Properties of Biochar Produced by Slow Pyrolysis of Stabilized Sewage Sludge

Abstract

Direct application of stabilized sewage sludge on agricultural soil is currently a big concern because of its significant content of detectable organic micropollutants. Proper sludge treatment should suppress its negative features and produce material suitable for soil amendment. Slow pyrolysis is one of such treatments. We studied the influence of pyrolysis temperature (400–800 °C) on material and energy balances and on elementary composition of the pyrolysis solid residue (biochar). Pyrolysis at higher temperatures resulted in lesser biochar yield and promoted gas yield. The macronutrient content of biochar increased with an increase in pyrolysis temperature (except for nitrogen).