Enhancing methane yield from crude glycerol anaerobic digestion by coupling with ultrasound or A. niger/E. coli biodegradation

Anaerobic digestion of crude glycerol from biodiesel production is a feasible way for methane production. However, crude glycerol (CG) contains impurities, such as long-chain fatty acids (LCFA) that can inhibit methanogenic microorganisms. Ultrasound promotes the hydrolysis of LCFA and deagglomerates the microorganisms in biological flocs. Furthermore, Aspergillus niger and Escherichia coli produce lipases capable of degrading LCFA. This study aims at improving the methane yield from anaerobic digestion by coupling with ultrasound or E. coli/A. niger biodegradation. The effect of the different treatments was first assessed in a perfectly mixed batch reactor (PMBR), using diluted CG at concentrations of 0.2%, 1.7%, and 3.2% (v/v). Later, the best conditions were replicated in an upflow anaerobic sludge blanket (UASB) reactor to simulate full-scale practical applications. Experiments in the PMBR showed that ultrasound or A. niger biodegradation steps improved methane yield up to 11% for 0.2% CG and 99% for 1.7% CG, respectively. CG biodegradation by E. coli inhibited the subsequent anaerobic digestion for all concentrations tested. Using a UASB digester, ultrasonic treatment of CG led to an average increase of 29% in methane production. The application of ultrasound led to a lower accumulation of propionic acid in the digested material and increased biogas production. On the other hand, an average 77% increase in methane production was achieved using a preliminary CG biodegradation step by A. niger, when operated at a loading rate of 2.9 kg COD m-3 day-1. Under these conditions, an energy gain of 0.48 kWh day-1, with the production of the 0.434 m3 CH4 kg-1 CODremoval and 0.573 m3 CH4 kg-1 VS, and a biogas quality of 73% in methane were obtained. The digested material was analyzed for the detection and quantification of added-value by-products in order to obtain a broad assessment of the CG valorization through anaerobic digestion. In some experiments, propionic and oxalic acid were detected. However, the accumulation of propionic caused the inhibition of the acetogenic and methanogenic microorganisms.info:eu-repo/semantics/publishedVersio

New insights on mechanisms of sulfonamide bio-transformation by environmental bacteria

info:eu-repo/semantics/publishedVersio

Enhancement of a solar photo-Fenton reaction by using ferrioxalate complexes for the treatment of a synthetic cotton-textile dyeing wastewater

Biological, photo-Fenton (PF) and photo-Fenton mediated by ferrioxalate complexes (PF/Ferrioxalate) processes were examined for the degradation of a synthetic cotton-textile dyeing wastewater. Aerobic biological treatment had a negligible effect on discolouration whereas total organic content decreased mainly due to the biodegradation of acetic acid initially present in the wastewater. PF process yielded a fast and pronounced dissolved organic carbon concentration decay, mostly associated to the abrupt precipitation of Fe(III)-organic complexes. The addition of oxalic acid limited iron precipitation, allowing mineralization of most organic contaminants. The influence of the different dyes and main dyeing auxiliary constituents of the synthetic textile wastewater on the PF and the PF/Ferrioxalate efficiency was systematically analysed. The suitability of combining PF/Ferrioxalate with conventional biological processes as a pre and/or post treatment was evaluated.This study highlights the potential of PF/Ferrioxalate reaction to mineralize the synthetic cotton-textile wastewater under appropriate experimental conditions, the best being: [Fe3+]=40mgL-1, iron/oxalate molar ratio=1:3, pH=4.0 and [H2O2]=50-100 (1.5-2.9)mgL-1 (mmolL-1). At these conditions, the PF/Ferrioxalate treatment was carried out under natural sunlight in a pilot plant equipped with compound parabolic collectors.Fil: Doumic, Lucila Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina. Universidad de Porto; Portugal. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; ArgentinaFil: Soares, Petrick A.. Universidad de Porto; PortugalFil: Ayude, María Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Cassanello Fernandez, Miryam Celeste. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; ArgentinaFil: Boaventura, Rui A.R.. Universidad de Porto; PortugalFil: Vilar, Vítor J.P.. Universidad de Porto; Portuga

Solar thermo-photocatalytic methanation using a bifunctional RuO2:TiO2/Z13X photocatalyst/adsorbent material for efficient CO2 capture and conversion

A novel bifunctional photocatalyst/adsorbent material based on the RuO2:TiO2/zeolite 13X (Z13X) composite was developed to enhance solar-driven methanation through simultaneous carbon dioxide (CO2) capture and thermo-photoconversion. The activity/stability of the hybrid material towards methane (CH4) production was assessed by varying the (i) photocatalyst composition (Ru load and semiconductor type), (ii) bifunctional material composition (photocatalyst-to-zeolite ratio) and impregnation method, (iii) illumination source and power (simulated sunlight and UVA/Visible LEDs), (iv) temperature, and (v) catalyst reuse. Additionally, adsorption equilibrium isotherms were determined to characterize the adsorption ability of the bifunctional material for both CO2 and CH4 gases. The hybrid RuO2(4.0%):TiO2(26.3%)/Z13X material (30 mg), synthesised by the solid-state impregnation method, showed the best results under simulated sunlight (0.75 W) at 150 ºC, achieving a 88% CO2 thermo-photoreduction after 100 min, corresponding to a specific CH4 production of 29.2 mmol gactive_cat−1 h−1 (309 mmol gRu−1 h−1) and apparent quantum yield of 20.7%. In adsorption equilibrium isotherms, the bifunctional material's adsorption was about 2.6-fold higher than the photocatalyst at 150 ºC, suggesting that enhanced methanation performance can be attributed to the synergistic action of CO2 capture and thermo-photoconversion.This work was supported by sources provided by: (i) national funds through Fundaç˜ao para a Ciˆencia e a Tecnologia (FCT), and Minist´erio da Ciˆencia, Tecnologia e Ensino Superior (MCTES), Portugal, in the framework of Programa de Investimento e Despesas de Desenvolvimento da Administraç˜ao Central (PIDDAC), under Project CO2-to-CH4, 2022.01176.PTDC (DOI: 10.54499/2022.01176.PTDC); and (ii) Norte Portugal Regional Operational Programme (NORTE 2020), in the framework of the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF), under the project HyGreen&LowEmissions, NORTE- 01–0145-FEDER-000077. This research was also funded by (iii) FCT/ MCTES (PIDDAC): LSRE-LCM - UIDB/50020/2020 (DOI: 10.54499/ UIDB/50020/2020) and UIDP/50020/2020 (DOI: 10.54499/UIDP/ 50020/2020); and ALiCE - LA/P/0045/2020 (DOI: 10.54499/LA/P/ 0045/2020). Larissa O. Paulista acknowledges the Ph.D. fellowship supported by FCT (reference SFRH/BD/137639/2018 and COVID/BD/152922/2022). Vítor J.P. Vilar and Tˆania F.C.V. Silva acknowledges the FCT Individual Call to Scientific Employment Stimulus 2017 (CEECIND/01317/2017 and CEECIND/0138/2017).info:eu-repo/semantics/publishedVersio

The role of ozone combined with UVC/H2O2 process for the tertiary treatment of a real slaughterhouse wastewater

The main goal of this work is to evaluate the usage of ozone (O3) as a pre-treatment or simultaneously combined with UVC/H2O2 process for the polishing stage treatment of real bio-treated slaughterhouse wastewater. Two different treatment strategies were tested: i) pre-ozonation of the wastewater followed by an UVC/H2O2 process (two-step treatment); ii) simultaneous application of O3/UVC/H2O2 combined process (one-step treatment). For the two-step strategy, the pre-treatment with 30 mg O3/min for 10 min reduces significantly total suspended solids (TSS), turbidity and colour, reducing light filtering effects and increasing the efficiency of the following UVC/H2O2 process. In turn, the one-step treatment strategy (O3/UVC/H2O2) allows a more efficient use of injected O3 by reducing the amount of O3 required (from 273 to 189 mg O3/Leffluent) to achieve similar mineralization levels. The real bio-treated slaughterhouse wastewater treated by O3/UVC/H2O2 process achieved final colour values of 20 Pt/Co, TSS of 35 mg/L and COD of 61 mg O2/L, allowing its direct discharge into water compartments according to European Council Directive 91/271/EEC

Enhancing methane yield from crude glycerol anaerobic digestion by coupling with ultrasound or A. niger/E. coli biodegradation

Anaerobic digestion of crude glycerol from biodiesel production is a feasible way for methane production. However, crude glycerol (CG) contains impurities, such as long-chain fatty acids (LCFA) that can inhibit methanogenic microorganisms. Ultrasound promotes the hydrolysis of LCFA and deagglomerates the microorganisms in biological flocs. Furthermore, Aspergillus niger and Escherichia coli produce lipases capable of degrading LCFA. This study aims at improving the methane yield from anaerobic digestion by coupling with ultrasound or E. coli/A. niger biodegradation. The effect of the different treatments was first assessed in a perfectly mixed batch reactor (PMBR), using diluted CG at concentrations of 0.2%, 1.7%, and 3.2% (v/v). Later, the best conditions were replicated in an upflow anaerobic sludge blanket (UASB) reactor to simulate full- scale practical applications. Experiments in the PMBR showed that ultrasound or A. niger biodegradation steps improved methane yield up to 11% for 0.2% CG and 99% for 1.7% CG, respectively. CG biodegradation by E. coli inhibited the subsequent anaerobic digestion for all concentrations tested. Using a UASB digester, ultrasonic treatment of CG led to an average increase of 29% in methane production. The application of ultrasound led to a lower accumulation of propionic acid in the digested material and increased biogas production. On the other hand, an average 77% increase in methane production was achieved using a preliminary CG biodegradation step by A. niger, when operated at a loading rate of 2.9 kg COD m-3 day-1. Under these conditions, an energy gain of 0.48 kWh day-1, with the production of the 0.434 m3 CH4 kg-1 CODremoval and 0.573 m3 CH4 kg-1 VS, and a biogas quality of 73% in methane were obtained. The digested material was analyzed for the detection and quantification of added-value by-products in order to obtain a broad assessment of the CG valorization through anaerobic digestion. In some experiments, propionic and oxalic acid were detected. However, the accumulation of propionic caused the inhibition of the acetogenic and methanogenic microorganisms.info:eu-repo/semantics/publishedVersio

Multistage treatment for olive mill wastewater: Assessing legal compliance and operational costs

A treatment train for the remediation of a raw olive mill wastewater (OMW) was investigated, aiming to comply with the emission limit values (ELVs) for direct discharge into water bodies. The following stages were proposed: (i) pre-treatment (filtration and sedimentation), (ii) coagulation, (iii) biological oxidation, and (iv) advanced oxidation process (AOP). Under the best-operating conditions for coagulation (0.8 g L- 1 of Al2(SO4)3, pH = 4.5), high removal of total suspended solids (TSS) (97%), turbidity (98%), and phenols (57%) was achieved, along with a decrease in the inhibition of the biological activity. A subsequent biological oxidation stage provided a high removal of organic matter (chemical oxygen demand (COD) removal of 73%). For the third stage, three AOPs were applied and compared – photo-Fenton with UVA radiation (PF-UVA), anodic oxidation (AO), and ozonation (O3). After 3 h of treatment, the PF-UVA process (pH = 2.8, [H2O2] = 400–500 mg L- 1, [Total dissolved iron]0 = 100 mg L- 1) allowed to meet the ELV for COD, but the other parameters exceeded the threshold, while O3 process (inlet concentration = 100 mg O3 Ndm- 3, gas flow = 0.2 Ndm3 min- 1) allowed to comply with phenols, TSS, and sulfate limits. The AO process (current density up to 200 mA cm- 2) was the least efficient AOP for all studied parameters. The operational costs for the coagulation and biological oxidation stages were estimated at 1.20 € m- 3. Regarding the most effective AOPs, ozonation presented an estimated cost 2.3-fold higher than PF-UVA (11.9 € m- 3 vs. 5.2 € m- 3).This work was financially supported by (i) LA/P/0045/2020 (ALiCE), UIDB/50020/2020 and UIDP/50020/2020 (LSRE-LCM), funded by national funds through FCT/MCTES (PIDDAC), and (ii) Project NORTE-01-0247-FEDER-072124, Bagaço+Valor - Tecnologia Limpa para a Valorização dos Subprodutos do Bagaço na Indústria Extratora de Azeite, funded by the European Regional Development Fund (ERDF). Srikanth Vuppala acknowledges the Joint Research Projects for the International Mobility of the XXXI and XXXII cycle PhD students for the project: CHEMBIOCAT, La Sapienza University of Rome. Larissa O. Paulista and Daniela F.S. Morais acknowledge their Ph.D. scholarships supported by FCT (SFRH/BD/137639/2018 and SFRH/BD/146476/2019, respectively). Francisca C. Moreira and Vítor J.P. Vilar acknowledge the FCT Individual Call to Scientific Employment Stimulus 2017 (CEECIND/02196/2017 and CEECIND/01317/2017, respectively).info:eu-repo/semantics/publishedVersio

AOPs: recent advances to overcome barriers in the treatment of water, wastewater and air

This is a post-peer-review, pre-copyedit version of an article published in Environmental Science and Pollution Research. The final authenticated version is available online at: http://dx.doi.org/10.1007/s11356-017-8425-7

Single and combined electrochemical oxidation driven processes for the treatment of slaughterhouse wastewater

Electrochemical oxidation (EO) and EO related processes, either alone or in combination with pre-ozonation, were investigated as a polishing step for slaughterhouse wastewater treatment. The wastewater had previously been subjected to grit removal, degreasing, biological treatment and settling, but failed to comply with European emission limits for treated urban wastewaters in regards to organic compounds, suspended solids and colour. Besides EO alone, the following processes were applied: EO with hydrogen peroxide (EO/H₂O₂), EO with ultraviolet C light (EO/UVC) and EO with ultraviolet C light and hydrogen peroxide (EO/UVC/H₂O₂). Without pre-ozonation, electrochemical processes could be arranged in the following order according to their ability to mineralisation and colour removal: EO ˂ EO/H₂O₂ ˂ EO/UVC ˂ EO/UVC/H₂O₂. To reach a colour of 25 mg Pt-Co/L, it took more than 480 min for EO, ῀400 min for EO/H₂O₂, ῀260 min for EO/UVC and ῀120 min for EO/UVC/H₂O₂. At this treatment time, chemical oxygen demand and suspended solids were below the European emission limit values. The pre-ozonation step improved organics removal by EO and all related processes by converting the original organic compounds into easily oxidisable compounds. Beyond that, ozonation itself led to suspended solids and colour abatement to values in agreement with the legislated/permissible discharge limits

Insights on sulfamethoxazole bio-transformation by environmental proteobacteria isolates

Although sulfonamide residues are frequently reported as freshwaters contaminants, information on the ability of native bacteria to modify these synthetic antibiotics is scarce. Our purpose was to investigate the potential of bacteria from different aquatic environments to cleave or transform sulfamethoxazole (SMX) and infer on their ability to reduce the toxicity of this antibiotic. From a collection of about 100 Proteobacteria, 47 strains previously isolated from drinking water, surface water, and wastewater grew in the presence of 200 μMSMX, and were further studied. Out of these, 14 strains, mostly from mineral drinking water, transformed SMX into equimolar amounts of the lesser toxic derivative N4-acetyl-sulfamethoxazole. The highest percentage of SMX transformation was recorded for two strains affiliated to Pseudomonas mandelii. For P. mandelii McBPA4 higher SMX transformation rate and extent were observed in fed-batch (∼8 μMSMX/h, 81%) than in batch conditions (∼5 μMSMX/h, 25%), but similar specific transformation rates were found in both cultivation modes (∼20 μmolSMX/gcell dry weight/h), indicating the dependence of the process on the microbial load. These results evidence that the capacity to transform synthetic antibiotics may be common among bacteria and highlight the potential of environmental bacteria in attenuating the potential adverse effects of pollution with sulfonamides.info:eu-repo/semantics/publishedVersio