Experimental study on treatment of leachate concentrate from disk-tube reverse osmosis treatment in a waste incineration plant by gas-liquid contact evaporation

Abstract Gas-liquid contact evaporation is a promising and effective technology for treatment of leachate concentrate (LC) in the waste incineration plant as this technology can utilize local resource such as anaerobic biogas and heat air passing through air preheater in the waste incineration plant turning LC into supplying water for circulating cooling water system. the influence of pH, temperature of air preheater and rate of evaporation on COD and NH 3 -N in condensate water were investigated in a laboratory-scale evaporator to identify the optimum operation of this technology. The results showed that the COD concentration in condensate water obviously decreased with increase of temperature of air preheater as higher temperature of air preheater led to higher the initial evaporation temperatures, the evaporation rate of water was significantly greater than that of small molecular organic matters with lower boiling point than water. COD in condensate water decreased with the increase of pH, as and the amount of volatile organic matters such as fatty acids, which were hydrolyzed, escaped from LC to condensate water decreased. The rate of evaporation had little influence on COD in the condensate water. NH 3 -N concentrations in condensate water in all experimental groups were far away from the limit value (14 mg/L) in the water quality standard for industry uses (GB/T 19923 − 2005) in China. When the condensate water can meet the water quality standard for using as supplying water for circulating cooling water system, the energy consumption, carbon emission and economic cost were lowest at the optimum condition which was at 450 ℃ of temperature of air preheater and pH = 6 of LC when CF = 10. The conclusions can promote the industrial application of direct contact evaporation treatment of LC.