Anaerobic digestion can be used to sustainably treat the organic byproducts of the biodiesel process (crude glycerol and biodiesel wastewater) while generating a renewable natural gas to be used for heating or electricity generation. The purpose of this thesis was to (1) investigate the possibility of co-digestion of biodiesel byproducts without use of external substrates or pretreatment and (2) assess the impact of various acclimatization rates on the stability and efficiency of such a system. Two inocula (effluent from a wastewater treatment plant digester and from an agro-industrial waste digester) and two acclimatization rates were studied. The results showed that co-digestion of crude glycerol and biodiesel wastewater at high organic loading rates(up to 6.8 g COD L-1day-1)is possible without addition of other substrates or pretreatment.Thecumulative biogas production of the digesters using inoculum from the agro-industrial waste digester was statistically greater than the digesters using the wastewater treatment plant digester, indicating that similar inoculum could be useful for additional experiments.In addition,maximum efficiency due to a slower rate of acclimatization was higher for both inocula, up to a maximum average daily biogas yield of 621 mL biogas g-1COD added.Finally, comparison of two methods for measuring gas production (mass difference and volumetrically using a syringe) revealed a reasonable correlation(R2= 0.97)between the methods. Additional validation could lead to use of the mass difference method as a validation method or an alternative gas production measurement method.

Made available in DSpace on 2015-05-14T13:21:37Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1224120 bytes, checksum: f64c0391dc1efdba15b19e77bab0b144 (MD5) Previous issue date: 2014-05-09 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Given the growing trend to explore biofuels as a renewable energy source with less environmental impact and considering thatthe transesterification by basic catalysis is the most used in the biodiesel purification, it becomes importantperform treatments order to reuse of wash water biodiesel. In this sense, the objective of this study was to apply and compare photolysis (UV) followed by advanced oxidation treatment; UV/H2O2; Fenton (Fe2+/H2O2) and photo-Fenton (Fe2+/UV/H2O2)as well as perform toxicity tests using seeds lettuce (Lactuca sativa) before and after treatment of effluents.washing water was collected in biodiesel industry located in Caetés - PE. Biodiesel obtained from cotton oil was washed sequentially with two portions of one hundred liters of water. It was found pH values of 3.8 and 3.4; The minimum turbidity of 158 NTU and a maximum of 7.369 and EC was 0.25 and 0.86, minimum of 160,000 and maximum of 184.000 mg.L-1 COD, BOD ranging 830 and 2,150 mg.L-1 and the content of oils and greases varied 2,852 and 21,761 mg.L-1, respectively for first and second washing water. After application of photolysis process, reduction occurred (82.6% and 72.5%) for the water turbidity resulting from two washes.For the first rinse water, UV/H2O treatment resulted in a reduction of turbidity (91.4%) and COD (70.4%). For water resulting from second wash, reduced turbidity (84%) and in COD (80%), determined by photo-Fenton process. Through toxicity tests using lettuce seeds, it was proven that the best IG% occurred in treatments photolysis (95.3%) and UV/H2O2 (92.8%) / Diante da crescente tendência de se explorar os biocombustíveis como a fonte de energia renovável e com menor impacto ambiental e considerando que a transesterificação pela catálise básica é a mais utilizada na purificação do biodiesel, torna-se relevante realizar tratamentos visando à reutilização da água de lavagem do biodiesel. Neste sentido, o objetivo deste trabalho foi aplicar e comparar aFotólise (UV)seguidados tratamentos oxidativos avançados; UV/H2O2; Fenton (Fe2+/H2O2) e foto-Fenton (Fe2+/UV/H2O2), bem como realizar ensaios de toxicidade usando sementes de alface (lactuca sativa), antes e após o tratamento dos efluentes. A água de lavagem foi coletada na usina de biodiesel localizada na cidade de Caetés PE. O biodiesel obtido a partir do óleo de algodão foi lavado, sequencialmente, com duas porções de cem litros de água. Foram encontrados valores de pH de 3,8 e 3,4; a turbidez apresentou valor mínimo de 158 e máximo de 7369 UNT; a CE foi de 0,25 e 0,86; o valor mínimo de 160.000 e máximo de 184.000 mg.L-1de DQO; a DBO variou de 830 a 2.150 mg.L-1 e o teor de óleos e graxas oscilaram de 2.852 a 21.761 mg.L-1, respectivamente, para água de primeira e segunda lavagem. Após a aplicação do processo por fotólise, ocorreu redução (82,6% e 72,5%) da turbidez para as águas resultantes das duaslavagens. Para a água da primeira lavagem, o tratamento por UV/H2O2 resultou na melhor redução da turbidez (91,4%) e DQO (70,4%). Para a água resultante da segunda lavagem a turbidez reduziu em (84%) e a DQO em (80%), determinadas pelo processo de foto-Fenton.Através dos testes de toxicidade utilizando sementes de alface, ficou comprovado que o melhor IG% ocorreu nos tratamentos por fotólise (95,3%) e UV/H2O2 (92,8%)

Algae have been the centre of recent research as a sustainable feedstock for fuel because of their higher oil yield in comparison to other plant sources. However, algae biofuel still performs poorly from an economic and environmental perspective due to the high reliance on freshwater and nutrients for cultivation, among other challenges. The use of wastewater has been suggested as a sustainable way of overcoming these challenges because wastewater can provide a source of water and nutrients for the algae. Moreover, the ability of the algae to remove contaminants from wastewater also enhances the total economic output from the cultivation. However, the success of this strategy still depends greatly on efficient strain selection, cultivation and harvesting. Therefore, this PhD thesis has focussed on strain isolation, characterisation, optimisation and cultivation in open pond systems. Five algae strains were isolated from wastewater treatment tanks at a municipal water treatment plant in North West England. The isolated strains were morphologically and genetically characterised as green single-celled microalgae: Chlamydomonas debaryana, Hindakia tetrachotoma, Chlorella luteoviridis, Parachlorella hussii and Desmodesmus subspicatus. An initial screening of these strains concluded that C. luteoviridis and P. hussii were outstanding in all comparisons and better than some of the strains previously reported in the literature. Further tests carried out to elucidate the underlying tolerance mechanisms possessed by these strains were based on stress tolerance and acclimation hypotheses. In the following experiments, C. luteoviridis and P. hussii were found to have higher anti-oxidant enzyme activity that helps in scavenging reactive oxygen species produced as a result of exposure to wastewater. This result provides a new argument for screening microalgae strains for wastewater cultivation on the basis of anti-oxidant activity. In addition, the two strains could grow heterotrophically and are better adapted to nutrient deficiency stress than the other three isolates. In order to understand the role of microalgae acclimation in wastewater cultivation, strains identical or equivalent to the wastewater treatment tank isolates were obtained from an algae culture collection. These strains had not been previously exposed to wastewater secondary effluent. The initial growth of these strains in wastewater secondary effluent was very poor. However, after two months of acclimation to increasing concentrations of secondary wastewater effluent, it was observed that growth, biomass and lipid productivities of most of the strains were significantly improved, although still not as high as the indigenous strains. Therefore, it was concluded that continuous acclimation is an additional factor to the successful growth of algae in wastewater. Furthermore, addition of 25% activated sludge centrate liquor to the secondary effluent was found to increase algal growth and biomass productivity significantly. Futher tests to examine the continous cultivation of C. luteoviridis and P. hussii in wastewater showed that a biomas productivity of 1.78 and 1.83 g L-1 d-1 can be achieved on a continual basis. Finally, the capability of C. luteoviridis and P. hussii for full seasonal cultivation in a 150 L open pond in a temperate climate was studied, using the optimised secondary wastewater +25% liquor medium. Each strain was capable of growth all year including in autumn and winter but with strongest growth, productivity and remediation characteristics in the summer and spring. They could maintain monoculture growth with no significant contamination or culture crash, demonstrating the robustness of these strains for wastewater cultivation in a northern European climate.