Effects of different concentration of Zn(II) on the organic material degradation and nitrification process in the treatment of real industrial wastewater

Abstract

In this study, three real industrial wastewaters containing different concentration of Zn (II) were treated with lab-scale sequential batch bioreactor (SBR) to determine the effects of Zn (II) on the organic material degradation and nitrification process. The effects of Zn (II) on nitrification performance were determined by monitoring the bioactivities of ammonium oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB), and effluent Zn (II) concentrations. It was observed that the organic matter removals of SBRs fed with wastewater containing different zinc concentrations show high similarity. Ammonium removal efficiencies (ARE) of reactors operated with a concentration of 2.1, 1.2, and 0.6 mg Zn (II)/L were observed as 88.9 & PLUSMN;1,7%, 89.8 & PLUSMN;1.0 % and 81.4 & PLUSMN;7.3 %, respectively. However, a remarkable effect on nitrate conversion rate (NaCR) was determined. NaCR was 98.3 & PLUSMN;8.2%, 47.5 & PLUSMN;11.4%, 27.6 & PLUSMN;6.7% for a concentration of 2.1, 1.2, and 0.6 mg Zn (II)/L, respectively. Additionally, it was concluded that NOB bioactivity and nitrate conversion rates were improved with increasing Zn (II) concentration. The effluent Zn (II) concentrations were measured as 0.67 mg/L, 0.33 mg/L and 0.07 mg/L for a influent concentration of 2.1, 1.2, and 0.6 mg Zn (II)/L, respectively. Results of the influent and effluent zinc concentrations showed that zinc was adsorbed on bioflocs.