Lateritic Soil-Leachate Compatibility Study Using MICP Approach

Increase in the rate of generation of household waste (i.e Municipal Solid waste, MSW) in Nigeria necessitated the growing demand for a safe way to dispose MSW. When MSW comes in contact with water, it generates leachates, a poisonous fluid, that are harmful to humans. The use of landfill system for disposal of MSW has been a good approach for waste disposal. This study evaluated the effect of some hydraulic conductivity (H) parameters (i.e void ratio, degree of saturation and microbial suspension) and permeating fluids on the interaction of lateritic soil subjected to varying steps of treatments with Bacillus coagulans (B. coagulans) and subject to leachate environment for landfill application. Soil was mixed with 0 to 2.4 × 10 9 cells/ml of B. coagulans. After mixing and compaction, Calcium solution was introduced by gravity on the compacted soil samples and were permeated to percolate to a point of partial saturation. After application of Calcium solution, compacted samples were saturated in water for 24 to 48 hours up until fully saturated, thereafter subjected to H test using water as well as leachate as permeating fluids for a period of 91 days. Results show that void ratio values varied in the ranges 0.550-0.471 and 0.481- 0.485 for specimens where water and leachate were used as permeation fluids. Degree of saturation varied meaningfully with permeation fluids. H values varied in the ranges 1.51 x 10 -9 -1.71 x 10 -9 m/s and 6.84 x 10 -10 - 8.27 x 10 -10 m/s for specimens where water and leachates were used as permeation fluids. Soil-leachate interaction study and micro structural investigations revealed that the modified soil is well-matched with leachate and met the regulatory H value of 1.0 × 10 -9 m/s for used in landfill applications.