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Poster apresentado em WASTES: Solutions, Treatments and Opportunities. 5th International Conference, September 4th - 6th, Almada/Caparica, Portugal Biomass of microalga Chlorella protothecoides, grown under autotrophic and heterotrophic conditions and subjected to pretreatments, were energetically valorized through anaerobic digestion process according to the substrates: autotrophic algae (A), heterotrophic algae (H), heterotrophic algae extracted (HE), autoclave pretreated heterotrophic algae (HPA), enzyme pretreated heterotrophic algae (HPE), ultrasound pretreated heterotrophic algae (HPU), and inoculum (I). Despite the application of pretreatments, the highest methane production was obtained in the algae extracted digestion with 172 mL CH4, against 153, 126 and 142 mL obtained in HPA, HPE and HPU, respectively. The COD removal capacity was higher in the HPA sample while the TS and VS removal reached higher values in the autotrophic alga. info:eu-repo/semantics/publishedVersion

This presentation will review the microbiological and physicochemical characteristics of Portuguese olive oil wastewaters (OOWW) based on data collected over the last 12 years (Eusébio 2011, Eusébio 2007, Eusébio 2005). These OOWW were all originated from the continuous oil extraction process (three-phase system) at diverse mills spread all over Portugal (Alfândega da Fé, Oliveira do Hospital, Santarém, Rio Maior, and Tavira). The most common physicochemical parameters pH, COD, TSS, VSS and total phenols content were determined, as well as the microbiological indicators, total aerobic heterotrophic bacteria, yeasts and molds (CFU/ml). Molecular characterization of OOWW bacterial consortia was also achieved using temperature gradient gel electrophoresis (TGGE) to identify the most abundant members. The obtained results and correlations between the measured parameters are presented and discussed based on statistical methods in order to characterize the Portuguese OOWW., MEDUSA WATER, EU Programme INCO-MED ICA3-CT-1999-00010; OLEICO, EU Programme LIFE04/ENV/IT/000409; MOTIVE, Portuguese FCT Programme POCI/AMB/56616/2004; LIFEN-Energia, Portuguese FCT Programme PTDC/ENR/69755/2006; MEDOLICO, EU Programme ENPI-CBCMED I-B/2.1/090, info:eu-repo/semantics/publishedVersion

Manuscript, An intermittent feeding strategy was applied to the anaerobic treatment of raw olive mill wastewater (OMW). Two reactors were operated under influent concentrations of 5 to 50 g COD L-1. Two and one batch (feed-less) periods were applied to reactor R1 and R2, respectively, operating in continuous thenceforth. It was demonstrated that the intermittent feeding of OMW improved the mineralization of accumulated Long Chain Fatty Acids (LCFA) inside the reactor. Nevertheless, LCFA accumulated again when the organic loading rate was increased from 2 to 3 and 5 kg COD m-3 d-1. The profiles of LCFA, obtained with OMW digestion, were different from previous studies with synthetic effluents. At the beginning of reactors operation, oleate was the main LCFA compound (~50%) followed by palmitate. Afterwards, a shift in the LCFA pattern accumulation was noticed for both reactors. At periods with higher OMW concentrations (30-50 g COD L-1, 3-5 kg COD m-3 d-1) palmitate was the main LCFA accumulated with 69% at R1 and 54% at R2. For real oily wastewaters, a periodically batch period could be a practical solution to maintain low values of LCFA inside the reactor. The addition of a nitrogen source was essential to enhance the methane yield.

Olive mill wastewater (OMW) is the effluent generated by olive oil industries, mainly produced in the Mediterranean areas. The production of olive oil generates huge amounts of wastewater. Anaerobic wastewater treatment processes appears as a promising technology for the treatment and energetic potential recovery of these high strength wastewaters since a renewable energy source (biogas) is generated. However, due to the high organic contents and presence of lipidic and phenolic compounds the treatment of OMW is sometimes toxic to the anaerobic microorganisms. Aiming at define the best strategy for the anaerobic sequencing batch reactor start-up, two reactors were operated with an hydraulic retention time of 10 days, fed with OMW at 5gCOD/L. In batch assays it was previously observed that when using an adapted microbial consortium to lipids, OMW was more efficiently converted to biogas and the overall methane production was higher. On the other hand an intermittent feeding start-up was proven to promote the degradation of long chain fatty acids to methane. Therefore, two reactors, R1 and R2 were inoculated with a biomass acclimated to oleate (BAO) and a biomass non-acclimated (BNA), respectively. The inoculum type effect on start-up efficiency and the benefits of an intermittent feeding were studied. In both reactors, the COD removal efficiency reached more than 80% after 50 days of operation. The reactor with BAO was more stable during the operation period than in the reactor with BNA. The inoculums effect was determinant in the initial phase of feeding, but, as expected, its effect was diluted after 30 days. The intermittent feeding was tested in R1. Promoting the degradation of the accumulated substrate was beneficial to increase the specific methanogenic activity of the sludge inside the reactor.

A digestão anaeróbia é um processo de tratamento de efluentes e simultaneamente uma fonte de energia, através da produção de biogás. A presença de compostos lipídicos nos efluentes não só causa problemas de inibição dos microorganismos como pode levar à lavagem do sistema, sendo frequente a aplicação de pré-tratamentos. Os tratamentos físico-químicos mostram-se, por vezes, insuficientes e originam lamas indesejáveis. Em alternativa, a oxidação electroquímica deste tipo de compostos orgânicos apresenta-se como um processo prometedor na medida em que proporciona a alteração dos lípidos e promove a respectiva conversão em biogás. No presente trabalho, as transformações electroquímicas do ácido oleico, em solução aquosa com eléctrodos de platina (Pt), chumbo (Pb) e grafite, são analisadas numa vasta gama de potenciais. Os dados obtidos permitem estabelecer as condições operativas para proceder à electrooxidação do lípido sob controlo potenciostático. Os rendimentos da oxidação electroquímica do composto lipídico sobre os diferentes substratos e de acordo com os parâmetros electroquímicos empregues são discutidos., Fundação para a Ciência e a Tecnologia (FCT)

Tese de doutoramento em Engenharia Química e Biológica, So far, there are no feasible solutions for the complete treatment of Olive Mill Wastewater (OMW). The effluent generated from the olive oil production is still directly discharged into sewer systems and water streams. The aim of this thesis was to develop a novel approach for the energetic valorisation and treatment of OMW. A two-step process combining anaerobic digestion and electrochemical oxidation was envisaged in order to maximize the energy recovery from OMW (biogas production) and to achieve the required effluent quality for sewer or land disposal. Anaerobic batch experiments were performed to select suitable conditions for the start-up of continuous anaerobic reactors and to optimize the methane production from OMW. The use of an acclimated inoculum to oleate promoted the conversion of OMW to methane and no inhibition occurred at OMW concentrations up to 10 kg COD m-3. Interestingly, hydrogen was selectively produced in detriment of methane during the anaerobic degradation of high OMW concentrations (≥ 25 kg COD m-3). The highest hydrogen production was noticed at 50 kg COD m-3 of OMW, where methanogenesis and homoacetogenesis were naturally inhibited. Two anaerobic reactors were operated continuously at OMW concentrations of 5 to 48 kg COD m-3. Intermittent feeding and nitrogen addition were found as good strategies to promote the recovery of inhibited reactors by OMW and to enhance the mineralization of long chain fatty acids (LCFA). The supplementation of a nitrogen source immediately boosted the methane yield from 21 and 18 % to 76 and 93 % in both reactors. The intermittent feeding also improved the removal of resilient phenolic compounds, reaching remarkable removal efficiencies of 60 and 81 % for the two reactors at the end of a feed-less period. A different approach for the anaerobic treatment of OMW was also tested. A hybrid digester, equipped with a packed bed of only 1/3 of its height, was operated at organic loading rates up to 7.1 kg COD m-3 d-1. A feeding strategy based on the amendment of OMW with a complementary effluent was performed. Raw OMW (about 94 % of total COD) was degraded without the addition of chemicals or dilutions with water. A biogas production of 3.16 m3 m-3 d-1 was reached. For the first time, the electrooxidation of anaerobically digested OMW was assessed and a complete mineralization was obtained over RuO2-type dimensionally stable anode (DSA) (removals: COD=99%; Phenols=100%; Colour=100%). An IrO2-type DSA proved to be efficient for the degradation of phenolic compounds and colour (91% and 85% removal), although the COD removal was only residual (14%). This feature may be important for the selective degradation of phenols in wastewater. The electrochemical post-treatment was effectively accomplished without the use of a supporting electrolyte and in the presence of the solids that remained from the anaerobic process, making this treatment simpler and cheaper. The two-step process had an overall COD removal efficiency of 95-98 % and colour and phenols removals of 99 - 100 %, working at the harshest studied conditions (initial OMW COD: 41-48 kg m-3). The values obtained for COD, colour and total phenols were below the legal discharge limits of sewer systems. The direct anaerobic degradation of OMW provided an energy production of up to 90 kWh m-3. The energy demand of the electrochemical step was significantly lowered by the anaerobic digestion step (biogas production and organic load reduction) when compared to the energy required in a single electrochemical step., Não existem soluções viáveis para o tratamento completo da água-ruça. O efluente gerado durante a produção de azeite continua a ser descarregado directamente para os sistemas de drenagem públicos e para os cursos de água. O objectivo desta tese foi desenvolver um novo processo para a valorização energética e tratamento da água-ruça. Com o intuito de maximizar a produção de energia a partir deste substrato (produção de biogás) e obter um efluente com a qualidade adequada à sua admissão nos sistemas de drenagem ou solos, concebeu-se um processo que compreende apenas dois passos e associa a digestão anaeróbia e a oxidação electroquímica. Testes anaeróbios em reactor fechado foram realizados para seleccionar as condições adequadas para o arranque de reactores anaeróbios contínuos e para optimizar a produção de metano a partir de água-ruça. A utilização de uma biomassa adaptada a oleato promoveu a conversão de água-ruça a metano e, até concentrações 10 kg CQO m-3 de água-ruça, não houve inibição. O hidrogénio foi selectivamente produzido em detrimento do metano durante a degradação anaeróbia de elevadas concentrações de água-ruça (≥ 25 kg CQO m-3). A produção mais elevada de hidrogénio foi obtida com 50 kg CQO m-3 de água-ruça, quando a metanogénese e a homoacetogénese foram naturalmente inibidas. Dois reactores anaeróbios operaram em contínuo com concentrações água-ruça de 5 a 48 kg CQO m-3. A alimentação intermitente e a adição de azoto foram boas estratégias para promover a recuperação de reactores inibidos pela água-ruça e para aumentar a mineralização de ácidos gordos de cadeia longa. A suplementação de uma fonte de azoto impulsionou de imediato o rendimento em metano de 21 e 18 % para 76 e 93 % em ambos os reactores. A alimentação intermitente também estimulou a remoção de compostos fenólicos resistentes, obtendo-se eficiências de remoção de 60 e 81 % para os dois reactores no final de um período sem alimentação. Foi testada uma diferente abordagem para o tratamento anaeróbio de água-ruça. Um digestor híbrido, com meio de enchimento que corresponde a 1/3 da sua altura, operou com cargas orgânicas até 7.1 kg CQO m-3 d-1. A estratégia de alimentação aplicada foi baseada na correcção da água-ruça com um efluente complementar. A água-ruça (~ 94 % do CQO total) foi degradada sem a adição de químicos e diluições com água, obtendo-se uma produção de biogás de 3.16 m3 m-3 d-1. A electrooxidação de água-ruça digerida anaerobiamente foi estudada pela primeira vez. A completa mineralização da água-ruça foi alcançada (remoções: CQO=99%; Fenóis Totais=100%; Cor=100%) utilizando-se, para o efeito, um ânodo dimensionalmente estável (ADE) revestido por RuO2. O ADE revestido por IrO2 provou ser eficiente na degradação de compostos fenólicos e cor (remoções de 91% e 85%), no entanto a remoção de CQO foi residual (14%). Esta característica pode ser importante para a degradação selectiva de fenóis em águas residuais. O pós-tratamento electroquímico foi realizado eficientemente sem o uso de electrólito de suporte e na presença de sólidos que permaneceram após a digestão anaeróbia, tornando o tratamento mais simples e económico. O processo de dois passos teve uma eficiência global de remoção de CQO entre 95-98 % e de cor e fenóis entre 99-100%, quando sujeito a um CQO inicial da água-ruça entre 41-48 kg m-3. Os valores obtidos de CQO, cor e fenóis são inferiores aos valores admissíveis para a descarga em sistemas de drenagem públicos. A degradação anaeróbia directa da água-ruça resultou numa produção de energia até 90 kWh m-3. A energia necessária para o passo electroquímico foi significativamente diminuída pelo passo anaeróbio (produção de biogás e redução de carga orgânica) quando comparada à energia necessária para um único passo electroquímico., The work presented in this thesis was financially supported by Fundação para a Ciência e Tecnologia (FCT), Programa Operacional Potencial Humano (POPH) and Fundo Social Europeu (FSE) through the grant (SFRH/BD/40746/2007) and the project (PTDC/ENR/69755/2006). De Nora Inc. supplied the dimensionally stable anodes used in this work.