We studied the decomposition of two haloacetic acids (HAAs),dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA),in water by single oxidants ozone (O3) and ultraviolet radiation (UV) and the advanced oxidation p...We studied the decomposition of two haloacetic acids (HAAs),dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA),in water by single oxidants ozone (O3) and ultraviolet radiation (UV) and the advanced oxidation processes (AOPs) constituted by the combinations of O3/UV,H2O2/UV,O3 /H2O2,and O3/H2O2/UV. The concentrations of HAAs were analyzed at specified time intervals to track their decomposition. Except for O3 and UV,the four combined oxidation processes remarkably enhance the decomposition of DCAA and TCAA owing to the generated very reactive hydroxyl radicals. The fastest decomposition process is O3/H2O2/UV,closely followed by O3/UV. DCAA is much easier to decompose than TCAA. The kinetics of HAA decomposition by O3/UV can be described well by a pseudo first-order reaction model under a constant initial dissolved O3 concentration and fixed UV radiation. Humic acids and HCO3-in the reaction system both decrease the decomposition rate constants for DCAA and TCAA. The amount of H2O2 accumulates in the presence of humic acids in the O3/UV process.展开更多
Wastewater containing high concentrations of ammonia can be harmful to aquatic life and degrade the water quality. Wastewater containing ammonia is usually removed by conventional methods such as aeration in towers, b...Wastewater containing high concentrations of ammonia can be harmful to aquatic life and degrade the water quality. Wastewater containing ammonia is usually removed by conventional methods such as aeration in towers, biological treatment and adsorption of the ammonium ion to the zeolite surface. However, these methods are less effective and relatively expensive. Therefore there is a need for alternative technologies that can improve the efficiency of ammonia removal from wastewater. This study aims to obtain the process of ammonia removal through a combination of absorption in the membrane contactor and the advance oxidation process in the hybrid plasma-ozone reactor. Wastewater containing ammonia used in the study was a synthetic wastewater with a concentration of about 800 ppm. In the experiment, the wastewater fi＇om the reservoir was firstly passed into the membrane contactor on the shell side, and then mixed with ozone from the ozonator befbre entering the plasma reactor, and finally was circulated back to the reservoir. Meanwhile, the absorbent solution was sent to the lumen fiber in membrane contactor. Experimental results showed that the ammonia removal efficiency increases with increasing in circulation rate and temperature of the wastewater. The highest efficiency of ammonia removal obtained from the experimental results was 77%.展开更多
基金Natural Science Foundation of Chongqing under Grant No. CSTC2008BB7299.
文摘We studied the decomposition of two haloacetic acids (HAAs),dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA),in water by single oxidants ozone (O3) and ultraviolet radiation (UV) and the advanced oxidation processes (AOPs) constituted by the combinations of O3/UV,H2O2/UV,O3 /H2O2,and O3/H2O2/UV. The concentrations of HAAs were analyzed at specified time intervals to track their decomposition. Except for O3 and UV,the four combined oxidation processes remarkably enhance the decomposition of DCAA and TCAA owing to the generated very reactive hydroxyl radicals. The fastest decomposition process is O3/H2O2/UV,closely followed by O3/UV. DCAA is much easier to decompose than TCAA. The kinetics of HAA decomposition by O3/UV can be described well by a pseudo first-order reaction model under a constant initial dissolved O3 concentration and fixed UV radiation. Humic acids and HCO3-in the reaction system both decrease the decomposition rate constants for DCAA and TCAA. The amount of H2O2 accumulates in the presence of humic acids in the O3/UV process.
文摘Wastewater containing high concentrations of ammonia can be harmful to aquatic life and degrade the water quality. Wastewater containing ammonia is usually removed by conventional methods such as aeration in towers, biological treatment and adsorption of the ammonium ion to the zeolite surface. However, these methods are less effective and relatively expensive. Therefore there is a need for alternative technologies that can improve the efficiency of ammonia removal from wastewater. This study aims to obtain the process of ammonia removal through a combination of absorption in the membrane contactor and the advance oxidation process in the hybrid plasma-ozone reactor. Wastewater containing ammonia used in the study was a synthetic wastewater with a concentration of about 800 ppm. In the experiment, the wastewater fi＇om the reservoir was firstly passed into the membrane contactor on the shell side, and then mixed with ozone from the ozonator befbre entering the plasma reactor, and finally was circulated back to the reservoir. Meanwhile, the absorbent solution was sent to the lumen fiber in membrane contactor. Experimental results showed that the ammonia removal efficiency increases with increasing in circulation rate and temperature of the wastewater. The highest efficiency of ammonia removal obtained from the experimental results was 77%.
