It is extremely hard to duplicate a wetland on a small scale. In universities when this is done, it is on a very large scale and they usually just build a small scale system outside. Researching wastewater treatment is even harder. What most students do is find a system and study what happens in a real system. Do a web search for wetland and “science project” and you will find examples of what other students study.
In general wetlands have limited applicability because of the amount of land needed. The joke (but not far off) is that if you did NYC, the wetland would be Connecticut.
