Application of Waste to Energy Crops

A case study for Willow

John Finnan, Paul Galbally,

Brendan Burke, John Carroll,

Declan Ryan, Kevin McDonnell

Presentation Content

• Waste in Ireland

• Advantages of using Energy Crops for

Bioremediation

• Potential Worries

• Energy Crop Offtakes – Nutrient Response

• What happens to the nutrients and heavy metals?

• Conclusions

Wastes Which could be Applied

Wastewater Treatment - Ireland

Source:EPA 2012: Focus on Urban Waste Water Discharges

Problems with Wastewater Disposal

Source:EPA 2012: Focus on Urban Waste Water Discharges

Can Energy Crops Help by acting as a biofilter

Advantages

• Reduced Cost of Waste Cleaning

• Element removal from waste streams

• No risk to the food chain

• Enhanced Greenhouse Gas Mitigation

• Greater Biomass Yield

• Avoidance of GHG emissions during fertilizer

manufacture

• Economic Advantages for the farmer

Wastes for Application

Form?

• Solids – typically sewage sludge

• Liquids- wastewater or liquid effluents

What’s in Them?

• Organic Matter

• Nutrients N,P,K

• Other Things

• Heavy Metals

• Pathogens

Possible problems and Worries

• Pathogens

• Potential Damage to Crops

• Potential contamination of groundwater

• Potential damage to soil microfauna and ecology

• Heavy Metals

• Introduction and build-up in soil, water

• Emissions to Air after Crop Uptake

Possible problems and Worries

• Pathogens

• Potential Damage to Crops

• Potential build-up of undesirable substances in soil

• Potential damage to soil microfauna and ecology

• Heavy Metals

• Introduction and build-up in soil

• Emissions to Air

Relevant Questions:

Does waste application to energy crops pose a greater risk to the

environment compared to

•The release of those waste streams to the environment

•The application of other fertilizers eg, chemical fertilizers, FYM, slurry

Pathogens

• Evidence from Oak Park trials has shown that there is no risk of

introducing high pathogen loads to soil after biosolid application once

sufficient liming of the sludge has been conducted

• Pathogens are retained and de-activated by soil.

• Reduced pathogen load to the environment after application of

wastewater to energy crops compared to releasing that wastewater to

surface water bodies

• BUT. There is a risk of groundwater contamination

• NOTE: A risk similar to that of slurry application

• No evidence of crop damage

Heavy Metals

• Heavy Metals: - Natural component of biological systems such as

animals, plants and soils

• Essential Metals: - some metals such as copper and zinc are essential

to plants and animals

• Toxicity: - other heavy metals can be toxic above certain levels and

their build up needs to be avoided.

• Heavy Metals in Wastes:

• Mainly from food

• Passage of water through copped and lead pipes

• Passage of rainwater across metal roofs

• Use of chemicals eg detergents

Heavy Metals in Organic Fertilizers

0

100

200

300

400

500

600

700

Zn Cu Ni Pb Cd Cr

Co

nc

en

tra

tio

n (

mg

/kg

DM

)

Dairy Cattle FYM

Dairy Cattle Slurry

Beef Cattle FYM

Beef Cattle Slurry

Pig FYM

Pig Slurry

Biosolid

Distillery Effluent

Crop Requirements

Annual Nutrient Offtakes – Willow harvested at Oak Park

0

10

20

30

40

50

60

70

N P K

Nu

trie

nt

Off

take (

kg

/ha)

Nutrient Offtakes – Multi Year Harvests

0

20

40

60

80

100

120

140

160

180

N P K

Off

takes (

kg

/ha)

1 year

2 years

3 years

Willow – Response to Nitrogen Fertilizer

Leaf Nitrogen - 1

64

66

68

70

72

74

76

0 75 150

kg N/ha

Le

af

Nit

rog

en

(m

mo

l/m

2)

Leaf Nitrogen -2

84

86

88

90

92

94

96

0 75 150

kg N/ha

Le

af

Nit

rog

en

(m

mo

l/m

2)

Yield Response to Nitrogen Fertilizer

0

2

4

6

8

10

12

0 75 150

kg N/ha

ton

ne

s D

M/h

a/y

r

Fate of Nutrients and Heavy Metals After Application

• Remain in Soil

• Crop Uptake

• Loss to Groundwater

• Loss to Surface Water via Overland Flow

Crop Uptake After Waste Application

0

5

10

15

20

25

30

35

40

45

50

DE100 DE50 DE0 BS100 BS50 BS0

Nu

trie

nt

Up

tak

e (

kg

)N

P

K

Nutrient Loss – Distillery Effluent

Loss over 18 Months after Distillery Effluent Application

0

10

20

30

40

50

60

70

80

90

100

W-D

E100

W-D

E50

W-D

E0

W-D

E100

W-D

E50

W-D

E0

W-D

E100

W-D

E50

W-D

E0

N N N P P P K K K

Nu

trie

nt

Lo

ss (

kg

/ha)

Loss to GW

Loss to OLF

Heavy metal Loss – Distillery Effluent

Loss over 18 months after Distillery Effluent Application

0

20

40

60

80

100

120

W-D

E100

W-D

E50

W-D

E0

W-D

E100

W-D

E50

W-D

E0

W-D

E100

W-D

E50

W-D

E0

W-D

E100

W-D

E50

W-D

E0

W-D

E100

W-D

E50

W-D

E0

W-D

E100

W-D

E50

W-D

E0

Cd Cd Cd Cu Cu Cu Cr Cr Cr Pb Pb Pb Ni Ni Ni Zn Zn Zn

Meta

l L

oss (

g/h

a)

Loss to GW

Loss to OLF

Nutrient Loss – Sewage Sludge

Loss over 18 months after Biosolid Application

0

10

20

30

40

50

60

70

80

W-BS100 W-BS50 W-BS0 W-BS100 W-BS50 W-BS0 W-BS100 W-BS50 W-BS0

N N N P P P K K K

Nu

trie

nt

Lo

ss (

kg

/ha)

Loss to GW

Loss to OLF

Heavy Metal Loss – Sewage Sludge

Loss over 18 months after Biosolid Application

0

10

20

30

40

50

60

70

80

90

W-B

S100

W-B

S50

W-B

S0

W-B

S100

W-B

S50

W-B

S0

W-B

S100

W-B

S50

W-B

S0

W-B

S100

W-B

S50

W-B

S0

W-B

S100

W-B

S50

W-B

S0

W-B

S100

W-B

S50

W-B

S0

Cd Cd Cd Cu Cu Cu Cr Cr Cr Pb Pb Pb Ni Ni Ni Zn Zn Zn

Meta

l L

osses (

g/h

a)

Loss to GW

Loss to OLF

Impact on Groundwater Quality - Biosolid

0%

40%

80%

120%

160%

200%

240%

eC NO3 K P Cd Cr Cu Pb Ni Zn

BS100 plot BS50 plot

BS0 plot

Impact on Overland Flow Water Quality - Biosolid

• Overland Flow events on most sites are relatively rare

• The quantity of water in overland flow is usually small

• Damage to surface water from overland flow can be minimised by

• Avoiding sites with a slope greater than 11%

• Avoid spreading on land prone to flooding

Further Research on Overland Flow being conducted as part of the

ANSWER project

NOx Emissions from Willow after Nitrogen Fertilization

0

50

100

150

200

250

300

0 75 150

kg N/ha

NO

X E

mis

sio

ns

(m

g N

m3)

0

2

4

6

8

10

12

0 75 150

kg N/ha

ton

ne

s D

M/h

a/y

r

Conclusions

• Energy Crops can be fertilized using waste – in so doing, cleaning the

waste

• There is a risk……….which can be reduced/eliminated by

• Careful Site Selection

• Matching application with crop nutrient requirements

• We already apply these wastes to food crops BUT

• A licence is needed to apply these wastes to energy crops

• Need to incorporate Energy Crops into Sewage Sludge in

Agriculture Regulations (SI 148/1998)