AWWA ACE59938

The goal of this research was to increase the understanding of the filtration mechanisms and toalso further the efforts of improved modeling of the filtration process. The macroscopic modelused in this research included the detachment mechanism and thus, it was able to model theentire cycle of filtration. An assessment of the ability of the model to predict the filtration process for varying types of particles, mainly hydrophobic and hydrophilic particles, was animportant aspect of this research. This is one of the first efforts to determine the importance ofparticle hydrophobicity and hydrophilicity on particle removal in deep bed filtration. To thispoint, past research efforts have suggested that this difference may be significant; however, nodetailed research into this area has been conducted.In order to alleviate the difficulty in having to determine model parameter values throughexperimental data, empirical equations for the direct calculation of the ripening, detachment,and headloss parameters were determined. Literature and prior research has indicated thatvalues of the three parameters are affected by filtration rate, filter media depth, diameter of themedia grains, and diameter of the influent particles. Since the experiments conducted as part ofthis research incorporates a wide array of filtration conditions, it was possible to deriveempirical equations for the three parameters. Previously determined empirical equations allcontain different combinations of the following filter operating variables: filtration rate, influentconcentration, particle diameter, and filter media diameter. However, none of the equationscontain all the filtration variables. Furthermore, the depth of the filter media is not consideredin any of the empirical relationships previously established. Therefore, more detailed equationsare needed to account for all the variables involved and thus, to accurately calculate the modelparameters. The empirical equations derived as part of this research were able to accuratelypredict the parameter values generated by the model through the simultaneous fit of theexperimental removal and headloss data. The empirical equations were most accurate for theripening and headloss model parameters. The equation derived for the detachment parameterwas less precise than the equations for the other two parameters.Another aspect of this investigation involved how the knowledge of the difference inremoval efficiency and headloss development for hydrophilic particles impact practicalfiltration and filtration modeling. To answer that question, Suwannee River natural organicmatter was added to the influent water containing hydrophobic particles, and a series ofexperiments were conducted in the exact fashion as the previous eight experiments usinghydrophobic latex particles. The effluent and headloss data generated through these newexperiments with the hydrophobic particle and Suwannee River natural organic matter mixturewas then compared to the data produced by the experiments using hydrophilic particles andhydrophobic particles. After making this comparison, it was noted that in all the experimentsconducted with hydrophobic particles and Suwannee River natural organic matter the removaland headloss curves closely modeled the curves generated for the same experimental conditionsbut with hydrophilic particles. Therefore, knowledge of particle hydrophilicity andhydrophobicity is important in understanding the removal of natural organic matter duringfiltration. Includes 21 references, table, figures.

Product Details

Edition:

Vol. - No.

Published:

06/17/2004

Number of Pages:

13

File Size:

1 file , 370 KB