Mechanism of Activated Sludge Floc Disintegration Induced by Excess Addition of NaCl. Issue 8 (29th June 2015)

• Record Type: Journal Article
• Authors: Cui, Youwei; Su, He; Chen, Yefei; Chen, Yongbao; Peng, Yongzhen
• Is Part Of: Clean. Volume 43:Issue 8(2015:Aug.)
• Page Start: 1197
• Page End: 1206
• Publication Date: 2015-06-29
• Subjects: Water quality -- Periodicals; Water -- Pollution -- Periodicals; Pollution -- Periodicals; Bioremediation -- Periodicals; Sewage -- Periodicals; Water chemistry -- Periodicals; 333.7205
• DOI: 10.1002/clen.201400219
• Languages: English
• ISSNs: 1863-0650

Abstract

<abstract abstract-type="main" xml:lang="en"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="clen201400219-sec-0001" sec-type="section"> <p>Abrupt salt intrusion in municipal wastewater treatment plants has triggered serious disturbances and deteriorated the biological treatment process from steady state into unsteady state. The effects of sodium (Na<sup>+</sup>) concentration on the structure and properties of activated sludge during the shock period were investigated in this paper. A floc disintegration characterized as the decreased floc size and increased porosity in the floc matrix was found when excess Na<sup>+</sup> was added to the bioreactor. Increased Na<sup>+</sup> resulted in a slight decrease in the normalized capillary suction time. About 53–57% of the total extracellular polymeric substances (EPS) derived from activated sludge was protein, at Na<sup>+</sup> concentrations <150.74 mmol/L, and this value even reached 68% at 286.04 mmol/L Na<sup>+</sup>. Over 50% of Na<sup>+</sup> in EPS was found in the loosely bound EPS (LB‐EPS). The Na<sup>+</sup> sorbed in LB‐EPS followed Langmuir model with a maxium sorption capacity of 2.086 mmol/g VSS. With the increase of Na<sup>+</sup> concentration in LB‐EPS, the Mg<sup>2+</sup> concentration in LB‐EPS decreased until reaching equilibrium while there was no significant change of Ca<sup>2+</sup> concentration. A concept model is proposed for the first time targeting to improve the understanding of sodium ion effects on activated sludge.</p> </sec> </abstract>