I am inclined to recommend construction of a simple anaerobic digester design that would also provide beneficial methane for cooking. The simplest system uses recycled plastic drums. Household waste is added via an inlet pipe and the drum is kept tightly sealed. Off gas is collected in a second drum or inflatable rubber bladder for use as fuel source (reduces need for firewood). A port for liquid discharge is also needed on the digester. The waste is only partially treated and should be land applied as fertilizer or treated in an oxidation pond to reduce ammonia and fecal counts before discharging into a river. A quick internet search gives plans for numerous digester plans an schematics.
By giving residents in developing areas simple recycled supplies and plans, they can get the benefits of waste treatment and obtain fuel for cooking. Numerous NGOs are helping to spread this technology and the benefits of operating a small anaerobic digester for households and farms.