bio-wastes – what are they worth ? eric evans. why the interest in bio-wastes ? methanogenesis...
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Bio-wastes – what are they worth ?
Eric Evans
Why the interest in bio-wastes ?
Methanogenesis
Landfill ban on Liquids
Landfill Tax£82.60
High Fertiliser
Costs
Fertilizers have many advantages
• Easy to store and handle• Convenient to apply• Concentrated form • Accurate analysis of
nutrients• Readily available nutrient
form
High dependence on energyin manufacturing process
leading to high cost.Long term availability
Bio-wastes - what can they offer ?
• Low cost materials
• Local supplies
• Additional source of organic matter Sulphur, Magnesium and Trace Elements
• High sustainability value
• Slow release of nutrients
However – there are drawbacks !
• Bulky materials• Relatively low nutrient concentrations• High handling and spreading costs• Narrow application window • May require specialist application equipment• Slow rate of nutrient release may be a
disadvantage
Their use is highly regulated by the
Environment Agency
What is available in our area ?
Digestate from Treated Sewage Sludge
PAS 100 Green Compost
Food WasteBlood
Water Cake
Non-PAS 100 Green
CompostAD Food Digestate
Paper Sludge
Eggshells
Segregated Green Waste Compost Large scale compost
production is relativelynew to the UK.
Previously green waste sent in landfill sites.
Currently there are over 150 sites operating in the UK processing nearly 3 million tonnes of green waste annually.
Quality Compost
This defines Compost as a product rather than a waste
Its use in agriculture does not require an exemption from the EA
There are 6 PAS 100 accredited Compost Producers in the North East
Land Spreading of Non-Hazardous Waste - Non PAS 100 Compost
Nutrient Value of Compost
Typical Analysis (Fresh weight basis)
Dry Matter 50 – 65%pH 7.5 – 8.5OM 50 – 60%Nitrogen 0.7 – 1.4%Phosphorus 0.2 – 0.4% P205
Potassium0.4 – 0.6 % K20Magnesium 0.2 – 0.3% Mg0Sulphur 0.1 – 0.25% S03
Calcium 1.3 – 2.0%
Recommendation
One tonne contains- 8.76 kg N 4.97 kg P205
6.9 kg K20 3.82 kg Mg0and 3.97 kg S03
20 t ha Dressing provides
175 kg N (18 kg RA) 99 kg P205 (50 kg RA)138 kg K20 (110 kg RA) 76 Kg Mg0 (38 kg RA) 79 kg S03 (40 kg RA)
Paper SludgePaper Sludge
Nutrient Value of Paper Sludge
Typical Analysis (Dry Matter Basis)
• Dry Matter 38 – 45%• pH 7.5 – 7.9• OM 25 – 30%• Nitrogen 0.2 – 0.4%• Phosphate 300 – 500 mg/kg• Potassium 120 – 200
mg/kg• Magnesium 0.2 – 0.3%• Sulphur 0.08 – 0.1%• Calcium 25- 30%
Recommendation
One tonne contains -1.7 kg N 0.9 kg P205
0.28 kg K20 and 1.94 kg Mg0
60t ha Dressing provides
102 kg N (5 kg RA)56 kg P205 (28 kg RA)17 kg K20 (13 kg RA)116 kg Mg0 (58 kg RA)
Water Cake
• Northumbrian Water have 9 Water Treatment Facilities throughout the Region
• Drinking water is extracted primarily from rivers and reservoirs
• Purification is achieved by flocculation of organic and inorganic particles by aluminium and iron compounds
Solid Sludge
Nutrient Value of Water Cake
Typical Analysis (DM Basis)
Dry Matter 40 – 60%pH 4.0 – 6.8OM 45 – 58%Nitrogen 0.6 – 0.9%Phosphorus 0.1 – 0.3% P205
Potassium 300 – 2000 mg/kgMagnesium 200 – 1800 mg/kgCalcium 0.1 – 0.5%
Recommendation Horsley Treatment WorksOne tonne contains- 2.1 kg N 0.44 kg P205
0.28 kg K20 and 0.11 kg Mg0
100 t ha Dressing provides
210 kg N (42 kg RA)44 kg P205 (22kg RA)28 kg K20 (22 kg RA)11 Kg Mg0 (5 kg RA)
AD Digestate
Agricultural Plants
Waste Plants
BiomassPre-
treatment
AnaerobicDigestion
Post-treatment Biofertiliser
Biogas
Electricity
CHP
Heat
The Anaerobic Digestion Process
Land Spreading of DigestateDefinition of WASTE
Traditionally manure and slurry are not considered waste when
spread directly on land as a fertiliser
Energy crops grown for AD are not considered waste
Digestate is no longer considered a waste if the only feedstock is manure,
slurry or energy crops
Off Farm Feedstocks are considered as WASTE
EA Deployment
PAS 110 Accreditation
Liquid Solid
MixtureD.M. 20 – 30%
D.M. 1 – 3%
D.M. 3 -14%
Nutritive Value of Digestate ( Food Waste)
Typical Analysis (Fresh Wt.)
Dry Matter 3 - 4%pH 8.2 – 8.5OM 2 – 3%Nitrogen 0.3 – 0.5%Phosphorus 300-600 mg/kgPotassium 1700–3000 mg/kgMagnesium 100–250 mg/kgSulphur 200-600 mg/kg
Recommendation
One m3 contains-
4.2 kg N 1.4 kg P205
3.65 kg K20, 0.25 kg Mg0, and
3.16 kg S03
50 m3 ha dressing provides
210 kg N (147 kg RA) 70 kg P205 (35 kg RA)183 kg K20 (128 kg RA) 13 Kg Mg0(7 kg RA)158 kg S03 (79 kg RA)
Nutritive Value of Digestate ( Sewage Sludge Derived)
Typical Analysis (Dry Matter basis.)
Dry Matter 25 - 30%pH 8.2 – 8.8OM 60-70 %Nitrogen 5 – 6 %%Phosphorus 3 - 5% P205
Potassium0.2 – 0.4% K20Magnesium 0.1 – 0.3 % Mg0Sulphur 1.0 –2.0 % S03
Recommendation
One m3 contains-
16.95 kg N 13.2 kg P205
0.49 kg K20, 0.5 kg Mg0, and
10.0 kg S03
14 m3 ha dressing provides
237 kg N ( 166 kg RA)185 kg P205 ( 93 kg RA) 7 kg K20 ( 5 kg RA) 7 Kg Mg0 ( 4 kg RA)140 kg S03 ( 70 kg RA)
To Recap
Waste Type
Form Rate OM pH N P K Mg S
Compost Solid 20 t ha √ >7 √ √√ √√ √ √Paper Sludge
Solid 60 t ha √√ > 7 √ × × √ ×
Water Cake Solid 100 t ha √√ < 7 M M M × √Food Digestate
Liquid 50 m3 M > 7 √ √√ √√ × √√
Sewage Digestate
Liquid 14 m3 × > 7 √√ × × × √√
What are their NPK values ?
Compost
Paper Sludge
Water Cake
Food Digestate
Sewage Digestate
£12.00 / t
£2.00 / t
£2.00 / t
£6.00 /t
£20.00 /t
How much do you value
Organic Matter ?
Sulphur
Mg and T.E.
Thank you for your attention