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An innovative wastewater treatment technology was developed to recover renewable resources, such as water, energy and nutrients, from sewage. First, a novel synthetic sewage was evaluated for its suitability to serve as an alternative substrate for lab-scale wastewater treatment (WWT) research. Based on granular dried cat food, Complex Organic Particulate Artificial Sewage (COPAS) is a commercially-available, flexible, and easy to preserve feed. Characteristics of COPAS, namely chemical composition, disintegration/dissolution kinetics, and anaerobic biodegradability, were determined. Anaerobic bioassays indicate that COPAS is highly biodegradable at the concentration used to simulate household sewage (1000 mg/L), with more than 72% of the theoretical methane content reached after 30 d of incubation. Results indicate that COPAS is a suitable substrate as a surrogate of domestic sewage. In the second stage of the research, a lab-scale, 10L gas-lift anaerobic membrane bioreactor (Gl-AnMBR) was designed, fabricated and tested. The AnMBR is a hybrid treatment technology that combines anaerobic biological treatment with low-pressure membrane filtration. Although AnMBR has been used in many instances for the treatment of high strength industrial or agricultural wastewater, relatively little has been reported about its application for the treatment of domestic sewage and further conversion and recovery of resources embedded in sewage, such as energy and nutrient enriched water. The 10L column reactor uses a tubular PVDF ultrafiltration membrane (with biogas as sparge gas) for sludge/water separation. COPAS was used as synthetic feed (at 1000 mg/L) to represent household wastewater. The configuration showed excellent removal efficiencies of organic matter (up to 98% and 95% in COD and TOC removal, respectively) while producing energy in the form of methane at quantities suitable for maintaining membrane scrubbing (4.5 L/d of biogas). Soluble nutrients were recovered in the effluent in the forms of NH4, (9.1±4.2 mg/L), NO3 (2.2±0.9 mg/L) and PO4 (20±7.13 mg/L). The energy footprint (net energy) of this reactor was evaluated and the energy requirements per volume of permeate produced was found to be in the range of -1.2 to 0.7 kWh/m3, depending on final conversion of methane to electric or thermal energy respectively. These values could potentially be improved towards energy surplus (-2.3 to -0.5 kWh/m3) if applied to plant scale operation, which would employ more efficient pumps than those used in the lab. Results from this study suggest that the Gl-AnMBR can be applied as a sustainable treatment tool for resource recovery from sewage, which can further be optimized for large scale operation. In the final stage of this research, further resource recovery from sewage was investigated by coupling the Gl-AnMBR with an innovative gas-lift algal photo MBR (APMBR). To our knowledge, this is the first reported application of membranes (in particular gas-lift tubular) for separation of algal cells from effluent in a continuous-flow photobioreactor. Nutrient rich effluent (9 mg/L NH4-N and 20 mg/L PO4-P) from the Gl-AnMBR treating domestic wastewater was used as substrate to grow the biofuel producing microalgae Chlorella sorokiniana (Cs). The initial set of operational conditions tested in this study (HRT of 24 hours, operational flux of 4.5 LMH, air-lift flow rate (Qa) of 0.1 L/min and 0.1 bars of membrane inlet pressure), achieved 100% removal efficiencies for NH4 and PO4. Flux remained constant during the experimental period which demonstrated the efficacy of gas lift as a membrane fouling control strategy for an algae bioreactor. Because the algae is photoautotrophic, little removal of organic carbon was expected nor observed. Further studies are required to better understand the fate and cycling of carbon in the APMBR. Limited information is available in the literature regarding biofuel-producing, algal photo MBRs utilizing anaerobic effluents as feedstock, which makes this study an important step in understanding the design and performance of combined anaerobic/algal biotechnology for large scale application of wastewater resource recovery.

CoordenaÃÃo de AperfeiÃoamento de NÃvel Superior / Microalgae, microscopic life forms with photosynthetic capacity, produce oxygen thanks to light energy. Due to this capacity, microalgae are used for sewage treatment in stabilization ponds, however, this activity generates a large amount of microalgal biomass. In view of this excess of biomass production and its disposal in water bodies produces unpleasant effects, it has been evaluated the re-use of this biomass as a substrate for methane production in anaerobic digestion. Since microalgae have a rigid cell wall, the application of microalgae hydrolysis tests was necessary in order to improve its biodegradability. Heat pretreatment for 30 minutes at 120ÂC and 1 kgf/cm2 resulted in the best pretreatment applied. In order to improve C/N ratio, residual glycerol coming from biodiesel production was used to perform co-digestion with microalgae. Residual glycerol coming from biodiesel production (1Kg of glycerol per 10 Kg of biodiesel generated) is an impure residue which is also produced at large scale as a byproduct from the trans-esterification of fats and oils. In fact, the presence of impurities limits its applications. In this study, different COD/N ratios of 20 (phase 2), 40 (phase 3) and 70 (phase 4) were tested and the organic loading rate (OLR) applied ranged from 0,06 to 0,75 kg/m3.d. In the phase 1 only microalgae was used on the influent. Two modified UASB reactors were used. One of them was fed with pretreated microalgae, while the other one was fed with non-pretreated microalgae. Both of them were operated in co-digestion with glycerol. COD removal efficiencies ranged between 40% and 90%. Biogas produced presented values of 73% and 84% for each bioreactor treating pretreated and non-pretreated microalgae, respectively. Neither nitrogen nor ammonia and total and volatile suspended solids was significantly removed. Moreover, microalgae were the sole source of macro and micro-nutrients in this work. Sodium bicarbonate was used as a buffer during the phase 4, since pH fall down enough to harm the anaerobic digestion process at the beginning of phase 4. Based on the maintenance of adequate VFA/Alk ratios, both reactors presented a stable operation, specially the reactors treating pre-treated microalgae. Instability periods were mainly observed in some operation phases in the reactor without pretreatment. Specific methanogenic activity tests were carried out in order to evaluate the quality of the inoculum in terms of activity and methane production. Methane production presented a mean value of 0,26 g DQO-CH4/g SSV.d. / As microalgas, seres microscÃpicos com capacidade fotossintÃtica, produzem oxigÃnio na presenÃa de energia luminosa. Devido a isso as microalgas sÃo utilizadas para tratamento de esgotos em lagoas de estabilizaÃÃo, porÃm essa atividade gera uma grande quantidade de biomassa algal. Tendo em vista a produÃÃo dessa biomassa e sua destinaÃÃo em corpos hÃdricos provocando efeitos desagradÃveis, buscou-se avaliar a reutilizaÃÃo dessa biomassa como substrato para produÃÃo de metano a partir da digestÃo anaerÃbia. Devido à presenÃa de uma parede celular rÃgida, verificou-se a necessidade da aplicaÃÃo de testes de hidrÃlise para as microalgas com a finalidade de melhorar sua biodegradabilidade, sendo observado o melhor prÃ-tratamento aplicado, o tÃrmico por 30 minutos a 120ÂC e 1 kgf/cm2. Para melhorar a relaÃÃo C/N, utilizou-se o glicerol residual do biodiesel para realizaÃÃo de co-digestÃo com microalgas. O glicerol residual do biodiesel (1 kg de glicerol para cada 10 kg de biodiesel produzido), alÃm de ser um resÃduo impuro, à tambÃm produzido em grande escala como subproduto da transesterificaÃÃo de Ãleos e gorduras e sem muitas aplicaÃÃes devido exatamente a presenÃa de impurezas. Foram testadas relaÃÃes DQO/N de 20 (fase 2), 40 (fase 3) e 70 (fase 4), alÃm da relaÃÃo apenas das microalgas (fase 1), sendo as COV aplicadas, variando de 0,06 a 0,75 kg/m3.d. Foram utilizados dois reatores semelhantes ao UASB (UASB modificado), nos quais continham microalgas brutas e prÃ-tratadas, ambos em co-digestÃo com o glicerol. As remoÃÃes de DQO variaram de 40 a 90%. O biogÃs produzido teve rendimentos de atà 73% para o reator degradando microalgas prÃ-tratadas e 84% para o reator degradando microalgas brutas. NÃo houve remoÃÃes significativas de amÃnia e sÃlidos suspensos totais e volÃteis, tambÃm nÃo foram utilizados macro e micronutrientes, sendo esses nutrientes fornecidos apenas pelas microalgas. O bicarbonato de sÃdio como tampÃo foi utilizado apenas na Ãltima fase (fase 4), devido a queda do pH para uma faixa nÃo aceitÃvel para digestÃo anaerÃbia, no inÃcio dessa fase. As condiÃÃes de estabilidade foram mantidas, baseadas na relaÃÃo AGV/Alc, que se manteve em faixas aceitÃveis, principalmente para o reator operando microalgas prÃ-tratadas, sendo observado valores indicativos de instabilidade em algumas fases no reator sem prÃ-tratamento. Foi realizado teste de atividade metanogÃnica especÃfica para avaliar o lodo de inÃculo quanto a atividade e produÃÃo de metano, obtendo-se valor mÃdio de 0,26 g DQO-CH4/g SSV.d.

Ce travail vise à développer une approche originale à micro et à méso-échelle pour étudier divers phénomènes et intensifier les performances du réacteur. A méso-échelle, l'accent est mis sur l'efficacité de la production de biogaz dans un réacteur anaérobie 2D sous différentes conditions hydrodynamiques ainsi qu’à différentes concentrations de substrat. Puis, dans un dispositif microfluidique transparent, une seule granule de différentes tailles a été utilisée sous différentes conditions d'exploitation. Les effets des différentes conditions hydrodynamiques et des concentrations de substrat associés à la taille et la densité des granules de boues sur la production de biogaz ont été étudiés / The present work is focused on developing an original micro to mesoscale approach to investigate various phenomena and then to intensify the performance of a reactor. At mesoscale, the emphasis is given to the interactions between granular sludge particles as well as the biogas production efficiency in a 2D reactor under various hydrodynamic conditions at different concentrations of substrate. Then, within the microdevices, a single sludge particle of various sizes was used under different operating conditions such as superficial liquid velocity and concentration of substrate. The effect of different hydrodynamic conditions and concentration of substrate was studied