Loading...
Ozone and biological activated carbon pretreatment for the enhanced removal of perfluoroalkyl acids from wastewater effluent by granular activated carbon
Clevenger, Erica
Clevenger, Erica
Citations
Altmetric:
Advisor
Editor
Date
Date Issued
2021
Date Submitted
Collections
Research Projects
Organizational Units
Journal Issue
Embargo Expires
Abstract
Perfluoroalkyl acid (PFAA) removal has been extensively researched in the context of drinking water treatment but relatively less is known about PFAA removal from wastewater effluents. Of the leading PFAA removal technologies, granular activated carbon (GAC) has emerged as the most economically viable and easily implemented strategy for PFAA mitigation in wastewater treatment and reuse scenarios. However, GAC treatment is associated with significant drawbacks due to the presence of effluent organic matter (EfOM) in wastewater matrices. The combination of ozonation and biological activated carbon (O3-BAC) has emerged as an integral component of non-membrane potable reuse treatment trains due to its ability to synergistically remove organic matter. Although O3-BAC is not expected to be a significant barrier for certain contaminants such as PFAAs, it has not been studied for its ability to improve downstream treatment processes through removal of organic matter.
The objective of this study was to determine if the O3-BAC process is a suitable pretreatment technique for downstream removal of PFAAs through GAC. This was accomplished through a review of the literature concerning PFAA removal from wastewater effluent, and GAC rapid small scale column testing (RSSCTs) with wastewater effluent after different levels of pretreatment including no pretreatment, ozonation, BAC, and combined O3-BAC. A review of the literature determined that GAC treatment capacity is considerably reduced when wastewater is treated, as compared to surface water or groundwater matrices, presumably due to the presence of EfOM. Through GAC RSSCT testing over a range of experimental conditions, it was found that an ozone dose of 0.75 mg O3/ mg DOC and a BAC empty bed contact time (EBCT) of 20min provided the greatest enhancement in downstream GAC performance and as a result, these conditions were selected for a final experiment with combined O3-BAC pretreatment of wastewater effluent. The total combined O3-BAC process produced the greatest improvement in removal of PFAAs of all experimental conditions with a 3-4 times increase in bed volumes treated to 20% breakthrough over untreated MBR effluent. The results of the study demonstrated the synergistic effects of combined O3-BAC pretreatment for the improvement in removal of PFAAs by GAC treatment.
Associated Publications
Rights
Copyright of the original work is retained by the author.