Wastewater Treatment Plants (WWTPs) can use reliable dissolved oxygen (DO) data to improve operations, especially with continuous DO monitoring and realtime data acquisition. When DO probes and controllers are connected to blower controls through a SCADA system, the Publicly Owned Treatment Works (POTW) or WWTP will be able to:
- Optimize sewage treatment
- Reduce energy bills
- Comply with National Pollution Discharge Elimination System (NPDES) permit requirements
The impact of reliable DO measurements for POTWs was investigated by comparing three different DO monitoring technologies:
- Galvanic electrochemical methodology used by the OxyGuard- International™ Membrane Electrode
- Optical intensity methodology used by the InsiteIG' Optical Probe
- Optical lifetime methodology used by In-Situ* Inc's RDO PRO Probe
This report summarizes the overall performance of these instruments in POTW mixed liquor tanks in their ability to:
- Monitor DO changes
- Provide quality data to manage the POTW process
- Reduce overall costs at the POTWs by reducing NPDES permit violations and by reducing energy costs on site by up to 50 percent
- Realize 100 percent return on investment
Online Monitor Installation
Each DO probe was placed in an active POTW mixed liquor tank at two facilities (Figures 1,2). The mixed liquor treated the primary effluent from a wastewater stream that contained both municipal and industrial sewage.
The DO probes in the mixed liquor were placed adjacent to each other and the depth of the probes was uniform at each POTW facility. All manufacturer recommendations were followed for all products.The RDO PRO Probes recorded the data at 5- or 15-minute intervals and the OxyGuard Probe and InsiteIG Probe results were manually collected by the POTW operators during their shifts.