Biosolid fertilizers are widely used for decades in turfgrass. That’s not a claim that they’re risk-free, but rather just noting that it’s a well-established process.

Milorganite is probably the best-known nationally available brand you can buy in the home center near you, but some municipal treatment plants also sell locally to small/home users in addition to the more commercial scale usage (golf courses, etc)

I’m not sure of their level of use in feed grasses.