SRC AS A BIOREMEDIATION SYSTEM

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SRC AS A BIOREMEDIATION SYSTEM Malcolm Dawson
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BIOMASS RENEWABLE ENERGYWhat are the changes?

• Policy Targets and Support
• Incresasing population increasing
• energy demand - demand doubles by 2050
• Rising oil and gas prices
• Single farm payment levels the playing field
• Bioremediation adds value

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BIOREMEDIATION USING SHORT ROTATION WILLOW

• Bioremediation - the plant
• systems
• - roots
• - leaves
• woody shoots / nutrient removal
• Legislation
• Installed bioremediation systems
• Economics

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BIOREMEDIATION USING SRC WILLOW
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Precipitation Evaporation
Transpiration
Evapotranspiration
Soil Evaporation
Interception
Soil Surface
Runoff
Root uptake
Outflow to ground water
Ground water inflow
Percolation
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ROOT

• Higher Root Shoot ratio than other tree
  species
• Generally fine shallow roots in shrub sp.
• Oxygen Demand - Aerenchyma O2
• diffusion
• Hygrophilous e.g. Abies 2.64
  cc/day/gm DM Populus 5.80
  cc/day/gm DM Salix 7.0
  cc/day/gm DM
• equivalent to 1.0 l/gm of DM over the
• growing season
• Fine Root Turnaround

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ROOT

• Anchorage
• Absorb water and minerals (osmosis)
• Store nutrients (coppicing)
• Soil structure - penetration
• - turnover
• - 85 in top 20cms

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LEAF

• Collect solar energy
• Photosynthesis - Release of 02 - Solar
  energy - Chemical energy
• Looses water (Transpiration) - Lifting
  power - Transport minerals - Cooling
• Recyling nutrients - Leaf litter

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LEAF

• Leaf Area Index (LA1) maximised early in
  coppice situation
• Looses water (transpiration)
• - lifting power
• - cooling
• Leaf fall
• - recirculation of
• nutrients
• - relocation prior
• to leaf fall - 5t org. matter/yr - 120
  kg N

May July
Oct
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WOODY SHOOTS

• YIELD
• Experimentally gt 20t DM/ha/yr
• Realistically 10-12t DM/ha/yr
• Poorer land 6-10t DM/ha/yr
• Reasonable short-term target 12-14t
  DM/ha/yr

• Yield-the engine for
• bioremediation
• Optimise to maximise water loss max
  nutrient non nutrient uptake.
• Nutrient removal

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ELEMENTS (gm/kg DM) macro elements
micro elements H 60
C1 0.1

C 450 B 0.02
O 450 Fe 0.1
N 15 Mn 0.05 K
10 Zn 0.02 Ca
5 Cu 0.006 Mg 2
Mo 0.0001 P 2 S
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Two year old Salix viminalis coppice
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• SOME ESTIMATES OF NUTRIENT REMOVAL(kg/ha/yr)
• LOUGHGALL DATA (1991-1997) Experimental Plots -
  3 harvests.
• N 55-60 kg ha-1 P 8.4 kg ha-1 K
  31.2 kg ha-1
• LONG ASHTON (1991) Single harvest of field trial
• N 93 kg ha-1
• GERMANY (1999) Experimental Plots - 2 Harvests
• N 92-270 kg ha-1 P 14-45 kg ha-1 K
  33-130 kg ha1
• SWEDEN (1992) Commercial Stand
• N 80-110 kg ha-1 P 15kg/ha K 48
  kg ha-1

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Principles of Bioremediation using SRC Willow

• Balance off-take and application.
  (sustainability)
• As a guide 125kgN, 15kgP, AND 40kg K annually
  (soil analysis)
• Phosphorus is generally the limiting factor
• P levels generally high in Ireland index 3
  (26-45mg/l P)
• Sludges applied every other year 2yr harvest
• - buried using special applicator minimise
  exposure
• - generally slow release
• - 250kgN
• Waste water applied regularly in small doses
• - retention in active feeding root zone
• - rate calculated to take account of soil
  type and climatic conditions.

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LegislationThe Nitrates Directive 91/676/EEC

• All of Northern Ireland subject to Nitrate
  Vulnerable Zone (NVZ)
• Nitrates Directive implemented 1st January 2007
• Closed period October to January
• Nitrate applied 250kg(per field)/170kg(per
  holding)

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Impact on Use of Willow

• Closed period for application of sewage sludge
  cake
• Sewage sludge cake considered by EU to be
  effluent not farmyard manure
• Level of P tends to be limiting factor for sludge
  application
• Potential to move to 2-year rotation

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Legislation Sludge Directive

• Directive 86/278/EEC
• Regulation sets permissible limits for
  potentially toxic elements (PTEs)
• Sludge must be treated
• Additional limits Mo, Se, As and F
• Safe Sludge Matrix DEFRA (voluntary code, not
  legislation)
• Code of good practice DoE (voluntary)

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Impact on use of Willow Coppice

• Licence/permit required
• Records of quantity and analysis and location
• PTEs not a problem with sewage sludge in
  Northern Ireland
• PTE soil concentrations not an issue (Ni, Cd)
• Soil limit values at different levels of pH, not
  an issue in Northern Ireland

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Legislation Wastes Directive

• Waste recovered/disposed of safely
• Focus on recycling
• Focus also on its use as an energy source
• Waste management licence or exemption
  registration required.
• Limited exemptions - benefit to agriculture
  ecological improvement

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Impact on use of Willow Coppice

• Agricultural benefit
• - nutrients
• - within nitrates directive to crop requirement
• - the addition of organic matter is a benefit
• Recycling of sludge wastewater in line with WFD -
  Recycling use for energy

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It should be noted that whilst these are the main
EC Directives involved in recycling wastes on
Short Rotation Coppice willow their implementing
legislation may differ in detail between member
countries and always should be referred to before
application.
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Other Legislation

• The Ground Water Regulations
• The Urban Wastewater Treatment Regulations
• Environment impact - uncultivated semi-natural
  areas
• Environmental Impact Assessment Regulations
• Shellfish / bathing waters Directives

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SOME EXAMPLES OF WORKING SYSTEMS
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CULMORE WATER TREATMENT WORKS
Aerial view showing 4.5ha willow coppice
One -year -old growth on the treated coppice
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CULMORE WATER TREATMENT WORKS

• Trend towards greater biomass yields at higher
  wastewater irrigation levels.
• No effect of irrigation treatment on N,P,K or
  trace metals in groundwater.
• No detectable levels of human pathogens in
  groundwater.
• Increased biodiversity compared with improved
  grassland

1 x PE 5M L supplies 114kg/ha N,
24kg/ha P 99kg/ha K
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Example of Willow Bio-filtration of Dirty Water
Earl of Desmond Hotel, Tralee, Co. Kerry, Ireland
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SWEDEN KAGEROD WATER TREATMENT PROJECT

• Established 1992
• Kagerod 1500 inhabitants milk-powder factory
  giving equivalent of 6,500 people.
• Tertiary treatment including phosphorus
  removal.
• Application rates range from 2-12mm/day
• Removal 0f pollutants
• BOD gt91-98
• P 95
• N gt85-95
• Zn, Cu, Pb Ni gt80-90

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HALMSTAD (SWEDEN) WASTE SORTING / RECYCLING
SEDIMENTATION/STORAGE POND
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SEWAGE SLUDGE RECYCLING

• 70 tonnes/ha - post 2007 35-40tonnes/ha
• application after harvest and before flushing.
  May need to extend this period reduce storage
• Phosphorus levels critical (analysis)
• Current cost of disposal 60/t

Sludge applicator working in Londonderry
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SRC Economics
Nett Farm Income /ha/yr
No land cost No Farmer income 7 years
Establishment 3x2-year Rotations 20/t
gate fee for sludge
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SRC the challenge and the opportunity
Energy expenditure 10 Billion
30Electricity 35 Heat (3.5B _at_
1 35M) 35 Transport
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SRC ESTABLISHMENT COSTS (/ha)

• Ground preparation
  120
• Herbicide, Ploughing, power harrow and roll
•  
• Mechanical planting
  300
• Carriage, tractor and step planter hire
•  
• Willow cutting
  
  920
• 15,000 cuttings/ha, carriage and cold store
• Post planting residual herbicide and leather
  jacket control 140
• Cut back, after first years growth
  30
• Reciprocating finger bar mower
•  
• Weed and pest control
  
  150
• Including post cut back herbicide and post
  planting leatherjacket control
• Total establishment costs
  
  1,640/ha
•  

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SRC Assumptions

• 25 year growing cycle 8 harvests
• Av yield 10t/ha/yr DM
• Drying 8t (50 DM-20 DM)
• Establishment 2000/ha
• Harvest (every 3 yrs) yield 36t _at_80 DM) 400/ha
• Management cost of 250/ha (after each harvest)
• Root removal site restoration 500/ha

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Cost of Biomass /t
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Value of Biomass /t
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MANAGING LANDFILL LEACHATE WITH SRC