APPLICATION OF SULFUR AND LIMESTONE AUTOTROPHIC DENITRIFICATION MRTHODS TO JOHKASOU TREATED WATER

Abstract

 More than 80% of johkasous do not have the nitrogen removal capabilities. Sulfur and limestone autotrophic denitrification (SLAD) methods were used as alternative nitrogen removal methods. These methods were applied to johkasous without nitrogen removal function and those with low nitrogen removal efficiencies. Johkasou-treated water was passed through the model device of the waterway type, which was filled with a base material. The average nitrogen removal rate was approximately 80% in summer. However, the average nitrogen removal rate was low from autumn to winter. Removal efficiency could be improved by increasing the retention time (decreasing the flow rate and increasing amount of contact with the base material). PCR-DGGE results showed that the dominant bacterial species in the suspended solids (SS) attached to the base material was of the genus Sulfurimonas. During the experimental period, abundant SS were attached to the base material. Therefore, periodic maintenance of the base material was required.