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, UK2Commons 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 unitA 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.

VOCContent

(%)

AshContent

(%)

pH(CaCl2)

Carbon content

(%)

Hydrogen content

(%)

Nitrogen content

(%)

Sulphur content

(%)

OxygenContent

(%)

CEC(cmol(+).kg-1)

ElectricalConductivity

(µS.cm-1 )

Rhododendron17.3- 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

  Thermaloxidiser on

Thermaloxidiser off

 Flue gastemperature(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.

Netadsorptionat 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 1580Activatedcharcoal 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.