Decomposition and Removal of Musty Odor Producing Phormidium tenue by Bacteria and Smaller Animals

A bio-film process such as an aerobic submerged filter process has an effect on the removal of algae and the purification of polluted lake water. In this process, it is thought that smaller animals will play an important role by the way filamentous algae belonging to Phormidium sp., Anabaena sp, and Oscillatoria sp. appear in polluted lake water. Particularly Phormidiumtenue in these filamentous algae produce musty odor which is caused by 2-methylisoborneol 2M1B). Therefore, deodorization has to be conducted in a water treatment plant especially. This study was conducted for the purpose of clarifying the feeding and decompositional capacity of P.tenue by Protozoa Trithigmosotomacucullulus having a mouth structure fitted to the predation of the filamentous algae. The results obtained from this study are as follows. 1) Sludge extract was extremely effective as the growth factor in the growth of T.cucullulus. 2) The optimum growth temperature of T.cucullulus was about 20~25°C and it was necessary to keep an aerobic condition in existence and growth. 3) Filamentous P.tenue among some algae was the suitable food for T.cucullulus. 4) The predation speed of T.cucullulus in the case using filamentous algae as food was about 10~30µ m/sec. 5) The content of chlorophyll a was extremely low in its reduction rate in the system without T.cucullulus, but markedly reduced in the system with T.cucullulus. 6) The turbidity, TOC and DOC in culture medium were markedly reduced in the system with T.cucullulus as compared without T.cucullulus. 7) Investigating the effect of bacteria and T.cucullulus on the removal of the musty odor produced by P.tenue, the removal activity of the musty odor was markedly enhanced by the predation of P.tenue by T.cucullulus compared with bacteria only. 8) T.cucullulus had high capacity for reducing TON through the predation and decomposition of musty odor producing filamentous algae represented by P.tenue. Furthermore the reduction of 2MIB by T.cucullulus was made clear by the method of gas chromatography.