| Title |
Performance Evaluation and Retrofit of Rapid Sand Filter in Water Treatment Plant |
| Authors |
임경호(Kyeong Ho Lim),박영오(Young Oh Park),배병욱(Byung Uk Bae) |
| Abstract |
Rapid sand filters in water treatment plants (WTP) is one of the most important step in order to remove fine particle including pathogens such as Criptosporidium and Giardia. Filters should be assessed based on their capability to achieve a treated water quality of less than 0.1 NTU on a continuous basis to ensure the integrity of the filtration process as a viable barrier in the treatment scheme. This is less than the 1.0 NTU standard, but operation of filters to produce filtered water quality confidence that pathogens are being removed prior to the last barrier, disinfection. In this study, to optimize existing filtration unit process, rapid sand filters working in S-WTP were evaluated for various factors. The results of comprehensive performance evaluation were followings. From the filter media analysis, effective size and uniformity coefficient of media was 0.90∼1.0 ㎜ and 1.44∼1.47, respectively. Therefore, the replacement of media is needed to optimize filter performance. Media loss was caused by air binding in the filter bed and improper operation of backwashing process. The ratio of the water used for filter washing to the amount of filtered water was 2.5∼3.0% during the winter and 1∼2% in the summer. At the beginning of a filter run, filtered water turbidity was over 0.5 NTU during about 20 min. Shorter filter run lengths was attributed to an overabundance of filter clogging algae (Synedra. sp), air binding, and too much floc in the filter influent. |