Conventional wastewater treatment plants do not effectively remove
pharmaceuticals and personal care products (PPCPs). As a result, PPCPs enter the
environment via treated wastewater discharge. Enzymatic treatment, using the laccasemediator
system, is a novel biochemical process that has been shown to effectively treat
some PPCPs. This study investigates the efficacy of the laccase-mediator system to treat
PPCPs using a process that can be easily implemented at an existing wastewater
treatment plant. Enzymatic treatment will be most beneficial after primary sedimentation
and before conventional biological treatment, where unoxidized PPCPs and byproducts
could have the opportunity for further degradation in biological treatment.
In this work, two enzymatic treatment configurations were studied. A step-wise
optimization process was used that alternately varied treatment conditions: pH, enzyme
activity, mediator concentration, and reactor detention time. In the optimization process
of each configuration, successful oxybenzone removal (~90%) was achieved in municipal
primary effluent. In a direct comparison of treatment configurations, both resulted in
vi
similar percent removals of oxybenzone. Therefore, the configuration with the simpler
operation and reactor design was chosen for further study.
During the optimization process, several noteworthy conclusions were made that
might have full-scale enzymatic treatment implications. Specifically, successful
oxybenzone removal occurred at unadjusted pH and without aeration, but increased
biological oxygen demand of the wastewater increased the required mediator
concentration. While the first finding would decrease enzymatic treatment costs, the
latter would increase the costs associated with the mediator. Thus, an alternative
mediator source, specifically one high in phenolic compounds, is desired. The use of
wine, as a surrogate of winery wastewater, was in investigated and proved ineffective.
Further investigation of alternative mediator sources is required.
Treatment of another PPCP, sulfamethoxazole, was less efficient (65% removal)
than that of oxybenzone, but nevertheless, the substantial removal might indicate that
other PPCPs can be treated with the laccase-mediator system. The most promising result
of this work was the simultaneous treatment of multiple PPCPs, oxybenzone and
sulfamethoxazole. Simultaneous treatment proved to be as effective as when each PPCP
was treated individually. / text
| Identifer | oai:union.ndltd.org:UTEXAS/oai:repositories.lib.utexas.edu:2152/21786 |
| Date | 29 October 2013 |
| Creators | Sharkey, Margaret E |
| Source Sets | University of Texas |
| Language | en_US |
| Detected Language | English |
| Format | application/pdf |
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