Measurements were made directly from the supernatant
tank (influent) and the open biofilter tops (effluent) utilizing both
inline and handheld probes (HACH HQ40d Portable meter with
either HACH IntelliCAL LDO101 or MTC101 ORP/redox probe;
HACH pHD sc Differential ORP sensor with HACH sc100 controller;
HACH Advanced LDO Process Dissolved Oxygen Probe with HACH
sc200 controller)