Environmental quality improvement on indoor swimming pools by application of chlorine dioxide

The main objective of this research is the environmental quality improvement of indoor swimming pools by using chlorine dioxide as a new type of disinfectant. The procedure is divided into three steps: (1) obtaining water and air samples from a local modern indoor swimming, pool, (2) performing chemical and microbiological analyses after proper preparation and culturing of samples and, (3) evaluating the efficiency of application of chlorine dioxide as a disinfectant when needed. The results indicate that if there is no proper amount of free chlorine remaining in the swimming pool, the water quality cannot meet the microorganism regulation requirements. For the air quality, the low bioaerosol count indicates that it is unnecessary to do any further disinfection because the ventilation is satisfactory for the general areas inside the indoor building except for the steam room. In the steam room, the air is enclosed in a high temperature, high humidity condition. The measured data of bioaerosols count Is at 19296 CFU/m(3)L, which is too high. Besides the natural sources of bloaerosols from various pools in the steam room, people entering the steam room act as additional sources. The tested data indicate that the steam room can be effectively disinfected (96.5%) by spraying 107 mL of chlorine dioxide solution (250 mg/L) into the space of 90 m with the average number of persons around 20 in the room. The data analysis also yields the disinfection time constant to be on the order of 10 minutes, which implies chlorine dioxide is a relatively fast acting disinfectant. Thus, it can be concluded that chlorine dioxide can be applied very effectively to improve the quality of indoor swimming, pools to comply with environmental regulations. The results from this research should be referenced by the indoor swimming pool management teams for indoor swimming pool quality improvement.