Sustainable landfilling in tropical conditions: comparison between open and closed cell approach

Two landfill test cells were constructed in a tropical climate using locally available low-cost materials. One cell was operated without a cover on the municipal solid waste to simulate ‘open landfill’ conditions and the other cell was covered to create ‘closed landfill’ conditions. Both test cells were monitored over a period of 290 days under rainy, dry and artificial wetting conditions. Due to the relatively high compaction density of waste in the closed test cell, the substrate settlement was gradual and comparatively lower than in the open test cell. Multiple top covers in the closed test cell resulted in significant run-off of incident precipitation during the rainy season, which delayed the waste stabilization and subsequently produced a lesser volume of leachate. On the other hand, operation of the open test cell was found to be advantageous in terms of leachate management and substrate settlement along with waste stabilization pattern. Infiltration of rain-water into the waste mass leached out the maximum organic pollutants and oxidized the nitrogen content, which is deemed to be a benefit of operating an open cell landfill under tropical conditions. Artificial wetting during dry periods by recirculation of stored leachate notably accelerated the waste stabilization and secondary substrate settlement in the open test cell. The continuous monitoring of ground-water quality from the site showed only seasonal variations.