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Article

Continuous Treatment of Refractory Wastewater from Research and Teaching Laboratories via Supercritical Water Oxidation–Experimental Results and Modeling

by
Mariana Bisinotto Pereira
1,
Guilherme Botelho Meireles de Souza
1,2,
Isabela Milhomem Dias
2,
Julles Mitoura dos Santos-Júnior
3,
Antônio Carlos Daltro de Freitas
3,
Jose M. Abelleira-Pereira
4,
Christian Gonçalves Alonso
2,
Lucio Cardozo-Filho
1 and
Reginaldo Guirardello
5,*
1
Programa de Pós-Graduação em Engenharia Química, Universidade Estadual de Maringá (UEM), Avenida Colombo, 5790-Zona 7, Maringá 87020-900, PR, Brazil
2
Programa de Pós-Graduação em Engenharia Química, Universidade Federal de Goiás (UFG), Avenida Esperança, s/n-Chácaras de Recreio Samambaia, Goiânia 74690-900, GO, Brazil
3
Engineering Department, Exact Sciences and Technology Center, Federal University of Maranhão (UFMA), Av. dos Portugueses, 1966, Bacanga, São Luís 65080-805, MA, Brazil
4
Department of Chemical Engineering and Food Technology, Faculty of Sciences, International Excellence Agrifood Campus (CeiA3), University of Cádiz, 11510 Puerto Real, Cádiz, Spain
5
School of Chemical Engineering, University of Campinas (UNICAMP), Av. Albert Einstein 500, Campinas 13083-852, SP, Brazil
*
Author to whom correspondence should be addressed.
Water 2023, 15(22), 3926; https://doi.org/10.3390/w15223926
Submission received: 14 October 2023 / Revised: 3 November 2023 / Accepted: 8 November 2023 / Published: 10 November 2023

Abstract

Teaching and research laboratories generate wastes of various compositions and volumes, ranging from diluted aqueous solutions to concentrated ones, which, due to milder self-regulation waste-management policies, are carelessly discarded, with little attention given to the consequences for the environment and human health. In this sense, the current study proposes the application of the supercritical water oxidation (SCWO) process for the treatment of complex refractory wastewater generated in research and teaching laboratories of universities. The SCWO, which uses water in conditions above its critical point (T > 647.1 K, p > 22.1 MPa), is regarded as an environmentally neutral process, uniquely adequate for the degradation of highly toxic and bio-refractory organic compounds. Initially, the wastewater samples were characterized via headspace gas chromatography coupled with mass spectrometry. Then, using a continuous tubular reactor, the selected operational parameters were optimized by a Taguchi L9 experimental design, aiming to maximize the total organic carbon reduction. Under optimized conditions—that is, temperature of 823.15 K, feed flow rate of 10 mL min−1, oxidizing ratio of 1.5 (50% excess over the oxygen stoichiometric ratio), and sample concentration of 30%—TOC, COD, and BOD reductions of 99.9%. 91.5% and 99.2% were achieved, respectively. During the treatment process, only CO2, methane, and hydrogen were identified in the gaseous phase. Furthermore, the developed methodology was applied for the treatment of wastewater samples generated in another research laboratory and a TOC reduction of 99.5% was achieved, reinforcing the process’s robustness. A thermodynamic analysis of SCWO treatment of laboratory wastewater under isothermal conditions was performed, using the Gibbs energy minimization methodology with the aid of the GAMS® 23.9.5. (General Algebraic Modeling System) software and the CONOPT 4 solver. Therefore, the results showed that SCWO could be efficiently applied for the treatment of wastewater generated by different teaching and research laboratories without the production of harmful gases and the addition of hazardous chemicals.
Keywords: supercritical water; refractory effluent; organic degradation; thermodynamic analysis supercritical water; refractory effluent; organic degradation; thermodynamic analysis

Share and Cite

MDPI and ACS Style

Pereira, M.B.; Meireles de Souza, G.B.; Dias, I.M.; dos Santos-Júnior, J.M.; de Freitas, A.C.D.; Abelleira-Pereira, J.M.; Alonso, C.G.; Cardozo-Filho, L.; Guirardello, R. Continuous Treatment of Refractory Wastewater from Research and Teaching Laboratories via Supercritical Water Oxidation–Experimental Results and Modeling. Water 2023, 15, 3926. https://doi.org/10.3390/w15223926

AMA Style

Pereira MB, Meireles de Souza GB, Dias IM, dos Santos-Júnior JM, de Freitas ACD, Abelleira-Pereira JM, Alonso CG, Cardozo-Filho L, Guirardello R. Continuous Treatment of Refractory Wastewater from Research and Teaching Laboratories via Supercritical Water Oxidation–Experimental Results and Modeling. Water. 2023; 15(22):3926. https://doi.org/10.3390/w15223926

Chicago/Turabian Style

Pereira, Mariana Bisinotto, Guilherme Botelho Meireles de Souza, Isabela Milhomem Dias, Julles Mitoura dos Santos-Júnior, Antônio Carlos Daltro de Freitas, Jose M. Abelleira-Pereira, Christian Gonçalves Alonso, Lucio Cardozo-Filho, and Reginaldo Guirardello. 2023. "Continuous Treatment of Refractory Wastewater from Research and Teaching Laboratories via Supercritical Water Oxidation–Experimental Results and Modeling" Water 15, no. 22: 3926. https://doi.org/10.3390/w15223926

APA Style

Pereira, M. B., Meireles de Souza, G. B., Dias, I. M., dos Santos-Júnior, J. M., de Freitas, A. C. D., Abelleira-Pereira, J. M., Alonso, C. G., Cardozo-Filho, L., & Guirardello, R. (2023). Continuous Treatment of Refractory Wastewater from Research and Teaching Laboratories via Supercritical Water Oxidation–Experimental Results and Modeling. Water, 15(22), 3926. https://doi.org/10.3390/w15223926

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