I’ve designed a purification process that uses a membrane to filter sewage from water. There are things you don’t think about. Like, if I made sewage, I’d store it in a bucket and keep it outside. In winter, I could just leave it out and freeze it, but in warmer weather it was a challenge. The sewage would get all over the place, down my driveway in the middle of suburbia. My girlfriend at the time hated me doing testing.