Pyrolysis of Fresh and Deposited Sewage Sludge and Investigation of the Products

The article presents results of studies of pyrolysis of fresh and deposited sewage sludge (DSS) in two regimes of heat input: conductive heating at a rate of 40 °C/s and convective heating at a rate of 10 °C/min. It was determined that the fresh sewage sludge (FSS) had the higher yield of organic liquid and gas, and the lower char yield. The higher heating rate led to a decrease in the char yield and an increase in the liquid yield. The investigation of liquid products showed that those of the FSS had greater proportions of alcohols, organic acids, and nitrogen-containing compounds, including heterocyclics. The liquid products of the DSS had the greater content of carbohydrates, esters, and unidentified compounds, which were probably condensed compounds.