Most of the sewage generated in the metropolitan area of Barcelona
is treated at site C, a WWTP designed to handle approximately
153 hm3/s of water using secondary and tertiary treatment.
Ninety-one samples were collected from the WWTP, first at the
inflow (C1, n ¼ 37), at the outlet of secondary treatment consisting
of a biological reactor and sedimentation (C2, n ¼ 32) and at the
outflow from the tertiary treatment (C3, n ¼ 22) that comprised
chlorination, Actiflo® filtration and flocculation and UV disinfection.
These samples were collected when the complete treatment
systemwas operating. Site D consists of a marine bathing water site
affected by the river plume diluted by Mediterranean seawater
(n ¼ 32). Water samples of 10 L were collected from the river, the
sea and the tertiary effluent, whereas only 50 mL were collected
from the secondary effluent and raw wastewater.