A large sewage treatment plant in Oregon is testing a process to make fertilizer from sewage. The process, from a Canadian company, is advertised as a win-win process that saves money and turns waste into a useful product.
The process uses Magnesium to capture phosphorus and ammonia and turn it into BB-sized pellets that can be spread as fertilizer. So long as there are no problems with toxics in the sewage, it ought to work.
Now about their proposal to put some of the fertilizer in streams to fertilize salmon production. Nice try, mimicking the natural nutrient delivery of dead salmon carcases, but I've seen this idea misused in the past. Most of our streams need fewer nutrients, not more. And pellets are not the same as salmon carcases, which are eaten directly instead of just fertilizing plant growth.