Analysis of Environmental Performances of Ferritization Method for the Treatment of Copper-ammonia Wastewater under the Optimized Condition via RSM

Abstract

Copper-ammonia wastewater from industrial processes is an important form of hazardous waste that can contaminate water resources. The conventional hydroxide precipitation method used to remove copper complexes produces a large volume of unstable precipitates which still require further treatment. Ferritization is a powerful technique to remove bivalent cations from wastewater in the form of metal ferrites. This method is highly efficient in removal of metal complex ions; in addition, sludge resulting from this method is stable. The objective of this study was to investigate optimum conditions for ferritization using Response Surface Methodology (RSM). After optimal conditions were determined, the environmental performance of ferritization compared with hydroxide precipitation was compared using Life Cycle Assessment (LCA) methodology. The IMPACT 2002+ method was used to calculate midpoints and damage levels. The experiment found that the model obtained from RSM was accurate and reliable with R2=98.37, Adj-R2=96.91, Pred-R2= 91.40, S=1.45 and PRESS =110.859. The optimal conditions for the pH, reaction temperature, and reaction time were found to be 10.8, 69 ºC, and 115 min, respectively. In addition, the actual experiment showed that the efficiency of copper-ammonia removal was 98.413.18%. The LCA results indicate that hydroxide precipitation shows more impact at midpoint levels than ferritization, except for aquatic acidification and global warming effects. On the other hand, the endpoint analysis showed that the ferritization has a higher performance in regard to human health, ecosystem quality, and resource consumption. Ferritization had a greater impact on climate change than hydroxide precipitation because the process requires electricity. Without the use of recycling sludge as catalyst, the endpoint of natural resources from ferritization could be higher than for hydroxide precipitation. In conclusion, ferritization demonstrated better performance both in terms of its efficiency of copper-ammonia removal and its environmental performance.