Stabilized pond ash barrier in municipal solid waste landfill

Abstract

The bottom liner is placed at the bottommost layer of an engineered landfill. To eradicate the swelling effect of traditionally used clay as liner material, in this research, pond ash is stabilized by using lime and gypsum. In the laboratory, experimental tests such as unconfined compressive strength and falling head permeability are performed to examine the engineering properties of pond ash and make it suitable for use as a construction material in landfill bottom liners. After 180 days of curing, the Unconfined Compressive Strength (UCS) of stabilized pond ash increased significantly, reaching 4.9 MPa and 5.4 MPa for the S6 and S7 samples, respectively. With stabilized pond ash barriers, Municipal Solid Waste (MSW) landfills are considered for this analysis. A significant negative correlation was seen for the relationship between curing time and permeability value of stabilized samples, irrespective of the variety of permeants. Effluent leachate coming out of cured samples was studied for metal concentrations of copper, lead, zinc, arsenic, and the inorganic component magnesium. The metal ions studied in Inductively Coupled Plasma - Optical Emission Spectroscopy (ICP-OES) indicated that the retention of metal ions like copper, lead, zinc, arsenic, and the inorganic component magnesium was increased by the adsorption of trace elements in the liner layer of the landfill. The effluent concentration of trace metals was observed to be well below the permissible limit of inland surface water disposal as per the notification given by the Ministry of Environment and Forest (2000) India, regarding the standard of inland surface water disposal, and less than the allowable limit of the World Health Organization (WHO) in water quality standards.