Project Appreciation and Objectives
Occurrence of metaldehyde in raw waters has greatly increased over recent months. Little information is available on the removal by water treatment of this pesticide, orginating from slug pellets, although available evidence would suggest that it could be difficult to remove. The liklihood of exceeding the 0.1ug/l pesticide standard in the treated water is therefore high.
This project identified the performance and limitations of water treatment processes for metaldehyde removal and the need for alternative treatment, design or operation, in the short and longer term.
Benefits to Clients
The study has allowed participating companies to make decisions on treatment design and opeartion to deal with metaldehyde in the raw water, and has provided support for communications with DWI relating to compliance with the pesticide standard.
- Identify possible reasons for the recent increase in occurrence of metaldehyde in raw waters, and whether this represents a long term trend.
- Review existing data on removal at treatment works from participating companies.
- Evaluate removal performance for a range of GAC and PAC types, and by ozone or ozone/peroxide, through laboratory batch tests.
- Carry out GAC rapid column tests with the most appropriate GAC to provide further information for design and operation.
- Review other potential treatment options, such as adsorbents or UV/peroxide, and support any findings with laboratory tests where appropriate.
- Provide recommendations for design and operation to remove metaldehyde in water treatment, and concentrations that could be treated to maintain compliance.