Study on the migration and degradation of organic compounds in coal-gasification wastewater with a novel treatment

The traditional treatment for coal-gasification wastewater is time-consuming and high-cost due to a great number of organic compounds. In this paper, a novel coal-gasification wastewater treatment is proposed. Pre-filtrated wastewater was sprayed into the gasifier instead of pure steam, and then organic constituents reacted at different temperatures. The migration and degradation of typical hydrocarbon and nitrogen-containing compounds in wastewater were experimentally studied. The release of nitrogenous and carbonous gas products were also analysed during a rapid combustion process. The results showed that the degradation rate of constituents increased with reaction temperature, and most organic constituents were degraded below 800°C. The initial concentration of phenol had a slight effect on the degradation rate, and NH3 held back the phenol reaction. The removal efficiency of COD and NH3-N ranked in different atmospheres as follows: oxidative > inert > reductive. The thermal decomposition of organic constituents was enhanced by increasing oxygen concentration and residence time. Furthermore, a simplified kinetic study of COD and NH3-N removal efficiency was carried out on the hypothesis of pseudo-first order reaction model. The pre-exponential factor and apparent activation energy for COD and NH3-N removal efficiency were obtained in the range of 3.63×10³-1.62×10⁶, 34.39-58.16 kJ·mol⁻¹ and 1.58×10⁴-8.71×10⁵ s⁻¹, 41.25-61.75 kJ·mol⁻¹, respectively.