In a column set-up, Fe modified biochar produced from date palm leaves was used to remove As (1 m... more In a column set-up, Fe modified biochar produced from date palm leaves was used to remove As (1 mg L-1) from a laboratory-prepared wastewater. The wastewater treatment process was monitored in real-time by spectral induced polarization (SIP), over a wide range of frequencies (0.01-1000 Hz). Both 5 and 10% biochar-amended columns achieved As removal exceeding 98%. The SIP parameters appear to be sensitive on As removal processes, with the recorded trend following the conventional geochemical monitoring, while offering higher temporal resolution.
Biochar produced by pyrolysis of organic residues is increasingly used for soil amendment and man... more Biochar produced by pyrolysis of organic residues is increasingly used for soil amendment and many other applications. However, analytical methods for its physical and chemical characterization are yet far from being specifically adapted, optimized, and standardized. Therefore, the COST Action TD1107 conducted an inter-laboratory comparison, in which 22 laboratories from twelve countries analyzed three different types of biochar for 38 physical-chemical parameters (macro- and micro-elements, heavy metals, polycyclic aromatic hydrocarbons, pH, electrical conductivity, and specific surface area) with their preferential methods. The data was evaluated in detail using professional inter-laboratory testing software. Whereas intra-laboratory repeatability was generally good or at least acceptable, inter-laboratory reproducibility was mostly not (20% < mean reproducibility standard deviation < 460%). This paper contributes to better comparability of biochar data published already, and provides recommendations to improve and harmonize specific methods for biochar analysis in the future.
Biochar produced by pyrolysis of organic residues is increasingly used for soil amendment and man... more Biochar produced by pyrolysis of organic residues is increasingly used for soil amendment and many other applications. However, analytical methods for its physical and chemical characterization are yet far from being specifically adapted, optimized, and standardized. Therefore, the COST Action TD1107 conducted an inter-laboratory comparison, in which 22 laboratories from twelve countries analyzed three different types of biochar for 38 physical-chemical parameters (macro- and micro-elements, heavy metals, polycyclic aromatic hydrocarbons, pH, electrical conductivity, and specific surface area) with their preferential methods. The data was evaluated in detail using professional inter-laboratory testing software. Whereas intra-laboratory repeatability was generally good or at least acceptable, inter-laboratory reproducibility was mostly not (20% < mean reproducibility standard deviation < 460%). This paper contributes to better comparability of biochar data published already, and provides recommendations to improve and harmonize specific methods for biochar analysis in the future.
Currently, char substrates gain a lot of interest since soils amended with such substrates are be... more Currently, char substrates gain a lot of interest since soils amended with such substrates are being discussed to increase in fertility and productivity, water retention, and mit-igation of greenhouse gases. Char substrates can be produced by carbonization of organic matter. Among different process conditions, temperature is the main factor controlling the occurrence of organic and inorganic contaminants such as phenols and furfurals, which may affect target and non-target organisms. The hydrochar produced at 200 °C contained both furfural and phenol with concentrations of 282 and 324 mg kg −1 in contrast to the 300 °C hydrochar, which contained only phenol with a concentration of 666 mg kg −1. By washing with acetone and water, these concentrations were significantly reduced. In this study, the potential toxic effects of hydrochars on the free-living nematode Caenorhabditis elegans were investigated via gene transcription studies using the following four matrices: (i) raw rice husk, (ii) unwashed rice char, (iii) acetone/water washed rice char, and (iv) the wash water of the two rice chars produced at 200 and 300 °C via hydrothermal carbonization (HTC). Furthermore, genetically modified strains, where the green fluorescent protein (GFP) gene sequence is linked to a reporter gene central in specific anti-stress regulations, were also exposed to these matrices. Transgenic worms exposed to hydrochars showed very weak, if any, fluorescence, and expression of the associated RNAs related to stress response and biotransformation genes was surprisingly downregulated. Similar patterns were also found for the raw rice husk. It is hypothesized that an unidentified chemical trigger exists in the rice husk, which is not destroyed during the HTC process. Therefore, the use of GFP transgenic nematode strains cannot be recommended as a general rapid monitoring tool for farmers treating their fields with artificial char. However, it is hypothesized that the observed reduced transcriptional response with the subsequent lack of energy-consuming stress response is an energy-saving mechanism in the exposed nematodes. If this holds true in future studies, this finding opens the window to an innovative new field of stress ecology.
Biochar is the carbon-rich product obtained when biomass, such as wood, manure or leaves, is heat... more Biochar is the carbon-rich product obtained when biomass, such as wood, manure or leaves, is heated in a closed container with little or no available air. In more technical terms, biochar is produced by so-called thermal decomposition of organic material under limited supply of oxygen (O 2), and at relatively low temperatures (< 700 • C). Hy-drochar differentiates from biochar because it is produced in an aqueous environment, at lower temperatures and longer retention times. This work describes the production of hy-drochar from rice husks using a simple, safe and environmentally friendly experimental setup , previously used for degradation of various wastewaters. Hydrochars were obtained at 200 • C and 300 • C and at residence times ranging from 2 to 16 h. All samples were then characterized in terms of yield, surface area, pH, conductivity and elemental analysis , and two of them were selected for further testing with respect to heating values and heavy metal content. The surface area was low for all hydrochars, indicating that porous structure was not developed during treatment. The hydrochar obtained at 300 • C and 6 h residence times showed a predicted higher heating value of 17.8 MJ kg −1 , a fixed carbon content of 46.5 % and a fixed carbon recovery of 113 %, indicating a promising behaviour as a fuel.
An inactive asbestos mine in Northern Greece, known as MABE, had been operational for 18 years, s... more An inactive asbestos mine in Northern Greece, known as MABE, had been operational for 18 years, showing an annual chrysotile production of ∼100,000 tons. It is estimated that a total of 68 million tons of the mineral serpentine were excavated from the mine, of which 881,000 tons of chrysotile asbestos were produced. The mine deposits are located very near to the river Aliakmonas. The water of the river is extensively used as drinking water, as well as for irrigation. This study estimated the amount of asbestos currently present in the deposits, to at least 1.33 million tons. This is a 10-fold increase since the start of mine operation in 1982. Water samples obtained throughout the river had high chrysotile concentrations, in most cases far exceeding EPA's standard value (7 × 10 6 f/l). Therefore, the mine and the deposits urgently require remediation works, such as removal of large contaminated objects from the mine buildings and revegetation of the deposit areas, in order to reduce the asbestos levels in the river water.
Biochar produced by pyrolysis of organic residues is increasingly used for soil amendment and man... more Biochar produced by pyrolysis of organic residues is increasingly used for soil amendment and many other applications. However, analytical methods for its physical and chemical characterization are yet far from being specifically adapted, optimized, and standardized. Therefore, COST Action TD1107 conducted an interlaboratory comparison in which 22 laboratories from 12 countries analyzed three different types of biochar for 38 physical−chemical parameters (macro- and microelements, heavy metals, polycyclic aromatic hydrocarbons, pH, electrical conductivity, and specific surface area) with their preferential methods. The data were evaluated in detail using professional interlaboratory testing software. Whereas intralaboratory repeatability was generally good or at least acceptable, interlaboratory reproducibility was mostly not (20% < mean reproducibility standard deviation < 460%). This paper contributes to better comparability of biochar data published already and provides recommendations to improve and harmonize specific methods for biochar analysis in the future.
In a column set-up, Fe modified biochar produced from date palm leaves was used to remove As (1 m... more In a column set-up, Fe modified biochar produced from date palm leaves was used to remove As (1 mg L-1) from a laboratory-prepared wastewater. The wastewater treatment process was monitored in real-time by spectral induced polarization (SIP), over a wide range of frequencies (0.01-1000 Hz). Both 5 and 10% biochar-amended columns achieved As removal exceeding 98%. The SIP parameters appear to be sensitive on As removal processes, with the recorded trend following the conventional geochemical monitoring, while offering higher temporal resolution.
Biochar produced by pyrolysis of organic residues is increasingly used for soil amendment and man... more Biochar produced by pyrolysis of organic residues is increasingly used for soil amendment and many other applications. However, analytical methods for its physical and chemical characterization are yet far from being specifically adapted, optimized, and standardized. Therefore, the COST Action TD1107 conducted an inter-laboratory comparison, in which 22 laboratories from twelve countries analyzed three different types of biochar for 38 physical-chemical parameters (macro- and micro-elements, heavy metals, polycyclic aromatic hydrocarbons, pH, electrical conductivity, and specific surface area) with their preferential methods. The data was evaluated in detail using professional inter-laboratory testing software. Whereas intra-laboratory repeatability was generally good or at least acceptable, inter-laboratory reproducibility was mostly not (20% &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; mean reproducibility standard deviation &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 460%). This paper contributes to better comparability of biochar data published already, and provides recommendations to improve and harmonize specific methods for biochar analysis in the future.
Biochar produced by pyrolysis of organic residues is increasingly used for soil amendment and man... more Biochar produced by pyrolysis of organic residues is increasingly used for soil amendment and many other applications. However, analytical methods for its physical and chemical characterization are yet far from being specifically adapted, optimized, and standardized. Therefore, the COST Action TD1107 conducted an inter-laboratory comparison, in which 22 laboratories from twelve countries analyzed three different types of biochar for 38 physical-chemical parameters (macro- and micro-elements, heavy metals, polycyclic aromatic hydrocarbons, pH, electrical conductivity, and specific surface area) with their preferential methods. The data was evaluated in detail using professional inter-laboratory testing software. Whereas intra-laboratory repeatability was generally good or at least acceptable, inter-laboratory reproducibility was mostly not (20% &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; mean reproducibility standard deviation &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 460%). This paper contributes to better comparability of biochar data published already, and provides recommendations to improve and harmonize specific methods for biochar analysis in the future.
Currently, char substrates gain a lot of interest since soils amended with such substrates are be... more Currently, char substrates gain a lot of interest since soils amended with such substrates are being discussed to increase in fertility and productivity, water retention, and mit-igation of greenhouse gases. Char substrates can be produced by carbonization of organic matter. Among different process conditions, temperature is the main factor controlling the occurrence of organic and inorganic contaminants such as phenols and furfurals, which may affect target and non-target organisms. The hydrochar produced at 200 °C contained both furfural and phenol with concentrations of 282 and 324 mg kg −1 in contrast to the 300 °C hydrochar, which contained only phenol with a concentration of 666 mg kg −1. By washing with acetone and water, these concentrations were significantly reduced. In this study, the potential toxic effects of hydrochars on the free-living nematode Caenorhabditis elegans were investigated via gene transcription studies using the following four matrices: (i) raw rice husk, (ii) unwashed rice char, (iii) acetone/water washed rice char, and (iv) the wash water of the two rice chars produced at 200 and 300 °C via hydrothermal carbonization (HTC). Furthermore, genetically modified strains, where the green fluorescent protein (GFP) gene sequence is linked to a reporter gene central in specific anti-stress regulations, were also exposed to these matrices. Transgenic worms exposed to hydrochars showed very weak, if any, fluorescence, and expression of the associated RNAs related to stress response and biotransformation genes was surprisingly downregulated. Similar patterns were also found for the raw rice husk. It is hypothesized that an unidentified chemical trigger exists in the rice husk, which is not destroyed during the HTC process. Therefore, the use of GFP transgenic nematode strains cannot be recommended as a general rapid monitoring tool for farmers treating their fields with artificial char. However, it is hypothesized that the observed reduced transcriptional response with the subsequent lack of energy-consuming stress response is an energy-saving mechanism in the exposed nematodes. If this holds true in future studies, this finding opens the window to an innovative new field of stress ecology.
Biochar is the carbon-rich product obtained when biomass, such as wood, manure or leaves, is heat... more Biochar is the carbon-rich product obtained when biomass, such as wood, manure or leaves, is heated in a closed container with little or no available air. In more technical terms, biochar is produced by so-called thermal decomposition of organic material under limited supply of oxygen (O 2), and at relatively low temperatures (< 700 • C). Hy-drochar differentiates from biochar because it is produced in an aqueous environment, at lower temperatures and longer retention times. This work describes the production of hy-drochar from rice husks using a simple, safe and environmentally friendly experimental setup , previously used for degradation of various wastewaters. Hydrochars were obtained at 200 • C and 300 • C and at residence times ranging from 2 to 16 h. All samples were then characterized in terms of yield, surface area, pH, conductivity and elemental analysis , and two of them were selected for further testing with respect to heating values and heavy metal content. The surface area was low for all hydrochars, indicating that porous structure was not developed during treatment. The hydrochar obtained at 300 • C and 6 h residence times showed a predicted higher heating value of 17.8 MJ kg −1 , a fixed carbon content of 46.5 % and a fixed carbon recovery of 113 %, indicating a promising behaviour as a fuel.
An inactive asbestos mine in Northern Greece, known as MABE, had been operational for 18 years, s... more An inactive asbestos mine in Northern Greece, known as MABE, had been operational for 18 years, showing an annual chrysotile production of ∼100,000 tons. It is estimated that a total of 68 million tons of the mineral serpentine were excavated from the mine, of which 881,000 tons of chrysotile asbestos were produced. The mine deposits are located very near to the river Aliakmonas. The water of the river is extensively used as drinking water, as well as for irrigation. This study estimated the amount of asbestos currently present in the deposits, to at least 1.33 million tons. This is a 10-fold increase since the start of mine operation in 1982. Water samples obtained throughout the river had high chrysotile concentrations, in most cases far exceeding EPA's standard value (7 × 10 6 f/l). Therefore, the mine and the deposits urgently require remediation works, such as removal of large contaminated objects from the mine buildings and revegetation of the deposit areas, in order to reduce the asbestos levels in the river water.
Biochar produced by pyrolysis of organic residues is increasingly used for soil amendment and man... more Biochar produced by pyrolysis of organic residues is increasingly used for soil amendment and many other applications. However, analytical methods for its physical and chemical characterization are yet far from being specifically adapted, optimized, and standardized. Therefore, COST Action TD1107 conducted an interlaboratory comparison in which 22 laboratories from 12 countries analyzed three different types of biochar for 38 physical−chemical parameters (macro- and microelements, heavy metals, polycyclic aromatic hydrocarbons, pH, electrical conductivity, and specific surface area) with their preferential methods. The data were evaluated in detail using professional interlaboratory testing software. Whereas intralaboratory repeatability was generally good or at least acceptable, interlaboratory reproducibility was mostly not (20% < mean reproducibility standard deviation < 460%). This paper contributes to better comparability of biochar data published already and provides recommendations to improve and harmonize specific methods for biochar analysis in the future.
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Papers by Dimitris Kalderis
applications. However, analytical methods for its physical and chemical characterization are yet far from being specifically
adapted, optimized, and standardized. Therefore, COST Action TD1107 conducted an interlaboratory comparison in which 22
laboratories from 12 countries analyzed three different types of biochar for 38 physical−chemical parameters (macro- and
microelements, heavy metals, polycyclic aromatic hydrocarbons, pH, electrical conductivity, and specific surface area) with their
preferential methods. The data were evaluated in detail using professional interlaboratory testing software. Whereas
intralaboratory repeatability was generally good or at least acceptable, interlaboratory reproducibility was mostly not (20% <
mean reproducibility standard deviation < 460%). This paper contributes to better comparability of biochar data published
already and provides recommendations to improve and harmonize specific methods for biochar analysis in the future.
applications. However, analytical methods for its physical and chemical characterization are yet far from being specifically
adapted, optimized, and standardized. Therefore, COST Action TD1107 conducted an interlaboratory comparison in which 22
laboratories from 12 countries analyzed three different types of biochar for 38 physical−chemical parameters (macro- and
microelements, heavy metals, polycyclic aromatic hydrocarbons, pH, electrical conductivity, and specific surface area) with their
preferential methods. The data were evaluated in detail using professional interlaboratory testing software. Whereas
intralaboratory repeatability was generally good or at least acceptable, interlaboratory reproducibility was mostly not (20% <
mean reproducibility standard deviation < 460%). This paper contributes to better comparability of biochar data published
already and provides recommendations to improve and harmonize specific methods for biochar analysis in the future.