Microbial Removal Efficiency of UV in Tehran Shahid Mahallati Wastewater Treatment Plant

Transcription

1 (// // )... /.. / NTU. / /... MPN/100mL MPN/100mL. : Microbial Removal Efficiency of UV in Tehran Shahid Mahallati Wastewater Treatment Plant Reza Dabbagh 1 (Received Feb. 22, 2008 Accepted Feb. 17, 2009) Abstract Shahid Mahallati Wastewater Treatment Plant was selected for installing a UV disinfection unit to investigate its germicidal effect on microbial removal. Low pressure mercury lamps were used to generate germicidal ultraviolet radiation (UV-C). The UV system was operated over a period of 6 months that included both warm and cold seasons. A maximum UV disinfection efficiency of 14.4m 3 /h was recorded for the system on the basis of design criteria within turbidity ranges of 9 to 32 NTU. The minimum UV dose applied in the UV unit was µw.s/cm 2 and the highest bacterial density in the UV unit influent was 5.6*10 7. Effluent total coliform or fecal coliform enumeration after exposure to UV ray showed the microbial density decreasing from four logs, or 99.99%, to as high as six logs, or % removal efficiency, under different conditions. Effluent microbial densities in terms of total and fecal coliforms were below 1000MPN/100mL and 400MPN/100mL, respectively. These values comply with wastewater discharge or agricultural irrigation standards according to Iran Department of Environment. From our results, it is concluded that UV disinfection may be an effective technique for wastewater disinfection in Iranian wastewater treatment plants. Keywords: Ultraviolet, Disinfection, Coliform, Wastewater Treatment Plant, Shahid Mahallati. 1. Assistant Professor, Nuclear Science and Technology Research Institute (NSTRI), (+98 21) , rdabbagh@aeoi.org.ir () - rdabbagh@aeoi.org.ir 59

2 ...[]. UV-C UV-B UV-A UV-C.( ) UV. UV.... DNA.[ ]. - UV 6 Thymine Base 7 Dimerization -.[ ]...[]...[] E.Coli.[ ].[ ].[-].[ ].[ ] 1 Downs 2 Blunt 3 Barnard 4 Morgan 5 Bang 60

3 ...[ ]. /* UV NTU. UV *.[]...[ ] /.[] / NTU. UV MPN.[] 5 Water Quality Factor (Wf) 6 / 7 40mJ/cm 2 8 Fecal Coliform.. -. /. UV-C.. ()..[]. *. **. 1 Starter 2 Transe 3 Anodized 4 O-Ring 61

4 - ( TSS ) 4L/s(14.4 m 3 /h, 350m 3 /d,64 GPM) 2.8L/s(10 m 3 /h, 240m 3 /d,45 GPM) 1.5L/s(5.4 m 3 /h, 130m 3 /d,24 GPM) µw.s/cm 2 ( nm) PHILIPS TUV 30W/G 30 T8-Germicidal Hz - - / / ) ( ( NTU ) ( NTU ) ( NTU ) UV-C ( ) UV ( ).. - : -... UV. -.. NTU.... D = I t () I D t.. 2 Stand by 1 Microorganism 62

5 . /..( ).[ ] UV /.[ ]. /. NTU.. /* /* /. NTU.. /* 1 Trojan Co. 2 Giardia 3 Cryptosporidium 1.0E E E MPN/100 ml MPN/100mL MPN/100mL MPN/100 ml 1.0E E E E E E E E+00 ( C) 22 NTU 9 L/s 3 20 NTU 16 L/s 2 ( C) 16 NTU 17 L/s 1/7 ( C) - 11 NTU 32 L/s 2 ( C) 10 NTU 27 L/s 3 ( C) 10 NTU 27 L/s 1/7 ( C) 63

6 1.0E E E MPN/100 ml MPN/100mL MPN/100mL MPN/100 ml 1.0E E E E E E E E E E+09 MPN/100mL MPN/100mL 400 MPN/100 ml 1.0E+08 MPN/100 ml 1.0E E E E E E E E

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