Process and apparatus for treating wastewater from a sewer system including the steps of: (A) removing solids contained in the influent to create solids-depleted preliminary effluent (PrE) and to protect downstream systems from premature failure due to wear from solid particles; (B) removing suspended solids from the PrE to produce a suspended solids-depleted primary effluent (PE); (C) treating the PE biologically by exposing it to bacteria-supporting media that removes soluble organic material, thereby creating trickling filter effluent (TFE); (D) separating the bacterial organisms by settling to create a secondary effluent (SE); (E) subjecting the SE to tertiary treatment including granular activated carbon pressure filters to remove PCB's and other compounds and create a carbon filter effluent; (F) disinfecting the CFE to create a final effluent (FE); and (G) discharging the FE to a receiving environment, separately settling and disposing the backwash solids in a backwash clarifier.