No trash around Sulani

That particular area - around the volcano - is the target area to complete the task of improving the Sulani environment.
The majority of the Conservationist career tasks are specific to that area.
You can also find/clean up trash anywhere in Sulani by clicking on sandy beach type areas and choosing the action to "Beachcomb for trash".
The resulting trash can they be cleaned up.

- EQ Avid Sims player

@Sam18072004  I've moved your post to the Sims 4 Game Info section.