Seen
from Figure 2, Di-CBs (78.3–93.1%) were the predominant
isomers in wastewater samples, followed by Tri-CBs (2.9–
7.9%) and Tetra-CBs (2.2–5.9%). The proportion of other
highly chlorinated biphenyls (Hexa-CBs to Deca-CBs) was
less than 5% in each stage effluent. Similar to the profiles
of PCB isomers in wastewater, Di-CBs (70.4–84.0%) were
the dominant isomers in sludge, followed by Mono-CBs
(7.9–15.2%) and Tri-CBs (5.4–16.8%), with less than 3% of
contribution of other PCBs isomers