This is a very ambitious project between Mexico City
and the State of Hidalgo. The objective is to treat 60% of the WW produced in Metropolitan Zone of
Mexico City (ZMCM), which has a population of nearly 25 million inhabitants. This Mega WWTP has a
maximum capacity of 35 m3/s and it is expected to be finished at the beginning of 2013 [14]. One more
point to consider is that the Federal Ministry of Environment (SEMARNAT) reported in 2008, that there
were 1833 WWTPs, with an installed capacity of 113,024.0 l/s , which represents 40.2% of the total
volume of WW generated in Mexico; while in 2009, this volume increased to 43.5% [18]. The annual
production of bio-solids in 2009 was 640 millions of tons; 64% of it was sent to landfills and open pits
[15], contributing to the GHG emissions. Therefore in the Law for the Use of renewable Energy and
Energy Transition Funding, was approved in 2008 [16], opening a possibility to WWTP for producing and
using in-situ green energy while selling part of it to the grit. Nevertheless, the selection of the most
suitable technology in WWTPs should consider its geographical, climate and socio-economical situation