Treatment of Sanitary Landfill Leachate by Photo-Fenton Process: Effect of the Matrix Composition

Silva, Jader O.; Silva, Valdislaine M.; Cardoso, Vicelma Luiz; Machado, Antônio Eduardo da Hora; Trovó, Alam G.

doi:10.5935/0103-5053.20160120

Cited by 6 publications

(9 citation statements)

References 31 publications

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“…It is important to take into account that the necessary acid concentration for decreasing the pH of the LL was very high due to its high alkalinity (13,244 mg/L CaCO 3 ). Therefore, this pH adjustment implies an increase of conductivity and concentration of salts (sulphates, as sulphuric acid was used for pH adjustment) which can also retard the Fenton process [43] and may imply posterior management difficulties. To decrease the pH from its initial value pH = 8.2 to pH = 7 and pH = 5, the conductivity increased from 24.9 mS/cm to 25.5 mS/cm and 26.4 mS/cm, requiring 1 and 7.2 g/L of sulphuric acid, respectively.…”

Section: Coagulation: Effect Of Ph and Dosage Of Coagulantsmentioning

confidence: 99%

Treatment of a Mature Landfill Leachate: Comparison between Homogeneous and Heterogeneous Photo-Fenton with Different Pretreatments

Tejera

Miranda

Hermosilla

et al. 2019

Water

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This study focuses on the treatment of a mature landfill leachate by coagulation and photo-Fenton at different conditions. Optimal coagulation is carried out with ferric chloride in acid conditions; and with alum in near-neutral conditions, to minimize the use of sulphuric acid for pH adjustment (1 g/L vs. 7.2 g/L), the generation of sludge and the increase of conductivity in the final effluent. In both cases, a similar chemical oxygen demand (COD) removal is obtained, higher than 65%, which is high enough for a subsequent photo-Fenton treatment. However, the removal of absorbance at 254 nm (UV-254) was significantly higher with ferric chloride (83% vs. 55%), due to the important removal of humic acids at acid pH. The best results for coagulation are 2 g/L ferric chloride at initial pH = 5 and 5 g/L alum at initial pH = 7. After coagulation with ferric chloride, the final pH (2.8) is adequate for a homogeneous photo-Fenton using the remaining dissolved iron (250 mg/L). At these conditions, using a ratio H2O2/COD = 2.125 and 30 min contact time, the biodegradability increased from 0.03 to 0.51. On the other hand, the neutral pH after alum coagulation (6.7) allows the use of zero valent iron (ZVI) heterogeneous photo-Fenton. In this case, a final biodegradability of 0.32 was obtained, after 150 min, using the same H2O2/COD ratio. Both treatments achieved similar results, with a final COD, UV-254 and color removal greater than 90%. However, the economic assessment shows that the approach of ferric chloride + homogeneous photo-Fenton is much cheaper (6.4 €/m3 vs. 28.4 €/m3). Although the discharge limits are not achieved with the proposed combination of treatments, the significant increase of the pre-treated leachate biodegradability allows achieving the discharge limits after a conventional biological treatment such as sequencing batch reactor, which would slightly increase the total treatment cost.

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Section: Coagulation: Effect Of Ph and Dosage Of Coagulantsmentioning

confidence: 99%

Treatment of a Mature Landfill Leachate: Comparison between Homogeneous and Heterogeneous Photo-Fenton with Different Pretreatments

Tejera

Miranda

Hermosilla

et al. 2019

Water

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“…, and SO 4 •-); and (iv) oxidation reactions involving these radicals (Kiwi et al 2000;Truong et al 2004;De Laat and Le 2006;De Laat et al 2004;Silva et al 2015Silva et al , 2016.…”

Section: •-mentioning

confidence: 99%

Degradation of Direct Red 81 mediated by Fenton reactions: multivariate optimization, effect of chloride and sulfate, and acute ecotoxicity assessment

Marson

Paiva

Gonçalves

et al. 2016

Environ Sci Pollut Res

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The role of different operational parameters related to Fenton reactions (pH, concentration of Fe and HO, and reaction time) and of Cl and SO was investigated in the degradation of the azo dye Direct Red 81, expressed in terms of its decolorization. The factorial design and Pareto's charts showed that only Fe concentration and pH influence the decolorization under the conditions evaluated. So, only these parameters were optimized using the response surface model. Under the best experimental conditions (initial pH 2.5, 11 mg L Fe, 78 mg L HO, and 20 min of reaction), 94 % of decolorization was achieved. However, even under the these conditions, but in the presence of Cl and SO , a striking loss of efficiency was observed as the concentration of these ions was increased, due the formation of chloride- and sulfate-iron complexes and less reactive inorganic radicals (Cl and SO). The results show that the presence of Cl is more deleterious, since sulfate-iron complexes are more reactive towards HO, and the SO turns out to favor the degradation. On the other hand, the negative effect of Cl can be compensated by increasing the chloride concentration up to 300 mmol L. In addition, although a high degradation level has been obtained by monitoring the dye absorbance and by HPLC-UV, a low mineralization occurred, being generated degradation products of higher ecotoxicity to Vibrio fischeri, showing the need of subsequent studies to identify these compounds as well as the application of additional treatments aiming the complete mineralization of the dye.

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“…In this way, the integration of this process to an additional treatment is necessary for removal of organic matter, oils and fats to attend the Brazilian legislation. Considering the high level of the remaining organic load in addition to toxicity, an advanced oxidation process, [26][27][28][29][30] electrochemical 31 or the coupling between advanced oxidation and biological processes, 32,33 would be the most appropriate options for the complete treatment of biodiesel wastewaters.…”

Section: +mentioning

confidence: 99%

Biodiesel Wastewater Treatment by Coagulation-Flocculation: Evaluation and Optimization of Operational Parameters

Gonçalves¹,

Neto²,

Machado³

et al. 2016

J. Braz. Chem. Soc.

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In this study the coagulation-flocculation process was evaluated as an alternative for treatment of biodiesel wastewater. The role of two coagulants, Al 3+ and Fe 3+ , as well as its dosage, pH, treatment time, stirring and aeration were evaluated. It was observed that in the treatment using Al 3+ the pH of the effluent (9.7) does not need to be adjusted, while for Fe 3+ a previous adjustment to pH 5.0 was necessary. On the other hand, a high concentration of Al 3+ (243 mg L -1) and a relatively long treatment time (70 min) were required to reach more than 96% of turbidity removal, when compared to the processing using Fe 3+ (56 mg L -1 and 53 min), attributed to the formation of different mole fractions of hydrolyzed cationic species. Under the optimized conditions, more than 96% of turbidity, apparent color and suspended solids, and 82% of oil and fats were removed. Keywords: aluminum sulfate, biodiesel effluent, ferric chloride, physical-chemical treatment, turbidity IntroductionThe quality of the biodiesel is directly dependent on its refinement process, which produces large volumes of wastewater inappropriate for disposal in water bodies. [1][2][3][4] In general, biodiesel wastewater is characterized by expressive values of chemical oxygen demand (COD) and biochemical oxygen demand (BOD 5 ), respectively between 9,500 and 230,000 mg L -1 and 1,650 and 3,200 mg L -1 , due the presence of glycerin, alcohols (methanol and/ or ethanol), oil, fats and other contaminants; 5 turbidity between 189 and 2,550 NTU; oils and fats between 124 and 7,200 mg L -1 ; color between 361 and 1,500 mg Pt-Co L -1 ; total solids between 3.7 and 25 g L -1 ; residual methanol between 8 and 29% (m/m) and residual glycerin between 0.6 and 1.6 (m/m). 3,4 In terms of oils and fats, the Brazilian legislation establishes as 50 mg L -1 the maximum disposal limit for wastewaters derived from the production of biodiesel.6 So, it is extremely important the study and proposition alternative processes for the efficient treatment of this kind of wastewater. This is a research field relatively new, once the first studies on biodiesel wastewater treatment started on 2005. 4 Three reviews on biodiesel wastewater treatment have been recently published. 1,4,5 One of them summarizes a significant number of possible processes and discusses their advantages and disadvantages as well as the possibilities of application for the improvement of the treatment of biodiesel wastewaters. The improvement of the operational parameters of the coagulation-flocculation process, based on the coupling of acidification and coagulation, has been pointed as promisor for this purpose. 4 Since biodiesel wastewaters contain soaps (presence of polar anionic and nonionic groups), oils and fats (presence of carboxylic groups), the cycle of emulsificationdemulsification tends to be strongly pH dependent. Low pH values favor the demulsification through the reduction of the electrical forces or by the commitment of the electrical double-layer, 7 with the opposite effect at...

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Treatment of Sanitary Landfill Leachate by Photo-Fenton Process: Effect of the Matrix Composition

Cited by 6 publications

References 31 publications

Treatment of a Mature Landfill Leachate: Comparison between Homogeneous and Heterogeneous Photo-Fenton with Different Pretreatments

Treatment of a Mature Landfill Leachate: Comparison between Homogeneous and Heterogeneous Photo-Fenton with Different Pretreatments

Degradation of Direct Red 81 mediated by Fenton reactions: multivariate optimization, effect of chloride and sulfate, and acute ecotoxicity assessment

Biodiesel Wastewater Treatment by Coagulation-Flocculation: Evaluation and Optimization of Operational Parameters

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