A thermal plasma treatment experiment was conducted on stormwater detention pond sludge. The original sludge compositions were analyzed by neutron activation multi-element analysis. Thirty-two elements were detected in the sludge samples, and nine of them were below detection limit. The assessment of Zn, As, Mn, and Fe concentrations against the Ontario Ministry of Environment's Sediment Quality Guidelines indicated a marginal-to-significant pollution, and the concentration of Cr presented a gross pollution. After thermal plasma treatment, the mean weight percentage removal at 0 and 2 L/min of air flow rates was 2.78 ± 0.51 and 3.85 ± 1.35 %, respectively. The maximum weight removal of 5.87 % was achieved with 2 L/min air flow rate and 2 h of treatment time. Reduction of total organic carbon (TOC) increased with increasing treatment time and air flow rate. Eight gas compounds, CO, CO2, NO, NO2, NO
x, SO2, H2S, and C xH ywere measured and observed during the treatment process.