A Research On Effect Of Ultrasonic Combined With Fenton-like On Tannery Sludge Dewaterability

The tannery industry in China developed rapidly since last decade with many problems occurred, and the disposal of the tannery sludge caught most of the attention. With its high level of moisture and concentration of chromium, tannery sludge is difficult to be dealt with directly due to its poor dewaterbility and complicated composition, so that in China there is no effective treatment at present. How to improve the tanning sludge dewatering performance, become the key technologies of sludge disposal and reuse.This experiment used ultrasonic combined with Fenton-like on tannery sludge, found the change rule of dewaterability and heavy metals after processing.Local failure of tannery sludge by used ultrasonic keeping DDCOD between0.8～4.0%is conducive to improves dewaterbility. In this paper, ultrasonic which works in frequency (53kHz), ultrasonic density (0.08W/mI), time (5s), keep DDCOD at1.79%improves the dewaterbility of tannery sludge in the best and CST from46.6s to40.6s. Heavy metals’concentration in tannery sludge liquid supernatant after using ultrasonic: Cu and Ni aren’t obvious; Zn and Cd increase by ultrasonic effect concentration; Pb has no effect; Cr and hexavalent chromium rise obvious; trivalent chromium rises more gently. Under the premise of improving dewaterability, hightest concentrations of heavy metals are19.0604μg/l,13.8695μg/l,133.3728μg/1、0.1256μg/l、0μg/13469.8750μg/1、2703.3750μg/1、766.5000μg/1and they are below the state hazardous waste leaching toxicity limit.Analysing the effect of ultrasonic combined with Fenton-like on tannery sludge use dewaterability, compatibility and second pollution. With factorial analysis, the method that ues28kHz ultrasonic frequency,300mg/1ferric iron and50ml/1hydrogen peroxide is conduvice to dewaterability and makes low second pollution; With15ml hydrogen peroxide and80mg ferric iron gets lowest SS and better settleability which produces more second pollution; Using28kHz ultrasonic frequency,300mg/1ferric iron and50ml/1hydrogen peroxide can capture Cr which reduces from2.9412mg/1to1.1610mg/1in tannery sludge liquid supernatant From the factorial experiment, ferric iron generally has intercrossing effects with other factors, and prove that ferric iron make roles as catalyst, flocculating agent in this study.In the conclusion obtained from factorial experiment has good repeatability, and small probability event is ruled out. Cr, which is similar to catalyst in a certain extent about the experimental results; PH change before and after may by the amount of Cr, Mn and Fe.