Significance of chemical conditioning to improve dewaterability of biosludge generated from tanneries

To improve the dewaterability, biosludge generated from activated sludge process and membrane bioreactor operated for treatment of tannery wastewater was conditioned with Fenton's reagent alone and Fenton's reagent in conjunction with polyelectrolyte, respectively. Studies were carried out at an optimum pH of 3.0 with a fixed Fe2+ concentration of 3,000 mg/L. Hydrogen peroxide and polyelectrolyte dosages were varied for the sludge generated from membrane bioreactor and activated sludge process. Optimum dosages were ascertained for hydrogen peroxide and polyelectrolyte. Hydrogen peroxide dosage of 900 and 750 mg/L were observed as optimum for membrane bioreactor sludge and activated process sludge with respect to volume of settled sludge. Polyelectrolyte dosage of 7.5 mg/L for membrane bioreactor sludge and 5 mg/L for activated process sludge in conjunction with Fenton's reagent was found to be the optimum with respect to volume of settled sludge. For the optimum dosage of Fenton's reagent in conjunction with polyelectrolyte, results were compared with respect to capillary suction time and release of bound water.