Session 5 - Advanced oxidation processes

[CEST2019_00766] Micro-pollutants, Oxidants, Catalysts and the Water Matrix: A Harmonic Quartet or the War of the Roses?
by Mantzavinos D.

Advanced oxidation processes (AOPs, e.g. heterogeneous and homogeneous photocatalysis, electrochemical oxidation, ozonation, ultrasound irradiation, Fenton and alike reactions, and many more) have been investigated for the treatment of emerging pollutants over the past 20 years (Klavarioti et al., 2009). In particular, the occurrence of persistence micro-pollutants in various water matrices, such as pharmaceuticals and personal care products, raises serious environmental concerns since these xenobiotics can re-enter the water cycle, i.e. escaping intact from the conventional wastewater treatment plants and finally ending up in surface and ground waters (Verlicchi et al., 2012).AOPs can effectively degrade organic pollutants typically found in environmental matrices (secondary treated effluents, surface waters, ground waters) at concentrations ranging from the ng/L to low mg/L level. This said, the specific treatment cost (i.e. the cost per unit mass of removed pollutant and/or per unit volume of effluent), as well as the environmental footprint are generally high; both are usually related to the treatment performance, which, in turn, depends on the specific treatment conditions and the quality of the water matrix.

Session: 5, Room: E, at Thu, 09/05/2019 - 09:00 to 09:30
Oral presentation in Advanced oxidation processes
[CEST2019_00259] Electrochemical Treatment of Landfill Leachate under Cold Climate Conditions
by Ambauen N.,Hallé C., Meyn T.

This study shows that electrochemical oxidation of landfill leachate (LL) is significantly affected by cold temperatures prevailing in Nordic climate areas. As hypothesized, the degradation of common wastewater parameters (TOC, COD) exhibited lower efficiency when low average temperature (13°C) was applied than compared to room temperature (25°C). At low temperature, 35 % of COD and 64 % of TOC were removed, compared to 69 % of COD and 74 % of TOC removal at high temperature. Electrochemical oxidation of ammonium (NH4) has also been observed, whereas only 1 % was removed at 13°C compared to 11 % at 25°C. In addition, the formation of three hazardous trihalomethanes (THMs) has been confirmed when a high current (7A) was applied, but THMs remained below the quantification limit of 3 ppb at low current (0.3 A). Even though kinetics decrease when cold temperatures are prevailing, electrochemical oxidation is considered still a suitable choice for the treatment of landfill leachate in areas with Nordic climate.

Session: 5, Room: E, at Thu, 09/05/2019 - 10:15 to 10:30
Oral presentation in Advanced oxidation processes
[CEST2019_00227] UV/H2O2 coupled with adsorption for decolorization of dye mixtures in water and phytotoxic effects
by Ortega A.C., Alvarez C.F., Cardona L., Arroyave C., Aristizábal A.

The present study reported the decolorization by UV/H2O2 of three dyes and their binary and ternary mixtures in water, simulating colored effluents of the textile industry. The effect of the initial concentration of H2O2, the initial concentration of dyes and the reaction kinetics in the decolorization of textile dyes in water was studied. The efficiency of decolorization of three treatment processes was compared (UV, H2O2 and UV/H2O2). Moreover, after decolorization of the simulated waters by UV/H2O2 the effluents were then treated by adsorption using a commercial aluminosilicate and a silica gel (waste from industry). The phytotoxicity of the effluents was determined before and after adsorption treatment using the Raphanus sativus bioassay.

Session: 5, Room: E, at Thu, 09/05/2019 - 10:00 to 10:15
Oral presentation in Advanced oxidation processes
[CEST2019_00206] Comparative Analysis of Chlorinated Intermediates Formed During Electrochemical and Photo(electro)catalytic Degradation of 4-Ethylphenol in Saline Media
by Brüninghoff R., Van Duijne A., Braakhuis L., Saha P., Jeremiasse A., Mei B., Mul G.

Formation of toxic by-products, such as chlorinated intermediates, is one of the major drawbacks of advanced oxidation processes for saline wastewater treatment. Here a comparative analysis of electrochemical oxidation and photocatalytic degradation of 4-Ethylphenol, a non-chlorinated starting model compound of the group of alkylphenols, is presented. Main intermediates have been identified and quantified for brackish [0.03 mol*L-1] and sea water [0.6 mol*L-1] salt concentrations representative for the salt levels in various industrial effluents. Our comparison indicates that photocatalytic treatment (using TiO2 photocatalysts) might be favorable over electrochemical treatments with Pt or BDD anodes due to the minor role of chlorination and the limited formation of chlorinated compounds in photocatalysis. Finally, using photoelectrochemical degradation an external surface recombination mechanism of photogenerated charge carriers will be presented explaining the absence of chlorinated compounds during photocatalytic wastewater treatment.

Session: 5, Room: E, at Thu, 09/05/2019 - 09:45 to 10:00
Oral presentation in Advanced oxidation processes
[CEST2019_00015] US/H2O2 combined technology applied to the paracetamol oxidation
by Villota N., Lomas J.M.

This study analyzes the colour acquired by oxidizing paracetamol aqueous samples through the combined US/H2O2 technology. When operating with only the action of the waves [US]=1.0 kWh/mmol C8H9NO2, the water acquires progressively hue according to a ratio of 0.0004 AU/min, with a degradation output of 14%. Working under these conditions, the presence of hydroquinone, muconic acid and formic acid is evaluated. Colour formation presents a maximum intensity when water containing paracetamol is degraded using molar ratios of 1.5 mol H2O2/mol C8H9NO2. This dosage leads to the formation of benzoquinone, as well as muconic and formic acids, reaching an efficiency of 30%. Oxidazing with 6.0 mol H2O2/mol C8H9NO2, colour formation occurs slowly during the first hour of reaction, leading to the formation of benzoquinone, hydroquinone, acetamide, phoroglucinol and formic and muconic acids. This last one presents a molecular structure that is prone to reacting with other species that are present in the system forming complexes.

Session: 5, Room: E, at Thu, 09/05/2019 - 09:30 to 09:45
Oral presentation in Advanced oxidation processes