pH and Mg/Ca control for biological treatment of an offensive flavour (2-MIB)

From a series of experimental observations, it was found that removal rates of the offensive flavor 2-methyl-isoborneol(2-MIB) and ammonia by a biological treatment for water supply were rather unstable and that the removal rates of them often became reverse such as low removal in 2-MIB and high removal of ammonia. One reason for the reverse phenomenon was found that the affinities of sludge around bacteria with 2-MIB and ammonia often became reversed. The affinities of sludge with 2-MIB and ammonia were found to be changeable depending upon pH along with magnesium (Mg) and calcium (Ca) concentrations in sludge. From these findings, control of pH and magnesium calcium ratio (Mg/Ca) of raw water was recommended for simultaneous and stable removal of 2-MIB and ammonia. From plant scale experiments equipped with automatic pH controller, the effects of pH and Mg/Ca control for biological treatment of 2-MIB and ammonia were observed in a biological activated filtration. Here, a biological activated carbon filtration means a longer filtration than 40 to 50 days from the beginning. The obtained results were almost as expected, showing high removal rates of both 2-MIB and ammonia.