4 research outputs found
Treatment of Municipal Wastewater Treatment Plant Effluents with Modified Photo-Fenton As a Tertiary Treatment for the Degradation of Micro Pollutants and Disinfection
The goal of this paper was to develop a modified photo-Fenton
treatment
able to degrade micro pollutants in municipal wastewater treatment
plant (MWTP) effluents at a neutral pH with minimal iron and H<sub>2</sub>O<sub>2</sub> concentrations. Complexation of Fe by ethylenediamine-<i>N</i>,<i>N</i>ā²-disuccinic acid (EDDS) leads
to stabilization and solubilization of Fe at natural pH. Photo-Fenton
experiments were performed in a pilot compound parabolic collector
(CPC) solar plant. Samples were treated with solid phase extraction
(SPE) and analyzed by HPLC-Qtrap-MS. The rapid degradation of contaminants
within the first minutes of illumination and the low detrimental impact
on degradation of bicarbonates present in the water suggested that
radical species other than HO<sup>ā¢</sup> are responsible for
the efficiency of such photo-Fenton process. Disinfection of MWTP
effluents by the same process showed promising results, although disinfection
was not complete
Comparison of Nitrilotriacetic Acid and [<i>S</i>,<i>S</i>]āEthylenediamineā<i>N</i>,<i>N</i>ā²ādisuccinic Acid in UVāFenton for the Treatment of Oil Sands Process-Affected Water at Natural pH
The application of
UVāFenton processes with two chelating
agents, nitrilotriacetic acid (NTA) and [<i>S</i>,<i>S</i>]-ethylenediamine-<i>N</i>,<i>N</i>ā²-disuccinic acid ([<i>S</i>,<i>S</i>]-EDDS),
for the treatment of oil sands process-affected water (OSPW) at natural
pH was investigated. The half-wave potentials of FeĀ(III/II)ĀNTA and
FeĀ(III/II)ĀEDDS and the UV photolysis of the complexes in Milli-Q water
and OSPW were compared. Under optimum conditions, UVāNTAāFenton
exhibited higher efficiency than UVāEDDSāFenton in the
removal of acid extractable organic fraction (66.8% for the former
and 50.0% for the latter) and aromatics (93.5% for the former and
74.2% for the latter). Naphthenic acids (NAs) removals in the UVāNTAāFenton
process (98.4%, 86.0%, and 81.0% for classical NAs, NAs + O (oxidized
NAs with one additional oxygen atom), and NAs + 2O (oxidized NAs with
two additional oxygen atoms), respectively) under the experimental
conditions were much higher than those in the UVāH<sub>2</sub>O<sub>2</sub> (88.9%, 48.7%, and 54.6%, correspondingly) and NTAāFenton
(69.6%, 35.3%, and 44.2%, correspondingly) processes. Both UVāNTAāFenton
and UVāEDDSāFenton processes presented promoting effect
on the acute toxicity of OSPW toward <i>Vibrio fischeri</i>. No significant change of the NTA toxicity occurred during the photolysis
of FeĀ(III)ĀNTA; however, the acute toxicity of EDDS increased as the
photolysis of FeĀ(III)ĀEDDS proceeded. NTA is a much better agent than
EDDS for the application of UVāFenton process in the treatment
of OSPW
Oxidation of Oil Sands Process-Affected Water by Potassium Ferrate(VI)
This paper investigates
the oxidation of oil sands process-affected
water (OSPW) by potassium ferrateĀ(VI). Due to the selectivity of ferrateĀ(VI)
oxidation, two-ring and three-ring fluorescing aromatics were preferentially
removed at doses <100 mg/L FeĀ(VI), and one-ring aromatics were
removed only at doses ā„100 mg/L FeĀ(VI). FerrateĀ(VI) oxidation
achieved 64.0% and 78.4% removal of naphthenic acids (NAs) at the
dose of 200 mg/L and 400 mg/L FeĀ(VI) respectively, and NAs with high
carbon number and ring number were removed preferentially. <sup>1</sup>H nuclear magnetic resonance (<sup>1</sup>H NMR) spectra indicated
that the oxidation of fluorescing aromatics resulted in the opening
of some aromatic rings. Electron paramagnetic resonance (EPR) analysis
detected signals of organic radical intermediates, indicating that
one-electron transfer is one of the probable mechanisms in the oxidation
of NAs. The inhibition effect of OSPW on <i>Vibrio fischeri</i> and the toxicity effect on goldfish primary kidney macrophages (PKMs)
were both reduced after ferrateĀ(VI) oxidation. The fluorescing aromatics
in OSPW were proposed to be an important contributor to this acute
toxicity. Degradation of model compounds with ferrateĀ(VI) was also
investigated and the results confirmed our findings in OSPW study
Advanced Analytical Mass Spectrometric Techniques and Bioassays to Characterize Untreated and Ozonated Oil Sands Process-Affected Water
Oil sands process-affected water
(OSPW) is a toxic and poorly biodegradable
mixture of sand, silt, heavy metals, and organics. In this study,
qualitative and quantitative comparisons of naphthenic acids (NAs)
were done using ultraperformance liquid chromatography time-of-flight
mass spectrometry (UPLC TOF-MS), Fourier transform ion cyclotron resonance
(FT-ICR) MS, and ion mobility spectrometry (IMS). The unique combination
of these analyses allowed for the determination and correlation of
NAs, oxidized NAs, and heteroatom (sulfur or nitrogen) NAs. Despite
its lower resolution, UPLC-TOF MS was shown to offer a comparable
level of reliability and precision as the high resolution FT-ICR MS.
Additionally, the impacts of ozonation (35 mg/L utilized ozone dose)
and subsequent NAs degradation on OSPW toxicity were assessed via
a collection of organisms and toxicity end points using Vibrio fischeri (nonspecific), specific fish macrophage
antimicrobial responses, and fish olfactory responses. Fish macrophages
exposed to ozonated OSPW for 1 week showed higher production of reactive
oxygen and nitrogen intermediates; however, after 12 weeks the responses
were reduced significantly. Fish olfactory tests suggested that OSPW
interfered with their perception of odorants. Current results indicate
that the quantification of NAs species, using novel analytical methods,
can be combined with various toxicity methods to assess the efficiency
of OSPW treatment processes