Removal of Selected Pharmaceuticals and Personal Care Products from Wastewater using Soybean Peroxidase.

Personal care products and pharmaceuticals have been reported in various concentrations in the effluent of municipal sewage treatment plants (STP). Although they are generally found in the nanogram to microgram per liter range, many of them might have adverse health effects on humans at these concentrations. Conventional treatments applied at the STP are unable to effectively remove most of these recalcitrant compounds, thus there is a necessity for development of alternative treatment techniques. In this article, the efficiency of enzymatic treatment using soybean peroxidase in treating some commonly found micropollutants is discussed. The target compounds were, two phenolic surfactant breakdown products, nonylphenol and octylphenol, two antimicrobial agents, Triclosan and sulfamethoxazole and three phenolic steroids. The effects of the most important parameters pH, enzyme concentration and peroxide concentration have been evaluated for each compound. The treatment of synthetic wastewater was shown to be effective (≥95% removal), except for sulfamethoxazole, in concentration ranges of 10 s of µM at neutral pH with 2-5 mU/L of catalytic activity and 2-3 molar equivalents of hydrogen peroxide. The effectiveness of the treatment has also been determined for lower concentrations (6-9 nM) which approximate those in real wastewater. A matrix effect was found in the treatment of Triclosan in spiked real wastewater indicating that re-optimization of important parameters for STP treatment would be required to achieve high removal efficiency. A reverse-phase, solid-phase extraction technique was used to concentrate target analytes in real wastewater, enabling chromatographic detection by UV absorbance.

Elimination of selected heterocyclic aromatic emerging contaminants from water using soybean peroxidase.

Widespread occurrence of various heterocyclic aromatic compounds is reported in concentrations from 1 to 20 µg/L in surface and groundwater as well as influents and effluents of wastewater treatment plants around the world. These so-called emerging contaminants and their metabolites can cause adverse effects on the environment and humans, even at very low concentration, hence raised environmental concerns. In this study, feasibility of soybean peroxidase-catalyzed removal of three selected heterocyclic aromatics from water was investigated, including sensitivity to the most important operational conditions, pH (range 3.6-9.0), H2O2 concentration (range 0.10-1.50 mM), and enzyme activity (range 0.001-5.0 U/mL). 3-Hydroxycoumarin and 2-aminobenzoxaozle were found to be substrates for the enzyme, having ≥95% and 45% removal efficiency with most effective pHs of 7.0 and 6.0, respectively. Time course study was also conducted to determine the initial first-order rate constants and half-lives; half-lives normalized for enzyme activity (0.0257 and 452 min for the respective substrates) are compared with those of 21 other compounds reactive with soybean peroxidase. High-resolution mass spectrometry was employed to characterize the plausible oligomerization products of enzymatic treatment, which revealed formation of dimers and trimers of the two substrates.

Soybean Peroxidase Catalyzed Decoloration of Acid Azo Dyes.

BACKGROUND: Some industrial manufacturing processes generate and release dyes as water pollutants, many of which are toxic and hazardous materials. There is a need for milder, greener methods for dye treatment. OBJECTIVES: The objective of the present study was to investigate and optimize azo dye decoloration by a crude soybean peroxidase (SBP), based on two dyes that have widespread industrial use, but that differ greatly in structural complexity, Acid Black 2 and Acid Orange 7, and to investigate the effects of specific parameters on the removal process. METHODS: Batch reactors were used to remove 95% of the dyes' color and to produce substantial precipitates. RESULTS: The optimum pH for enzymatic decoloration of Acid Black 2 was in the acidic region, pH 4.4, and that of Acid Orange 7 occurred under neutral conditions, pH 6.9. The minimum enzyme activity needed for sufficient removal was 1.2 U/mL for both dyes at 0.5 mM. The minimum molar hydrogen peroxide/substrate ratio was 3 for Acid Orange 7 and 2.5 for Acid Black 2 to achieve approximately 95% removal. First-order fitting of progress curve data collected under the respective optimum conditions gave half-lives of 23.9 and 28.9 minutes for Acid Orange 7 and Acid Black 2, respectively. CONCLUSIONS: The feasibility of SBP-catalyzed treatment of industrial dyes Acid Black 2 and/or Acid Orange 7, or dyes that resemble them, as they might occur in industrial effluents, was successfully demonstrated. COMPETING INTERESTS: The authors declare no competing financial interests.