KAGAKU KOGAKU RONBUNSHU, Vol.46, No.4, 108-115, 2020
Behavior of Carbon and Nitrogen in Hydrothermal Treatment of Excess Sludge
Excess sludge was hydrothermally treated, and the effect of hydrothermal treatment temperature on the carbon and nitrogen properties in the sludge was evaluated. In the experiment, sludge slurry was hydrothermally treated at 373-473 K, and the behaviors of carbon and nitrogen were clarified by analyzing the carbon and nitrogen components in the solid and liquid, respectively. The decomposition and dissolution behaviors of carbon and nitrogen components in sludge varied depending on the treatment conditions: the carbon components dissolved in solution at 393K, while nitrogen components dissolved at 433K or higher and the formation of ammonium compounds was observed at a treatment temperature of 473K. Approximately 65% of the solubilized nitrogen component in untreated sludge was ammonium nitrogen, but the proportion of ammonium nitrogen in the solubilized component varied significantly depending on the treatment conditions. At a treatment temperature of 473K, the proportion of ammonium nitrogen decreased to 35% because of the formation of ammonium compounds.