@epictittus @VaxxSabbath @thefinn @Jewpacabra @SK1ZM @Escoffier Thanks, I couldn't recall. I think the wind helps it dry and crystalize, so yes. I know "Sewer Gas" is H2S, so that's a sulfur source if needed. Vat with an exhaust tube to collect and burn and viola sulfur. There's likely a few better sources, but that's passive. The question would combining a few of those processes into a small scale bio reactor. Also urine to ammonia can be done in several ways. Urease is an enzyme found in a lot of places that converts urea to ammonia + CO2. That's found in pea seeds and watermelon seeds and a lot of other things.