Side stream treatment for overflow

A system for treating wastewater, comprising:

• a first biological reactor fluidly connected to a source of wastewater and having a treated wastewater outlet, further comprising a first clarifier fluidly connected to the treated wastewater outlet and configured to provide a first treated effluent;
• a second biological reactor being a fixed film biological reactor connected to the source of wastewater and having a fixed film effluent outlet;
• a ballasted system fluidly connected to the fixed film effluent outlet, the ballasted system comprising:
• a ballast reactor tank configured to provide a ballasted effluent;
• and
• a source of ballast material fluidly connected to an inlet of the ballast reactor tank;
• and
• a bypass line having an inlet fluidly connected to the source of wastewater, a first outlet fluidly connected to the ballasted system, and a second outlet fluidly connected to the fixed film biological reactor, the bypass line configured to bypass the fixed film biological reactor.