Hello and thank you for your question. Am not from Bangladesh but I suggest the following.
1. Check from the environmental management regulatory agencies of your country.
2. Check the following articles that could help with some data
Mourshed, M., Masud, M. H., Rashid, F., & Joardder, M. U. H. (2017). Towards the effective plastic waste management in Bangladesh: a review. Environmental Science and Pollution Research, 24(35), 27021–27046.
National River Conservation Commission of Bangladesh (NRCCB). the state-run legal guardian of all Bangladesh rivers has called the verdict "a great achievement".
Please check this link, " https://github.com/Yilmazgithub/ex2-Plastic-Marine-Pollution-Global-Dataset ". It contains the dataset for plastic marine pollution all around the world.