transduction element [2]. Since the first published report of a
biosensor [3], several kinds of biosensors have been developed.
Most BOD biosensors are based on synthetic or natural polymeric
gel membrane containing immobilized living microorganisms as
a biological recognition element and a dissolved oxygen sensor
as an electrochemical transduction element. Microbial BOD sensors
rely on measurement of respiratory activity of microorganisms
as a result of diffusion and oxidation of organic substances in the
membrane containing immobilized microorganisms [4–6]. Various
modifications in biosensor design include a biosensor that enabled
easy renewal of biological recognition element [7], the use of carbon
dioxide analyzer [8] and dissolved oxygen optical fiber [9]. In
recent years, several spectrophotometric and chemiluminescence
BOD measuring methods have been reported [10,11].
The correlation between standard BOD results and sensor-BOD
is often low if universal BOD sensors are used to analyze wastewaters
containing refractory compounds [12,13]. Natural waters and
industrial wastewaters contain several specific refractory compounds
which microorganisms are not able to use and degrade
within short measuring time of biosensor. Traditional BOD analysis
include incubation period of 5 or 7 days. During this time
microbes have enough time to induce appropriate enzymes for the