Microorganisms detected in the biofilm not only cause secondary pollution of drinking water such as taste, odor and pathogenic disease but also increase the amount of disinfectant due to microbial regrowth during the transportation of tap water. In this work, the influence of C/N ratio in tap water on the characteristics of biofilm growth was examined. The C/N ratio of the tap water sample was controlled at 100:5, 100:10, 100:20, 100:30, and 100:40 by adding appropriate amounts of dextrose and (NH4)2SO4. Of the five C/N ratios, heterotrophic plate counts (HPC) was highest at the ratio of 100:10. Following the initial formation in all the five experimental conditions, natural detachment of the biofilm was observed. Extracellular enzyme activity (EEA) analyses showed that the change of the EEA during the experimental period was similar to that of the HPC, demonstrating a positive correlation between HPC and EEA. For TOC concentration in the tap water sample, approximately 75% of the TOC was consumed in 7 days of the experiment and 96% in 28 days. The TOC appeared to be relatively rapidly consumed at the initial phase of the biofilm growth. Consumption pattern of the ammonia nitrogen was different from the TOC consumption pattern showing the different role of ammonia nitrogen on the growth of biofilm.

ABSTRACT
 1. 서 론
 2. 실험 재료 및 방법
  2.1 수돗물 시료
  2.2 실험 및 분석방법
 3. 결과 및 고찰
  3.1 생물막 시료의 분석결과
 4. 결 론
 References

• 조지민(강원대학교 환경공학과) | Ji-Min Cho (Kangwon National University, Department of Environmental Engineering)
• 김영관(강원대학교 환경공학과) | Yeong-Kwan Kim (Kangwon National University, Department of Environmental Engineering) Corresponding author