Removal of pathogenic and indicator microorganisms from wastewater by natural systems

Persistent Link:
http://hdl.handle.net/10150/282861
Title:
Removal of pathogenic and indicator microorganisms from wastewater by natural systems
Author:
Quinonez-Diaz, Maria de Jesus
Issue Date:
1998
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The purpose of this study was to determine the removal efficiency of natural systems for the reduction of enteric protozoa (Giardia and Cryptosporidium), and enteric viruses in wastewater. The first part of the study used bench-scale soil columns to determine the potential effectiveness of Soil Aquifer Treatment (SAT) for the removal of Cryptosporidium oocysts and Giardia cyst from treated wastewater. Sand and sandy loam were used to pack 18 to 200-cm long columns. Results from this study showed that removal of oocysts increased as increasing length of the soil column. Although substantial removal of Cryptosporidium occurs (>99.99%) within 200 cm of soil, oocysts are likely to penetrate beyond this depth. Giardia was removed far below detectable levels, probably due to its larger size. The next phase of the project investigated the removal of pathogenic and indicator microorganisms from untreated wastewater by a surface flow wetland, the importance of plants in wetlands, as well as the potential for groundwater contamination passed by pathogens with the use of constructed wetlands. This small-scale study was conducted in a large tank divided into two cells. Both cells were filled with sand and one cell was planted with bulrushes and the other was unplanted. About 90 percent of all microorganisms were removed by either of the systems. Neither Giardia nor Cryptosporidium were found to penetrate through the 2-m of sand in either the planted or unplanted cells. Lower numbers of viruses and bacteria were transported through the sand in the planted wetland cell versus the unplanted cell. This could indicate that vegetated wetlands are more likely to prevent microbial transport to groundwater. The objective of the last part of this study was to determine the survival of Cryptosporidium oocysts in wastewater effluent applied to a constructed vegetated wetland, when exposed to and when protected from sunlight, and the effect of temperature during different seasons. Viability of Cryptosporidium oocysts was determined using the excystation technique. Results from this study indicated that sunlight and/or temperature play a significant role in the survival of Cryptosporidium. Thus, it was concluded that oocyst reduction in wastewater applied to wetlands can be enhanced by natural die-off due to the effects of temperature or UV irradiation in sunlight, and greater removal could be achieved if designing of wetland systems take into consideration such factors.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Biology, Microbiology.; Engineering, Sanitary and Municipal.; Environmental Sciences.; Engineering, Environmental.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Soil, Water and Environmental Science
Degree Grantor:
University of Arizona
Advisor:
Gerba, Charles P.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleRemoval of pathogenic and indicator microorganisms from wastewater by natural systemsen_US
dc.creatorQuinonez-Diaz, Maria de Jesusen_US
dc.contributor.authorQuinonez-Diaz, Maria de Jesusen_US
dc.date.issued1998en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThe purpose of this study was to determine the removal efficiency of natural systems for the reduction of enteric protozoa (Giardia and Cryptosporidium), and enteric viruses in wastewater. The first part of the study used bench-scale soil columns to determine the potential effectiveness of Soil Aquifer Treatment (SAT) for the removal of Cryptosporidium oocysts and Giardia cyst from treated wastewater. Sand and sandy loam were used to pack 18 to 200-cm long columns. Results from this study showed that removal of oocysts increased as increasing length of the soil column. Although substantial removal of Cryptosporidium occurs (>99.99%) within 200 cm of soil, oocysts are likely to penetrate beyond this depth. Giardia was removed far below detectable levels, probably due to its larger size. The next phase of the project investigated the removal of pathogenic and indicator microorganisms from untreated wastewater by a surface flow wetland, the importance of plants in wetlands, as well as the potential for groundwater contamination passed by pathogens with the use of constructed wetlands. This small-scale study was conducted in a large tank divided into two cells. Both cells were filled with sand and one cell was planted with bulrushes and the other was unplanted. About 90 percent of all microorganisms were removed by either of the systems. Neither Giardia nor Cryptosporidium were found to penetrate through the 2-m of sand in either the planted or unplanted cells. Lower numbers of viruses and bacteria were transported through the sand in the planted wetland cell versus the unplanted cell. This could indicate that vegetated wetlands are more likely to prevent microbial transport to groundwater. The objective of the last part of this study was to determine the survival of Cryptosporidium oocysts in wastewater effluent applied to a constructed vegetated wetland, when exposed to and when protected from sunlight, and the effect of temperature during different seasons. Viability of Cryptosporidium oocysts was determined using the excystation technique. Results from this study indicated that sunlight and/or temperature play a significant role in the survival of Cryptosporidium. Thus, it was concluded that oocyst reduction in wastewater applied to wetlands can be enhanced by natural die-off due to the effects of temperature or UV irradiation in sunlight, and greater removal could be achieved if designing of wetland systems take into consideration such factors.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectBiology, Microbiology.en_US
dc.subjectEngineering, Sanitary and Municipal.en_US
dc.subjectEnvironmental Sciences.en_US
dc.subjectEngineering, Environmental.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineSoil, Water and Environmental Scienceen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorGerba, Charles P.en_US
dc.identifier.proquest9923165en_US
dc.identifier.bibrecord.b39471706en_US
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