Real Time BOD Monitoring for Wastewater Process Control

Abstract

This is a preliminary investigation of a method for the timely monitoring of wastewater biochemical oxygen demand (BOD). Many ecological and economic pressures support the use of BOD measurement methods fast enough to prevent process upsets. Since the standard laboratory procedure takes five days, and previously used fast tests are unsatisfactory for various reasons, tests were made on the Nissin Electric BOD-2000 instrument, which uses a yeast-based biosensor to measure soluble BOD in 30 min. It has been used successfully in the pharmaceutical and food industries. An initial attempt was made to place the instrument in field service. This attempt was unsuccessful, so the present study concentrated on comparing its operation in the laboratory with the results of the standard five-day BOD test (BOD\d5) procedure. The two types of tests were compared for samples from Terminal Island Treatment Plant (TITP), Bureau of Sanitation of the city of Los Angeles, using various combinations of filter porosities and wastewater sources in an attempt to establish a measurement routine that would not suffer from clogging problems that plagued the field test. Under these conditions the results from the instrument are excellent, and we briefly discuss further work needed to bring it into field use. This test is believed to be the first effort to assess the capability of this technology in a wastewater application in the United States.