Mitigation options
Option I: upgrade treatment type
Upgrade the treatment type means, for example, that a WWTP is upgraded from a tertiary to a quaternary treatment. Here is how to do it:
Go to the attribute table of WWTP.shp
Click on the “Toggle editing mode” (pencil icon in the top left corner)
Click on the “New field” icon
Add a new field called TC_upgr, type “Integer (32 bit)”
In the drop-down menu, select TC_upgr between all the available fields
In the equation box, write tech_class and click on “Update All”
Change the value of TC_upgr from one of the WWTPs to “4”
Save the edit
Re-do the workflow from API parameter selection until Risk Assessment to see the updated concentration values
Option II: relocate the WWTP
Another mitigation option could be to relocate the WWTP to other larger facilities with higher removal rates. It is possible to do it accordingly:
Go to the attribute table of WWTP.shp
Click on the “Toggle editing mode” (pencil icon in the top left corner)
Click on the “New field” icon
Add a new field called conn_upgr, type “Integer (32 bit)”
In the drop-down menu, select conn_upgr between all the available fields
In the equation box, write conn_inh and click on “Update All”
Remove the value of conn_upgr from one WWTP and add it to another WWTP
Save the edit
Re-do the workflow from API parameter selection until Risk Assessment to see the updated concentration values
Option III: redirect treated effluent
Finally, a last mitigation option is to redirect the discharge point of a WWTP to a larger or less-sensitive receiving water body. The steps to do this are:
Left click on emission_load.shp in order to have it as your active layer
Click on the “Toggle editing mode” (pencil icon in the top left corner)
Click on “Vertex Tool”
Click on the emission point that you want to redirect and move it to a different river section
Save the edit
Re-do the workflow from Accumulation until Risk Assessment to see the updated concentration values