Impact of artificial waterfall using reclaimed water to VOCs and its health risk assessment

To study the impact of an artificial waterfall using reclaimed water on volatile organic compounds(VOCs) in air, air samples around the waterfall sight and over the CASS pond of a wastewater treatment plant were collected and VOCs were analyzed by MC-MS with USEPA Method TO-14. The total volatile organic com-pounds (TOVCs) concentration of a background sample is 2112μg/m3, and the sample over the CASS pond has a TVOC concentration of 1858μg/m3. The TVOC concentrations of air samples within 10 m of the artificial waterfall are between 3216μg/m3 and 6362μg/m3, which are 1.52-3.0 times that of the background sample. The VOCs in air sample impacted by reclaimed water or waste water exhibit a relatively high proportion of toluene but low proportion of benzene. B/T/E/X (Benzene/Toluene/Ethylbenzene/Xylene) ratio of the air sample around the artificial water fall is(0.36/11.78/1/1.10). Health risk assessment (HRA) was done with the USEPA four-step approach. The result indicates that the artificial waterfall using reclaimed water indeed leads to the increase of human risk value. The total risk value of the sample around the waterfall is 2.8-1.6times that of the background sample. However, the total risk value of the air sample around the waterfall (2.8×10-6) for common people is still lower, compared to the acceptable public risk level( 10-5). For occupation-al workers of the wastewater treatment plant, the sum of lifetime non-carcinogenic and carcinogenic risk values(1.26×10-5) is higher than that of the acceptable public risk level.