Ultrasound coupled with Fenton oxidation pre-treatment of sludge to release organic carbon, nitrogen and phosphorus

We focused on the effects of ultrasound and Fenton reagent in ultrasonic coupling Fenton oxidation (U + F) pre-treatment processes on the disintegration of wastewater treatment plant sludge. The results demonstrated that U + F treatment could significantly increase soluble COD, TOC, total N, proteins, total P and PO43 concentrations in sludge supernatant. This method was more effective than ultrasonic (U) or Fenton oxidation (F) treatment alone. U + F treatment increased the soluble COD by 2.1-and 1.4-fold compared with U and F alone, respectively. U + F treatment increased the total N and P by 1.7-and 2.2-fold, respectively, compared with F alone. After U + F treatment, sludge showed a considerably finer particle size and looser microstructure based on scanning electron microscopy, and the highest OH center dot signal intensity increased from 568.7 by F treatment to 1106.3 using electron spin resonance. This demonstrated that U+ F treatment induces disintegration of sludge and release of organic carbon, nitrogen and phosphorus better. (c) 2015 Elsevier B.V. All rights reserved.