Research 375: Development of Quality Standards for Compost and Digestate in Ireland

Authors: Percy Foster and Munoo Prasad

Summary: In Ireland, there are no national end-of-waste criteria for compost and digestate derived from source-separated materials. This study developed a quality standard for digestate and an updated standard for compost, it also recommends a strategy on how Ireland should implement national end-of-waste criteria for compost and digestate. It also examined best practice in other countries and options for having end-of-waste criteria.

Research 375 cover

Published: 2021

ISBN: 978-1-84095-994-9

Pages: 84

Filesize: 4,253 KB

Format: pdf

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Project Highlights

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Identifying Pressures

In Ireland, there are no national end-of-waste criteria for compost and digestate derived from source-separated materials. There are varying quality standards being used by composting and anaerobic digestion plants. Overall, the system needs a uniform set of quality standards for compost and digestate, which would replace existing standards being applied. This study will also recommend a strategy on how Ireland should implement national end-of-waste criteria for compost and digestate.

Informing Policy

Recent European Union (EU) circular economy and bioeconomy policies and the New European Green Deal promote the recycling of nutrients from organic wastes into products that can be used as soil improvers and fertilisers, thereby reducing the use of mineral fertilisers. This has renewed interest in the use of compost and digestate as potential fertilisers. This study developed a quality standard for digestate and an updated standard for compost. It also examined best practice in other countries and options for having end-of-waste criteria.

Developing Solutions

The research developed should be used by the National Standard Authority of Ireland to update Irish Standard (IS 441) on compost and develop a new IS standard for digestate. The findings of this study can be used in an application to the Environmental Protection Agency by industry for national end-of-waste standards for compost and digestate.

The possible approach that could be taken in Ireland to define end-of-waste criteria is by implementing either biowaste ordinance legislation or a national fertiliser regulation. It should include the requirement that compost or anaerobic digestion plants proposing to produce an end-of-waste product be compliant with a Quality Assurance Scheme that is monitored by a quality assurance organisation.

By achieving end-of-waste status, it generates a level playing field. It also supports the development of a circular economy while still respecting the precautionary principle by avoiding pollution when compost and digestate are used on soil.

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