Environmental engineering has immense scope in India for professionals who are qualified in chemical, biological, thermal, radioactive or even mechanical engineering as environmental engineering is a diverse field and requires people from diverse background. Moreover, professionals from process engineering, environmental chemistry, water and sewage treatment, waste reduction management, pollution prevention, etc are required in large numbers. 
Job prospects for professionals with qualification in environmental engineering are bright in research centres, NGOs and various governmental departments working towards green development. Candidates with M.Tech in environmental engineering have opportunities to work for government built assessment committees which study and analyse the environmental risks involved in certain projects. The report of such a committee is then submitted to the concerned authority for further observation. Scholars with PhD in environmental engineering can opt for teaching jobs in colleges and universities

Hello!
Environmental engineering is a very new and upcoming field. It understands environmental issues and finds solutions for them in various ways. Here I'm linking an article which will help you understand more about environmental engineering, it's job prospects and much more:

https://www.careers360.com/environmental-engineering-course

Good luck!