Exposure dose of reclaimed water for car wash
再生水在洗车利用中的暴露剂量研究

Determination of exposure dose is the premise in pathogen risk assessment of reclaimed water for car wash and an important issue for the establishment of reclaimed water quality standard. The exposure doses of reclaimed water to typical population during manual car wash and mechanical car wash by reciprocating gantry machine were determined in this study. Firstly, the exposure time was measured. The wash time and wiping time of workers during manual car wash were 4.8 min and 8.4 min, respectively. The flushing dust time, mechanical wash time and wiping time during mechanical car wash were 1.5 min, 2.5 min and 8.0 min, respectively. Thereafter, reclaimed water fog concentration at car wash plants was measured by evaluating weight changes of water contents in air. In the manual wash plants, the water fog concentration at washing field was about 2.0 mg·L-1. In the mechanical wash plants, the water fog concentrations at flushing dust field and reciprocating gantry machine field were 1.3 mg·L-1 and 3.2 mg·L-1, respectively. The exposure dose of reclaimed water to workers and car owners were determined based on the exposure time, reclaimed water fog concentration, and respiration rate. The exposure dose of reclaimed water to workers during manual car wash is the highest (15.5 mL·d-1) among different populations.