Journal
SCIENCE OF THE TOTAL ENVIRONMENT
Volume 695, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.scitotenv.2019.133825
Keywords
Hydrocyclone treatment; Density sorting; Settleability; Carbon release
Categories
Funding
- Fundamental Research Funds for the Central Universities
- National Natural Science Foundation of China (NSFC) [51808225]
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The settleability performance of activated sludge (AS) is a very important indicator in the biological treatment of wastewater. In this paper, we investigated the influence of hydrocyclone treatment on sludge settleability and explored the influence mechanism by sorting the excess sludge (ES) with a hydrocyclone. A lateral-line test of the treatment process of the campus wastewater treatment plant (WWTP) at East China University of Science and Technology (ECUST) was carried out by using a sequencing batch reactor (SBR) AS process equipped with a hydrocyclone. The results showed that the sludge flocs rotate and revolve in the hydrocyclone; the resulting shear and centrifugal stress cause the flocs to crack into smaller pieces and can break the extracellular polymeric substances (EPS) on the floc surface, thus changing the floc structure and density. After density sorting by the hydrocyclone, the particle size of the sludge floc returned to the bioreactor decreased, the compactness increased, the settleability performance improved, the sludge volume index (SVI) decreased by 6.1%, and the effluent suspended solid (SS) concentration decreased by 6.1%. Meanwhile, the broken EPS caused organic carbon sources, such as polysaccharides and proteins, in the floc channels to be released into the water phase, supplementing the carbon source for denitrification and improving the effluent water quality: the removal rates of soluble chemical oxygen demand (SCOD), total nitrogen (TN), and NH4-N increased by 6.9%, 8.9%, and 8.4%, respectively. (C) 2019 Published by Elsevier B.V.
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