Removal of Iron Oxide from Indoor Air at a Subway Station Using a Vegetation Biofilter: A Case Study of Seoul, Korea

Abstract

Recently, metallic particulate pollutants floating underground have been reported to negatively affect the human body. Thus, there is an urgent need for a public health policy pertaining to the air quality in subway stations. In this study, we investigated whether a vegetation biofilter is effective in reducing metal particle contaminants, especially iron oxide. After selecting a subway station, a vegetation biofilter system was installed, and samples were collected three times, at three intake areas and one exhaust area. The average weight ratio of the detected elements was calculated. The iron oxide reduction effect was evaluated using the Wilcoxon signed rank test. In the return air, C, O, and Fe were detected at 64.9, 27.3, and 5.2 wt.%, respectively; in the supply air, C, O, and Fe were detected at 67.2, 30.4, and 0.7 wt.%, respectively. The difference in the average Fe weight ratio was statistically significant. Air quality has a considerable effect on human health. We confirmed the possibility of reducing Fe in particulate matter using biofilters. However, we could not confirm whether the air quality was improved enough to not have a negative effect on the human body. This should be elucidated through follow-up studies.

Purification Effect of Vegetation Biofilters on Particulate Transition Metals in Multi-Use Facilities

“…Among those, the average weight ratio (AWR) of Fe detected from R.A. and S.A. samples was estimated to be 3.28wt% (SD = 0.84) and 0.25wt% (SD = 0.13), respectively. This seems to be in line with the findings of the previous study that the AWR of Fe detected from S.A. samples converged to a minimum of 0 wt% through an SEM-EDS-based chemical species analysis (Kim et al, 2021;Fig. 5).…”

“…In this study, our experiment was conducted with multi-modular vegetation biofilters that improved on the limited air-conditioning airflow volume of the existing single-modular vegetation biofilters (Choi and Kim, 2021), and the biofilter system was installed at the same place as in the preceding study .…”

“…For the AC module, the AC fan was operated every 6 hours, and the experimental conditions of the previous study were applied to the filtering wind speed of R.A. panels; the module was set to maintain a wind speed level of 0.126 m/s, at which plants are not stressed by wind speed, and to secure a total AC capacity of 177.18 m/h . For the ALS module, LED lights were turned on from 6:00 to 22:00 by applying the photo-environment conditions of the previous study to create a photo-environment with an average PPFD of 28.5μmol/㎡s in the middle of each panel (Kim et al, 2021). The irrigation module was set to supply water at a rate of 1.5 L/min per panel by driving the pump at all times.…”

Investigation of the Effects of Ventilation Performance on Energy Consumption in Subway Stations and Tunnels

“…Havalandırma sistemlerinin enerji ihtiyacı ile metro istasyonlarındaki iç hava kalitesinin beraber değerlendirilmesi gerekir. Bugüne kadar yapılan çalışmalara bakıldığında bitki biyofiltresinin havadaki demir oksiti azalttığı [68], manyetik hibrit filtre kullanımının PM10 konsantrasyonlarında azalmaya neden olduğu [69] kanıtlanmıştır. Bunların yanı sıra hava giriş menfezlerinin yakınında bir kirletici tespit edilmesi durumunda kirleticilerin girmesini önlemek amacıyla bir izolasyon cihazı kurulması [70] ve PM2.5 konsantrasyonlarının aynı filtrenin 90 günden fazla kullanılmasından etkilenmediğinden dolayı bu durumun maliyet tasarrufu sağlayabileceği [71] araştırmacılar tarafından sunulan önerilerden bazılarıdır.…”