While there are a few ways to accomplish this, the easiest, in my opinion, is to Apply a formula [set] to your column (see here: https://docs.trifacta.com/display/PE/Set+Transform) using the MERGE( ) function (see here: https://docs.trifacta.com/display/PE/MERGE+Function).
This would follow the form:
Transformation: set
Columns: your_column
Formula: MERGE(['0', your_column])