My current understanding is: As long as there is no Urinary infection the urine is sterile. If an infection of the urinary tract is present then bacteria can be passed in the Urine. This may or may not be accompanied by blood in the urine, and/or painful urination. As a general operating basis: The sick person could urinate in with the solids. A well person could urinate so as to add to the fertilizer liquid nutrients. Another approach would be to pass all urine past a strong ultraviolet light to kill any possible pathogens. In this case one would need to filter out solid particles to about 3 micron before exposure to the light. Bacteria can hide behind dirt particles.
Offered by Mike.
Urine is perfectly safe unless very dark or contains pus (cloudy).
Offered by Jan.