Wastewater Treatment Plant

Henrique,
Have you checked to see if you meet the Minimum Program Requirements #4 for minimum floor area (using the MPR's definition of Gross Floor Area) and MPR #5 for minimum occupancy? If there is an office or maintenance area that's part of the facility that might provide the necessary area and staff FTE.
http://www.usgbc.org/Docs/Archive/General/Docs6473.pdf

It can be difficult to calculate the energy savings for facilities with large amounts of energy used for industrial processes. On the EAp2 and EAc1 forum pages there are more discussions about how to model process energy, and how to define the "baseline" building that you have to compare your project to and show you are saving energy.

Right now the water credits don't look at industrial process water - only water used for fixtures like sinks, toilets, showers, etc. So that won't be an issue. You might look into an ID credit for addressing any process water efficiency.

There is a searchable on-line database of certified projects, so you could try looking for wastewater treatment facilities there, but the project names don't always tell you the full story.