Performance of an aerobic granular sequencing batch reactor fed with wastewaters contaminated with Zn2

Abstract

The main aim of this study was to investigate the performance of an aerobic granular sludge sequencing batch reactor (AGS-SBR) receiving water streams supplied with different loads of Zn2þ (50 and 100 mg L"1) during an operation of 866 cycles (ca. 109 days). When the metal was not fed, chemical oxygen demand (COD), PO3" 4 and NHþ4 were efficiently removed, with efficiencies of 56, 23 and 72% respectively. DGGE profiles showed that Zn2þ supply negatively affected the bacterial diversity and community structure of the granules. Consequently, the shock loadings with Zn2þ, particularly at the higher levels (100 mg L"1), affected the nutrient removal in the AGS-SBR, although the reactor still generally complied with admissible legal values concerning organic matter, nitrogen and Zn. Simultaneous removal of PO34" and TSS in such conditions needs further refining but the application of aerobic granular SBR in the treatment of Zn2þ contaminated wastewaters seems viable.