REMOVAL OF POLLUTANTS FROM WASTEWATER BY COAL BOTTOM ASH

ABSTRACT

Coal bottom ash produced from a thermal power plant was used in a batch experiment to investigate the adsorption characteristic of this bottom ash. The adsorbate solutions were synthetic wastewaters contained copper (Cu²⁺) or COD and a sanitary landfill leachate. The influences of various factors, such as contact time, pH, initial adsorbate concentration and temperature on the sorption have been studied. Experimental results show that coal bottom ash had a good adsorption capacity for copper and COD and could reduce the concentrations of various pollutants in the leachate. The adsorption capacities of each gram of coal bottom ash were 0.48 mg Cu (at pH 4 and temperature 25°C) and 7.5 mg COD (at pH 5 and temperature 25°C); their adsorption behaviors conformed to Freundlich's adsorption model. In treating leachate, the removal efficiencies of COD, NH₃–N, total Kjeldah nitrogen, phosphorus, Fe³⁺, Mn²⁺ and Zn²⁺ were 47, 39.4, 31.1, 92.9, 96.5, 94.3 and 82.2%, respectively. Based on these results we can conclude that it is possible to use coal bottom ash for removing pollutants from wastewaters. The adsorption capacities of coal bottom ash for pollutants were also determined.

Keywords:

• Coal bottom ash
• Landfill leachate
• Adsorption

ACKNOWLEDGMENT

The authors would like to thank the National Science Council of the Republic of China for financially supporting this manuscript under Contract No. NSC 87-2211-E-035-002.