Effect of Salinity on Cr(VI) Bioremediation by Algal-Bacterial Aerobic Granular Sludge Treating Synthetic Wastewater

Heavy metal-containing wastewater with high salinity challenges wastewater treatment plants (WWTPs) where the conventional activated sludge process is widely applied. Bioremediation has been proven to be an effective, economical, and eco-friendly technique to remove heavy metals from various wastewa...

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Published inProcesses Vol. 9; no. 8; p. 1400
Main Authors Nguyen, Bach Van, Yang, Xiaojing, Hirayama, Shota, Wang, Jixiang, Zhao, Ziwen, Lei, Zhongfang, Shimizu, Kazuya, Zhang, Zhenya, Le, Sinh Xuan
Format Journal Article
LanguageEnglish
Published Basel MDPI AG 13.08.2021
Subjects
Activated sludge
Activated sludge process
Algae
Bacteria
Biomass
Bioreactors
Bioremediation
Carbon
Chemical oxygen demand
Chromium
Excretion
Exposure
Filamentation
Heavy metals
Membrane separation
Morphology
Nitrogen
Phosphorus
Pollutants
Polysaccharides
Reactors
Salinity
Salinity effects
Sludge
Trace elements
Variance analysis
Wastewater treatment
Water treatment
Japan
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Summary:Heavy metal-containing wastewater with high salinity challenges wastewater treatment plants (WWTPs) where the conventional activated sludge process is widely applied. Bioremediation has been proven to be an effective, economical, and eco-friendly technique to remove heavy metals from various wastewaters. The newly developed algal-bacterial aerobic granular sludge (AGS) has emerged as a promising biosorbent for treating wastewater containing heavy metals, especially Cr(VI). In this study, two identical cylindrical sequencing batch reactors (SBRs), i.e., R1 (Control) and R2 (with 1% additional salinity), were used to cultivate algal-bacterial AGS and then to evaluate the effect of salinity on the performance of the two SBRs. The results reflected that less filamentation and a rougher surface could be observed on algal-bacterial AGS when exposed to 1% salinity, which showed little influence on organics removal. However, the removals of total inorganic nitrogen (TIN) and total phosphorus (TP) were noticeably impacted at the 1% salinity condition, and were further decreased with the co-existence of 2 mg/L Cr(VI). The Cr(VI) removal efficiency, on the other hand, was 31–51% by R1 and 28–48% by R2, respectively, indicating that salinity exposure may slightly influence Cr(VI) bioremediation. In addition, salinity exposure stimulated more polysaccharides excretion from algal-bacterial AGS while Cr(VI) exposure promoted proteins excretion.
ISSN:2227-9717
2227-9717
DOI:10.3390/pr9081400