| Title |
Performance of Two High - Rate Algal Ponds ( HRAP ) without Paddle - Wheel Mixina and with Night Aeration |
| Authors |
김영철(Young Chul Kim), 김완중(Wan Joong Kim) |
| Abstract |
This paper presents a comparative study of two experimental systems, high-rate algal ponds(HRAP) treating sewage; i.e., one without paddle-wheel mixing (nm-HRAP) to eliminate the use of mechanical elements, the other with a night aeration system(na-HRAP) for preventing HRAP from undergoing possible lower dissolved oxygen or completely anaerobic state in the absence of photosynthetic activities during the night. Although the nm-HRAP did not provide normal levels of pH and dissolved oxygen characterized by HR,AP with paddle-wheel mixers, they did not drop to low levels at night to affect its performance. The nm-HRAP system was poor for reducing COD but gave similar nutrients removal efficiencies as obtained from slowly mixed-HRAP. Aerating HRAP at night was not helpful at all in keeping the pH and DO from decreasing but rather, it resulted in lower reductions of COD and nutrients. It could be concluded that the nm-HRAP was reliable and efficient as the normal mixed-HRAP and could be easily built and operated without much of the excavation and maintenance works. |