Thursday, 29 September 2011

Package for wastewater aeration control

Endress+Hauser has announced their Instrumentation for Aeration Control package geared specifically toward advanced aeration control strategies. Instruments available measure dissolved oxygen, nitrate, ammonium, pH, suspended solids, temperature, air flow rates, air pressures and water levels in aeration basins to provide enhanced and reliable control of a process.  Direct measurement of these parameters can drastically reduce energy costs associated with operating aeration basins.

The combination of sensors and transmitters ensures that the proper amount of air is blown through the system at the correct basin level, and that the process is removing nutrients from the water efficiently and reliably.

This family of aeration control sensors easily connects to any plant’s PLC or SCADA system via 4-20mA with HART, Profibus or other digital interfaces. This allows any wastewater treatment plant to add aeration basin control measurements quickly and easily. Digital communications and advanced diagnostics in E+H instruments simplify maintenance and commissioning and provide state-of-the-art condition monitoring.

Primary savings come from controlling air flow. Aeration blowers can account for up to 70% of the energy usage of a wastewater treatment plant. In a typical process, microorganisms consume organic carbon as a nutrient—creating carbon dioxide, water and biomass—while dissolved oxygen is used to convert ammonium to nitrate which is later broken down into its components.  Oxygen is forced into the aeration basin with large blowers (see Figure). Using blowers at full capacity when ammonia levels are low can be expensive and unnecessary.

They offer a simple and cost-effective solution for measuring ammonium and nitrates present in the aeration basin: Liquiline CM442 transmitters and CAS40D sensors, both with the digital Memosens protocol, monitor the ammonium and nitrates of the incoming and/or treated water with a single sensor array that can provide additional parameters such as pH, temperature, chloride and potassium.

Endress+Hauser Oxymax optical or amperometric dissolved oxygen sensors with the digital Memosens protocol monitor dissolved oxygen to make sure minimum levels are maintained. With the CM442’s dual channel digital technology, one transmitter can measure ammonium, nitrates, dissolved oxygen, temperature and pH.

To ensure that the air delivery system is functioning properly, a T-Mass 65I thermal mass insertion flowmeter can be placed in the blower air line.

Because blowers must overcome the hydrostatic pressure of the basin to force air into the process, an Endress+Hauser Cerabar S pressure transmitter is available to measure air line pressure. A Prosonic FMU90 ultrasonic or a Waterpilot FMX21 hydrostatic instrument can be used to measure and control level.

Using aeration basins is an excellent way to remove nutrients, but the energy costs can be high. The Endress+Hauser Aeration Control measurement package helps provide better efficiency of  the process, helps a plant meet permit levels efficiently and reliably, and saves energy.

“We offer a complete instrumentation package for easy integration into virtually any aeration basin control system thanks to our advanced analytical, flow, pressure, level and temperature instrumentation with digital communication protocols,” says Nick Camin, product manager in the Endress+Hauser Environmental Group. “From on-line ammonium and nitrate measurement to blower air flowrates, Endress+Hauser is the single-source supplier for aeration control measurements.”

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