The biochemical oxygen demand (BOD) is one of the most widely used and important tests in the measurement of organic pollution. The conventional BOD test requires a 5 day incubation period and values of the test results depend upon the skill of the operator. Therefore, rapid and reproducable methods are desirable for the BOD test. The sensor utilizes a yeast called Trichopsporon cutaneum for waste water treatment. The micro-organisms were immobilized on a porous acetylcellulose membrane and sandwiched between an oxygen permeable teflon membrane and a porous membrane. Then, the membrane was directly fixed on the surface of the platinum cathode of an oxygen probe. A continuos flow system using a new microbial sensor was developed for automatic estimation of 5 day BOD tests.
Furthermore, the BOD of various types of untreated industrial waste water can be estimated by the sensor. The BOD values estimated by the sensor depend upon compounds in the waste water.