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Application of drinking water treatment sludges to land: opportunities and implications

Applying drinking water treatment residuals to land: opportunities and implications.

Scottish Water has identified the need to transition the outlet for water treatment residuals (WTR) from land restoration to agricultural land due to the increase in WTR, landfill charges, reduced lifespan of sites and sustainability. 

This study supports transition by addressing knowledge gaps e.g.,

  • what are the benefits and disbenefits of applying drinking WTR to land?
  • How does this align with the circular economy?  
  • What is best practice for application to land? 

The key findings, published here, are that application of WTR has resulted in benefits to soil properties i.e., water retention, porosity, hydraulic conductivity and P storage capacity without negative impacts on groundwater. No change in plant yield was reported. Application of WTR to lands with pH<5.5 should be avoided. The parameters to be assessed for application are described. Sole application of WTR is suitable for land restoration. However, if separate applications of fertilisers are made, WTR application could enhance soil and plant properties in agricultural land and forestry. The circular economy may benefit through the recovery of chemical resources, although investment and appropriate legislation are missing. A decision support tool for the application of WTR to land in Scotland was developed (available on the here).

Project Objectives

Contact Nikki Dodd