The modular waste water treatment system receives waste water from a waste water source containing organic waste and produces a treated water effluent. The modular system includes bioreactors and a bioreactor support module. The bioreactors receive a waste water mixture from the bioreactor support module and produce treated water substantially free of organic waste. The bioreactor support module is a transportable unit fabricated upon a frame adapted for transport by a truck upon a public roadway. The bioreactor support module includes items of equipment needed for conditioning waste water for intake by the bioreactors, items of equipment for receiving, processing and discharging treated water from the bioreactors and may include other items of equipment for receiving and processing other byproducts from the bioreactors. The transportable bioreactor support module is sized to support the operation of between one and preferably as many as six bioractors. Accordingly, the modular waste water treatment system can be fabricated off site in a controlled shop environment, transported to a site, placed at a site and even later expanded to include additional bioreactors for increased capacity with a minimum of cost, time and effort.