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Microalgae photobioreactors integrated with biogas cogeneration plants: Preliminary analysis for CO2 capture, nitrogen removal and energy recovery
S164
Special Abstracts / Journal of Biotechnology 150S (2010) S1–S576
Discussion: The increase of the biogas yield (generated electricity and heat) and the decrease of the electric energy demand can improve the energy balance of the plants. Minimization of the energy input can consequently be achieved in two ways: digesting more sludge (or other biodegradable waste), or improving the efficiency of the devices of fluid and air mixing and transport. Biotechnological developments that allow the separate nitrogen removal from the reject water of the anaerobic digestion via nitrite or the increase of biogas yield by the preliminary ulrasonic treatment of sludge before digestion can mean great savings as well, by the increase of the methane yield. Fig. 1. doi:10.1016/j.jbiotec.2010.08.424 [P-B.72] Microalgae photobioreactors integrated with biogas cogeneration plants: Preliminary analysis for CO2 capture, nitrogen removal and energy recovery C. Caprara 1,∗ , L. Colla 2 , G. Stoppiello 1 , D. Zanella 2 , G. Zucchi 2 1
Agricultural Economics and Engineering Dept., University of Bologna, Italy 2 Klyma S.r.l., Italy Keywords: Microalgae photobioreactors; Biogas cogeneration plants; CO2 capture; Energy recovery Introduction: Some of the issues open for cogeneration plants fueled with biogas from anaerobic digestion of manure are: - CO2 capture from the exhaust gases, in order to reduce greenhouse gases emissions; - nitrogen removal from the manure after anaerobic digestion, for a perspective agronomic use in sensitive areas like the Po Valley. The chemical and physical processes nowadays adopted for these tasks are expensive and feasible for large installations only. Fixing CO2 by bioreactors for algae production seems to be an alternative methodology better suitable for distributed cogeneration plants, more over this also allow to considerably reduce nitrogen loads from manure anaerobic digestion. The aim of this study is to propose a multidisciplinary approach to bioprocess engineering aspects, providing indications of system design. Methods: The proposed technology for cogeneration system consists of an internal combustion engine and an anaerobic digester fed with sewage and manure from cattle, and supplemented vegetable biomass. The plant is 200 kW nominal electric power. It is supposed to produce exhaust gases with CO2 contents for about 5100 kg/day loading and a liquid digestate flow as about 50 m3 /day. The simulation model is expected to use the Spirulina microalgae for the algal biomass production in photobioreactors for CO2 sequestering and nitrogen removal. The algal produced biomass is dried up to 15% moisture content and successively sent to a gasification unit. Results: The system analysis allows to estimate a projected capacity of CO2 fixation by about 136 kg/h and a nitrogen removal rate by about 4 kg/h, according to the considered size of cogeneration plant. The analysis also simulates the thermodynamic behavior of a downdraft gasification reactor fed with dried Spirulina sp. Two alternative gas mixtures were considered as gasifying agents: Oxygen with Water Vapor and Air with Water Vapor. Equiv-
alence ratio was respectively fixed to 0.25 and 0.30 in the two cases. The simulation model provided the following results: Oxygen + Water Vapor: gas flow = 157 Nm3 /h; LHV = 8814 KJ/Nm3 Air + Water Vapor: gas flow = 266 Nm3 /h; LHV = 4782 KJ/Nm3 Conclusions: The preliminary carried out analysis provides a tool for plant engineering evaluating choices in terms of environmental sustainability and energy efficiency. doi:10.1016/j.jbiotec.2010.08.425 [P-B.73] Development of a Simple method for the determination of phosphorus in biodiesel E.L.C. Silveira ∗ , L.B. Caland, M. Tubino University of Campinas, Brazil Keywords: Biodiesel; Phosphorus; spectrophotometry Considering the rising importance of biodiesel as alternative fuel in many countries, it is absolutely necessary to establish standards for the description of the quality of the product. The quality of the produced biodiesel through chemical and physical analysis is of fundamental importance. Phosphorus in biodiesel comes from phospholipids. The transesterification of vegetable crude oils without pretreatment or degumming can result in reduced reaction yield and in the production of biodiesel with high phosphorus content. The maximum amount of phosphorus that can be present in biodiesel is regulated to 10 mg kg−1 by EN-14214. In this communication a new spectrophotometric method for the determination of phosphorus in biodiesel, based in formation molybdenum blue, is described. Samples of biodiesel were subjected to ashing. The obtained residue is dissolved in ca. 25 mL of H2 SO4 1 mol L−1 . Ammonium molybdate solution was added for the formation of the molybdenum complex (Mo(VI)) followed by the addition of 1amino-2-naphtol-4-sulfonic solution. The formed Mo(V) species is spectrophotometrically quantified at 800 nm. The accuracy of the method was checked by means of recovery tests. Soybean lecithin (2.4% w/w of P) was used as standard. The limits of detection (LOD) and quantification were, respectively, ca. 0.7 and 2.1 mg P kg−1 of biodiesel. The phosphorus content of corn biodiesel falls below of the limit of detection of the method; therefore it is far under the established EN-14214 limit. The obtained recovery ranged between 81 and 92%, but it can be improved using smoother heating increase in the furnace up to 550 ◦ C. The first results obtained (mg kg−1 ) with the proposed method suggest than it could be a good alternative for phosphorus determination in biodiesel. Biodiesel
Initial conc.
Added conc.
Found conc.
Recovery/%
Corn Canola
< LOD 3
12 13
11 13
92 81
doi:10.1016/j.jbiotec.2010.08.426
Special Abstracts / Journal of Biotechnology 150S (2010) S1–S576
Discussion: The increase of the biogas yield (generated electricity and heat) and the decrease of the electric energy demand can improve the energy balance of the plants. Minimization of the energy input can consequently be achieved in two ways: digesting more sludge (or other biodegradable waste), or improving the efficiency of the devices of fluid and air mixing and transport. Biotechnological developments that allow the separate nitrogen removal from the reject water of the anaerobic digestion via nitrite or the increase of biogas yield by the preliminary ulrasonic treatment of sludge before digestion can mean great savings as well, by the increase of the methane yield. Fig. 1. doi:10.1016/j.jbiotec.2010.08.424 [P-B.72] Microalgae photobioreactors integrated with biogas cogeneration plants: Preliminary analysis for CO2 capture, nitrogen removal and energy recovery C. Caprara 1,∗ , L. Colla 2 , G. Stoppiello 1 , D. Zanella 2 , G. Zucchi 2 1
Agricultural Economics and Engineering Dept., University of Bologna, Italy 2 Klyma S.r.l., Italy Keywords: Microalgae photobioreactors; Biogas cogeneration plants; CO2 capture; Energy recovery Introduction: Some of the issues open for cogeneration plants fueled with biogas from anaerobic digestion of manure are: - CO2 capture from the exhaust gases, in order to reduce greenhouse gases emissions; - nitrogen removal from the manure after anaerobic digestion, for a perspective agronomic use in sensitive areas like the Po Valley. The chemical and physical processes nowadays adopted for these tasks are expensive and feasible for large installations only. Fixing CO2 by bioreactors for algae production seems to be an alternative methodology better suitable for distributed cogeneration plants, more over this also allow to considerably reduce nitrogen loads from manure anaerobic digestion. The aim of this study is to propose a multidisciplinary approach to bioprocess engineering aspects, providing indications of system design. Methods: The proposed technology for cogeneration system consists of an internal combustion engine and an anaerobic digester fed with sewage and manure from cattle, and supplemented vegetable biomass. The plant is 200 kW nominal electric power. It is supposed to produce exhaust gases with CO2 contents for about 5100 kg/day loading and a liquid digestate flow as about 50 m3 /day. The simulation model is expected to use the Spirulina microalgae for the algal biomass production in photobioreactors for CO2 sequestering and nitrogen removal. The algal produced biomass is dried up to 15% moisture content and successively sent to a gasification unit. Results: The system analysis allows to estimate a projected capacity of CO2 fixation by about 136 kg/h and a nitrogen removal rate by about 4 kg/h, according to the considered size of cogeneration plant. The analysis also simulates the thermodynamic behavior of a downdraft gasification reactor fed with dried Spirulina sp. Two alternative gas mixtures were considered as gasifying agents: Oxygen with Water Vapor and Air with Water Vapor. Equiv-
alence ratio was respectively fixed to 0.25 and 0.30 in the two cases. The simulation model provided the following results: Oxygen + Water Vapor: gas flow = 157 Nm3 /h; LHV = 8814 KJ/Nm3 Air + Water Vapor: gas flow = 266 Nm3 /h; LHV = 4782 KJ/Nm3 Conclusions: The preliminary carried out analysis provides a tool for plant engineering evaluating choices in terms of environmental sustainability and energy efficiency. doi:10.1016/j.jbiotec.2010.08.425 [P-B.73] Development of a Simple method for the determination of phosphorus in biodiesel E.L.C. Silveira ∗ , L.B. Caland, M. Tubino University of Campinas, Brazil Keywords: Biodiesel; Phosphorus; spectrophotometry Considering the rising importance of biodiesel as alternative fuel in many countries, it is absolutely necessary to establish standards for the description of the quality of the product. The quality of the produced biodiesel through chemical and physical analysis is of fundamental importance. Phosphorus in biodiesel comes from phospholipids. The transesterification of vegetable crude oils without pretreatment or degumming can result in reduced reaction yield and in the production of biodiesel with high phosphorus content. The maximum amount of phosphorus that can be present in biodiesel is regulated to 10 mg kg−1 by EN-14214. In this communication a new spectrophotometric method for the determination of phosphorus in biodiesel, based in formation molybdenum blue, is described. Samples of biodiesel were subjected to ashing. The obtained residue is dissolved in ca. 25 mL of H2 SO4 1 mol L−1 . Ammonium molybdate solution was added for the formation of the molybdenum complex (Mo(VI)) followed by the addition of 1amino-2-naphtol-4-sulfonic solution. The formed Mo(V) species is spectrophotometrically quantified at 800 nm. The accuracy of the method was checked by means of recovery tests. Soybean lecithin (2.4% w/w of P) was used as standard. The limits of detection (LOD) and quantification were, respectively, ca. 0.7 and 2.1 mg P kg−1 of biodiesel. The phosphorus content of corn biodiesel falls below of the limit of detection of the method; therefore it is far under the established EN-14214 limit. The obtained recovery ranged between 81 and 92%, but it can be improved using smoother heating increase in the furnace up to 550 ◦ C. The first results obtained (mg kg−1 ) with the proposed method suggest than it could be a good alternative for phosphorus determination in biodiesel. Biodiesel
Initial conc.
Added conc.
Found conc.
Recovery/%
Corn Canola
< LOD 3
12 13
11 13
92 81
doi:10.1016/j.jbiotec.2010.08.426