WATER TREATMENT PLANT SLUDGE CHARACTERIZATION, RECOVERY OF COAGULANT AND ITS REUSE

Alok Suman, Kafeel Ahmad, InamulHaq

Abstract: In the purification of water, conventional coagulants are mostly used, which produces large quantity of sludge. Therefore, the possibilities of sludge volume reduction, recovery of chemicals and their reuse as coagulant in the treatment of water and wastewater need to be explore. The objective of the study is to determine the physio-chemical characteristics of sludge obtained from water treatment plant and to investigate the regeneration of chemicals from WTS as coagulant for its re-use in wastewater treatment plants. WTS was collected from the Delhi Jal Boards water treatment plant (Chandrawal Water Works, New Delhi) which uses poly aluminum chloride (PAC) as coagulant in water treatment plant. The physio-chemical property of water treatment sludge was determined by using advance techniques such as Scanning Electron Microscope (SEM), Energy-Dispersive X-Ray Diffraction (ED-XRD), Fourier Transform Infrared Spectroscopy (FTIR). The sludge characteristic showed that it contains maximum amount of SiO2 at 67.75% .The other oxides observed by ED-XRD method in sludge samples were Al2O3 (16.76%), Fe2O3 (5.52%) and MgO (3.33%). The analysis results of WTS also showed the presence of different trace metals such as Ni (21.97mg/kg), Cu (38.31mg/kg), Zn (83.08 mg/kg), As (18.00 mg/kg), Rb (136.26 mg/ kg), Sr (68.41mg/kg), Ba (485.94 mg/kg),and Pb (24.00 mg/kg) determined by ED –XRD. The WTS collected was acidified with different normality of sulfuric acid from 1N to 4N to produce chemical as a regenerated coagulant. The sludge acidified by 3N H2SO4 was found to be an optimum condition for regeneration of coagulant. The regenerated coagulant of relatively high dose of 25 ml solution with 3N sludge acidification, when used to treat 1liter of synthetic dairy wastewater, produced better turbidity removal efficiency found at about 94%. Thus, regenerated coagulant has the potential to substitute the conventional coagulant used in the water purification. This approach provides reuse potential of WTS and thus minimizes disposal cost, environmental damage, and health risk. This strategy of sludge management would achieve the economic, social, and environmental sustainability

Keywords: coagulation-flocculation, Water Treatment, Sludge, Regenerated coagulant, SEM, ED-XRD, FTIR, XRD,

DOI: https://doi.org/10.15623/ijret.2018.0707029