Revised Waste Framework Directive (Directive (EU) 2018/851)}