Irish Water has published a long-term National Wastewater Sludge Management Plan (NWSMP) that outlines its strategy to ensure a nationwide, standardised approach for the management, treatment, transport, storage and disposal of wastewater sludge over the next 25 years.

Since its incorporation in 2014, Irish Water has taken over the responsibility of providing water and wastewater services in Ireland from 31 local authorities. This includes managing approximately 1,000 wastewater treatment plants.

Irish Water has looked at how wastewater sludge is currently managed throughout the country and estimates that the quantity of wastewater sludge generated is expected to increase by more than 80% by 2040 as new and upgraded plants to treat wastewater are completed.

Currently 98% of wastewater sludge is treated to produce a biosolids product, which is being reused in agriculture. There are very limited alternative options currently available in Ireland. In response to feedback from two public consultations, the NWSMP focuses on future biosolids use being targeted at crops such as non-agricultural and crops for animal feed.

A feasibility study will also be carried out to investigate alternative outlets for sludge reuse in order to reduce the risks associated with depending on a single outlet for wastewater sludge.

Irish Water’s Plan focusses on quality assurance, monitoring and reporting on a national level which will include an annual audit of the management activities pending the development of a full wastewater treatment quality assurance scheme, in addition to the development of Standard Operating Procedures.

The Plan also proposes that a network of hub treatment centres and satellite dewatering sites be further developed to optimise the balance between treatment and transport costs. The location of ‘hubs’ will be considered on a regional rather than county basis and will maximise the use of energy recovery where possible.

Key Measures in the NWSMP include:

Treatment and Transport

• The network of hub treatment centres and satellite dewatering sites will be further developed to optimise the balance between treatment and transport costs;
• The location of ‘hubs’ will be considered on a regional rather than county basis and will maximise the use of energy recovery where possible;
• While thermal drying will continue to be provided where practically and economically viable, advanced anaerobic digestion is the preferred sludge treatment option for the majority of Sludge Hub Centre sites;
• Lime stabilisation at off-site centres will be phased out and any on-site lime treatment will be strictly controlled for effective treatment.

Quality Assurance, Monitoring and Reporting

• The introduction of a quality assurance system for the whole sludge management process from sludge treatment through to sludge transport, storage and reuse;
• An annual audit of sludge management activities will be undertaken by Irish Water until the quality assurance scheme is fully developed;
• Standard Operating Procedures (SOPs) for wastewater sludge management will be developed by Irish Water and requirements with respect to landspreading of treated wastewater sludge (biosolid) will be included in these SOPs.

Sludge Outlet Options

The preferred option for reuse of treated wastewater sludge (biosolids) is reuse on land. Non-food tillage crops and animal feed crops will be the primary focus for reuse of biosolids. To reduce the dependence on the use of agricultural land for wastewater sludge reuse Irish Water will carry out a detailed feasibility study to investigate alternative sludge outlet options.

Speaking at the launch, Irish Water’s Head of Asset Management, Sean Laffey, said:

“I am delighted that Irish Water is publishing the National Wastewater Sludge Management Plan at the National Ploughing Championships today. The Plan outlines our strategic, sustainable approach to this crucial issue. This Plan has been influenced by widespread and comprehensive consultation from the earliest stages of development and, given that the reuse of sludge obviously has big implications for farming and rural communities, Irish Water is grateful for the engagement of individuals, organisations and representative groups.”

“ It was essential for us to get as diverse a view as possible on this issue as that will help to ensure the effective management of sludge from the treatment of the wastewater we all create. As a single national utility, Irish Water has the capacity and the expertise to ensure that a strategic, standardised national approach can be taken to the management of wastewater sludge. This 25-year strategy sets out how we will improve the way wastewater sludge is managed in Ireland, including the introduction of a quality assurance system for the wastewater treatment process from start to finish.”

Click here to download the NWSMP