Enzymes: The New Wastewater Treatment Chemical for Water Reuse
Year Released: 2014
Type: Scientific Investigation
Funding Partner: Bureau of Reclamation
Total Investment: $211,278.31 (Cash: $149,088.68, In-Kind: $63,189.63)
Principal Investigators: Desmond F. Lawler and Kerry A. Kinney, The University of Texas at Austin
Conventional wastewater treatment plants do not effectively remove all pharmaceuticals and personal care products (PPCPs). As a result, some PPCPs enter the environment via treated wastewater discharge. Enzymatic treatment using the laccase-mediator system is a novel biochemical process that has been shown to effectively treat some PPCPs.
Goals and Objectives
The project 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.
In this work, two enzymatic treatment configurations were studied, focused on the removal of two representative PPCPs—oxybenzone and sulfamethoxazole. 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 higher biological oxygen demand of the wastewater required higher mediator concentrations. Whereas 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 (which contains high concentrations of phenolics) was investigated and proved ineffective. Further investigation of alternative mediator sources is required.
Findings and Conclusions
Treatment of another PPCP, sulfamethoxazole, was less efficient (65% removal) than that of oxybenzone, but nevertheless, the considerable removal of this substantially different compound suggests that the laccase-mediator system might be suitable for other PPCPs. The most promising result of this work was the simultaneous treatment of both PPCPs, oxybenzone and sulfamethoxazole. Simultaneous treatment proved to be as effective as the treatment of each PPCP individually.