Everswinkel Waterworks: An Automated Oxidation Air Metering System Success Story
Drinking water pumped from the ground is rich in valuable minerals. These include iron and manganese, high concentrations of which can cause problematic precipitations in pipes and valves, as well as discoloring of the water and changes in taste. The Environmental Protection Agency therefore specifies limits for both elements.
To comply with these limits, untreated water is injected with air or oxygen in the waterworks, based on the quality of the raw water. The oxides precipitated out of the water can then be removed by using conventional filters. Oxidation can be carried out with various chemicals like chlorine or ozone but it is mostly done with compressed air. If the composition or quantity of the drinking water fluctuates, for example due to the changing interconnection of several wells with different water qualities, a readjustment is necessary, which is costly and time-consuming.
In many waterworks, correct metering of the oxidation air in the treatment of drinking water depends on one factor: Many years of experience on the part of the waterworks supervisor, who manually supplies the air to the untreated water by means of a simple needle valve. With the Bürkert oxidation air unit, this experience is readily available in a controlled and documented process.
Bürkert’s oxidator box operates on the basis of a high-performance, flexibly configurable mass flow controller. The compact system solution can automatically regulate the gas quantity needed for oxidation based on the untreated water supply in order to achieve the required limits with minimal gas consumption. In addition to constant water quality and documented, traceable processes, the automated oxidation air metering system also offers substantial economic benefits due to reduced oxygen consumption and optimized operation of the compressors during metering of the air or the oxygen.
Modular System for Tailor-Made Solutions
The control cabinets for the oxidator box are manufactured and assembled at the Bürkert Systemhaus. Oxidator boxes used for oxygen are equipped with only oil- and grease-free components that are suitable for the application. All pipework is also free of oil or grease. The Burkert mass flow controllers (MFC) Types 8626 and 8712 provide a high-performance basis for the oxidator box. Other safety-related functions such as pressure monitoring, emergency valves, check valves, optional manual operation or field displays are offered on an individual basis and delivered as a ready-for-connection solution in a stainless-steel control cabinet or on a mounting base. The mass flow controllers 8626 and 8712 are compact systems consisting of flow meters with control electronics and actuators. The system generally obtains the set point for the air metering from the higher-level PLC via a 4-20 mA standard signal or an optional bus interface, e.g., Profibus DP.
Everswinkel Waterworks in the Warendorf District, North Rhine-Westphalia, Germany, experienced the benefits firsthand. The intelligent design of the Bürkert oxidator box gave the utility precise control of the oxygen input based on the current quantity of untreated water. This oxygen quantity is always reproducible and no longer depends on the expertise of the waterworks supervisor.
Every year, Everswinkel found it had to replace about 10 pumps at the wells, which in the past required one week for adjustment of the oxygen quantity. This adjustment work has now been eliminated and the metering rate is always precise. According to the staff at Everswinkel Waterworks, the precisely controlled oxidation has resulted in less iron in the treated water tank, which saves them the costly and time-consuming task of cleaning the tank. It also eliminates the subsequent use of disinfectants, which is good for Everswinkel and the environment.
Bürkert Fluid Control Systems is exhibiting at AWWA’s ACE16 expo in Booth 1634.