Presentation at Wexford County Ireland November 21th. 2007

1. Willow Evapotranspiration
Zero Discharge Sanitation
Arne Backlund
www.BACKLUND.dk

2. From the first known
”unknown” system in 1991/1992
to best known practice in 2007
recommended by authorities in
Denmark for highest demands

3. BACKLUND
Small R&D Consultant Engineering
and Lecturing family company
established 1986
Located 10 km north of Copenhagen
City in Denmark
Working in many countries in Europe
Main Focus Ecologically Sustainable
Sanitary Solutions

4. Research & Development
BACKLUND participation in Sustainable
Sanitation projects carried out for the
Danish Environmental Protection
Agency EPA (funded through the "
Action Plan for the Promotion of
Ecological Urban Renewal and
Wastewater Treatment" and
European Union FAIR-Programme

5. BACKLUND R & D
• Short Rotation Willow Biomass Plantations
Irrigated and Fertilised with Wastewater
in Sweden, Northern Ireland, France and
Greece
• Willow Evapotranspiration Beds with Zero
discharge in Denmark
• R & D in Denmark, Sweden and Germany
concerning Diverting NoMix Toilets and
Waterless Urinals to Enable Reuse of
Energy Resources and Nutrients in
Humane Urine and Human Faeces

6. BACKLUND R & D
• Vacuum Toilets in Sweden, Denmark and
Germany – Reduction in Wastewater
production and Treatment of the Collected
Material at Biogas Works
• Collection, Storage and Irrigation of
Human Urine in Agriculture in Denmark
and Sweden
• Draining and Composting of Collected
Black Wastewater in Denmark and Sweden

7. BACKLUND R & D
• Sustainble Handling of Urine, Faeces and
Grey Water from Danish Allotment
Gardens by means of Diverting (No-Mix)
Toilet Systems and Evapotranspiration
Willow Beds
• Evaluation of Functioning of Alternative
Toilet Systems and their Ability to Reduce
Pathogens in Denmark and Sweden

8. Reflex or Reflection
• Mixing - Discharge & Dilution
– best solution to polution?
• Problems are not automaticly solved with
more of the same thinking (Paradigm) that
created the problem in the first place.

9. EU Water Framework Directive
from Year 2000
• Before 2015
• Good conditions in:
• Surface water (streams, lakes, coast)
• Ground water

10. Flow or Stream of Material
• Urine
• Faeces
• Toilet paper
• Flush water
• Grey water

11. Flow or Stream of Material
• We almost excrete the same amount of
nutrients as we consume
• Human urine contributes with only 1 % of
the volume of household wastewater but
contains 80 % of N, 55 % of P and 60 %
of K in household wastewater and less
than 0.6 % of cadmium and 0.06 % of
lead

12. Selected Components
• Waterless urinals
• No-Mix/Diverting toilet stools
• Collection and composting units
• Anaerobic fermentation
• Willow evapotranspiration bed
• Willow plantation

13. Wastewater Fractions from
households
• Type Content
• Classic Toilet, bath, kitchen, wash
• Black Toilet
• Grey Bath, kitchen, wash
• Light grey Bath, wash
• Yellow Urine
• Brown Faeces

14. Elements in Alternative
Handling of Wastewater
• Source control
• Collection
• Storage
• Transport
• Treatment
• Discharge / recycling

15. Water consumption Today With savings
Toilet 50 25
Bath 40 25
Kitchen 50 25
Wash 10 5
Total 150 80
Fractionated water consumption, l/(cap·d)

16. No-Mix flushing toilets

17. Removal processes in
constructed wetlands
Particulates settle
Degradation of organic
matter
Little nitrification
Denitrification
Plant-uptake (N and P)
P is filtrated/adsorbed
Degradation of organic matter

18. Proces NH4
+
-N
(%)
Total-N Total-P Organic matte
(as BOD)
(%)
Septic tanks ~ 0 10 10 30
Biological
sandfilters*
80-90 25-30 50 97
Constructed
wetlands*
30-50 50 50 95
Willow plants* ~ 100 ~ 100 ~ 100 ~ 100
*all includes pretreatment in septic tanks
Removal rates in alternative
wastewater management

19. Drip Irrigation

20. Drip Irrigation

21. Drip Irrigation

22. Short-Rotation Willow
Biomass Plantations
Irrigated and Fertilised
with Wastewaters

23. Short-rotation Willow biomas
Plantations Irrigated and Fertilised
with Wastewaters
• Results from a 4-year
multidisciplinary field project in
Sweden, France, Northern Ireland
and Greece
• Results www.BACKLUND.dk

28. Willow Zero Discharge System
Components in Denmark
• Household Sanitary Installations
• Flushing Tank
• Settling Tank
• Pumping Tank
• Irrigation/Distribution System
• Willow Bed

29. Household Sanitary Installations
• Optimizing Sanitary Household
Installations
• Kitchen – dishwasher
• Bathroom – shower/bathtub
• Toilet – Flush >6l – 6/3 – 4/2
• Vacuum toilet
• NoMix With/Without flush

31. Standard Construction Willow
Bed and Distribution System
• Soil Barrier 30 cm High
• Distribution system and layer
• LDPE/HDPE Lining
• Geotextiles
• Reused soil in bed
• Willow
•

32. Distribution System
• Distribution Pipe Ø32-63mm in the middle
• Holes Ø8-10mm – 1m between holes from
4 m
• Distribution layer 16-32mm stones or
plastic
• Inspection/Emptying Tank at the end
• Drainage Pipe Inner Ø90-110mm

33. Application in Denmark
• Wastewater with or without WC
• Calculated water consumption not as a
gven standard but known or expected
from the household
• Dimensioning m2/m3
• Willow Bed Dimensions

34. Running Manual in Denmark
• Settlement Tank
• Pump and Pumping tank
• No heavy weight on surface
• Flush Distribution Pipe ever 2-3 years
• Total Weeding first year
• Planting if necessary
• After 1st season cut 50% down to 15cm in
Jan/Febr. The last 50% following year
• Then one half, third or fourth every year

35. Running Manual
• If Water Level on surface more than 20
cm in December – Remove
• Check Concentration of Chloride every 5th.
year

36. Running & Maintenance
• Empty Settlement Tank
• Flush Distribution Pipes
• Service of Mechanical Parts
• Control and taking care of Willow
• Control of Water Level
• Chloride Concentration

37. Hydralic Load - Dimension
• Expected or Actual Wastewater Load from
existing persons in household/households
• Not due to 1 household 5PE = 5 x
150/180l
• Accepted loads 80 – 120 l/p/d
• Minimum load 100m3/year
• Minimum willow bed surface 100 m2
• Also for Greywater load alone

38. Willow Evapotranspiration Beds
WILLOW EVAPOTRANSPIRATION
BED AT MARJATTA Tappernøje

40. Marjatta Evapotranspiration Bed

41. Technical Data
• Plants on 556 m2 surface, 50.5 m2/p
• Willow clones 78-195 + 78-082, 2400 Sticks
• Total surface, 707 m2, 64 m2/p
• 690 m3 over fibre textile, 150 m3 under
• Estimated water storage volume, 35 %
• 520 mm wastewater/a,11 p, 80-90 l/p/a
• 512 kg N/a, 95 kg P/a and 188 kg K/a

42. Wastewater Load
• Average 1 m3/11p/d 365m3/a
• If to sewer 365 x 4 Euro = Euro 1460

43. Precipitation and Evaporation
• Average 30-years precipitation 562 mm
• Average 1992-96 + 1999 769 mm
• 1993 910 mm
• 1994 970 mm
• 1999 907 mm
• Penman evaporation 572 mm
• Potential evaporation 610 mm
• Evapotranspiration 1310 - 1370 mm

44. Biomass Growth and
Evapotranspiration
Biomass growth
• 1992 3 t DM/ha/a
• 1992-1994 14.4 t DM/ha/a
• 1996-1999 8.5 t DM/ha/a
• 2003 17.1 t DM/ha/a
Evapotranspiration
• 1992-1996 1301 mm/a
• 1999 1366 mm/a

45. Results
• Good running stability
• Good evapotranspiration, 1310 – 1370
mm/a
• Up to 60 % capacity used for precipitation
• 30 – 40 % storage volume in bed
• No indications of heavy metals as limiting
factor for future handling of soil
• Sodium-cloride a limiting factor but can be
pumped out during low water levels

46. Further Developement
• Potential use of source controle sanitation to
reduce the amount of sodium chloride and surplus
of nutrient directed to the bed.
• Use of optimal willow clones with a even bigger
evapotranspiration potential in order to minimise
the surface and cost of the bed.
• Discharge of rainwater from the surface before
contact with the wastewater to minimise volume,
surface and cost of the bed.
• Raising the pore volume in the beds from 35 %
up to 80 %.
• Easy access to pump out sodium chloride

48. Premises – Dimensioning Model
• Willow Evapotranspiration Wastewater
System Without Discharge
• 8 m WIDE – with a DEPTH of 1.5m and
45° GRADIENT on the sides and ends of
the system
• Useable PORE VOLUME in the bed is
expected to be 40 %

49. Premises – Dimensioning Model
• EVAPOTRANSPIRATION from the system
s expected to be 2.5 TIMES LARGER
than the calculated Potential Evaporation
from the local area
• Calculations are made with 30-years
average figures of MONTHLY
PRECIPITATION and POTENTIAL
EVAPORATION in 20 x 20 km grid cels

50. Premises – Dimensioning Model
• SURFACE AREA dimension to avoid
water storing on the surface in a year
with normal precipitation and with a
maximum of 10 cm of surface water with
a precipitation which statisticly occurs in
one out of 10 years
• Same LOAD of wastewater every month

51. Dimensioning due to Grid Cels
• Average Precipitation 524 to 903 mm/y
• EVAPOTRANSPIRATION 1343 to 1470
mm/y
• Potential Capacity to Evapotranspirate
wastewater from 452 to 936 mm/y
• Calculated load after reduction due to
lacking storage capacity 357-894 mm/y

52. Dimensioning due to Grid Cels
• Surface Willow Bed Area from 124 to 292
m2/100m3 WW (Average 173 m2/100 m3)
due to Grid Cell

53. Surface Area – m2/100m3 WW

54. Tappernøje - Pilehuset
• POTENTIAL EVAPORATION
572mm/y
• Calculated EVAPOTRANSPIRATION from
WILLOW SYSTEM 2.5 x 572mm/y =
1430mm/y

55. Tappernøje – Pilehuset (from
1992)
• Grid cell calculated surface area
141m2/100m3
• Wastewater load to system
365 m3/y
• Calculated specific surface area
514.65 m2

57. r

61. Wexford Ireland
• Potential Evapotranspiration Johnstown
Castle, Co. Wexford 543mm/year
• Estimated Willow Evapotranspiration 2.5 x
543mm = 1357.5mm/year
• Precipitation 1000 mm/year
• Wastewater Evapotranspiration Capacity
357.5mm/m2/year

62. Dimensioning Wexford Ireland
• Without source controll (eg. Without dual
flush toilets)
• 2 – 5 P 150l/p/d = 306m2-766m2
• 2 – 5 P 180l/p/d = 368m2-919m2
• 6 P 180l/p/d = 3021 m2

63. Dimensioning Wexford Ireland
• Going from single flush 6x9l to dual flush
4x2l + 2X4l could save 38/l/p/d
• Surface Willow Bed Area (SWBA)
279.72m2/100m3
• SWBA 1P (120l/P/d) = 122.51 m2
• SWBA 3P = 367.53 m2
• SWBA 6P = 735.06 m2

64. Irish Modell?
• Reduced Wastewater Production/Inlet
• Precipitation Cover
• Higher Pore Volume
• Deeper Bed
• Longer with less width

65. Conclusion
• After 25 years in Denmark
• Considered best practice by Authorities for
highest demands
• Good experiences from performance
•