About how long have wastewater treatment plants been in existence?

Wastewater treatment plants have been existing for already 120 years of time. Ever since the period of 1800's, the existence of wastewater treatment plants is present. Dating from today up to 1800's, it's been 120 years already. So the answer to the following question is 120 years.

Answermost of the time it would be ground into fine sediment,and sometimes they are carried away from the original location;