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Dissertation
Geotextile filter treatment of combined sewer discharges
Doctor of Philosophy (Ph.D.), Drexel University
Feb 2006
DOI:
https://doi.org/10.17918/etd-891
Abstract
This project investigated the use of geotextile filters to remove organic particles from combined sewer overflows. This addressed the need for a compact end-of-pipe treatment system that could be retrofitted at an existing outfall or regulation chamber. The premise was that nonwoven geotextiles with complex pore structures and interior porosity could serve cake, medium and depth filter functions to capture light, suspended and colloidal particles of varying size distributions. To provide a large filter surface contact area and avoid high head losses, the filters were arranged in a sinuous pattern in a containment vessel. The applicability of the manufacturer's material properties developed for soil filters was investigated using an inert analog for degradable sanitary solids, i.e. granulated anthracite. Three sizes (areal densities) of the same manufacturing process for staple fiber nonwoven needle-punched geotextiles were investigated to determine the relative importance of the common indices of AOS, permittivity, and interior porosity. After some disparities were noted, a large one-dimensional permittivity apparatus for use with low hydraulic heads was built, including features to measure particle capture efficiency. It was observed that much of the capture of lighter materials was by a surficial cake filter, such that, at the cessation of flow, much of the intercepted suspended solids sloughed off the filter face into a sump. A hydraulic model of the permeable baffles with alternating bypass channels was compiled and used to optimize dimensioning of the filter system geometry. Prototypes with six filter baffles using 100 quart coolers were run with both the anthracite and combined sewage or dry weather flow from a nearby treatment plant. The ability of the baffles to filter out the degradable particles was higher than for the hard-surfaced anthracite granules, due to the adsorptive or cohesive behavior of the former. It is estimated that a filter array of 20 geotextile baffles will have the potential to remove over 75% of the suspended material in the waste stream.
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Details
- Title
- Geotextile filter treatment of combined sewer discharges
- Creators
- Roger Joseph Marino - DU
- Contributors
- Joseph Paul Martin (Advisor) - Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- Civil (and Architectural) Engineering [Historical]; College of Engineering (1970-2026); Drexel University
- Other Identifier
- 891; 991014632308704721