Title:
Fate of phytosterols in pulp and paper wastewater treated in a simulated aerated stabilization basin

dc.contributor.advisor Banerjee, Sujit
dc.contributor.advisor Pavlostathis, Spyros G.
dc.contributor.author Dykstra, Christine M.
dc.contributor.committeeMember Huang, Ching-hua
dc.contributor.department Civil and Environmental Engineering
dc.date.accessioned 2014-08-27T13:33:25Z
dc.date.available 2014-08-27T13:33:25Z
dc.date.created 2014-08
dc.date.issued 2014-07-03
dc.date.submitted August 2014
dc.date.updated 2014-08-27T13:33:25Z
dc.description.abstract Phytosterols are steroid chemicals produced by plants for the purposes of membrane function and hormone production. Phytosterols can cause endocrine disruption in aquatic species at very low concentrations and are suspected of contributing to endocrine disruption linked to pulp and paper effluent. Wastewater from the pulp and paper industry is often treated biologically in aerated stabilization basins (ASBs) that expose phytosterols to a range of redox zones. Phytosterol removal in ASBs varies and stigmasterol has even been shown to increase across the treatment system. Little is known about the microbial processes that occur within ASBs and their effect on phytosterol removal. The objective of this research was to assess the biotransformation potential of phytosterols in a simulated ASB treatment system and to improve understanding of the processes that occur within the various redox zones and their impact on the removal of phytosterols. To assess the biotransformation of phytosterols under aerobic conditions, three assays were conducted using a stock aerobic culture fed with pulp and paper wastewater. The assays tested three conditions: phytosterols present as a sole added carbon source, phytosterols with dextrin as an added carbon source, and phytosterols with ethanol as a solubilizing agent and added carbon source. Phytosterol biotransformation was found to be limited by low phytosterol solubility. When solubilized, phytosterol removal occurred in two phases: an initial near-linear removal, followed by accelerated removal during the culture's stationary stage, possibly due to the release of extracellular cholesterol oxidase. The anoxic and anaerobic biotransformation of phytosterols was examined through a series of three semi-batch cultures maintained under nitrate-reducing, sulfate-reducing and fermentative/methanogenic conditions, all developed from stock cultures fed with pulp and paper wastewater. Phytosterol removal was significant in the nitrate-reducing culture, although microbial activity and phytosterol removal declined in later stages. Phytosterol removal was also observed in the sulfate-reducing culture, although there was a significant lag period before removal occurred. No phytosterol removal was observed in the fermentative/methanogenic culture. Phytosterol biotransformation was also examined in the context of a lab-scale ASB fed continuously with pulp and paper wastewater. The steady-state ASB effluent and sediment characteristics were examined over three hydraulic retention times (HRTs). Effluent quality was not significantly affected by a change in HRT but sediment characteristics were significantly affected and, at shorter HRTs, phytosterols accumulated in the sediment. Wastewater bioassays demonstrated the release of phytosterols during the breakdown of solids. This research improves the understanding of biological processes within ASBs and their effect on phytosterol removal.
dc.description.degree M.S.
dc.format.mimetype application/pdf
dc.identifier.uri http://hdl.handle.net/1853/52209
dc.language.iso en_US
dc.publisher Georgia Institute of Technology
dc.subject Phytosterols
dc.subject Beta-sitosterol
dc.subject Stigmasterol
dc.subject Campesterol
dc.subject Aerated stabilization basin
dc.subject ASB
dc.subject Lagoon
dc.subject Pulp and paper
dc.subject Aerobic biodegradation
dc.subject Anoxic biodegradation
dc.subject Anaerobic biodegradation
dc.subject Cholesterol oxidase
dc.title Fate of phytosterols in pulp and paper wastewater treated in a simulated aerated stabilization basin
dc.type Text
dc.type.genre Thesis
dspace.entity.type Publication
local.contributor.advisor Pavlostathis, Spyros G.
local.contributor.advisor Banerjee, Sujit
local.contributor.corporatename School of Civil and Environmental Engineering
local.contributor.corporatename College of Engineering
relation.isAdvisorOfPublication 4b10037e-c1df-45bc-abca-1da6d3389c46
relation.isAdvisorOfPublication c7c678e2-25fb-4158-949e-b6e3f8c14d97
relation.isOrgUnitOfPublication 88639fad-d3ae-4867-9e7a-7c9e6d2ecc7c
relation.isOrgUnitOfPublication 7c022d60-21d5-497c-b552-95e489a06569
thesis.degree.level Masters
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