A novel microbial sensor for sulfate detection has been developed. Thi
obacillus ferrooxidans was immobilized on an oxygen electrode and the
relationship between the current decrease at the microbial electrode a
nd the sulfate concentration was examined. The system consisted of a m
icrobe electrode, a potentiometer and a recorder, which is simple and
one tenth the cost of standard ion chromatography equipment. The respo
nse time, the optimal amount of microbe immobilized on the electrode,
and the optimal temperature and pH were also examined. The lifetime of
the sensor and the effect of possible coexisting ions in rain water i
s reported and the application of the system is discussed.