Characterization of Leachate Clogging Solids

The Solid Waste Authority (SWA) of Palm Beach County collects leachate from its landfill in a gravity pipe leachate collection system (LCS), which is experiencing clogging due to calcium carbonate scale. An investigation was conducted to determine the solids composition and provide engineering solutions to this challenge.
During testing, it was found that aerated leachate produced foam, which after vibration and evaporation, formed crystalline solids similar to those found in the SWA LCS. The following tests were conducted to determine the water quality of the leachate and the properties of the solids: pH, turbidity, chemical reactivity, biological growth, surface characteristics, and microscopic analysis.
After five days of evaporation, the solids collected in all samples represented 46-47% of the leachate’s initial weight. On visual observation, the leachate remnants left both a crystalline and a dark slimy solid, with larger particles in the aerated samples, a possible source of the clogging.