| Title |
Nutrient removal efficiency in the existing wastewater treatment facilities |
| Authors |
이인선 ; 정동일 ; 신상철 ; 문현생 ; 김원덕 ; 이길철 ( In Seon Lee ; Dong Il Jung ; Sang Chul Shin ; Hyun Seng Mun ; Won Deok Kim ; Kil Chul Lee ) |
| Abstract |
The study was focused on the investigation of the existing secondary treatment facilities to develop a nutrient removal technology that can be applied to the existing activated sludge treatment facilities with minimum modification of the system. 12 sewage and industrial wastewater treatment plants were investigated to examine the status of the facilities, operation, and the characteristics of both influent and effluent. The nitrogen and phosphorus removal efficiencies from primary treatment in the existing facilities were 14∼42% and 27∼52% respectively, depending upon the overflow rate. The nitrification rate in secondary treatment varied from 4 to 67%, depending upon the SRT. The BOD/TN and BOD/TP ratios in the influent of the sewage treatment plants were 1.0∼3.2 and 10.7∼37.8 respectively. The values are mostly lower than those literatrue values from the biological treatment processes. Nitrification rates were in the range of 4 to 80%. It varied with the STR and little nitrification occurred at the SRT of lower than 3.5 days. The relationship between nitrification rate(Y) and SRT(X) was linearly expressed as Y=6.955 X-24.078(r=0.929). Nitrification was also affected by the F/M ratio. A F/M ratio less than 0.23 was required to have nitrification, and it should to be maintained below 0.08 for an efficiency of more than 40%. The nitrogen and phosphorus removal efficiencies in the aeration tank were 10.5∼21.1 % and 8.0∼33.0% respectively. The values were similar to the theoretical removal efficiencies in a conventional activated sludge process. The TN and TP contents of MLSS were 2.3∼6.6% and 0.9∼1.9% respectively. The removal efficiency(Y) increased with the increase of TP content of sludge(X), and the relationship between the two was Y=21.901X-14.100(r=0.883). |