1. Biochar Colonization by Aanaerobic Microorganisms
Maja Werner*, Ulf Lüder, Jan Mumme
* Corresponding author:
Terra preta do indio is a typical hortic anthrosol in the amazonas region derived from long-term human landscape cultivation. This distinct type of soil is characterized by a high storage capacity of plant nutrients as well as a high content of carbon enabling agriculture even on soils with low humus and/or nutrient content. Due to certain similarities in consistence and composition, biochar is recently discussed as a value artificial soil amendment to obtain similar positive effects on soil fertility like terra preta. In addition to the structural and compositional analysis of biochars the interaction of the chars with living microorganisms is studied, to explain the effect of biochar enriched soils from a microbiological point of view. Due to seclusion of a biogas system and the consequent creation of a separate world the study of effects by biochar colonization with microorganisms by minimizing the confounding factors is more easier compared with soil tries.
Experimental Design
Biochar production
Anaerobic digestion
mesophilic
230 °C, 6 h
500 °C, 1 h
HTC-char
digestate
pyro-char
specifications of reactors
3 parallel anaerobic gaslift reactors
gas circulation rate: 33 l/ h
total volume: BAR 65 l
miniBAR 35 l
experimental setup
HTC & pyro-char: kg/ 10 l
incubation period: 175 d
temperature: 37 °C
feeding
substrate: model maize substrate Guebitz et al. 2010
loading rate: kg oDM/ d m3
Hydrothermal carbonization (HTC) – moderate temperature (180 – 270 °C), high pressure (10 – 55 bar) reaction
Pyrolysation – high temperature (500 – 900 °C), ambient pressure, oxygen-free reaction
Operating principle of Biochar Activation Reactor - BAR
Results
Rate of biogas
Content of DNA
IR spectroscopy
pyro-char
pyro-char:
- fast first settlement
- tendency for decreasing amount of organisms
HTC-char
pyro-char: approx. 14 % higher rate of biogas
HTC-char: - continuous increase in the population of organisms
HTC-char
qPCR – archea
Although the HTC-char has a better biodegradability, the pyrolysed char supports the biogas process better and leads to higher biogas yields. The colonization of the pyro-char with anaerobic microorganisms is more rapidly, compared to HTC-char, while after 175 days the amount of attached microorganisms is higher for HTC-char. The treatment by anerobic digestion From the results of the FTIR can be deduced, that the treatment of both chars by anaerobic digestion leads to structural changes. This, however, at different locations.
pyro-char
Summary and Conclusion
Caused by feedstock and process conditions during carbonization the pyrochar shows
higher stability while fermentation and has a positive effect on the metabolic activity of anaerobic microorganisms. A similar beneficial effect on soil micro-organisms should be checked. With regard to the use of both types of biochars as a soil amendment, a combination of both chars, due to the different results for the settlement, could be make sense.