NEWAPP Conference Berlin, April 14 th, 2016 Formation of new soil products based on HTC Biochar Dirk Krischenowski, TERR PETRA GmbH Christoph Knauer, ttz Bremerhaven
Introduction Pyrolyis char from woody feedstock has been the basis in successful soil amelioration products so far As wood is becoming scarce and expensive, alternative processes and feedstock for the production of char need to be found One of these new processes could be the Hydrothermal Carbonisation (HTC) of biomass Question: Can hydrochar be a suitable substitute for pyrolysis char in soil amelioration products? 2 / 10
Production of char-based soil amelioration products Step 1 Activation and loading The different char samples are loaded with water and microorganisms. Duration: 2 days Step 2 Fermentation The substrates are prepared by adding different concentrations of char (1.25, 2.5, 5, 10, 20 %) to potting soil. Fermentation for 14 days (uptake of nutrients by the char) Step 3 Usage The prepared substrates are applied to soils (germination and growth tests) 3 / 10
Assessment of the suitability of hydrochar Tests conducted Germination rate Growth rate Compliance with EBC standards Nutrient storage capacity Water storage capacity Decomposition rate Soil ph Germination and growth rates pre-tested in small series 4 / 10
Characterization of the char samples Tests conducted with 5 hydrochars / 1 pyrolysis char All hydrochar samples produced by Ingelia in Spain: NEWAPP poda produced from green waste Lodos produced from sewage sludge Pimiento residues from a pepper plantation RSU 1 & RSU 2 both produced from the organic fraction of municipal solid waste Pyrolysis char obtained by TERRA PRETA in Germany: Carbon Terra Pflanzenkohle pur produced from residues from agriculture and forestry 2 different soil substrates as basis for tests: ttz: average quality garden soil TERRA PRETA: premium quality worm humus soil 5 / 10
Growth rate pre-test (cress) Reduced growth in hydrochar substrates Test 6 / 10
Growth rate pre-test (basil) Reduced growth in hydrochar substrates 7 / 10
Growth rate pre-test (basil) HTC char underperforms 8 / 10
Lactuca sativa - lettuce 9 /33
Avena sativa - oat 10 /33
Raphanus sativus - radish 11 /33
Germination rate test 12 / 10
Germination rate test (Lactuca sativa) NEWAPP LODOS PIMENTO RSU1 RSU2 13 / 10
Germination rate test (Avena sativa) NEWAPP LODOS PIMENTO RSU1 RSU2 14 / 10
Germination rate test (Raphanus sativus) NEWAPP LODOS PIMENTO RSU1 RSU2 15 / 10
Growth rate test 16 / 10
Growth rate test (Lactuca sativa) 17 / 10
Growth rate test (Avena sativa) 18 / 10
Growth rate test (Raphanus sativus) 19 / 10
Compliance with EBC standards None of the hydrochars complied with all thresholds Pyrolysis char usually does (often certified) Parameter Unit NEWAPP poda RSU I Pyrolysis char Surface area [db, m²/g] 7.3 6.1 > 150 C content [db, wt.%] 58.4 57.6 > 50 Black carbon content [db, wt.% of total C] 0.2 1.8 > 10 Molar ratio H/C org 1.34 1.36 < 0.7 O/C org 0.37 0.39 < 0.4 Heavy metals Pb [db, g/t] 7.44 102 < 150 Cd [db, g/t] 0.15 1.22 < 1.5 Cu [db, g/t] 33.9 285 < 100 Ni [db, g/t] 7.15 23.9 < 50 Hg [db, g/t] < 0.01 0.39 < 1 Zn [db, g/t] 130 618 < 400 Cr [db, g/t] 18.4 37.2 < 90 Dioxins [ng/kg] 0.42 8.3 < 20 Furans [ng/kg] < 20 PAH [db, mg/kg] 0.06 0.26 < 12 PCB [db, mg/kg] < 0.1 < 0.1 < 0.2 20 / 10
Nutrient storage capacity The nutrient storage capacity was determined only indirectly Nutrient storage capacity is proportional to surface area Surface area of pyrolysis char more than 20 times higher than that of tested hydrochars 21 / 10
Water storage capacity [ml] Water storage capacity Hydrochars: 472 to 1,148 ml water per kg char Pyrolysis char: 1,784 ml/kg 2000 1800 1600 1400 1200 1000 800 600 400 200 0 NEWAPP poda Lodos Pimiento RSU I RSU II PL char 22 / 10
Decomposition rate The decomposition rate was determined only indirectly Decomposition rate is inversely proportional to black carbon (polycondensed aromatic compounds) content Black carbon content of hydrochars: between 2 and 20 % of that of pyrolysis char -> Hydrochars are much faster decomposed in soils 23 / 10
ph ph value ph values increase with char concentrations ph values of hydrochar and pyrolysis char substrates similar 8 7 6 5 4 3 2 1 0 0% 1,25% 2,50% 5% 10% 20% Char concentration NEWAPP poda Lodos Pimiento RSU I RSU II PL char 24 / 10
Discussion of the results Biggest problems of hydrochar and possible solutions: Low surface area Low nutrient (and water) storage capacity Can be increased by activation Low black carbon content Fast decomposition in soils Can be increased by higher production temperatures Toxic substances? Reduced growth (biomass production) Can be removed by washing or composting 25 /33
Conclusions Further research is necessary to confirm/correct the very heterogeneous results in heterogeneous hydrochars the sector in general Suitability of hydrochar can be increased (flexible process, adaptation of process parameters, posttreatment, etc.) Tests with different soils need to be performed to ascertain further potential 26 /33
Thank you for your attention! Dirk Krischenowski, TERRA PRETA GmbH Gustav-Müller-Str. 1, 10829 Berlin, Germany Phone: +49 30 78711909 Fax: +49 30 78711908 Christoph Knauer, ttz Bremerhaven Alte Jakobstr. 77, 10179 Berlin, Germany Phone: +49 471 809 34 153 Fax: +49 471 9448-722