중·소하천에서 부착미생물군집의 성장에 따른 불소 제거 효과 평가

Evaluation of Fluoride Removal Effect with Growth of Attached Microbial Community in Middle and Small Stream

Abstract

본 연구는 경기도 중소하천에서 하상의 부착미생물군집의 시간에 따른 생장 변화와 부착미생물군집의 성장에 따른 불소의 제거 효율을 파악하기 위해 수행하였다. 방류수가 유입되는 지점인 P1과 그 곳에서 약 2 km 유하한 하류 지점인 P2에서 12주 동안의 현장 모니터링을 실시하고, 조사 지점의 수질과 부착미생물군집의 생체량 분석을 진행하였다. 부착미생물군집의 성장량은 7차 조사 시점까지 증가하다 이후 탈리현상이 발생하는 것으로 관찰되었으며, 부착미생물군집의 성장에 영향을 미치는 요인으로는 유량, 유속, 영양물질(질소, 인) 등으로 조사되었다. 한편, 부착미생물군집 체내의 불소 함유량 또한 7차 조사 시기까지 증가하다 8차 시점부터 감소하는 경향을 보였다. 이는 부착미생물군집의 탈리현상에 의해 불소의 함유량 또한 감소하였음을 사사한다. 이를 통해 하천 관리의 방안으로서 부착미생물군집의 활용법에 대한 평가 및 관리에 기여할 수 있을 것으로 기대된다. 부착미생물군집을 활용한 기법의 적용 시에는 부착미생물군집의 성장에 영향을 미칠 수 있는 요인에 대한 기초 조사 및 탈리 시점에 따른 부착판 교체 방안 등이 포함되어야할 것으로 사료된다.

This study was conducted to understand the growth of attached microbial community in small and medium streams of Gyeonggi-do and the removal efficiency of fluoride with changes in growth. The sites monitoring were carried out for 12 weeks at the P1 and P2(P1 is the point where the discharge water flows. P2 is the downstream point of about 2 km flow), and investigated the water quality and the biomass analysis of the attached microbial community. The growth of the attached microbial community increased up to the 7th investigation, and it was observed that detachment phenomenon occurred. Influencing factors about growth of the attached microbial community were flow rate, velocity, and organic material(T-N & T-P). Meanwhile, fluoride content of attached microbial community also tended to increase until the 7th investigation, and decrease from the 8th. It is assumed that fluoride content has also be reduced with the detachment phenomenon of the attached microbial community. It is expected that this will contribute to the evaluation and management of the use of attached microbial community as a means of stream management. The application of techniques using the attached microbial community should include basic investigation of factors that may affect the growth of the attached microbial community and replacement of the attachment plate according to the time of removal.

Figure 1. Hydrological characteristics of the investigation target (a : flow rate, b : velocity).

Figure 2. Temporal changes of water quality parameters (a : BOD, b : TOC, c : T-N, d : T-P, e : F-).

Figure 3. Temporal changes of ash-free dry weight(AFDW, a) and chlorophyll a(Chl-a, b) biomass for attached microbial community at the P1. In each graph, CB is concrete brick, RB is clay brick, BB is basalt brick and RCB is red clay brick.

Figure 4. Temporal changes of ash-free dry weight(AFDW, a) and chlorophyll a(Chl-a, b) biomass for attached microbial community at the P2. In each graph, CB is concrete brick, RB is clay brick, BB is basalt brick and RCB is red clay brick.

Figure 5. Temporal changes of fluoride uptake by the attached microbial community at the P1 and P2. In each graph, CB is concrete brick, RB is clay brick, BB is basalt brick and RCB is red clay brick.

Table 1. Four types of artificial bricks for growth of attached microorganisms.

Table 2. Analysis equipment and methods for the experiment.

Table 3. Basic properties of the target stream.

Table 4. Pearson correlation coefficients between velocity, flow rate, BOD, TOC, T-N, T-P, ash-free dry weight(AFDW) and chlorophyll a(Chl-a) at the P1.

Table 5. Pearson correlation coefficients between velocity, flow rate, BOD, TOC, T-N, T-P, ash-free dry weight(AFDW) and chlorophyll a(Chl-a) at the P2.

Table 6. Pearson correlation coefficients between ash-free dry weight(AFDW), chlorophyll a(Chl-a) and fluoride in the body of the attached microbial community. The analysis was conducted with whole data obtained from the P1 and P2.