Environmental Performance of Lime–Rice Husk Ash Stabilized Lateritic Soil Contaminated with Lead or Naphthalene

This study evaluates the environmental performance of a lime–rice husk ash stabilized lateritic soil that had been contaminated with either lead or naphthalene. The Lime and Rice husk ash mixed in a ratio of 1:2 was used as a stabilizing binder and added to the contaminated soil at diverse quantities of 5 and 10% by weight of the contaminated samples. Environmental performance of the soil-contaminant-binder mixes were evaluated from the leaching and batch equilibrium adsorption tests conducted on the samples. Mineralogical analysis was also carried out on the leached samples using the X-ray diffractometer to determine the predominant minerals. The leaching test revealed that the lead concentration in the leachate was reduced below the allowable standard limit of 5 mg/l for lead, even after a duration of disturbed shaking at pH 3 ± 0.5 as the binder addition was increased from 0 to 5 to 10%. The binder addition was not effective to reduce the leachate concentrations of the naphthalene contaminant below the allowable standard limit for naphthalene in soil which is 0.2 µg/l. The batch equilibrium adsorption test showed that lateritic soil had a good adsorption capacity for both contaminants, which increased with an increase in the binder addition.