The Electrocoagulator: Utilizing Electrocoagulation Flotation To Combat Harmful Algal Blooms

By Mark Hao Jun Pan and Mihailo Misic
Intermediate Category (Grades 9-10)
Innovation | Chemistry, Environment

As humans continue to pollute the environment, wastewater and fertilizer runoff is continuously drained inadvertently into freshwater and saltwater bodies alike, causing a detrimental impact to the environment and causing Anthropogenic eutrophication. Aquatic photosynthetic organisms, namely algae and cyanobacteria, multiply rapidly in the suitable conditions and grow at the epilimnion of the water, vying for sunlight. They multiply to a point where the algal density is so high that aquatic plants at the bottom cannot receive ample sunlight and begin to die. Thereafter, the algae have exploited all the nutrients in the water, and they, too, begin to decompose; bacteria multiply due to the sheer amount of organic matter. The bacteria use up the available oxygen in the water, thereby causing oxygen depletion: killing all the oxygen-dependant organisms in the water. By this point, most life in the water is dead.

Therefore, to prevent such a catastrophe from ensuing, we have designed a small prototype craft that will attempt to remove the algae prior to its decomposition: not to combat Anthropogenic eutrophication, but merely to clean up its consequences. The craft removes algal matter and neutralizes the algae via environmentally compatible chemicals: the decomposing algae can be utilized as fertilizer.

The craft utilizes an electrocoagulation flotation reactor to gather the algae: two electrodes are placed in the water, and a current is supplied and passes from the cathode to the anode. The current causes the decomposition of water into H2 gas and O2 gas: the cathode forms the H2 gas, and the anode forms O2 gas. As the gas bubbles float upwards, small suspended particles (in this case algae) are inadvertently attached and brought upwards: therefore, this forms a layer of flocculant at the epilimnion of the water. Thus, it is much easier to collect the algae, for they have been coagulated into a layer, and thereafter an Archimedes screw pump is implemented to bring the water into a containment tray where hydrogen peroxide (H2O2) is utilized to neutralize the algae. Hydrogen peroxide was chosen due to its environmentally compatible properties and it being readily available.
The craft utilizes an ultrasonic sensor in the front to guide it, and so as to prevent a collision with another object: the sensor is connected to a main microcontroller and driver shield, which control two DC motors at the back, and they are utilized as both as propulsion and as a steering mechanism.

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