Looking for sustainable faecal sludge management solutions.

  Dear friends, we are in process of constructing community toilets for a population of around 20000. We will be constructing 300 nos. community latrines in total. Latrines will be having a storage tank of required capacity. Our storage tank design suggests de-sludging of tank at one months interval. De-sludging is going to be a problem for us as we do not have much land for treating or disposing the waste . We are looking for a some sustainable solution for this faecal sludge management project. If you have worked on any similar project, what treatment or management solution did you adopt?