Wednesday, January 5, 2011

CONTINUOUS MONITORING OF NITROGEN COMPOUNDS IN WASTEWATER WITH WIRELESS DATA TRANSMISSION

PRESENTED AT PITTCON 2008 in New Orleans, LA

John N. Driscoll, Walter Johnson, Pol Perov, Patricia Hogan, Nicholas Hennigan, Brian Muccioli, John Hamm, George Heufelder, and Keith Mroczka

Denitrification of wastewater on Cape Cod is an important process because of the nitrogen problems in this area. As a result, there are a number of denitrification systems in use and are being tested at Otis Air Force Base on Cape Cod.
The continuous measurement of nitrogen compounds in wastewater is important in determining the long-term effectiveness of control techniques. It is difficult to judge the long-term performance of any system with only grab samples (weekly/biweekly). The continuous systems will send a signal wirelessly to a PC in a nearby trailer that is connected to the internet. The data will be available to Suffolk University, the Town of Barnstable, and the vendor of the wastewater system. The advantage of the wireless system is that built-in diagnostics (calibration, pump, etc.) will improve the uptime as well as the quality and quantity of the data. We will be adding MODBUS (bidirectional RS232) communications to the analyzer to further enhance the diagnostics. If MODBUS was added to the control system, remote tuning of the control system would be possible.
The analyzer will be a PID Model 610 that uses ion-selective electrodes for ammonia, nitrite, and nitrate. Each of the sensors will have a separate pump for the addition of ionic strength adjustment buffers prior to the measurement. A single meter will be used to display the results and convert the output to a linear voltage proportional to concentration. Samples of wastewater (24-hour integrated) will be collected daily and run by standard methods at the Barnstable County water labs. We will compare the 24-hour integrated sample results with the results from the continuous analyzers, and determine the effectiveness of these electrochemical techniques for continuous monitoring of wastewater.

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