Can I join the army as an officer after graduating from environmental engineering? How to get in? Can this major be admitted to a military academy?

Yes, the army has reserve officer training points in some schools, which is what we often call national defense students. After entering school, you can become a national defense student through school contact, reduce tuition fees and join the army directly after graduation. In fact, the state saves the construction cost of military schools and only pays tuition fees for you. Another way: before and after the job fair every year, troops go to local colleges to recruit officers, but it is said that these troops are either remote places or Fujian border guards. Once something happens in the Taiwan Strait, these people will basically give them away for nothing. It's not your turn in a good place.

According to my classmate's experience and the experience of the officers who have been transferred to other jobs in the current unit (basically colonel rank, about 40 years old, various troops), I strongly advise you not to go to the army.