Comparative analysis of existing disinfection models

Transcription

1 Comparaive aalysis of exisig disifecio models T. ANDRIANARISON, H. JUPSIN, A OUALI* ad J-L. VASEL Uié Assaiisseme e Eviroeme Uiversié de Liège Campus d Arlo *CERTE, BP 273 Solima, 8020 Tuisia

2 Iroducio Oe of he major advaages of WSP: Efficie baceria removal (Removal efficiecies: 1 o 4 log uis) Mai disifecio mechaisms : Suligh radiaio, sedimeaio ad predaio The mos impora cause of disifecio: Suligh exposure

3 Iroducio Disifecio mechaism by suligh exposure (Davies-Colley e al., 1999) Mechaism 1: UVB radiaio damage o cellular DNA Disifecio mechaism idepede of DO ad ph Mechaism 2 (Davies-Colley e al., 1999): Phoo-oxidaio by reacive oxyge species Caalys: Edogeous phoo-sesiisers absorbig solar UVB Damage o ieral srucures of micro-orgaisms Disifecio mechaism idepede of ph

4 Iroducio Mechaism 3 (Curis e al., 1992 ; Davies-Colley e al., 1999 ) : Phoo-oxidaio by reacive oxyge species Caalys: Exogeous phoo-sesiisers absorbig a wide rage of λ i suligh Damage o exeral srucures of micro-orgaisms Elevaed ph acig i syergy wih DO o disifecio mechaism Disifecio models : dn d = ()N (Chic's Law) wih geeral empirical or semi-empirical formulae of : = d + s I or = ' d. e χ. I

5 Iroducio To mae suggesios o improve disifecio modellig i WSP : Comparaive aalysis of exisig models Explaaory variables (drivig facors) Looig a he dyamic of he process (Assumig ha solar radiaio as a mai disifecio mechaism)

6 Maerials ad mehods ()N d dn = Models predicios: Soluios of he equaio ( ) ( ) ( ) ( ) ( ) = I E e N N PFR: ( ) ( ) ( ) ( ) ( ) E E I E E N N V Q N V Q N N. 1 = Δ CSR: τ = 0 wih Virual pod characerisics: Iflue flow rae: 3000 m 3.d -1 RTD : 10 days Iiial No value 10 5 /100 ml Deph: 1m Volume: m 3 ( ) ( ) ( ) ( ) ( ) = e N N SBR:

7 Maerials ad mehods Models sudied 1) Daily models Auhors d (d -1 ) T Marais (1974) = Mayo (1989) * Z ν ( 1 e ) Auer e Niehaus (1993) KZ * + 4 Mayo (1995) 0.135pH * Fallowfield e al. (1995) Z ** d s I ( 20) Z s KZ Z ν =1.38m.j -1 K=0.64 SS wih SS=70mg.L -1 (Xu e al., 2001) *cal -1.cm 2 **W -1.m 2

8 Maerials ad mehods - Daily models 2) Auhors (d -1 ) (J -1.cm 2 ) *Xu_1 e al. (2001) **Xu_2 e al. (2001) ' e χ. I = d. ' d ( T 20) ( T 20) *Xu_1 ieic Field moiorig daa i firs eriary pod **Xu_2 ieic Field moiorig daa i secod eriary pod Average values chose for: ph = 8.3; DO = 4.6 mg.l -1 T = 15.0 C ; I = 86.0 J.cm -2.h -1 χ ( ) 1 e KZ KZ ( ) e KZ KZ

9 Maerials ad mehods: Hourly models Hourly models Auhors (h -1 ) = Curis e al. (1992) ** Craggs e al. (2004) *** d d + s I [ ] ph O 2 s **W -1.m 2 Daily variaios of I, ph, [O2] ad T Siusoidal fucios ***MJ -1.m 2

10 Maerials ad mehods: Hourly models Daily variaios of I: I = si si

11 Maerials ad mehods: Hourly models Daily variaios for : O 2, ph ad T DO = si ph = si T = si

12 Resuls ad discussio The effec o model predicios of : The choice of drivig facors The use of average values of variables

13 Resuls ad discussio The effec drivig facors Daily models

14 Resuls ad discussio: The effec of he choice of explaaory variables Hourly models

15 Resuls ad discussio The effec of he use of he average of variables Curis e al. model

16 Resuls ad discussio: The effec of average values Craggs e al. model

17 Coclusios Disifecio models: Empirical or semi-empirical Explaaory variables arbirary chose Huge differeces bewee predicios ha are derimeal for a good desig To improve disifecio modellig : Ehace owledge of mechaisms

18 Coclusio If he mos impora of disifecio mechaisms is suligh We mus ae io accou (ad measure) daily variaios of variables such as I, ph DO.ad oher meeorological daa Very few daa are available a a appropriae ime scale Use of average values of such variables ca lead o a overesimaio of disifecio. Measuremes have o be combied wih a good owledge of he hydrodyamic of he reacor. New measureme mehodologies have o be developed : a rasporable pilo pla is beig desiged

19 ACKNOWLEDGMENT The auhors wish o acowledge he suppor of he Naioal Research Fud (FNR) of Luxembourg for he pos-docoral fellowship graed o he firs auhor.