30 2009 ENVIRONMENTAL SCIENCE Vol. 30,No. Jan.,2009, 3,, (,, 00084) :.. ( 0003 00 ),.,,.., - 023 0 s -, 006 73.., 45 7 m 3 d -, 03 32 m 3 h -.. : ;;; ; :X72 :A :02502330 (2009) 020070205 Assessment Method of the Pathogenic Microbial Exposure Caused by Aerosolization of Reclaimed Water XIE Xing, HU Hong2ying, GUO Mei2ting, WU Qian2yuan (Division of Environmental Biology, Department of Environmental Science and Engineering, Tsinghua University, Beijing 00084, China) Abstract: Inhalation is one of the main exposure routes to pathogenic microorganisms during wastewater reuse. An applicable method is introduced to assess the pathogenic microbial exposure from inhalation. Firstly, emission intensity of pathogenic microorganisms during reclaimed water spraying is determined by the concentration of pathogenic microorganisms in reclaimed water, spraying intensity and aerosolizing efficiency factor. The value of the aerosolizing efficiency factor is usually between 0003 and 00. Then the concentration of pathogenic microorganisms in air is calculated by referring to the model of air pollutant dispersion and considering the microorganisms decay. The value of the microbial viability decay factor is between - 023 s - and 0 s -, and that of the environmental impact factor is between 006 and 73, varied by different kinds of microorganisms. And then the exposure from inhalation route can be finally attained by multiplying inhalation rate and exposure time. The daily average inhalation rate is 4527 m 3 d -, and the hourly average inhalation rate is 03232 m 3 h -, differentiated by age, gender, and activity of susceptible population. The method proposed in this study can be directly used to assess the pathogenic microbial exposure caused by reclaimed water used for agriculture irrigation, gardening, or fountain spraying. Key words :wastewater reuse ; inhalation route ; exposure assessment ; microbial aerosol ; risk assessment.,, 00 [ ].,, [2 8 ].,, [9 ], [0 ].., 2 [ ].,,.,,.,.,, [2 4 ]., [4 ]., 200 m [5 ]. :20082022 ;:2008204225 :(5082580) :(984 ),,,,E2mail :xiex02 @mails. tsinghua. edu. cn 3,E2mail :hyhu @tsinghua. edu. cn
: 7. Asano [6 ]. [7 9 ]. Asano,. [20 ],,,.,,.,,,.,,.,,.,..,,., [2 ],. ( ), ;,..,,,, [3].,., [22 ]. c air = Q D R + B (), c air (mass m - 3 ) ; Q (mass s - ) ; D (s m - 3 ) ; R ( ) ; B (mass m - 3 ),.,..,,,. (2) [22 ]. Q = c water q A (2), c water (mass m - 3 ) ; q (m 3 s - ) ; A ( )., c water. q,,. A 0003 00,(3) [22 ]. log 0 A = 003 t + 0000 096 u i - 30 (3), t ( ) ; u (m s - ),,, ; i (W m - 2 ). 2.,(4) [23 ]. D = e - 2 u y z 2 y 2 y e - 2 z- H 2 z + e - 2 z+ H 2 z (4), x (m) ; y (m) ; z (m) ; u (m s - ) ; y (m) ; z (m) ; H (m). x y z H, y z [24 ].
72 30 3 R (5) [22 ]. R = I e t (5), I ( ) ; (s - ) ; t (s), x u. I,, I,. I.,. 2 [22 ]. I. R,, 2.,,25 % 75 %.,,75 %, 25 %. I >, [ ].,, R. c air. () (5) I [ 22] Table Estimation values of environmental impact factor I I ) Π% 0 25 40 50 60 75 90 3 0068 03 058 44 006 0060 03 06 023 055 33 0036 0 09 02 024 035 2 43 007 0094 08 034 052 09 8 8 077 089 2 024 2 65 3 027 07 097 7 27 6 32 3 7 4 73 ) n % n %, 2 [ 22] Table 2 Estimation values of microbial viability decay factor Π% 0 25 40 50 60 75 90 3-09 - 0070-0023 0 44-023 - 0094-0050 - 0032-0020 - 0004 0 33-02 - 0020-0006 - 0004 0 0 43-0 - 005-0029 - 00 0 0 0 8-05 - 0009 0 0-00 - 0039-0004 0 0 3-006 - 0006 0 0 0 0 0 3-008 - 0008 0 0 2, (6) [25 ]. N = c air v t (6), N (mass) ; c air (mass m - 3 ) ; v (m 3 d - m 3 h - ) ; t (d h). v, 2.,
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