Proposed thesis topic / general area of research

Environmental engineering:
I need a proposal for thesis topic or general area of research for PhD program (approximately 1000 words ) contains the aims and objectives.
The core research priorities one of those topics:
1-water and food security
2-energy efficiency & renewable energy
3-environment & biodiversity
4-oil & gas
The transformative research priorities could be.
1-waste to value solutions for food, water & energy sectors