Effect of ammonia stripping and influence of contaminants in zinc plating wastewater. (15th November 2021)

• Record Type: Journal Article
• Authors: Morikubo, Satoshi; Kosaka, Yukio; Enomoto, Daisuke; Nishida, Aoi; Takuma, Yasuhiko
• Is Part Of: Journal of environmental management. Volume 298(2021)
• Publication Date: 2021-11-15
• Subjects: Ammonia stripping -- Effluent regulation -- Plating chemicals -- Wastewater treatment -- Zinc wastewater; Ethylenediamine-N, N, N′, N′-tetraacetic acid (EDTA) -- Total nitrogen (TN) -- Inductively coupled plasma optical emission spectroscopy (ICP-OES); Environmental policy -- Periodicals; Environmental management -- Periodicals; Environment -- Periodicals; Ecology -- Periodicals; 363.705
• DOI: 10.1016/j.jenvman.2021.113459
• Languages: English
• ISSNs: 0301-4797

Abstract

Abstract: Because many heavy metals, such as zinc, are used in plating plants, it is important for wastewater treatment technologies to comply with wastewater regulations. In zinc wastewater treatment, zinc is separated from wastewater via hydroxide precipitation. However, ammonia tends to enter the wastewater produced from the plating process and inhibits hydroxide precipitation, which causes difficulties in treating wastewater. In this study, we investigated the effect of ammonia stripping on plating wastewater to remove ammonia, which inhibits wastewater treatment. Based on the results of this study, it was observed that the effectiveness of ammonia removal depends on the pH and air flow rate. It was also found that the presence of zinc increased the ammonia removal effect in most cases. This increase was due to the transformation of some of the precipitated zinc hydroxide in the wastewater into zinc oxide, which afforded an ammonia adsorption effect. After the addition of ethylenediamine-N, N, N′, N′-tetraacetic acid disodium salt dihydrate (EDTA・2Na), which is a complexing agent, the ammonia removal effect was slightly decreased. This result is attributed to the decrease in the amount of zinc oxide, which occurs due to the complex formation of EDTA with zinc precipitates in the wastewater. Furthermore, the addition of an excess amount of EDTA・2Na increased the concentration of free ammonia in the wastewater and increased the removal effect. Moreover, the effect of ammonia stripping was successfully applied to wastewater obtained from a zinc plating plant, and zinc wastewater treatment was improved with the removal of ammonia. These results indicate that ammonia stripping is effective in zinc wastewater treatment. Highlights: The effect of ammonia stripping on zinc plating wastewater was investigated. pH, airflow rate, and zinc concentration affected ammonia removal from wastewater. The effect of contaminants on ammonia removal was determined. Ammonia stripping was observed to improve the zinc wastewater treatment. Ammonia stripping was effective in wastewater obtained from zinc plating plant.