| Author | Paudel, Arjun Bhakta |
| Call Number | AIT Thesis no. EV-91-2 |
| Subject(s) | Sewage--Purification--Filtration
|
| Note | A thesis submitted in partial fulfillment of the requirements tor the degree of Master of Engineering, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Abstract | Crossflow microfiltration is a pressure driven membrane process in which the fluid to be filtered flows parallel to the membranes surface allowing better permeate. Laboratory scale microfiltration experiments with Mea-Wit clay in distilled water were carried out to study the membrane filter performances with respect to operating parameters. These operating parameters included membrane pore size, influent concentrations, ionic strength and particle size. Chemical interactions among the suspended particles and membra ne play an important role in membrane filter performance. The effect of forces during chemical interactions depend on the zeta potential of both membrane and suspension. In this study the zeta potential of the suspension was varied with varying Nae1 concentrations. From the study it was found that the membrane filter performance changed with ionic strength concentrations. The filter performance remained minimum at low ionic strength values where zeta potential value of particles in suspension was maxi mum negative and ionic strength which reveal ed a zeta potential value to a minimum negative tending towards zero of suspension exhibited a better filter performance. But in higher suspension concentration the filter performance was Found less dependent with ionic strength of suspension. For different suspension concentrations the maximum zeta potential value remained unchanged with varying ionic strength of suspension. Only the maximum negative range of zeta potential value was found to increase with the increase in suspension concentration in different ionic strengths of suspension. In this study long term use of membranes with cleaning was also studied. This study showed that the clogging rate remained higher in greater pore size compared to the smaller pore size membranes. A considerable improvement in filtrate flux rate was found after the membranes were cleaned. In the same study, the clogging rate was found to decrease with the increase in particle size distribution. Internal clogging in crossflow microfiltration during long term filtration occurred during the first 30 seconds of filtration and the rate was found to be higher in the fluid with smaller particle size. Based on initial filtrate flux of different filter runs, empirical equations were also developed for different pore size membranes used for long term filtration with membrane cleaning. |
| Year | 1991 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Environmental Engineering and Management (EV) |
| Chairperson(s) | Kim, Sun II; |
| Examination Committee(s) | Chongrak Polprasert ;Mino, Takashi; |
| Scholarship Donor(s) | The Government Of France; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1991 |