Reinventing the Toilet for a Healthier City

One big problem is never addressed by these initiatives: Pharmaceuticals. The OP doesn't even mention the word.

Composting human waste into biogas works. Composting it into something akin to fertilizer, not so much. People today are flushing away incalculable numbers of drugs, especially antibiotics, that cannot be spread on land. Such schemes may work in developing countries where the average user isn't on drugs regularly, but the average american is on at least one regular prescription. Amongst older people (55+) one is near universal and many are on five or more.