Treatment of Commercial Surfactants With Chemical and Photochemical Advanced Oxidation Processes

© 2012 by World Scientific Publishing Co. Pte. Ltd. All rights reserved. Surfactants are among the most abundant, man-made organic pollutants with a high potential to enter the environment through the discharge of domestic and industrial wastewater as well as sewage sludge. Due to their amphiphilic structure, they not only are present in natural waters at concentrations varying between nondetectable to several μg/L’s, but also tend to significantly sorb onto sewage sludge, ultimately bioaccumulating in soil sediments of receiving water bodies. According to extensive biodegradability and ecotoxicological studies, most surfactants are readily biodegradable regarding the parent compound; however complete oxidation is usually achieved neither in engineered treatment systems nor in the natural environment. In addition, acute toxicity data reveal that most surfactants are fairly toxic toward aquatic as well as terrestrial organisms. Considering these facts, treatment with alternative, advanced oxidation processes (AOPs) could be a promising option to alleviate the problem of uncontrolled bioaccumulation and biodegradation of surfactants in the environment. The present work reviews the application of chemical and photochemical AOPs for the detoxification and mineralization of commercial surfactant formulations. Special emphasis has been given to the main limitations of advanced oxidative treatment applications, namely toxicity of advanced oxidation intermediates/end products

Treatment of textile dye bath wastewater with ozone, persulfate and peroxymonosulphate oxidation

In this study, the treatment of wastewater of two different reactive dye bath wastewater (WW1, WW2) belonging to a yarn dyeing textile industry was evaluated by ozone, heat-activated persulfate (PS) and heat-activated peroxymonosulfate (PMS) oxidation methods. WW1 and WW2 contains azo group dyes and BOD5 values are 245 and 105 mg/L, Total Organic Carbon (TOC) values are 793 and 3016 mg/L respectively. TOC and color removal and BOD5/TOC ratio were investigated in samples taken at specific time intervals (15, 30, 45, 60, 90 and 120 min). For WW1, the TOC and color removal rates for heat-activated PS oxidation were 19% and 100%, respectively, and these removal rates were higher than the oxidation results for ozonation (15% and 76%) and heat-activated PMS (16% and 99%). Although the ozone dose applied to WW1 was about 3 times that of the ozone dose applied to WW2, the color removal rate in WW2 (94%) was higher than WW1 (76%) and the TOC removal rates were almost the same. In the result of oxidation studies, no significant increase in BOD value was observed for both wastewater. However, an increase in BOD5/TOC was achieved by decreasing the TOC value in heat-activated PS oxidation for WW1

Assessment of organic carbon removal by particle size distribution analysis

Particle size distribution (PSD)-based fractionation, an alternative methodology in wastewater characterization, was employed to gather detailed information on the organic matter content of a raw olive mill wastewater (OMW) and to investigate the changes brought about in this characteristic after application of certain chemical treatment alternatives, namely, lime precipitation-coagulation, Fenton oxidation, and electrocoagulation. PSD-based analysis of the untreated OMW demonstrated that more than two-thirds of its organic carbon content, measured as chemical oxygen demand (COD) (69%), total organic carbon (TOC) (74%), as well as antioxidant activity (AOA) (74%) caused by the polyphenolic carbon fraction, was at the soluble range (<2 nm). Treatability experiments, with maximum overall removal efficiencies below 50% even under optimized conditions, indicated that none of the applied chemical pretreatment methods was sufficiently effective in removing the organics from the investigated OMW. Nonetheless, PSD-based fractionation of the pretreated samples provided an insight about the treatment alternatives and the size fractions where they performed better. Electrocoagulation was capable of removing particulate and colloidal matter and provided a relatively higher overall performance with 23, 20, and 34% decreases in COD, TOC, and polyphenol contents of the OMW, respectively. Fenton process, on the other hand, showed a lower overall performance in terms of COD and TOC removal (17 and 15%, respectively), yet it was significantly effective on the soluble fraction, and thus more successful in removing the polyphenols mostly originating from the soluble range, with an overall efficiency of 42%. Based on these observations, PSD analysis was suggested as a useful tool to perform detailed wastewater characterization, as well as to differentiate between specific impacts of different pretreatment processes and help choose between alternatives, especially when a particular pollutant is targeted. Copyright 2009, Mary Ann Liebert, Inc

EFFECT OF CHEMICAL TREATMENT ON THE AROMATIC CARBON CONTENT AND PARTICLE

The present experimental work was carried out to examine the physicochemical treatability of a high-strength olive oil mill wastewater (OMW). Firstly, the wastewater was subjected to environmental characterization and particle size distribution-based COD-TOC-UV254-UV280 analyses. The following treatment schemes were selected for the study: Coagulation-flocculation in the presence of anionic and commercial polymers at varying pH and coagulant/polymer dosages Fenton treatment at different pH's and Fe(II): H2O2 concentrations as well as electrocoagulation using stainless steel electrodes at different electrolyte concentrations and current densities. Results of the study have indicated that none of the investigated physicochemical treatment methods was capable of removing the organic carbon content of the wastewater by more than 30% in terms of COD and 20% in terms of TOC that is at least partially attributable to the high, soluble organic carbon content of the wastewater. Alternative treatment processes and/or combinations have to be explored for effective treatment of OMW effluent

Iprodione Removal by UV-Light-, Zero-Valent Iron- and Zero-Valent Aluminium-Activated Persulfate Oxidation Processes in Pure Water and Simulated Tertiary Treated Urban Wastewater

The degradation of iprodione (IPR), a once frequently used but recently banned dicarboximide fungicide, by UV-C light-, zero-valent iron- (ZVI), and zero-valent aluminium (ZVA)-activated persulfate (PS) oxidation processes was comparatively studied in distilled (pure) water (DW) and simulated, tertiary treated urban wastewater (SWW). The performance of PS-activated oxidation processes was examined by following IPR (2–10 mg/L) removal, PS (0.01–1.00 mM) consumption, metal ion release (for the two heterogeneous catalytic oxidation processes), dissolved organic carbon (DOC) removal as well as hydroxylated aromatic and low molecular weight aliphatic degradation products. The effect of pH and PS concentrations on IPR removal was examined in DW. While the experiments in DW highlighted the superior performance of UV-C/PS treatment (with 78% DOC removal after 120 min at pH = 6.2), the performance of UV-C/PS treatment decreased sharply (to 24% DOC removal after 120 min at pH = 6.8) in the complex wastewater matrix (in SWW). Complete IPR (in 20 min) and 40% DOC (in 120 min) removals were obtained with ZVI/PS treatment (1 g/L ZVI, 1.5 mM PS, pH = 3.0), which was the most effective oxidation process in SWW. The treatment performance was strongly influenced by the SWW constituents, and UV-C/PS treatment appeared to be the most sensitive to it

Degradation and toxicity assessment of the nonionic surfactant Triton??? X-45 by the peroxymonosulfate/UV-C process

The degradation and mineralization of the nonionic surfactant octylphenol ethoxylate (OPEO), commercially known as Triton??? X-45, by the peroxymonosulfate (PMS)/UV-C process were investigated. Three different toxicity tests (Daphnia magna, Vibrio fischeri and Pseudokirchneriella subcapitata) as well as the Yeast Estrogen Screen (YES) bioassay were undertaken to evaluate the potential toxic and estrogenic effects of OPEO and its oxidation products. OPEO removal was very fast and complete after 7 min via PMS/UV-C treatment under the investigated reaction conditions (OPEO = 20 mg L???1 (47 ??M); TOC = 12 mg L???1; PMS = 2.5 mM; initial reaction pH = 6.5; applied UV-C dose = 21 Wh L???1). TOC removal also proceeded rapidly; a gradual decrease was observed resulting in an overall TOC removal of 84%. The toxic responses of PMS/UV-C treated OPEO solutions varied according to the test organism used in the bioassay. Daphnia magna was found to be most sensitive to aqueous OPEO, whereas Pseudokirchneriella subcapitata appeared to be the least sensitive one. Daphnia magna and Vibrio fischeri tests revealed that the inhibitory effect of OPEO decreased significantly during the course of treatment. On the other hand, PMS/UV-C oxidation products exhibited a high toxic effect towards Pseudokirchneriella subcapitata (around 60%). YES test results underlined the need for improving the PMS/UV-C treatment performance to remove the estrogenic activity of OPEO and its oxidation products

S2O8(2-)/UV-C and H2O2/UV-C treatment of Bisphenol A: Assessment of toxicity, estrogenic activity, degradation products and results in real water

The performance of S2O8 2/UV-C and H2O2/UV-C treatments was investigated for the degradation and detoxification of Bisphenol A (BPA). The acute toxicity of BPA and its degradation products was examined with the Vibrio fischeri bioassay, whereas changes in estrogenic activity were followed with the Yeast Estrogen Screen (YES) assay. LC and LC–MS/MS analyses were conducted to determine degradation products evolving during photochemical treatment. In addition, BPA-spiked real freshwater samples were also subjected to S2O82/UV-C and H2O2/UV-C treatment to study the effect of a real water matrix on BPA removal and detoxification rates. BPA removal in pure water was very fast (67 min) and complete via both H2O2/UV-C and S2O82/UV-C treatment, accompanied with rapid and significant mineralization rates ranging between 70% and 85%. V. fischeri bioassay results indicated that degradation products being more toxic than BPA were formed at the initial stages of H2O2/UV-C whereas a rapid and steady reduction in toxicity was observed during S2O82/UV-C treatment in pure water. UV-C treatment products exhibited a higher estrogenic activity than the original BPA solution while the estrogenicity of BPA was completely removed during H2O2/UV-C and S2O82/UV-C treatments parallel to its degradation. 3-methylbenzoic and 4-sulfobenzoic acids, as well as the ring opening products fumaric, succinic and oxalic acids could be identified as degradation products. BPA degradation required extended treatment periods (&gt;20 min) and TOC removals were considerably retarded (by 40%) in the raw freshwater matrix most probably due to its natural organic matter content (TOC = 5.1 mg L1). H2O2/UV-C and S2O82/UV-C treatment in raw freshwater did not result in toxic degradation products