system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What happens to urine and fecal matter after we flush the toilet?

How is it treated and, in particular, where does the solid waste end up?
gpt
That's a question with a ton of detail. 

There are two types of sludge treatment; primary and secondary. Most of these processes require a press of some sort or a drying bed to assist in removing water content. After that, the sludge is most often used as a soil treatment, just like manure, after another facility processes it. 

As far as water, there are multiple types of treatment, plants and results. The basic rundown is that the water goes through a device called a clarifier. This separate the liquid, floatables and setables. Floatables are anything that floats to the surface and setables are essentially the sludge. The water then goes through a series of processes to remove bacteria. Some of those are natural trickling, some are chemical, and some are a combined force. 

The water can end up being crystal clear and reused as clean water, mostly clear and used as reclaimed water, or still very dirty and sent to a disposal site where the earth is the last stage to making clean water again. 

And i could go on for hours...