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C. Rius-Alonso1, L. Olivares de LaChica2, M.J. Aboitiz-Violante2, V. Becker-Hernandez2, A.S. Morá-Michei2, M.S. Rodriguez-Merayo2, J. Gracia-Fadrique1

1Universidad Nacional Autonoma de Mexico (MEXICO)
2Instituto Godwin (MEXICO)
The aim of this project was to develop awareness between young students of the big problems the civilization is facing and a way in which they can contribute to solve them. A team of 4 undergraduate students were involved in the project with the aim of bringing a real and cheap solution to one problem. The problem was to reuse the Grey-water coming from the washing machine to flush the toilets without the problem of soapy water. A constant supervision was given during all the project and it took one semester to accomplish.

Potable water is becoming each day more difficult to find, new treatments and procedures has been developed in order to solve the problem. The recycle of Grey-water (water with soap or detergent) can be reused if the detergent can be eliminated in a simple and cheap way. From the beginning of the project it was clear that a batch process was not adequate because it involved many steps and a lot of hand labor. Thus it was decided that a continuous process has to be developed in order to have a simple and reproducible process. It is known that Ca++ precipitates an insoluble salt from soaps and detergents. The first step of the process was the precipitation using Ca(OH)2 that is very cheap and widely available from the construction industry. In order to have a good elimination of the soaps and detergents an excess of calcium hydroxide has to be used. This give a basic solution with excess of Ca++ in order to eliminate the excess the use of a weak acid like carbonic acid formed when CO2 is dissolved in water precipitates CaCO3 and the amount of CO2 can be controlled to have the right PH around 7. This was done with a vertical absorption column, the separation of the precipitate was done with a column with 10° inclination after it the water was pumped into a filter to eliminate any residue and in the case of using waste waters it was used an ultraviolet lamp to clean the bacteria’s and at the end the water was complete purified using ozone. One additional advantage of using ozone was the destruction of the non ionic tensoactive that are used in the commercial formulation. Detailed steps for the construction of the continuous device will be provided. This type of projects is very good to fulfill one of the most important tasks in education, self motivation and deep learning.