A study looked at how well a special reactor cleaned up wastewater from a paper mill. They changed how dirty the water was and how long it stayed in the reactor. The reactor did a great job, removing almost all the bad stuff in the water. It made a lot of methane gas too. The reactor worked best when the water stayed longer in it. The first parts of the reactor did most of the cleaning. The water that came out was safe and had a good pH level. Overall, the reactor did a good job cleaning the water, especially when it stayed in the reactor longer.