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In some AguaClara plants, a surface foam develops at the end of rapid mix. The first experiment goal was to understand the chemical conditions required for this surface foam to develop at the end of rapid mix and the first baffle. The first test trials were conducted with a constant supply of clay and varying amounts of alum but these did not exhibit any form of surface foam formation. Subsequent trials included organic matter: humic acid, but these only produced large non persistent bubbles. It was not until a stronger surfactant, liquid soap, was added to the baffle spacing that a surface foam with strong persistent bubbles developed. From these experiments it was concluded that air entrainment along with a surfactant in the raw water are the main factors behind surface foam formation. In Honduras, the raw water may contain decaying matter which decays to fatty acids acting as the surfactant while the waterfall at the LFOM creates- the perfect- condition for air entrainment. The process of air entrainment along with natural surfactants in the water thus allow for the formation of surface foam formation. With this in mind, the research is now focused on retrofitting AguaClara's designs so that no air entrainment occurs in the entrance tank and rapid mix chamber by eliminating waterfalls and or implementing hydraulic jumps.
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