Removal of Zn2+ and Cu2+ by a sequencing batch reactor (SBR) system

Both resting (living) and autoclaved (dead) bio-sludges showed almost the same Cu2+ and Zn2+ adsorption capacities with synthetic industrial estate wastewater (SIEWW). The resting bio-sludge showed not only Cu2+ and Zn2+ adsorption abilities but also organic matter adsorption ability. But, the organic matter (COD and BOD5) adsorption ability of bio-sludge with SIEWW containing 60 mg/L Cu2+ was about half of that with SIEWW containing 60 mg/L Zn2+. The adsorbed Cu2+ and Zn2+ were easily eluted (70–75%) from bio-sludge with 0.1 N HNO3 and 0.1 M EDTA solutions. Bio-sludge from a wastewater treatment plant could be used as an adsorbent for metal ions (Cu2+ and Zn2+). Cu2+ and Zn2+ could repress the SBR system efficiency but its efficiency could be increased with the increase of mixed liquor suspended solids (MLSS), and Cu2+ had more effect than Zn2+ to repress the system efficiency. The SBR system showed very low removal efficiencies of the pollutants with industrial estate wastewater (IEWW), but its pollutant removal efficiencies with IEWW could be increased with the addition of glucose. The Zn2+, Cu2+, BOD5, COD and TKN removal efficiencies of the system with IEWW containing 1.27 g/L glucose, 10 mg/L Cu2+ and 10 mg/L Zn2+ under MLSS of 4500 mg/L were 92.61 ± 0.28%, 83.77 ± 0.93%, 98 ± 0%, 92 ± 0% and 78.1 ± 0.1%, respectively.