| Analysis and Assessment of Removal Efficiency for T-P in Sewage Treatment |
| 하수처리장에서의 총인 분석 및 처리효율 평가 |
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김종민1, 나종범2, 안병용3, 김승호3, 김동수3, 김연희3, 최영섭1, 윤상훈3, 배석진3, 조영관3, 김은선3, 송명석2 |
1광주광역시보건환경연구원
2광주광역시 환경공단
3광주광역시 보건환경연구원 |
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| Abstract |
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This study was conducted to assess removal efficiency and develop improvement plans for a T-P treatmentplant in the 1st sewage treatment plant in Gwangju. The findings of this study are as follows: among all processes,the T-P removal process achieved the highest efficiency (84%), whereas the T-N removal processshowed the lowest (1.2%). About 77% of the 84% T-P removal efficiency was credited to the sedimentationbasin, indicating that coagulant injection is essential. Comparing coagulants using jar tests found that the optimalPAC input was 20~25 ppm and its T-P removal efficiency was 94~95%, whereas the optimal LAS inputwas 25~30 ppm with T-P removal efficiencies of 84~89%. This shows that PAC can achieve a better removalefficiency than LAS. Although the jar tests suggested the best PAC input of 20~25 ppm, the actual input atthe plant was 28~36 ppm, about 8~11 ppm higher. This may be attributable to the significantly shortened retentiontime in the sedimentation basin due to the high-rate coagulation of an inclination plate settler using microsand.
The degrees of coagulation by rapid mixing were measured, and zeta potentials were found moderateranging between -8.44~-8.40 mV. This indicates that a pump injection method should be adopted for the bestcoagulation (zeta potential: 0~+3 mV). Replacing the four existing rapid-mixing coagulant injectors (powerconsumption: 85.6 kW/h) with one device using pump injection (power consumption: 1.5 kW/h) may not onlyimprove T-P removal efficiency but also reduce the annual electricity cost by 60 million won. |
| Key Words:
T-P removal efficiency, Zeta potential, Pump injection method |
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