This document discusses using biochar production as a biosecurity tool for managing invasive and infected plant biomass. It notes that traditional disposal methods waste resources and increase carbon emissions, while invasive plants harm the environment and economy. The aim is to use a mobile pyrolysis unit to produce biochar from cleared biomass on-site, reducing transportation costs and emissions while sequestering carbon and retaining nutrients. Preliminary results found the biochar reduced emissions compared to open burning and had potential for soil remediation without harming earthworms.

1. Biochar as a biosecurity tool for the management of
invasive and/or infected plants.
Philip J.E.Harries1, J. James Fielding1, F. Alayne Street-Perrott1, Stefan H.Doerr1,
Sion Brackenbury2.
1Department of Geography, College of Science, Swansea University, Singleton Park, Swansea SA2 8PP, UK
2Commons Vision Ltd., 31 Pennard Drive, Southgate, Swansea SA3 2BL UK
Traditional disposal methods waste a potentially valuable
resource and incur significant carbon debt
Traditional methods of disposal release carbon back into the atmosphere that could potentially be
stored in the biomass for many years. Much of the nutrient content contained in the ash is blown or
washed away from the site, or completely removed when the biomass is transported to landfill sites.
Transportation to landfill sites or employing curtain burners increases the carbon debt incurred
through use of fossil fuels. Open burning releases particulate matter and hydrocarbons into the
atmosphere.
Invasive- and nuisance-plant species are harmful to the
environment and the economy
Invasive alien plant species such as Japanese knotweed (Fallopia japonica), buddleia (Buddleja
davidii) and rhododendron (Rhododendron ponticum) :
• reduce biodiversity by out-competing native species
• damage buildings and infrastructures
• incur high costs for control and eradication
• may act as hosts for plant pathogens e.g. the fungus-like Phytophthora ramorum.
Clearance of certain native plant species such as bracken and gorse is necessary to maintain
biodiversity and for agricultural purposes.
mindsManag
Clearance of R. ponticum
infected with Phytophthora
ramorum blight at Penllergaer
Forest, Swansea.
Clearance of invasive
R.ponticum at Cwm Dulais,
Swansea.
Open burning or air-
curtain burning releases
most of the carbon stored
in the biomass. Landfill
also releases CO2 and
CH4 to the atmosphere.
In contrast, biochar
production for use as a
soil amendment
sequesters carbon and
offsets the carbon debt
incurred by clearance
work.
The aim of this project is to produce biochar at the biomass-
clearance site to reduce carbon debt and retain plant nutrients
Use of a mobile pyrolysis unit to produce biochar at the disposal site would:
• Reduce the use of fossil fuels in transportation to landfill sites
• Reduce emissions from open burning
• Produce a saleable commodity
• Sequester carbon and retain nutrients
• Avoid expensive landfill costs (Japanese knotweed)
• Reduce the risk of transporting infected biomass (rhododendron, larch residues)
The Soil
Fertility
Project ,
R H Southern
Trust
Biochar production offers an environment-friendly method
for disposal of infected biomass
Management of Phytophthora ramorum infection in the UK has resulted
in the clearance of invasive Rhododendron ponticum from woodlands
and commercial timber stands. P.ramorum is caused by a fungus-like
oomycete now prevalent throughout Europe. In August 2009 the
disease jumped from rhododendron (the principal host) to Japanese
larch (Larix kaempferi). Best estimates suggest that widespread
outbreaks in the maritime, western regions of the UK, have resulted in
the felling of over 3 million trees up to 2012. Over 5000 ha of larch are
currently being felled or planned for felling by the end of 2013 (Forestry
Commission).Transportation of infected brash (residues) to disposal
sites may be contributing to dispersal of inoculum to surrounding areas
(P. Lanfear, pers. comm.).
Disposal of infected waste by biochar production using a mobile
pyrolysis unit, followed by incorporation of the resulting char into the
soil at the clearance site would:
• retain nutrients on-site
• help to reduce the spread of infection
• reduce the carbon debt incurred by clearance work.
“Torgoch” – an experimental, pilot-scale, mobile pyrolysis unit
A mobile fast-pyrolysis unit designed by Black is Green Pty. Ltd.,
Australia, is being used to produce biochar from a range of
invasive- and nuisance-plant feedstocks. The unit consists of a
pyrolysis kiln and thermal oxidiser. Operating temperatures of ~450
-600 oC in the kiln and ~900-1000 oC in the thermal oxidiser have
been measured using rhododendron, ash and larch wood chips.
The unit can process a continuous input of ~180 kg of chipped and
dried feedstock per hour. At normal operating temperatures, the
thermal oxidiser unit burns particulate matter and oxidises harmful
gaseous emissions before venting to the atmosphere.
Harmful emissions are significantly reduced compared to
traditional methods of biomass disposal
Flue gases are being analysed using a
Testo 350XL gas analyser. Readings
were taken with the thermal oxidiser at
normal operating temperature and
during the cool-down period
(comparable to open burning of the
biomass). The thermal oxidiser
eliminated hydrocarbon output in the
flue gases, with a significant reduction
in CO emissions. Particulate emissions
(PM10,PM2.5 and PM1) measured using
a Dekati cascade impactor were
typically in the range
18- 42 mg/Nm3 (total particulate
emissions).
Preliminary results suggest that rhododendron biochar has
significant potential for remediation of clearance sites
Results suggest that biochar may benefit the acidified soils under former rhododendron stands.
Preliminary earthworm-avoidance tests using 1% and 2% w/w biochar:soil mixtures indicated no
significant preference for soil versus biochar:soil (H.J.Rallison, pers.comm.). X-ray fluorescence
(XRF) spectroscopy indicated that all toxic metals were within recommended limits. Surface area
measurements using BET N2 adsorption gave measurements of 18- 420 m2/g dependent on
feedstock and production conditions.
Images
obtained using
a Hitachi Ultra-
High Resolution
FE-SEM S-
4800 at ILS2,
Swansea
University.
Chemical analyses of Rhododendron ponticum
biochar using the EDX /SDD(Energy-Dispersive
X-Ray Spectroscopy/ Silicon Drift Detector)
analyser in Life Sciences, Swansea University.
Results show elemental content of crystalline
structures on the surface of the biochar sample,
confirming the retention of nutrients derived from
the feedstock
Acknowledgements: Thanks to James Bruges & Marion Wells of the R.H. Southern Trust; David Friese-Greene; Reflex
Metal Fabrications Ltd., Stroud ; Lee Dawson, Forestry Commission Wales; Peter Lanfear, Commons Vision Ltd. and Hazel
Rallison, Swansea University.
VOC
Content
(%)
Ash
Content
(%)
pH
(CaCl2)
Carbon
content
(%)
Hydrogen
content
(%)
Nitrogen
content
(%)
Sulphur
content
(%)
Oxygen
Content
(%)
CEC
(cmol(+).kg-1)
Electrical
Conductivity
(µS.cm-1 )
Rhododendron
17.3-
25.5
2.4-
5.3
6.7-
8.2
63.7-
85.9
0.4- 0.8 0.4-
0.8
0.27-
1.79
4.1-
27.4
18.6- 49.8 267-
1505
Larch
14.0-
30.8
0.8-
1.4
5.6-
8.0
84.1-
91.7
1.8- 3.1 0.3-
0.8
0.42-
0.69
4.1-
10.7
15.0- 35.4 81- 238
Philip Harries e-mail: 450433@swansea.ac.uk
Forestry Commission
Thermal
oxidiser on
Thermal
oxidiser off
Flue gas
temperature(OC)
675-805 315-345
O2 (%) 10-15 19-20
CO (ppm) 10-18 13-6591
CO2 (ppm) 6-11 9-78
NOx (ppm) 19-27 1-68
SO2 (ppm) 0-3 1-233
HC (ppm) 0 0-2768
Biochar as an alternative to activated charcoal for water
remediation
Biochar produced from rhododendron was used to adsorb heavy metal and metalloid contamination
from a disused mine adit in Frongoch, Wales. Samples of the biochar were activated using
hydrogen peroxide and the adsorption characteristics of the unactivated and activated biochars
compared to those of a commercially available coal derived activated charcoal. Results suggest
that biochar produced from rhododendron may offer an effective, sustainable alternative to fossil
fuel derived activated charcoal.
Net
adsorption
at 192 hrs
Al (ppm) As (ppm) Cu (ppm) Pb (ppm) Zn (ppm)
Rhododendron
(unactivated)
520 28 76 1200 1561
Rhododendron
(activated)
550 26 304 1905 1580
Activated
charcoal
10443 6 50 549 1650
Biochar produced from
invasive rhododendron
proved to be comparable
or more effective than
activated charcoal in
adsorbing certain metals
from contaminated water.