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Biodiesel production by Cryptococcus curvatus using volatile fatty acids from lipid-extracted sewage sludge digestion

Sanchez Sanchez, Raul

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초록 moremore
In this study, the objective is first to create a system where lipid production can be performed using food waste and activated sludge and second the reutilization of the lipid extracted biomass coming from the first stage to produce more lipids. Food waste water was utilized as a substrate for the ...
In this study, the objective is first to create a system where lipid production can be performed using food waste and activated sludge and second the reutilization of the lipid extracted biomass coming from the first stage to produce more lipids. Food waste water was utilized as a substrate for the lipid enhancement in activated sludge controlling the C:N ratio. After lipid enhancement, the effluent obtained was centrifuged to concentrate the biomass. Consequently, the biomass was dried and undergone a particle size reduction to perform lipid extraction. The final lipid content after four days was in average 25.15% ± 3.7% in dry basis. Residual biomass was processed in a one-stage anaerobic digester to produce volatile fatty acids in continuous process. The reactor was feeding with different concentrations of lipid-extracted biomass (10 g · L-1, 20 g · L-1 and 30 g · L-1). In steady state, the concentrations of total volatile fatty acids were 5.98 ± 0.21 g · L-1, 10.56 ± 0.21 g · L-1 and 15.20 ± 0.20 g · L-1, respectively. The effluent with highest concentration was pretreated to reduce ammonium concentration by generation of struvite increasing the C:N ratio. After the pretreatment Cryptococcus curvatus was inoculated and lipid production performance was evaluated in a repeated fed-batch system. Final concentration of lipid after four batches was 2.25 ± 0.11 g · L-1 and 57.98% of lipid content. Produced lipids were transesterified and the fatty acids content was analyzed.
목차 moremore
I. Introduction 1
1.1.GeneralBackground 1
1.2. Research objectives 4
...
I. Introduction 1
1.1.GeneralBackground 1
1.2. Research objectives 4
II. Material and methods 5
2.1. Lipid enhancement in activated sludge 5
2.1.1. Feedstock for lipid production 5
2.1.2. Mixing ratio 5
2.1.3. Operation conditions 5
2.2. Anaerobic digestion of lipid extracted biomass 8
2.2.1. Feedstock for anaerobic digestion 8
2.2.2. Inoculum for VFA production 8
2.2.3. Anaerobic digestion in continuous culture 9
2.3. Lipid production with Cryptococcus curvatus 10
2.3.1. VFA effluent 10
2.3.2. Inoculum for lipid production 10
2.3.3. Pretest of lipid production 11
2.3.4. Repeated fed batch operation 11
2.4. Analytical method 13
2.4.1. Physico-chemical analytical method 13
2.4.2. Determination of total organic carbon (TOC) and NH4+ 13
2.4.3. Dry cell weight 14
2.4.4. Lipid extraction 14
2.4.5. Fatty acid methyl esters 14
III. Results and Discussion 15
3.1. Lipid enhancement in activated sludge 15
3.1.1. C:N ratio control with food waste water 15
3.2. Anaerobic digestion of the lipid extracted biomass 21
3.2.1. VFA production using CSTR 21
3.2.2. VFA yield 26
3.2.3. NH4+ content reduction in the VFAs medium 28
3.3. Lipid production with Cryptococcus curvatus 31
3.3.1. Batch test 31
3.3.2. Repeated fed batch production of lipid 34
3.3.3. Fatty acid composition profile 40
IV. Conclusion 42
References 43