We selected an advanced aerobic treatment plant (ATS) and a typical STS as model systems for a comparative effluent
water quality evaluation to the MTP. The ATS included a 5678 L multi-chambered system that was conceptually similar to the MTP because it contained an activated sludge process. The ATS used in this study also included a pretreatment tank, an aeration chamber and a final clarifier (HOOT Systems, Lake Charles, Louisiana, USA), but did not receive benefit from additional soil treatment. The STS was a basic, two-chambered 2800-l tank with no filter on the effluent discharge and also without benefit of a soil treatment unit, which may simulate a malfunctioning septic system scenario.