very practical idea, we at Nifindia.org gave an award to school student Moxad for similar idea in 2007 http://www.usmp.edu.pe/pdf/welcome_conti.pdf moxad suggested this in 2006, http://nif.org.in/innovation/generating_energy__from_movement_of_sewage/341 also see another awarded tech on electricity generation from sewage http://nif.org.in/innovation/power_generation__through__sewage-slow__moving__water/49...