Willow Evapotranspiration Systems

Willow Wastewater Cleaning Facilities with Zero Discharge

BACKLUND has participated in many projects and is working as a consultant in different countries advising private enterprise and authorities based on continues R & D.

For the time being annexes are worked out to Danish Waste Water Planning to include Willow Evapotranspiration Systems. BACKLUND is involved in this work as a consultant to Municipalities and Consultancy Companies.

"On-Site Wastewater Treatment Research" "Assessment of disposal options for treated wastewater from single houses on low permeability subsoils".
Research Project "Science, Technology, Research & Innovation for the Environment" (STRIVE). 

BACKLUND take part in the 3-year Research Project (2011 - 2014) in Ireland for the Irish EPA.

Arne Backlund is an external Expert Member of the Project Team in co-operation with 3 Irish Universities and contributes with Expert Knowledge about Willow Evapotranspiration Systems and Sustainable Sanitation / Ecological Sanitation.

Appendix to Wastewater Plan Number 2/September 2011 - Klinteby/Karrebækstorp. Assessment regarding Willow Evapotranspiration Systems regarding Technology and Economy. Project and Consultancy Work for Niras A/S and Næstved Municipality. 2010 - 2011.

Willow Evapotranspiration Systems compared to Traditional Wastewater Sewage Systems for Rural Houses as foreseen in the approved Appendix to current Wastewater Plans in Næstved Municipality from 2009.

The project was carried out for NK-Spildevand A/S in co-operation with Nielsen & Risager A/S in 2009 - 2010 and reported in:  NK-Spildevand A/S, Nielsen & Risager A/S, Backlund ApS 2010: Statement - Willow Evapotranspiration Systems as an Alternative to Planned Sewage Systems in " Appendix to existing wastewater planning" Næstved 2010 (In Danish).

Dewatering of Bio-Sludge in GeoTubes Planted with Willow.

Arne Backlund contributes with knowledge and Willow (2010) to a Test Site at Central Wastewater Treatment Plant in Næstved.

Willow Evapotranspiration Systems and Sustainable Sanitary Solutions.

Arne Backlund Advices (2009-2010) Næstved Municipality regarding Alternatives to Central Wastewater Solutions Based on Sewers.   

Willow Evapotranspiration System at Tappernøje, Denmark

Human wastes/resources have been used on land since ancient times. A sewage irrigation system commenced at Bunslaw, Germany in 1531 and was in operation for over 300 years.

Loading wastewater to a vegetation bed without outlet is a much more recent phenomenon.

Willows are especially suited for this purpose due to a very large evapotranspiration ability, flexible root development and ability to supply the roots with air.
The oldest known Willow Evaporation System - Willow Wastewater Cleaning Facility, was established in 1991/1992 and has been running since then.

It is located in Tappernøje by "Pilehuset" a shared living complex as a part of an institution for handicapped "Marjatta" and receives wastewater from 11 persons + precipitation.

BACKLUND has monitored the system from the start and has among others in a project in a co-operation with the county ordered by the Danish Environmental Protection  documented design, construction and running. Inlet of wastewater, precipitation, willow production and evapotranspiration.

We estimate that 1.500 - 3.000 willow beds have been constructed.

With proper design, dimensions, constructions and maintenance the experiences are very good.



Water Balance


System and Components


Oasis Effect


Clothe Line Effect


Willow Bed Area Demand due to Grid Cells in Denmark - m2/m3 Wastewater


Willow Evapotranspiration System on Møn, Denmark April 2004

February 2005

August 2005

November 2008

.Last modified:  07.07.2016   +45 60931453   Holmebjerg 21, DK-2950 Vedbæk Danmark