Wastewater Examples

As process engineers we never have as much information as we want.  That is, until now.

The WaterFeature8 is uniquely suited to monitoring a wide range of wastewater treatment processes.  It can also be deployed in PID loops for fully controlled subsytems.

For these examples we will refer to the classic Anaerobic-Anoxic-Aerobic (A2O) Process.

Although we have not personally visited too many real-life A2O plants, this process offers a great example of the various items that can be monitored and controlled at a wastewater treatment plant.

Water Quality Example

Starting with water quality, we know that the dissolved oxygen concentration in each of the Anoxic, Aerobic, and Post Aeration reactors is particularly important.  To facilitate accurate DO readings we will add a temperature sensor (RTD) in each tank with a dissolved oxygen sensor.

To properly execute biological phosphorus removal via PAO luxury uptake the operator needs to obtain anaerobic conditions in the first reactor, and the oxidation reduction potential (ORP) offers insight into these conditions.  An ORP in the range of -200 mV to -250 mV indicates suitably anaerobic conditions for a municipal strength wastewater.

Finally, effluent pH is almost always monitored, so one of those is installed in the Post Aeration reactor.

To set this up we need the following:

1 ea WaterFeature8 System Builder Kit

1 ea ORP sensor kit with EZO circuit

3 ea DO sensor kits with EZO circuits

3 ea RTD probe kits with EZO circuits

1 ea pH probe kit with EZO circuit

Mounting hardware and coaxial wiring to deployment sites

Our water quality monitoring system now looks something like this:

The EZO circuits can be installed in any order, but we chose to line them up from the front of the treatment process towards the back:

ORP:  Channel 1

DO:  Channel 2

RTD:  Channel 3

DO:  Channel 4

RTD:  Channel 5

DO:  Channel 6

RTD:  Channel 7

pH:  Channel 8

WWTP Example Sensors EZOs.png

This configuration can monitor for ideal conditions in the anaerobic reactor, dissolved oxygen concentrations in three other reactors, and effluent pH required for permit reporting.  In addition, the RTD sensors can be used to Temperature Compensate the DO and pH probes readings for additional accuracy.

Flow Monitoring Example

A major part of any treatment process strategy is managing solids return rates, particularly Return Activated Sludge (RAS) and Internal Recycle (IR).

You can also monitor Waste Activated Sludge (WAS) rates and record and totalize with a PLC to perform mass balances on your process.

Influent and Effluent flow is also important to know, but do not assume the meters will always be equal ... they. just. never. are.  Consider that turbine style meters are rarely accurate enough for permit reporting, but many higher quality, higher accuracy meters also have DC pulse output features that are compatible with the WaterFeature8.  The flow readings through a FLO EZO and WaterFeature8 will be as accurate as the meter they are connected to.

To set this up we need the following:

1 ea WaterFeature8 System Builder Kit

5 ea Flow meters with FLO EZO circuits

Mounting hardware and wiring to deployment sites

In the following image we have deployed five DC pulse flow meters to track flowrates around the plant:

WWTP Example Meters EZOs.png

We can install the FLO EZO circuits in any order we want, but we didn't want to rock the boat so they are in channels 1 through 5 for this example.  You could put them in channels 2, 6, 4, 7, 3, we won't tell anyone.

Channel 1:  FLO

Channel 2:  FLO

Channel 3:  FLO

Channel 4:  FLO

Channel 5:  FLO

A brief note about FLO EZOs and DC pulse flow meters.


This type of meter is not calibrated the way a DO probe or ORP sensor is calibrated.  The K-value of the meter must be changed in the FLO EZO software to modify the volume calculated per revolution of the meter.

Please refer to our FAQ page for more information regarding flow meter programming and calibration.

What can you do with 8?


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