A comprehensive air quality investigation at an aquatic centre: Indoor/outdoor comparisons

Air quality and comfort parameters in a naturally ventilated aquatic centre were studied in relation to the outdoor pollution levels. Simultaneous measurements of PM 2.5, as well as of volatile organic compounds, were carried out for the indoor and outdoor environment of the aquatic centre. The chemical analysis of ionic species and trace elements associated with particulate matter was also performed. In addition, automated analyzer for NO₂ and O₃ was used in order to record the indoor and outdoor levels of these pollutants. Analysis of diurnal variation of the pollutants' concentration was applied to the collected data, allowing the identification of potential variation on the sources affecting the indoor air quality. PM 2.5 concentration was almost two times higher indoors than outdoors with average values of 13.96 and 6.78 μg/m³, respectively. Concerning the ion fraction of PM 2.5, SO₄^2- and Ca²⁺ were the ions with higher concentration indoors with values of 1.06 and 0.93 μg/m³, respectively, while the percentage of Cl^- to the PM 2.5 fraction of the indoor atmosphere (9%) was too high than outdoor ones (1%). These results showed that indoor air of swimming pool concerning PM 2.5 and ionic species is mainly affected by the chlorination process along with the comfort conditions (high relative humidity) created during the operation of the facility. The common volatile organic compound concentrations at indoor air are generally in higher levels, compared to the outdoor air with p,m-xylene and toluene to be the substances with the higher concentration for indoor and outdoor area, respectively (7.80 and 1.57 μg/m³); nevertheless, values were rather low compared with the findings of other studies. Also, they clearly demonstrate a diurnal variation as a result of poor ventilation during night. As it was expected, chloroform showed the highest concentration compared to the other volatile organic compounds with values ranging from 3.35 to 135.89 μg/m³, with an average of 54.50 μg/m³. Concerning the NO₂ concentration, indoor levels showed an increased pattern when the swimming pool was fully occupied, a fact that reveals a possible correlation. As an overall conclusion, the natural ventilation and the disinfection process seem to play a key role to the air quality of the indoor air of the aquatic centre.

Degradation of micropollutants in water matrices using light activated - Persulfate: A review

The escalating challenge of eliminating persistent micropollutants from aquatic environments acted as a driving force for the development of innovative Advanced Oxidation Processes (AOPs). Among various AOPs, Light-Activated Persulfate (LAP) stands out for its efficacy due to its homogeneous nature and the potential for coupling with renewable sources, leading to enhanced sustainability. From this perspective, this review summarizes the research on LAP for the degradation of micropollutants over the previous six years. It examines the effect of operational parameters such as persulfate concentration, light type and intensity, and pH, with particular emphasis on the effect of water matrices consisting of inorganic ions and organic matter and the application in environmentally relevant water matrices. Particular emphasis was given to the investigation of toxicity variation during the treatment. In addition, some elements of a preliminary estimation of the energy and cost needed are included. Finally, this comprehensive review includes some indicative hybrid systems that achieve dual activation of persulfate with enhanced efficiency and provides suggestions for the intensified future research needed for the transition from the lab scale to industrial application.