Resizable 3-D Printed MDC for Optimizing Desalination

By Jodh Singh Nahal
Intermediate Category (Grades 9-10)
Experiment | Energy and Natural Resources

It’s so devastating that every 90 seconds a child dies from a water-related disease. Currently, 1.1 billion people live without clean drinking water and 2.4 billion without basic sanitation facilities, which kills more than 900 children under the age of 5 every day. This situation will get much worse in the future with population boom. By 2025, two-thirds of the world’s population may face water shortages.

Although 71% of earth’s surface is covered with water, but 97% of this water is saline water, so desalination only might be able to solve the global water crisis. The main desalination technologies that are used are expensive and highly energy-intensive and so, are not sustainable, such as the conventional distillation requires around 25 kWh/m³, electrodialysis requires 0.4-4 kWh/m³, and even the most efficient reverse osmosis (RO) still requires 3-4 kWh/m³. Therefore, we urgently need to find a less energy intensive and cheap way to get freshwater, and need more renewable sources to produce clean electricity.

An MDC (Microbial Desalination Cell) has gained much interest due to its energy-free desalination capacity. It integrates the Microbial Fuel Cell (MFC) process and electrodialysis. Instead of applying external energy, MDCs utilizes the potential difference created by the oxidation of anodic bacteria to desalinate the salt water in the middle chamber by separating the salt ions to each side chambers (as shown in ‘Background Research’). An MDC is an environmentally-friendly new technology that not only desalinate the salt water without energy, but also treat the wastewater simultaneously and even generate electricity, and has zero pollution. MDC is a promising way to simultaneously solve world’s three major problems- energy and water crisis, and global warming. However, it is overlooked due to its high cost and less efficiency.

The aim of this study was to design and build an efficient low-cost MDC, capable of A). desalinating salt water, B). treating wastewater, and C). generating electricity, simultaneously; and to test its long term efficiency. Furthermore, in an attempt to increase MDC’s desalination efficiency, 7 factors have been analyzed- type of electrodes, energy input, type of anolyte, amount of anolyte, size of AEM and CEM, number of days, and with-&-without recirculating the catholyte and anolyte. Also, designed on an Onshape, a low-cost and resizable MDC was 3-D printed on an Afinia 3-D printer and was successfully tested.

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