Researchers at the UPM have developed a carbonaceous material from sewage sludge that when applied to soil can help to improve its quality.
The material is called biochar and was prepared and characterized by the research group of Resource Exploitation of the Technical University of Madrid (UPM). The biochar has promising effects because its addition can enhance the quality of soil, and consequently it can enhance crop yields. In addition, it has beneficial properties for the environment.
The generation of sewage sludge is increasing and its management and treatment have been studied over the last years. Among the different usages of the sludge in countries such as Spain, where soil has a low content of organic material, we should stress its direct addition to soil. However, there are some factors that threaten this practice due to high level of salts, metals and organic compound which can even be toxics.
Researchers at the group of Resource Exploitation of the UPM have been working on the preparation and characterization of the biochar for several years. They also worked on the biochar from sewage sludge and also the effect of physical, chemical and biological properties of the soil, as a result improving this material. The obtained results so far are quite encouraging as they show how the addition of biochar to soil can enhance its quality (for example, its ability for moisture retention, pH or biological activity) and therefore, to enhance crop yields.
Other positive effects of the biochar use from sewage on the environment are, firstly, the reduction of the solubility of the existing metals in sewage sludge. Secondly, it allows a soil carbon sequestration thanks to the higher stability of the biochar which reduces its degradation and contributes to reduce emissions of greenhouse gases.
The researchers of the UPM are currently extending these studies for its application in the field of biochar from sewage sludge and other types of organic residues susceptible to be changed into biochar. This research is a joint collaboration between the group of Treatment and reuse of organic wastes of the Institute of Agricultural Sciences at the CSIC, the department of Department of Environmental Engineering of the Technical University of Crete (Greece) and the Institute of Applied Ecology, Chinese Academy of Sciences.
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More information: A. MÉNDEZ, A.M. TARQUIS, A. SAA-REQUEJO, F. GUERRERO, G. GASCÓ. "Influence of pyrolysis temperature on composted sewage sludge biochar priming effect in a loamy soil". Chemosphere 93 (2013) 668-676.
A. MÉNDEZ, M. TERRADILLOS, G. GASCÓ. "Physicochemical and agronomic properties of biochar from sewage sludge pyrolysed at different temperaturas". Journal of Analytical and Applied Pyrolysis 102 (2013) 124–130.
J. PAZ-FERREIRO, G. GASCÓ, B. GUTIÉRREZ, A. MÉNDEZ. "Soil biochemical activities and the geometric mean of enzyme activities after application of sewage sludge and sewage sludge biochar to soil". Biology and Fertility of Soils 48 (2012) 511–517.
G. GASCÓ, J. PAZ-FERREIRO, A. MÉNDEZ. "Thermal analysis of soil amended with sewage sludge and biochar from sewage sludge pyrolysis". Journal of Thermal Analysis and Calorimetry 108 (2012) 769–775.
A. MÉNDEZ, A. GÓMEZ, J. PAZ-FERREIRO, G. GASCÓ. "Effects of sewage sludge biochar on plant metal availability after application to a Mediterranean soil". Chemosphere 89 (2012) 1354–1359.
J. PAZ-FERREIRO, S. FU, A. MÉNDEZ, G. GASCÓ. "Interactive effects of biochar and earthworm on plant productivity and soil properties". Journal of Soil and Sediments, en prensa.