8 research outputs found

    ESTUDO HIDR√ĀULICO DOS ORIF√ćCIOS DOS FLOCULADORES DE BANDEJAS PERFURADAS SUPERPOSTAS DE ESTA√á√ēES DE TRATAMENTO DE √ĀGUA

    Get PDF
    Orif√≠cios afogados, com di√Ęmetros variando entre 6 e 15 mm, foram ensaiados em laborat√≥rio com o objetivo de determinar seus coeficientes de descarga ao trabalharem com vaz√Ķes correspondentes a n√ļmeros de Reynolds n√£o superiores a 11000. Trata-se de di√Ęmetros e condi√ß√Ķes aplic√°veis a floculadores do tipo hidr√°ulico, de bandejas perfuradas, utilizados em esta√ß√Ķes de tratamento de √°gua pr√©-fabricadas, destinadas a tratarem pequenas vaz√Ķes. Os resultados obtidos mostram que o valor 0,61 ‚Äď normalmente adotado para o coeficiente de descarga de orif√≠cios - n√£o se aplica a essa faixa de di√Ęmetros, quando operando nas condi√ß√Ķes ensaiadas

    High rate algal ponds for post-treating sewage from UASB reactors : treatment efficiency, anaerobic co-digestion and sustainability

    Get PDF
    Tesi en modalitat de cotutela: Universitat Polit√®cnica de Catalunya i Universidade Federal de Minas GeraisThis PhD thesis aimed at evaluating the performance of high rate algal ponds (HRAP) to post-treat the anaerobic effluent from an upflow anaerobic sludge blanket (UASB) reactor fed with sewage. The work analysed the system complishment in terms of treatment efficiency, micropollutants removal and biogas production, through the anaerobic co-digestion of raw sewage and microalgal biomass (with and without solar thermal pre-treatment), in a demonstration-scale system. In addition, the research intended at assessing the sustainability of the UASB+HRAP system using life cycle assessment (LCA), in terms of its environmental impact in comparison with other UASB post-treatment technologies. Sewage treatment efficiency was analysed through BIO_ALGAE 2 mathematical model, which enabled the understanding and optimisation of the symbiotic relation between microalgae and bacteria. To this, experimental data from demonstrationscale systems in tropical climate conditions were used for model calibration. In addition, different scenarios were considered by varying HRAP hydraulic retention time (HRT) (4, 6 and 8 days). Results obtained showed an efficient removal of COD (70%), TSS (42%), N-NH4 (57%) and P-PO4 (30%) in the UASB+HRAP system. From the valuated scenarios, the operation of HRAP at 4 days of HRT showed to be optimal in terms of sewage treatment and energy production, with lower area requirement. Regarding the removal of micropollutants (pharmaceuticals and endocrine disruptors), amples were collected periodically from raw sewage, UASB reactor and HRAP effluents. All monitored compounds were found in raw sewage, with occurrence rates ranging from 70 to 100%. Micropollutant removal in the UASB reactor ranged from none (-25.12% for the hormone EE2-ethinylestradiol) to 85% removal (E2-estradiol), due to the incapacity of anaerobic processes. However, the overall UASB+HRAP system was highly efficient for removing most compounds, with removal rates ranging between 65% (ibuprofen) to 95% (estrone). To evaluate the co-digestion of raw sewage and microalgal biomass in UASB reactors two phases were considered: without and after thermal pre-treatment using solar heating. In both cases, an UASB reactor fed with only raw sewage was used as control. During the first phase, the results showed a methane yield increase of 35% after anaerobic co-digestion with microalgae, from 156 to 211 NL CH4 kg-1 VS. An energy assessment showed a positive energy balance, with an annual average net ratio of 2.11 in the UASB+HRAP system. Regarding the results after microalgal biomass pre-treatment, organic matter solubilization reached 32% increase in terms of total COD. Furthermore, methane yield was increased by 45% compared to mono-digestion with raw sewage, from 81 to 117 NL CH4 kg-1 COD. The energy assessment showed a positive energy balance, with an annual average net ratio of 2.52 in the sewage treatment system. Finally, the environmental impact of HRAP as post-treatment technology following UASB reactors was carried out using LCA for comparison with other post-treatments: trickling filters, polishing ponds and constructed wetlands. The results showed that among the 8 categories evaluated, HRAP showed better performance in 4 of them. The study concluded that HRAP may be considered a potential technology following UASB reactors and its environmental impacts can be further improved by using appropriate materials and construction techniques.Esta tesis tuvo como objetivo evaluar el desempe√Īo de lagunas de alta tasa (LAT) como postratamiento del efluente anaer√≥bico de un reactor UASB depurando aguas residuales dom√©sticas. El trabajo analiz√≥ el desempe√Īo de este sistema evaluando la eficiencia del tratamiento, remoci√≥n de microcontaminantes y producci√≥n de biog√°s, mediante la codigesti√≥n anaer√≥bica de aguas residuales brutas y biomasa de microalgas (con y sin pre-tratamiento t√©rmico solar), en escala de demonstraci√≥n. Adem√°s, esta investigaci√≥n tambi√©n evalu√≥ el impacto ambiental del flujo de tratamiento UASB + LAT, utilizando de la herramienta de evaluaci√≥n del ciclo de vida (ACV), compar√°ndolo con otros flujos de tratamiento ya consolidados para la realidad brasile√Īa. La eficiencia de la depuraci√≥n de las aguas residuales se analiz√≥ por el modelo matem√°tico BIO_ALGAE 2, que permiti√≥ comprender y optimizar la relaci√≥n simbi√≥tica entre microalgas y bacterias. Para ello, se utilizaron datos experimentales del sistema en escala de demostraci√≥n y en condiciones clim√°ticas tropicales para calibrar el modelo. Adem√°s, a partir del modelo calibrado, se simularon diferentes escenarios variando el tiempo de detenci√≥n hidr√°ulico (TDH) de las lagunas (4, 6 y 8 d√≠as). Los resultados mostraron una eficiente remoci√≥n de DQO (70%), SST (42%), N-NH4 (57%) y P-PO4 (30%) en el sistema UASB + LAT. De los escenarios evaluados, la operaci√≥n de las LAT con 4 d√≠as de TDH result√≥ excelente para la depuraci√≥n de aguas residuales y potencial de producci√≥n de energ√≠a, con menor necesidad de √°rea. Acerca de la remoci√≥n de microcontaminantes (f√°rmacos y disruptores endocrinos), peri√≥dicamente se recolectaron muestras de las aguas residuales sin tratar, reactor UASB y efluentes de las lagunas. Todos los compuestos monitoreados se encontraron en las aguas residuales sin tratar, con tasas de ocurrencia que oscilan entre el 70 y el 100%. La eliminaci√≥n de los microcontaminantes en el reactor UASB oscil√≥ entre nada (-25,12% para la hormona EE2-etinilestradiol) y 85% de eliminaci√≥n (E2-estradiol), debido a la incapacidad de los procesos anaer√≥bicos. Sin embargo, el sistema UASB + LAT en general fue muy eficaz en la eliminaci√≥n de la mayor√≠a de los compuestos, con tasas de eliminaci√≥n que desde el 65% (ibuprofeno) al 95% (estrona). Para evaluar la codigesti√≥n de aguas residuales sin tratamiento y biomasa de microalgas en reactores UASB, se consideraron dos fases: sin y despu√©s del pretratamiento t√©rmico con calentamiento solar. En ambos casos, se utiliz√≥ como control un reactor UASB alimentado solo con aguas residuales sin tratar. Durante la primera fase, los resultados mostraron un aumento del 35% en el rendimiento de metano despu√©s de la co-digesti√≥n anaer√≥bica con microalgas, de 156 NL CH4 kg-1 SV a 211 NL CH4 kg-1 SV. Una evaluaci√≥n energ√©tica demostr√≥ un balance positivo, con un ratio medio anual entre energ√≠a producida y consumida de 2,11 en el sistema UASB + LAT. En cuanto a los resultados tras el pretratamiento de la biomasa de microalgas, la solubilizaci√≥n de la materia org√°nica alcanz√≥ una eficiencia del 32% en t√©rminos de DQO total. Adem√°s, el rendimiento de metano aument√≥ en un 45% en comparaci√≥n con la mono-digesti√≥n con aguas residuales sin tratar, de 81 NL CH4 kg-1 DQO a 117 NL CH4 kg-1 DQO. La valoraci√≥n energ√©tica arroj√≥ un saldo positivo, con una ratio medio anual entre energ√≠a producida y consumida de 2,52 para el sistema evaluado. Finalmente, el impacto ambiental del LAT como postratamiento de efluentes de reactores UASB se llev√≥ a cabo utilizando LCA como comparaci√≥n con otras tecnolog√≠as ya consolidadas para el postratamiento del reactor UASB en Brasil: filtro biol√≥gico percolador, lagunas de pulimiento y humedal construido. Los resultados mostraron que, entre las 8 categor√≠as evaluadas, el sistema LAT se desempe√Ī√≥ mejor en 4. El estudio concluy√≥ que LAT puede considerarse una tecnolog√≠a potencial y sostenible para el postratamiento de efluentes de reactores UASB y sus impactos ambientales pueden mejorarse utilizando materiales y t√©cnicas de construcci√≥n adecuada.Esta tese teve como objetivo avaliar o desempenho de lagoas de algas de alta taxa (LAT) como p√≥s-tratamento do efluente anaer√≥bio de um reator UASB alimentado com esgoto dom√©stico. O trabalho analisou o desempenho desse sistema em termos de efici√™ncia de tratamento, remo√ß√£o de micropoluentes e produ√ß√£o de biog√°s, atrav√©s da co-digest√£o anaer√≥bia de esgoto bruto e biomassa microalgal (com e sem pr√©-tratamento solar t√©rmico), em escala de demonstra√ß√£o. Al√©m disso, essa pesquisa tamb√©m a avaliou o impacto ambiental do fluxo de tratamento UASB+LAT, atrav√©s da ferramenta de avalia√ß√£o do ciclo de vida (ACV), comparando com outros fluxos de tratamento j√° consolidados para a realidade brasileira. A efici√™ncia do tratamento de esgoto foi analisada por meio do modelo matem√°tico BIO_ALGAE 2, que possibilitou o entendimento e otimiza√ß√£o da rela√ß√£o simbi√≥tica entre microalgas e bact√©rias. Para isso, dados experimentais do sistema em escala de demonstra√ß√£o e em condi√ß√Ķes de clima tropical foram utilizados para calibra√ß√£o do modelo. Ademais, a partir do modelo calibrado, diferentes cen√°rios foram simulados variando o tempo de deten√ß√£o hidr√°ulica (TDH) das LAT (4, 6 e 8 dias). Os resultados obtidos mostraram uma remo√ß√£o eficiente de DQO (70%), SST (42%), N-NH4 (57%) e P-PO4 (30%) no sistema UASB + LAT. Dos cen√°rios avaliados, a opera√ß√£o das LAT com 4 dias de TDH mostrou-se √≥tima em termos de tratamento de esgoto e potencial de produ√ß√£o de energia, com menor necessidade de √°rea. Em rela√ß√£o √† remo√ß√£o dos micropoluentes (f√°rmacos e desreguladores end√≥crinos), foram coletadas periodicamente amostras de esgoto bruto, reator UASB e efluentes das Lagoas. Todos os compostos monitorados foram encontrados no esgoto bruto, com taxas de ocorr√™ncia variando de 70 a 100%. A remo√ß√£o do micropoluente no reator UASB variou de nenhum (-25,12% para o horm√īnio EE2-etinilestradiol) a 85% de remo√ß√£o (E2-estradiol), devido √† incapacidade dos processos anaer√≥bicos. No entanto, o sistema UASB + LAT em geral foi altamente eficiente para remover a maioria dos compostos, com taxas de remo√ß√£o variando entre 65% (ibuprofeno) a 95% (estrona). Para avaliar a co-digest√£o de esgoto bruto e biomassa microalgal em reatores UASB foram consideradas duas fases: sem e ap√≥s pr√©-tratamento t√©rmico com aquecimento solar. Em ambos os casos, um reator UASB alimentado apenas com esgoto bruto foi usado como controle. Durante a primeira fase, os resultados mostraram um aumento no rendimento de metano de 35% ap√≥s a co-digest√£o anaer√≥bia com microalgas, de 156 NL CH4 kg-1 SV para 211 NL CH4 kg-1 SV. Uma avalia√ß√£o energ√©tica mostrou um balan√ßo energ√©tico positivo, com uma rela√ß√£o m√©dia anual entre energia produzida e consumida de 2,11 no sistema UASB+LAT. Em rela√ß√£o aos resultados ap√≥s o pr√©-tratamento da biomassa microalgal, a solubiliza√ß√£o da mat√©ria org√Ęnica atingiu uma efici√™ncia de 32% em termos de DQO total. Al√©m disso, o rendimento de metano aumentou em 45% em compara√ß√£o com a mono-digest√£o com esgoto bruto, de 81 NL CH4 kg-1 DQO para 117 NL CH4 kg-1 DQO. A avalia√ß√£o energ√©tica apresentou balan√ßo positivo, com rela√ß√£o m√©dia anual entre energia produzida e consumida de 2,52 para o sistema avaliado. Finalmente, o impacto ambiental das LAT como p√≥s-tratamento de efluente de reatores UASB foi realizado usando ACV para compara√ß√£o com outras tecnologias j√° consolidadas para o p√≥s-tratamento de reator UASB no Brasil: filtro biol√≥gico percolador, lagoas de polimento e wetland constru√≠do. Os resultados mostraram que dentre as 8 categorias avaliadas, o sistema de LAT apresentou melhor desempenho em 4. O estudo concluiu que as LAT podem ser considerado uma tecnologia potencial e sustent√°vel para p√≥s tratar efluente de reatores UASB e seus impactos ambientais podem ser melhorados usando materiais e t√©cnicas de constru√ß√£o apropriadosPostprint (published version

    Nature-based solutions for wastewater treatment and bioenergy recovery: a comparative Life Cycle Assessment

    No full text
    The aim of this study was to assess the environmental impacts of up-flow anaerobic sludge blanket (UASB) reactors coupled with high rate algal ponds (HRAPs) for wastewater treatment and bioenergy recovery using the Life Cycle Assessment (LCA) methodology. This solution was compared with the UASB reactor coupled with other consolidated technologies in rural areas of Brazil, such as trickling filters, polishing ponds and constructed wetlands. To this end, full-scale systems were designed based on experimental data obtained from pilot/demonstrative scale systems. The functional unit was 1 m3 of water. System boundaries comprised input and output flows of material and energy resources for system construction and operation. The LCA was performed with the software SimaPro¬ģ, using the ReCiPe midpoint method. The results showed that the HRAPs scenario was the most environmentally friendly alternative in 4 out of 8 impact categories (i.e. Global warming, Stratospheric Ozone Depletion, Terrestrial Ecotoxicity and Fossil resource scarcity). This was associated with the increase in biogas production by the co-digestion of microalgae and raw wastewater, leading to higher electricity and heat recovery. From an economic point of view, despite the HRAPs showed a higher capital cost, the operation and maintenance costs were completely offset by the revenue obtained from the electricity generated. Overall, the UASB reactor coupled with HRAPS showed to be a feasible nature-based solution to be used in small communities in Brazil, especially when microalgae biomass is valorised and used to increase biogas productivity.The research was funded by the National Council for Scientific and Technological Development from Brazilian Ministry of Education ‚Äď CNPq, the Reference Centre of Sustainable Sewage Treatment Plants - CR ETES, the Institute of Sustainable Sewage Treatment Plants - INCT ETEs, the Coordination for the Improvement of Higher Education Personnel ‚Äď CAPES, the Foundation for Research of the State of Minas Gerais ‚Äď FAPEMIG, and the CNPQ and to National Health Foundation ‚Äď FUNASA from Brasil. Lucas Vassalle is grateful to the CNPQ (scholarship 204026/2018-0). Ivet Ferrer and Marianna Garf√≠ are grateful to the Government of Catalonia (Consolidated Research Group 2017 SGR 1029), and Marianna Garf√≠ to the Spanish Ministry of Economy and Competitiveness (RYC-2016 20059).Peer ReviewedObjectius de Desenvolupament Sostenible::7 - Energia Assequible i No ContaminantObjectius de Desenvolupament Sostenible::6 - Aigua Neta i SanejamentPostprint (author's final draft

    Bioremediation of emerging micropollutants in irrigation water: the alternative of microalgae-based treatments

    No full text
    The present study evaluated the efficiency of a semi-closed horizontal tubular photobioreactor (PBR) at demonstrative scale to remove a total of 35 target compounds, including benzotriazoles, benzophenones, antibiotics and different pharmaceuticals present in irrigation water in a peri-urban rural area. This water run through an open channel and was a mixture of reclaimed wastewater from a nearby wastewater treatment plant (WWTP) and run-off from the different agricultural fields in the area. Most of the compounds studied are usually not fully eliminated during conventional wastewater treatment, which justifies the need to investigate alternative treatment strategies. A total of 21 of these compounds were detected in the irrigation water. Benzotriazoles were only partially removed after the microalgae treatment, with elimination rates similar to those of conventional WWTPs. The UV filter benzophenone-3 (BP3) showed variable removals, ranging from no elimination to 51%, whereas 4-methylbenzilidenecamphor (4MBC) was completely eliminated. Regarding pharmaceuticals, average removals were higher, in the range of 60‚Äď100%, with the exception of the antibiotics sulfamethoxazole (46%) and sulfapyridine, which was not removed. Despite the low biomass productivity of the PBR, parameters such as the size of the reactors, the specific mixed cultures developed and the high temperatures and pH in the closed system may account for the overall good results, The efficiency and sustainability of these systems make them a solid, feasible treatment choice.This research is sponsored by FEDER funds through Portugal 2020 (PT2020), by the Competitiveness and Internationalization Operational Program (COMPETE 2020) and national funds through the Portuguese Foundation for Science and Technology, under the projects: UID/EMS/00285/2020, POCI-01-0145-FEDER-00763 and Friction 4.0 (POCI-01-0145-FEDER-032089). The author, D.G. Andrade is supported by the Portuguese Foundation for Science and Technology through SFRH/BD/130196/2017 fellowship. All supports are gratefully acknowledged.Peer ReviewedPostprint (author's final draft

    Upflow anaerobic sludge blanket in microalgae-based sewage treatment: co-digestion for improving biogas production

    No full text
    Upflow anaerobic sludge blanket (UASB) reactors are widely used to treat domestic sewage and frequently require post-treatment. Little is known about the use of high rate algal ponds (HRAP) for post-treating UASB reactors‚Äô effluent. This study aimed to evaluate a UASB reactor followed by a HRAP in terms of sewage treatment efficiency and biogas production, during one year at demonstration‚Äďscale. The UASB reactor co-treated raw sewage and the harvested microalgal biomass from the HRAP, which was recirculated to the reactor. An identical UASB reactor, treating only raw sewage, was used as control. The results showed an overall removal of 65% COD and 61% N-NH4 in the system. Furthermore, methane yield was increased by 25% after anaerobic co-digestion with microalgae, from 156 to 211 NL CH4 kg-1 VS. An energy assessment was performed and showed a positive energy balance, with a net ratio of 2.11 to the annual average.Peer ReviewedPostprint (author's final draft

    Can high rate algal ponds be used as post-treatment of UASB reactors to remove micropollutants?

    No full text
    The present study evaluated the removal capacity of a UASB-HRAP treatment system, combining anaerobic and microalgae-based, aerobic treatment, for eleven organic micropollutants present in raw sewage, including pharmaceuticals, estrogens and xenoestrogens. The UASB reactor and the HRAP were operated at a hydraulic retention time (HRT) of 7 h and 8 days, respectively. Influent and effluent samples from the UASB and HRAP were collected periodically. All the target compounds were detected in raw sewage, with an occurrence ranging from 70 to 100%. Removal rates in the UASB reactor were generally incomplete, ranging from no removal (-25.12% for the hormone EE2-ethinylestradiol) to 84.91% (E2 - estradiol). However, the overall performance of the UASB + HRAP system was highly efficient for the majority of the compounds, with removal rates ranging from 64.8% (ibuprofen) to 95% (estrone). Gemfibrozil and bisphenol A were the only exceptions, with overall removal rates of 39% and 43%, respectively. Hormones were the compounds with the highest removal rates in the system.Peer ReviewedPostprint (author's final draft

    Scaling-up the anaerobic digestion of pretreated microalgal biomass within a water resource recovery facility

    Get PDF
    Microalgae-based wastewater treatment plants are low-cost alternatives for recovering nutrients from contaminated effluents through microalgal biomass, which may be subsequently processed into valuable bioproducts and bioenergy. Anaerobic digestion for biogas and biomethane production is the most straightforward and applicable technology for bioenergy recovery. However, pretreatment techniques may be needed to enhance the anaerobic biodegradability of microalgae. To date, very few full-scale systems have been put through, due to acknowledged bottlenecks such as low biomass concentration after conventional harvesting and inefficient processing into valuable products. The aim of this study was to evaluate the anaerobic digestion of pretreated microalgal biomass in a demonstration-scale microalgae biorefinery, and to compare the results obtained with previous research conducted at lab-scale, in order to assess the scalability of this bioprocess. In the lab-scale experiments, real municipal wastewater was treated in high rate algal ponds (2 √ó 0.47 m3), and harvested microalgal biomass was thickened and digested to produce biogas. It was observed how the methane yield increased by 67% after implementing a thermal pretreatment step (at 75 ¬įC for 10 h), and therefore the very same pretreatment was applied in the demonstration-scale study. In this case, agricultural runoff was treated in semi-closed tubular photobioreactors (3 √ó 11.7 m3), and harvested microalgal biomass was thickened and thermally pretreated before undergoing the anaerobic digestion to produce biogas. The results showed a VS removal of 70% in the reactor and a methane yield up to 0.24 L CH4/g VS, which were similar to the lab-scale results. Furthermore, photosynthetic biogas upgrading led to the production of biomethane, while the digestate was treated in a constructed wetland to obtain a biofertilizer. In this way, the demonstration-scale plant evidenced the feasibility of recovering resources (biomethane and biofertilizer) from agricultural runoff using microalgae-based systems coupled with anaerobic digestion of the microalgal biomass.This research was funded by the European Commission (H2020 project INCOVER, GA 689242); the Spanish Ministry of Science, Innovation and Universities (MCIU), Research National Agency (AEI), and European Regional Development Fund (FEDER) (AL4BIO project, RTI2018-099495-B-C21); and the Generalitat de Catalunya (Consolidated Research Group 2017 SGR 1029).Peer ReviewedPostprint (published version

    Behavior of micropollutants in polishing units that combine sorption and biodegradation mechanisms to improve the quality of activated sludge effluent.

    No full text
    The current study evaluated the removal of six micropollutants (estrone (E1); 17?-estradiol (E2); 17?-ethynylestradiol (EE2); ibuprofen (IBP), diclofenac (DCF), and paracetamol (PCT)) from the final effluent of an activated sludge domestic sewage treatment plant using polishing filters. Four polishing filters were assembled as columns and filled with a mixture of sand and vermiculite, sand and charcoal, sand and granulated activated carbon (9:1 by volume), and sand only. The column filters were placed near the outlet of a full-scale activated sludge treatment plant and were fed with a treated effluent containing from 4.71 to 28.93 ng L-1 of the target compounds at a hydraulic loading rate (HLR) of 50 m3 m?2 day?1. Samples were collected periodically from the influent (biologically treated sewage) and effluent of the four columns and analyzed for estrogens, anti-inflammatories, and analgesic compounds. Liquid samples were submitted to a solid phase extraction (SPE) and analyzed by gas chromatography coupled with mass spectrometry after their derivatization. Among the compounds found, diclofenac was distinguished by the high occurrence of detection in the samples (85%) and higher mean concentration (~?17 ng L?1). High removal efficiency (>?90%) of the estrogens was observed in the polishing systems studied, while for the other targets, the removal efficiency varied from 10 to 30%. The concentration values of some compounds were low, probably due to rainfall during the sampling period
    corecore