Abstract
Hydrogen sulphide ( H 2 S) emissions from wastewater surfaces are commonly measured using dynamic flux chambers, although chamber construction and operating conditions may influence the results. This study compared two dynamic flux chambers, DFC1 and DFC2, both built according to USEPA geometric specifications, to evaluate how chamber type and internal fan configuration affect the overall mass transfer coefficient ( K L ) of H 2 S. The chambers differed mainly in construction material, with DFC1 made of acrylic and DFC2 of fiberglass, and were tested under five operating conditions: no fan, small fan up, small fan down, large fan up, and large fan down.
Experiments were carried out using standard aqueous H 2 S solutions with an initial concentration of 5 mg/L, and K L was obtained from the liquid-phase concentration decay. Mean K L values ranged from 1.30 to 5.11 cm/h for DFC1 and from 1.64 to 3.64 cm/h for DFC2, with the highest values observed under forced ventilation. A two-way ANOVA with replication showed that chamber type, fan configuration, and their interaction significantly affected K L (F=15.87, p=0.000731; F=40.26, p<0.001; and F=6.63, p=0.00145, respectively).
The highest mass transfer coefficient was obtained for DFC1 under the large fan up condition, whereas the lowest values were observed under no fan operation. These results show that even chambers designed under the same regulatory concept may produce different H 2 S transfer measurements, highlighting the importance of clearly reporting chamber characteristics and internal ventilation conditions when comparing data across studies.
