I know this is a little specific but definitely worth looking into. It's called an Omni Processor, it takes human waste and biomass and produces clean water, electricity, and ash out of it. Any harmful waste is destroyed and the clean water, electricity, and ash can be reused within the community. The initial investment may be expensive, but once divided by the number of people using it and the long term output of renewable sources it produces, it is well worth it.
It's very new technology and Bill Gates invested in the copy to help make it.