Human waste could be turned into energy, insect feed, and/or fertilizer
Algae could become biofertilizer, bioplastic, pollution control (sewage and fertilizers), food / vitamins, fuel, fish and mushroom feed, and dyes/stabilizers
Leaky septic tanks and fertilizer runoff could be prevented to provide seagrass to manatees
Nitrogen fertilizer could be produced by the air
Urine / human waste could be used as large scale fertilizers
Single use, compostable toilets could be available in developing countries and humanitarian crises
Industrial effluent could be regulated for release / made into a profitable business to prevent pollution
Fertilizer and sewage runoff could be prevented to not cause ocean dead zones
Composting toilets could be available in areas lacking sanitation
Dead plants could heat homes, enrich soil, and sequester carbon
Goats, cows, and sheep could be lawnmowers