Gasification is regarded as a prospective and promising method for rendering sewage sludge (an example of unconventional biomass) harmless [1-4]. Unfortunately, apart from the valuable gas fuel produced, the process results in solid and liquid waste by-products [5, 6, 7]. The solidification of mineral substances during gasification produces solid products, mostly ash, but also char coal in some cases [5,6]. The formation of the latter depends on the composition of nonflammable inorganic substances in the sludge which considerably decreases the Debye characteristic temperatures of the ash [6]. Liquid products, i.e., tar, as a result of the condensation of the contaminants present in gas [7].