I saw this on Treehugger.com:
View Larger Map
That such a large, sprawling operation is now starting to compost its waste material is a good thing. However, one hopes that there is good oversight of health and public safety issues that might well arise from a lot of rotting [former] foodstuffs. Hopefully, too, there's a good method of ensuring that no meat or dairy gets into the vegetable matter (or animal waste, either).
That said, one has to wonder what method of composting will be used for such a large operation. If something like this is really going to be "green", then one would hope for as little use of fossil fuel energy as possible, but yet having an adequate amount of tilling and turning to ensure methane production is kept to a minimum. (Remember that methane is 25 times more-potent a greenhouse gas than CO2.)
Also, composting up to 5,100 tons of organic waste per day is going to require a lot of land area. Looking around Mexico City, it is difficult to easily see where one might be able to build such an operation, and so it is likely that any single operation will be limited primarily by size. I think (since I'm not an expert on these things) that the tighter the area you need, the more energy-intensive your operation (to ensure proper aeration and turning of the compost).
Under optimal conditions, fresh compost can be had in as little as 2 months. However, two months is a long time in a start-up business. Luckily, the Mexican government is providing start-up funds (since it is eventually a saving for them on waste management costs). If the people are smart enough, they will set up the system to operate on a continuing rotation of compost production.