They have pneumatic chutes on Roosevelt Island, in New York City’s East River. I think this technology has promise, especially in a high-density urban future. A long time ago, we decided we wanted our sewage out of site in tubes underground, but for some reason we are still trucking garbage around on the surface. Theoretically, you could have one tube system to collect all the organic waste (human waste, kitchen waste, yard waste) and take it to a central point for aerobic composting or anaerobic digestion, yielding useful products like energy (electricity, heat, natural gas) and fertilizer. Mixing high-carbon sewage and yard waste with high-nitrogen kitchen waste can also create a more balanced waste stream for digestion. Using suction instead of gravity to transport sewage opens up a new world of no- or low-water transport of waste, which is simply the direction we have to be headed in many warming, drying, and densely populated parts of the world. And sucking stuff through a tube has to be cleaner, safer, and quieter than a fleet of diesel-powered trucks.

Taking this even further, if you generate methane gas you could feed it into a fuel cell, creating electricity and clean water, and potentially sequestering carbon although I don’t fully understand where the technology is at the moment. But this seems to me like a very nice water-energy-waste system that could work at a building, institutional, or neighborhood scale, not exactly a closed loop but much more efficient than the production-use-disposal system we have now.