I found a very good complete set of 30,000-ton CASS process design drawings for you. It is the construction drawing design of a sewage treatment plant that has been built in Beijing. It is very exquisite. I will not post the other ones. I feel that the level of this set of pictures is very representative. If you send too many pictures, you will not be able to learn. If you are just getting started, you might as well take a good look at this set.
After mastering this set of drawings, you will be able to use them directly to enter the design institute after work. It contains the "flow chart" you want. If you want to learn design, you should not just look at flow charts, which are relatively rough. You should look for sets of good drawings from good design institutes and learn from them. You will make rapid progress.
The sewage treatment process flow chart you want. Many of the drawings I have here are construction drawings of large sewage treatment plants. Just ask me directly for it from now on.
In addition, there are many drawings on the two websites NetEase Water Supply and Drainage and Water World, which you can easily download for your study.