Formation of chlorinated by-products during photo-Fenton degradation of pyrimethanil under saline conditions. Influence on toxicity and biodegradability

► Photo-Fenton treatment in DW showed a completely elimination of PYR after 11.8 min and 50% of the initial DOC was reduced after 79 min of illumination time. ► In DWNaCl, the same decrease in DOC took 110 min and PYR was completely degraded at a similar illumination time. ► Six TPs were identified in DW and ten in DWNaCl. ► The four chlorinated TPs showed greater resistance to photo-Fenton treatment than other TPs. ► Photocatalytic TPs can only be partly biodegraded by activated sludge.