The use of Leachate as a Fertiliser or to Gain Better Crop Yields from Irrigation
In the UK and Ireland there are several schemes where leachate is treated and disposed of by the "beneficial use of leachate" for such purposes as using the contaminants in the leachate as a fertiliser, or the water for irrigation, where crop yields can be increased by such use.
Beneficial uses of leachate irrigation suggested in the UK are:
- grass irrigation: for grazing and/or silage;
- crop irrigation: for example, sugar beet - consumes a lot of sulphate, so the sulphate often present in leachate is beneficial. Other crops even grass can b
 enefit in most soils from some added common salt (Sodium chloride);
- short rotation willow coppicing: (with the willow being used mostly for fuel where it can be a useful biofuel to reduce use of non-renewable energy resources). Willow coppice product can also be used to revive traditional local crafts of basket making, fencing, etc. Willow has a very heavy evapotransporation rate so the provision of additional water can be shown to be beneficial over the widest areas of the UK);
- general woodland species irrigation (ground level spraying): this one is hard to prove to be beneficial as there is seldom a soil moisture deficit, let alone a drought, in much of the UK.
The main problem with landfill leachates initially, and from all but the oldest landfills, is that they are too heavily contaminated for continuous direct irrigation of any crop.
Leachates from modern landfills are of such high BOD/COD, ammoniacal nitrogen etc, that they will usually also simply chemically burn the leaf surfaces, and may also coat them with iron oxides shutting out the light and causing stress.
So for beneficial-use, leachate will usually have to be pre-treated in some form, unless it is already very diluted by groundwater intrusion, or the leachate source is a leachate contaminated groundwater. Under these circumstances direct irrigation on to the crop may be possible, but whether it will be allowed under the UK Waste Management Regulations or PPC Regulations is a matter for discussion with the regularity authority (in the UK the Environment Agency (EA).
Licensing & Permitting Considerations
Leachate is a waste material when it leaves the waste. It remains a waste material as far as waste licensing and PPC permitting is concerned, even after treatment, and therefore Waste management or PPC regulations continue to apply to its use/disposal.
For the landfill operator wishing to use leachate as a fertiliser, or for irrigating a crop in dry weather, there are operational benefits which can be obtained if the “waste” leachate can be reclassified as a “product”.
Irrigating a “waste” entails compliance with a PPC permit or a Waste Management Licence, which will incurs significant monitoring and licensing costs.
None of these apply to a “product” which is applied to the land for beneficial purposes.
We think that EA Guidance will be developed in due course of time. However, the requirements for establishing the reclassification of a leachate (pre-treated or not) as a product (eg fertiliser), is as far as we are aware, a matter of discussion with the EA. Indications are that to apply for “beneficial use” status for an irrigation project it will be necessary to establish agreed scientific quality controls, and there may be other requirements.
Want to know more about leachate irrigation?
We are carrying out research on the frequency and methods of leachate-irrigation used in the UK, in Europe and worldwide.
If you are interested in finding out more about this research read more at our Leachate-Irrigation web site here.
If you want us to consider one of your landfills for leachate treatment and disposal by land irrigation you should fill in the details on our Contact Form here.
Note: All leachates referred to on this page are non-hazardous leachates, (ie do not contain “Dangerous Substances”). Irrigation is not normally possible with a hazardous leachate.
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