Browsing by Author "Paulista, Larissa Oliveira"
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- Anaerobic digestion performance in the energy recovery of kiwi residuesPublication . Paulista, Larissa Oliveira; Boaventura, Rui; Martins, RamiroWorld production and trade of fruits generate losses in the harvest, post-harvest, handling, distribution and consumption phases, corresponding to 6.8% of total production. These residues present high potential as a substrate for the anaerobic digestion process and biogas generation. Thus, the energy valuation of the agro-industrial residues of kiwifruit production was evaluated by anaerobic digestion, aiming at optimizing the biogas production and its quality. Ten assays were carried out in a batch reactor (500 mL) under mesophilic conditions and varying a number of operational factors: different substrate/inoculum ratios; four distinct values for C: N ratio; inoculum from different digesters; and inoculum collected at different times of the year. The following parameters were used to control and monitor the process: pH, alkalinity, volatile fatty acids (VFA), volatile solids (VS) and chemical oxygen demand (COD). Among the tests performed, the best result obtained for the biogas production corresponded to the use of 2 g of substrate and 98 mL of inoculum of the anaerobic digester of the Wastewater Treatment Plant (WWTP) of Bragança, with addition of 150 mg of bicarbonate leading to a production of 1628 L biogas.kg-1 VS (57% methane). In relation to the biogas quality, the best result was obtained with 20 g of substrate and 380 mL of inoculum from the anaerobic digester sludge of Ave WWTP (plus 600 mg of sodium bicarbonate), presenting a value of 85% of CH4, with a production of 464 L biogas.kg-1 VS.
- Anaerobic digestion performance in the energy recovery of kiwi residuesPublication . Martins, Ramiro; Boaventura, Rui; Paulista, Larissa OliveiraWorld production and trade of fruits generate losses in the harvest, post-harvest, handling, distribution and consumption phases, corresponding to 6.8% of total production. These residues present high potential as a substrate for the anaerobic digestion process and biogas generation. Thus, the energy valuation of the agro-industrial residues of kiwi production was evaluated by anaerobic digestion, aiming at optimizing the biogas production and its quality. Ten assays were carried out in a batch reactor (500 mL) under mesophilic conditions and varying a number of operational factors: different substrate/inoculum ratios; four distinct values for C: N ratio; inoculum from different digesters; and inoculum collected at different times of the year. The following parameters were used to control and monitor the process: pH, alkalinity, volatile fatty acids (VFA), volatile solids (VS) and chemical oxygen demand (COD). Among the tests performed, the best result obtained for the biogas production corresponded to the use of 2 g of substrate and 98 mL of inoculum of the anaerobic digester of the Wastewater Treatment Plant (WWTP) of Bragança, with addition of 150 mg of bicarbonate leading to a production of 1628 L biogas.kg-1 VS (57% methane). In relation to the biogas quality, the best result was obtained with 20 g of substrate and 380 mL of inoculum from the anaerobic digester sludge of WWTP of Ave (with addition 600 mg of sodium bicarbonate), presenting a value of 85% of CH4, with a production of 464 L biogas.kg-1 VS.
- Enhancing methane yield from crude glycerol anaerobic digestion by coupling with ultrasound or A. niger/E. coli biodegradationPublication . Paulista, Larissa Oliveira; Boaventura, Rui; Vilar, Vítor J.P.; Pinheiro, Alexei; Martins, RamiroAnaerobic 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.
- Multistage treatment for olive mill wastewater: Assessing legal compliance and operational costsPublication . Vuppala, Srikanth; Paulista, Larissa Oliveira; Morais, Daniela F.S.; Pinho, Inês L.; Martins, Ramiro; Gomes, Ana I.; Moreira, Francisca C.; Vilar, Vítor J.P.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).
- New designsns of solar collectors for heterogeneous TiO2 photocatalytic processesPublication . Peri, P.; Silva, Tânia Cristina; Paulista, Larissa Oliveira; Martins, Ramiro; Soares, P.; Boaventura, Rui; Vilar, Vítor J.P.Solar hardware design for photocatalytic processes includes aspects of optics, geometry and reactor materials. Compound parabolic collectors (CPCs) have widely been used to promote heterogeneous and homogeneous photocatalytic reactions. In this work, different reflective surface (RS) materials (anodized aluminum with [MS] and without [R85] protective coating, soiled aluminum [R85s] and stainless steel [SS]) and geometries (flat [F], single piece-double parabola [SP] and two pieces-double parabola [DP]) were tested aiming the degradation of a recalcitrant organic compound, gatifloxacin (GAT), by using a heterogeneous TiO2 photocatalytic system. Firstly, the photonic flux entering the system was measured by 2-nitrobenzaldehyde actinometry, considering the different RSs. After that, the catalyst (TiO2-P25) was immobilized in the surface of a static mixer and axially inserted in the tubular borosilicate photoreactor. Finally, the efficiency of the heterogeneous photocatalytic system was evaluated for GAT removal from aqueous solution using the best photoreactor configuration.
- Performance do processo de digestão anaeróbia na valorização energética de resíduos de kiwiPublication . Gonçalves, Bárbara Camacho; Paulista, Larissa Oliveira; Kreutz, Cristiane; Martins, RamiroA produção mundial e o comércio de frutas geram perdas nas etapas de colheita, pós-colheita, manipulação, distribuição e consumo, correspondendo a 6,8% da produção total. Esses resíduos apresentam elevado potencial como substrato para um processo de digestão anaeróbia e geração de biogás. Dessa forma, avaliou-se a valorização energética dos resíduos agroindustriais da produção de kiwi por digestão anaeróbia, tendo como meta otimizar a produção de biogás e a sua qualidade. Foram desenvolvidos 10 ensaios em reator batch (500 mL) em condições mesófilas e variaram-se vários fatores operacionais: diferentes proporções para a razão substrato/inóculo; quatro valores distintos para a razão C:N; inóculo proveniente de diferentes digestores; e inóculo recolhido em épocas distintas do ano. Para controle e monitorização do processo foram usados os seguintes parâmetros: pH, alcalinidade, ácidos gordos voláteis (AGV), sólidos voláteis (SV) e carência química de oxigénio (CQO). Entre os ensaios realizados, o melhor resultado obtido para a produção de biogás correspondeu à utilização de 2 g de substrato e 98 mL de inóculo do digestor anaeróbio da Estação de Tratamento de Água Residual (ETAR) de Bragança, com adição de 150 mg de bicarbonato de sódio, registando-se uma produção de 1628 L biogás.kg-1 SV (57% de metano). Já em relação à qualidade do biogás, o melhor resultado foi obtido com 20 g de substrato e 380 mL de inóculo da lama do digestor anaeróbio da ETAR do Ave (mais 600 mg de bicarbonato de sódio), apresentando um valor de 85% de CH4, com uma produção de 464 L biogás.kg-1 SV.
- Solar-driven thermo-photocatalytic CO2 methanation over a structured RuO2:TiO2/SBA-15 nanocomposite at low temperaturePublication . Paulista, Larissa Oliveira; Ferreira, Alexandre; Castanheira, Bruna; Ðolić, Maja B.; Martins, Ramiro; Boaventura, Rui; Vilar, Vítor J.P.; Silva, Tânia F.C.V.A new hybrid catalyst composed of mesostructured silica SBA-15 functionalized with TiO2 and further loaded with RuO2 was developed to efficiently promote thermo-photocatalytic CO2 hydrogenation into methane at low temperatures. The catalytic activity was assessed with respect to TiO2:RuO2 loading, catalyst dosage, illumination source (polychromatic sunlight and monochromatic LEDs) and power, [H2]:[CO2] molar ratio, temperature, and catalyst reusability. The best methanation yields were attained for the RuO2(6.4%):TiO2(16.9%)/SBA-15 nanocomposite at 150 ºC, under simulated sunlight (0.21 W) and stoichiometric [H2]:[CO2] molar ratio, reaching: a specific CH4 production rate of 13.6 mmol g-c1a t h-1; 99.8 % selectivity; 96.8 % CO2 conversion (110- min; 40 mL); and apparent photonic efficiency/quantum yield of 39.5 %/42.1 %. Considering only the active RuO2:TiO2 photocatalyst mass (23.3 %), the CH4 production rate increased to 58.6 mmol g-a1c tive_cat h-1. Besides, this highly-active photocatalyst featured excellent UV-Vis-IR light absorbance, high surface area, and stability for reuse when moist gas was removed between cycles.
- Tratamento de efluente agroindustrial em reator UASB com valorização energéticaPublication . Mansano, Tatiane; Paulista, Larissa Oliveira; Boaventura, Rui; Martins, RamiroO acelerado crescimento da população traz consigo um aumento na geração de efluentes agroindustriais. A descarga inadequada desses efluentes afeta significativamente a qualidade dos recursos hídricos. Dessa forma, torna-se imperioso investir em processos de tratamento dos efluentes agroindustriais, em particular processos de baixo custo. Nesse contexto, o presente estudo compreende a concepção e construção de um reator UASB e otimização do tratamento por digestão anaeróbia do efluente bruto da produção de castanha pela empresa agroindustrial Sortegel. A eficiência do sistema foi avaliada mediante a determinação/monitorização dos parâmetros Carência Química de Oxigênio (CQO), Carência Bioquímica de Oxigênio (CBO5), Sólidos Suspensos Totais (SST), taxa de produção e qualidade (% de metano) do biogás. O reator foi alimentado durante 25 semanas e operado em condições mesofílicas (temperatura 30-40ºC). Foram testados diferentes valores para o tempo de retenção hidráulica (HRT) e caudal volumétrico (QV): 0,66 d (QV=1509 L.m-3.d-1); 1,33 d (QV=755 L.m-3.d-1); 2,41 d (QV=415 L.m-3.d-1). A eficiência média de remoção de CQO alcançou valores de 69%, 82% e 75%, respetivamente e, simultaneamente, a eficiência de remoção de CBO5 associada foi de 84%, 91% e 70%. Relativamente ao teor de SST, os valores de remoção foram 78%, 94% e 63%. A taxa de produção de metano situou-se entre 2500 e 4800 L.CH4.kg-1 CQO removido d-1. Para o conjunto dos tempos de retenção hidráulico testados, foram registadas elevadas concentrações de metano no biogás gerado: 66 - 75%, 70% e 75% para HRT de 0,66, 1,33 e 2,41 dias, respetivamente.
- Tratamento e valorização energética de efluente agroindustrial em reator UASB (Upflow Anaerobic Sludge Blanket)Publication . Mansano, Tatiane; Paulista, Larissa Oliveira; Boaventura, Rui; Martins, RamiroO acelerado crescimento da população traz consigo um aumento na geração de efluentes agroindustriais. A descarga inadequada desses efluentes afeta significativamente a qualidade dos recursos hídricos. Dessa forma, torna-se imperioso investir em processos de tratamento dos efluentes agroindustriais, em particular processos de baixo custo. Nesse contexto, o presente estudo compreende a concepção e construção de um reator UASB e otimização do tratamento por digestão anaeróbia do efluente bruto da produção de castanha pela empresa agroindustrial Sortegel. A eficiência do sistema foi avaliada mediante a determinação/monitorização dos parâmetros Carência Química de Oxigênio (CQO), Carência Bioquímica de Oxigênio (CBO5), Sólidos Suspensos Totais (SST), taxa de produção e qualidade (% de metano) do biogás. O reator foi alimentado durante 25 semanas e operado em condições mesofílicas (temperatura 30-40ºC). Foram testados diferentes valores para o tempo de retenção hidráulica (HRT) e caudal volumétrico (QV): 0,66 d (QV=1509 L.m-3.d-1); 1,33 d (QV=755 L.m-3.d-1); 2,41 d (QV=415 L.m-3.d-1). A eficiência média de remoção de CQO alcançou valores de 69%, 82% e 75%, respetivamente e, simultaneamente, a eficiência de remoção de CBO5 associada foi de 84%, 91% e 70%. Relativamente ao teor de SST, os valores de remoção foram 78%, 94% e 63%. A taxa de produção de metano situou-se entre 2500 e 4800 L.CH4.kg-1 CQO removido d-1. Para o conjunto dos tempos de retenção hidráulico testados, foram registadas elevadas concentrações de metano no biogás gerado: 66 - 75%, 70% e 75% para HRT de 0,66, 1,33 e 2,41 dias, respetivamente.
- Treatment and energy valorisation of an agro-industrial effluent in upflow anaerobic sludge reactor (UASB)Publication . Martins, Ramiro; Boaventura, Rui; Paulista, Larissa OliveiraThe accelerated growth of the population brings with it an increase in the generation of agro-industrial effluents. The inadequate discharge of these effluents significantly affects the quality of water resources. In this way, it becomes important to invest in treatment processes for agro-industrial effluents, particularly low-cost ones. In this context, the present study includes the design and construction of an UASB reactor and optimization of the anaerobic digestion treatment of the raw effluent from sweet chestnut production in the agro-industrial company Sortegel. The efficiency of the system was evaluated through the determination / monitoring of oxygen chemical oxygen demand (COD), biochemical oxygen demand (BOD5), total suspended solids (TSS), biogas production rate and quality (% methane). The reactor was fed for 25 weeks and operated under mesophilic conditions (temperature 30-40 °C). Different values were tested for the hydraulic retention time (HRT) and volumetric flow rate (VF): 0.66 days (VF=1509 L.m-3.d-1); 1.33 days (VF=755 L.m-3.d-1); 2.41 d days (VF=415 L.m-3.d-1). The average COD removal efficiency reached values of 69%, 82% and 75%, respectively, and simultaneously the associated BOD5 removal efficiency was 84%, 91% and 70%. As regards TSS, removal values were 78%, 94% and 63%. In addition, high methane production rates were obtained, between 2500 and 4800 L CH4.kg-1 COD removed d-1. For all the hydraulic retention times tested, high concentrations of methane in the biogas were recorded: 66-75%, 70% and 75% for HRT of 0.66, 1.33 and 2.41 days, respectively.