A picture is worth a thousand words...

In recent weeks we've posted a variety of articles in this "news" section discussing the various challenges associated with process control in wastewater plants, and particularly the problem of good aeration control (here); and the deficiencies of PID schemes (here).  

Here is what good aeration control looks like.  This plant (Lebanon, PA) uses dynamic DO setpoints, optimized for conditions as determined by our BIOS; and uses our patented BACS aeration control system to hit and maintain them.  The DO setpoint is represented by the redline, while the actual DO concentration is shown in blue:   (you may click on the image to enlarge it)

Note how tightly the actual DO concentration follows the setpoint, up and down, throughout the day. This level of control translated at this plant to 20% energy savings.

By contrast, shown below are the typical results of a PID system (one of the better ones):

See how the actual DO concentration (blue) constantly over and undershoots, and rarely matches the targeted concentration?   Those constant deviations, constant corrections, are wearing out the actuators, wasting energy, and compromising process effectiveness.  It doesn't have to be this way! Get a BACS!