Improvement of sludge dewaterability and disintegration efficiency using electrolytic zero-valent iron activated peroxymonosulfate

Abstract

Electrolysis zero-valent iron activated peroxymonosulfate (EZVI-PMS) was applied to enhance sludge dewaterability and disintegration performance. Sludge dewaterability was characterized by capillary suction time (CST), specific resistance to filtration (SRF), and disintegration performance was explored by measuring sludge DNA content, ammonia nitrogen, chemical oxygen demand (COD), extracellular polymeric substances (EPS) and dissolved organic carbon (DOC). EPS, including soluble EPS (SB-EPS), loosely bound EPS (LB-EPS), and tightly bound EPS (TB-EPS) were analyzed by three dimensional fluorescence excitation-emission spectrum (3D-EEM) to confirm the proteins' transformation tendency. DOC, protein and polysaccharide in EPSs were quantified to investigate the conditioning mechanism. The results showed that sludge CST and SRF were reduced significantly when the current was 0.2 A and PMS dosage was 130 mg/gDS with the reductions of 43.8% and 74.1%, respectively, and DNA was released from sludge cells to the liquid phase. Mechanically, sludge TB-EPS converted to SB-EPS with DOC in TB-EPS decreasing from 367.0 mg/L to 210 mg/L, while DOC in SB-EPS increased from 44 mg/L to 167.4 mg/L. Besides, the changes of protein and polysaccharide contents in SB-EPS and TB-EPS were similar to DOC, and protein in TB-EPS transformed to other protein-like or organic substances obviously. Highlights Electrochemically activated peroxymonosulfate (PMS) was useful for conditioning.; An electric current of 0.2 A was enough to produce Fe(II) to activate PMS using iron bar as the cathodes.; Electrochemically activated PMS could oxidize extracellular polymeric substances in sludge to enhance sludge dewaterability.;

Keywords

• electrolysis zero-valent iron
• extracellular polymeric substance (eps)
• peroxymonosulfate (pms)
• sludge disintegration
• sludge filterability