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Influence of pyrolysis temperature on production and nutrient properties of wastewater sludge biochar

Hossain, Mustafa K., Strezov, Vladimir, Chan, K. Yin, Ziolkowski, Artur, Nelson, Peter F.
Journal of environmental management 2011 v.92 no.1 pp. 223-228
biochar, nitrogen content, sludge, temperature, trace elements, wastewater, wastewater treatment
The important challenge for effective management of wastewater sludge materials in an environmentally and economically acceptable way can be addressed through pyrolytic conversion of the sludge to biochar and agricultural applications of the biochar. The aim of this work is to investigate the influence of pyrolysis temperature on production of wastewater sludge biochar and evaluate the properties required for agronomic applications. Wastewater sludge collected from an urban wastewater treatment plant was pyrolysed in a laboratory scale reactor. It was found that by increasing the pyrolysis temperature (over the range from 300 °C to 700 °C) the yield of biochar decreased. Biochar produced at low temperature was acidic whereas at high temperature it was alkaline in nature. The concentration of nitrogen was found to decrease while micronutrients increased with increasing temperature. Concentrations of trace metals present in wastewater sludge varied with temperature and were found to primarily enriched in the biochar.