FYI, coming from someone who just passed, that book is OK but I highly recommend getting this updated version:
There are more practice problems and more topics are covered (risk assessment, biological treatment, etc.) which the first edition is a little weak in. However, the newer version does NOT have a review of all the necessary equations which the first version you're after does.
Also, in the newer version they write in bold next to the solutions, which part of the FE manual you should be using for that problem. I found that helpful.
Imo if you do all the practice problems (110) and just one of the practice exams (110) you'll be fine.
I started out by trying to work my way through the Brightwood Environmental Engineering FE manual, but found it to be pretty unhelpful. I don't think the proportions of questions on certain topics match the proportions of those topics on the exam, if that makes sense. There were a ton of waste water problems but only like 10 review problems, and like 50 review problems on material science but there aren't very many of those on the exam. Those questions are much more difficult though than the exam, so if you can solve all those problems in that book you'll be golden. However, I don't think this is necessary and probably a waste of your time.
I ended up studying pretty much exclusively from Naimpally and Sinclair: https://www.amazon.com/Environmental-Practice-Ashok-Naimpally-PhD/dp/159126636X
I worked my way through all the problems and then went back and reviewed the ones I had trouble with.
Gregory Michaelson's videos on YouTube can be helpful.
I passed on the first try and my undergrad is in geology, not environmental engineering so I had to teach a lot of this stuff to myself, and found the Naimpally book to be a great resource.