Air control for wastewater treatment aeration

Aeration Process Introduction: Waste Water Treatment removes impurities and contaminants from a com¬munity`s sewage utilizing a number of different processes and a variety of equipment. One of the processes is the use of surface aerated basins that use aerobic micro-organisms to remove 80 to 90% of organic matter in waste water. Oxygen concentration in the water basins is a critical factor to promote the optimum micro-organism growth rate needed to treat the water in the shortest amount of time. As a result, large compressors are used to force air through hundreds of air diffusion filters at the bottom of the aeration basins, providing a constant 24/7 supply of oxygen to the micro-organisms in the water.

There are several primary challenges facing Waste Water Treatment Plants in the aeration process. The first is the energy management of the blower in order to contain operating expenses. Secondly, the dissolved oxygen content in the water basins must be monitored. Lastly, plants need to monitor and correct for the temperature and climate factors throughout the day that affect the open water basins. These measurement readings are all very important in order for the plant to ensure the aeration process is running at peak perfor-mance.

Customer Application and Performance Issues

A Southern California Municipal Waste Water Treatment Plant has been using Kurz 450 Insertion Mass Flow Meters with the Adam 155 Computer with great success for over 10 years. The City runs six extremely large compressors with output pipes up to 96' in diameter. Air is pumped through the system to the diffusion filtration system at the base of 25 aeration basins.

The customer wanted to update all their original Kurz flow meters to take ad¬vantage of digital controls and outputs to their main control center. They rec¬ognized the improved performance and advanced features of the Kurz 454FTB and decided to upgrade their plant to the new devices.

The Kurz Solution

The customer plant was equipped with over 40 of the Kurz 454FTB Insertion Thermal Mass Flow Meters. Each flow element totalizes the flow rate readings and sends a 4-20 mA output signal proportional to the flow rate to the control station.

In addition, Kurz K-Bar 2000B devices were installed for multi-point monitor¬ing of compressor air at the main headers of each compressor unit.