Countercurrent stacked floc blanket reactor
Is the axisymmetric geometry of the jet reversor inferior to the plane jet used in AguaClara sed tanks because flocs bridge as they slide toward the jet reversor?
What upflow velocity works well for a floc blanket that is made with PACl and no other suspended solids?
Can flocs be transported in countercurrent flow between floc blanket reactors in series using the venturi effect at the base of the floc blanket connected to the floc hopper from the next floc blankets?
Do PACl precipitate floc blankets effectively remove fluoride or arsenic? If so, what floc blanket depth is required in the first reactor?
Fall 2015
The presence of contaminants such as arsenic and fluoride in drinking water is a major health concern for rural communities around the world. Some of the most severe cases are in South-Asian countries such as India and Bangladesh, several regions in South America, and Africa. Arsenic and fluoride are natural occurring elements widely distributed throughout the environment and are highly toxic in their inorganic form. People in these parts of the world are exposed to elevated levels of inorganic arsenic through contaminated groundwater, which is often used for drinking, food preparation, and irrigation. Long-term exposure to these inorganics can lead to chronic poisoning, severe cases of which may lead to organ failure and internal hemorrhaging.
A previous research team was able to successfully remove arsenic from contaminated synthetic groundwater by running the water through a sand filter in which the sand was coated in a coagulant, specifically polyaluminum chloride (PACl). This process, however, required frequent filter backwashing due to clogging seen through large pressure differentials. Despite being able to successfully remove arsenic from contaminated groundwater, the process was deemed inefficient due to its excessive consumption of treated water.
A potential solution to this problem of water wastage is to utilize a facet of AguaClara’s sedimentation tanks--the floc blanket. The floc blanket is a consistently suspended and highly concentrated collection of flocs in sedimentation tanks. The Countercurrent Stacked Floc Blanket Reactor (CSFBR) team is researching to see if heavy metals such as arsenic and fluoride can be removed from contaminated waters by running contaminated water through multiple floc blankets, which have been previously loaded with the coagulant PACl.
