To zdanko brzmi bardzo dyplomowo:
Sewage Sludge as a Biomass Resource for the Production of Energy
http://pubs.acs.org/cgi-bin/abstract.cgi/enfuem/2008/22/i01/abs/ef700267m.html
Wpisz w google 'sewage sludge + biogas + energy' i cos sobie skomponuj.
Biogas fuel production from sewage sludge?