Would removing one spaecies completely disrupt an ecosystem

It wouldn't completely disrupt the system but, it'd make some major changes. Removing a species would be like removing a piece in the game of bricks. More bricks you'd remove the more unstable it'd get. So, I'd say don't remove any species from ANY ecosystem, for the safety of the world. If one ecosystem is disrupted, an entire species could die off. If one dies off, so would another and it'd keep going.

Hope this helped, have a good day!

they had the law tat factories that produces smoke cannot be built near residential buildings.

building of proper sewage system was done to ensure that the waste is carried away from the humans so that they do not get diseases from it.

also they built water systems to provide water in those areas which are drought prone.