Disclosed are apparatus and methods for treating wastewater. In one example there is provided a wastewater treatment system. The wastewater treatment system comprises a settling basin having a first sidewall and a second sidewall, a first headshaft mount disposed on the first sidewall, a second headshaft mount disposed on the second sidewall, a headshaft comprising a shaft extending between and engaging the first headshaft mount and the second headshaft mount and including a bull sprocket and a collector headshaft sprocket.