The effects of varying Zn2+ on the activated sludge properties and its distribution patterns

https://doi.org/10.1016/j.biteb.2022.100990Get rights and content

Highlights

Low concentration of Zn2+ promoted the pollutants removal and sludge activity.

Concentration distribution of Zn2+: RS > TB-EPS > supernatant >LB-EPS > SMP.

High concentration of Fesingle bondMn oxidation state Zn decreased sludge flocculation.

Sludge flocculation rose first and then worsened as Zn2+ concentration increased.

Lower pH decreased the EPS functional groups and the adsorption of Zn2+.

Abstract

Metallurgy, electroplating and pharmaceutical industries generate a large amount of wastewater containing Zn2+, which influences the activated sludge properties. The present work investigated the effects of Zn2+ on sludge properties and its distribution patterns and chemical forms under a Zn2+ concentration range of 0–20 mg/L. When the influent Zn2+ concentration was 1 mg/L, parameters indicating sludge properties such as Zeta potential (−14.80 mV), contact angle (78.93°), particle size (54.43 μm) and re-flocculation (FA, 30%) reached the optimal states. Zn2+ was adsorbed by the functional groups of extracellular polymeric substances (EPS) and low EPS promoted the sludge flocculation. The lower pH affected the EPS functional groups, which in turn affected the adsorption of Zn2+. The Fesingle bondMn oxidation state Zn (2.66–6.86 mg/gVSS) predominated in the sludge and decreased as sludge flocculation increased. The results provided evidence to make full use of low concentration of Zn2+ to ensure wastewater treatment performance.

Keywords

Zn2+
Distribution patterns
Chemical forms
Flocculation
EPS
1

Lanhe Zhang and Yaling Liu are co-first authors.

View Abstract