Static Mixers for Coagulation and DisinfectionAmerican Water Works Association, 2001 - 225 pagine Static mixers are an attractive alternative for the mixing of chemicals in water treatment plants. The attraction comes from the fact that static mixers do not require an external input of energy and do not have moving parts. Static mixers consist of mixing elements fixed on the inside of a pipe of channel. The elements do not move. Chemicals, added just upstream of the mixers, mix with the bulk fluid because of the complex, three-dimensional fluid motion generated by the elements. The goal of this project is to explore the use of static mixers in two of the key processes in drinking water treatment: for the mixing of coagulants for destabilization and the mixing of disinfectants for the inactivation of Cryptosporidium parvum oocysts in disinfection. The role of mixing in both of these processes is not well understood. But for each process experimental and theoretical evidence suggests that, at least in some circumstances, the mixing environment provided when chemicals are introduced into the flow will affect the resulting destabilization or inactivation. |
Sommario
INTRODUCTION AND BACKGROUND | 1 |
PILOTSCALE TESTING OF STATIC MIXERS FOR COAGULANT MIXING | 13 |
BENCHSCALE EXPERIMENTS OF THE INACTIVATION OF CRYPTOSPORIDIUM PARVUM OOCYSTS WHEN USING STATIC MIXERS | 65 |
A NEW PHYSICOCHEMICAL MODEL OF DISINFECTANT MIXING INCLUDING THE EFFECTS OF MIXING ON CRYPTOSPORIDIUM PAR... | 103 |
COMPUTATIONAL FLUID DYNAMICS PREDICTIONS OF THE FLOWFIELD IN HELICAL STATIC MIXERS | 129 |
CONCLUSIONS | 189 |
Parole e frasi comuni
4-gpm run 6-element agulation alum dose Amirtharajah Anthracite AWWA backmixer BM KMS BM carboy cells CFD model charge neutralization chemical conditions Chlorine Dioxide coagulation Computational Fluid Dynamics concentration cross-section Cryptosporidium oocysts Cryptosporidium parvum Cryptosporidium parvum oocysts developed diameter disinfection disinfection process downstream drinking water effect empty pipe equations Filter Run filtered water filtration flocculation flow rate flowfield Fluid Mechanics friction factor G-value gradients grid Gyürék head loss helical mixer helical static mixers Hom model Inactivation of Cryptosporidium infectivity curve KMS BM KMS KMS mixer laminarization log inactivation Log Removal mean longitudinal velocity mean vorticity measured mg/L micromixing mixer performed mixer versus monochloramine number of elements oocysts ozone parameter particle counts pathogens predictions Proc rapid mixing raw water Reynolds number Run Time hours samples shown in Figure shows simulations Six Element Sotiropoulos Stata-tube streaming current studies three-dimensional transverse turbulent flow two-element vorticity
Riferimenti a questo libro
Guidance Manual for Coagulant Changeover James DeWolfe,AWWA Research Foundation Visualizzazione estratti - 2003 |