Why not go for something ...
Published by Ian Robert Wickham Fontanini, Independent Business Owner at Globalian: Australian Italian National
Why not go for something like this design here used in Nepal for remote villages produce their own methane gas, if required you could install a Petrol & Oil separation or Grease Trap process inside so water volume removed quicker whilst fermentation solids remain, and like Paul Comet stated you design wetands for outlet effluent too ultimately become purified for completion it!
