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Team:Warsaw/EXTRAS
From 2014.igem.org
Technology
Bioprocess
Electronic equipment is the fastest growing waste category of waste in many developed countries. Amount of electronic waste grows rapidly because markets in which electronic is produced cross the other side of the ‘Digital Divide’. We stand in front of the following problem: what we are we going to do with all those computers, smartphones which we buy? All these products become obsolete or just unwanted within 1-3 years of purchase. Where will we find a new source of metals necessary to fabricate electronic equipment? Using old and broken WEEE in our project not only gives us a source of metals to produce new smartphones or computers, but also solves problem of storing WEEE.
This figure shows a view on the context of re-use of EEE or its components. At the end of the use EEE returns to producers or to companies, which specialize in reuse of e-waste.
The next step is preparation for re-use. On this step wasted electronic equipment is deconstructed. Not only computer memories or other parts which contains valuable metals are re-use. We also want to recover such materials as plastic or glass. That step requires labor work or special machines which will prepare WEE for another point of the plan.
Some parts of the TVs or computers may not be useful in another manufactory. Sometimes we need to remarked parts which we need and work in place with special equipment.
In the future we can use our bacteria with lanthanides binding sequences to re-use lanthanides.
1) Removing from WEEE plastic and stirring parts which are abundant of rare earth metals such as lanthanides, especially computer memories. Stirring increase availability WEEE with acid which is produced by Thiobacillus ferrooxidans. It display terbium from alloy.
2) Effluent from our bioreactor has low pH (about 2,5) what is a lethal for E.coli. This is the reason why we add Ca(OH)2 to effluent. It increases our pH to a level which is optimal to E.coli (about 7). Ca(OH)2 is also cheap and it is not increasing cost of the process very much.
3) Effluent goes to packed column bioreactor in which E.coli is immobilized. It gets across whole column. Ions of terbium binds and senses trough periplasmic domain.
4) Column (with no initial effluent) is flushed by NaCl. PmrB can easily denaturate in NaCl solution losing its conformation. Ions of terbium do not precipitate with NaCl aq and do not make insoluble components with it.
5) Ions of terbium are recovered from solution by electrolysis
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Discussion
Our process finds not only a way to recovery the lanthanides, but also other metals such as copper ( it takes place at first point of it) and other rare metals.We not only gain rare metals, but also solve the problem of WEEE. There are alternative ways to recycle metals such as cooper or iron by using bacteria, but lanthanides are usually extraced from motherlode, which nowdays is really costly. Our way of recovery lanthanides does not produce pollution but it also is a safe way of managing with WEEE. Other methods of gaining lanthanides use mix of concentrated acids such as HCl or HNO3. The most common problems with these methods are difficult to neutralise byproducts. Byproducts, especially Ca(NO3)2 are environmental-threatening. Their storing is very difficult and costly.Mining of lanthanides by old methods need to be placed on big areas, but our process takes less place. Area which will be taken to run it strictly depends on scale (in contrast to minors which always will take more space). Method which we presented is eco-friendly and solves the problem of full landfills with WEEE. In our opinion using microorganisms to recycle e-waste will be a standard way of raising lanthanides.Up↑
Alternative methods
Our final system was of course not the only possibility. There were some points where we had to decide...
