Influence of Biogas Flow Rate on Biomass Composition During the Optimization of Biogas Upgrading in Microalgal-Bacterial Processes

Question

1. What are the future works in this paper?

2. What are the contributions in this paper?

3. What was the main mechanism of removal of NH4+ from the biomass?

4. What was the effect of the increased CO2 concentrations in the treated biogas?

Accepted Answer

Unfortunately, 403 O2 concentrations in the upgraded biogas were above maximum recommended levels for 404 biomethane injection in natural gas networks in Europe, which represents a niche for further 405 research.. 2010, 20, 1–7. 469 ( 23 ) Leis, J. ; Member, S. ; Buttsworth, D. ; Snook, C. ; Holmes, G. Detection of Potentially 470 Explosive Methane Levels Using a Solid-State Infrared Source.

Accepted Answer

In this paper, the influence of biogas flow rate on the elemental and macromolecular composition of algal-bacterial biomass produced from upgrading in a 180 L photobioreactor interconnected to a 2.5 L external bubbled absorption column was investigated using diluted anaerobically digested vinasse as cultivation medium.

Accepted Answer

A carbon mass balance 261 calculation over the entire experimental period revealed that assimilation into biomass was the 262 main C removal mechanism.

Accepted Answer

Despite O2 238 concentrations in the treated biogas also remained stable at L/G ratios above 15 (3±1%), the rapid 239 DO fluctuations in the algal broth of the HRAP (DO ranged from 3.4 to 7.3 mg L-1 along the 175 240 days of experimentation) used for CO2 and H2S absorption could eventually increase O2 241 concentrations in the upgraded biogas above 5%, which constitutes the lower explosive limit 242 (LEL) for methane/O2 mixtures.

Accepted Answer

159 Biomass harvesting was performed twice a week from stages The authorto III and every day in stages IV 160 and V (due to the fact that the high external liquid recirculation drawn from the settler implied a 161 high biomass accumulation in the settler, which also entailed the need for daily settled biomass 162 recirculation to the HRAP in order to avoid biomass wash-out).

Accepted Answer

8 Lower CO2-REs (40±6%) were reported by Bahr et al.10 when 320 assessing biogas upgrading in a AC-HRAP using diluted centrate wastewater instead of mineral 321 salt medium (CO2-REs ≈86±5%), while H2S-REs remained at 100% regardless of the cultivation 322 medium in this preliminary study.

Accepted Answer

This increase in CO2 removal concomitant 225 with the higher O2 concentrations observed in the treated biogas were likely due to the combined 226 effects of an increase in the overall mass transfer coefficients (klaCO2 and klaO2) at increasing 227 L/G ratios (higher turbulence in the AC) and of the enhanced CO2/O2 carry over potential of the 228 external liquid recirculation in the AC (which avoided liquid saturation with CO2, thus increasing 229 CO2 concentration gradients available for gas-liquid mass transport, and increased the amount of 230 O2 potentially stripped-out).

Accepted Answer

In this context, the microalgae population present in the HRAP 383 during experimentation was mainly composed by cyanobacteria, which are known to contain 384 glycogen rather than starch as storage carbohydrates.

Accepted Answer

The results obtained also showed that CO2-RE and the O2 concentration in the 222 upgraded biogas increased linearly at increasing the L/G ratio up to a ratio of 15 (Fig. 2b).

Accepted Answer

This was confirmed by the low starch 385 content of the algal-bacterial biomass (5±1%) in stage V. Based on the results obtained in stage V 386 and assuming both a yield of carbohydrate extraction (prior hydrolysis) into glucose of 80% and a 387 theoretical maximum conversion of glucose into ethanol of 0.51 g ethanol per g glucose,36 388 1000 m3 d-1 of biogas could eventually produce 328 Kgbiomass d-1 and be converted to 102 L of 389 ethanol.

Accepted Answer

304 The CO2 and H2S-REs remained constant at 84±2% and 100%, respectively, as well as the O2 305 (1±1%) and N2 (8±1%) concentrations in the upgraded biogas.

Accepted Answer

398In brief, this research work confirmed the potential of algal-bacterial processes to support an 399 integral upgrading of biogas coupled to both wastewater treatment and the production of biomass 400 with a high plasticity in terms of macromolecular composition.

Influence of Biogas Flow Rate on Biomass Composition During the Optimization of Biogas Upgrading in Microalgal-Bacterial Processes

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Most frequently asked questions

1. What are the future works in this paper?

2. What are the contributions in this paper?

3. What was the main mechanism of removal of NH4+ from the biomass?

4. What was the effect of the increased CO2 concentrations in the treated biogas?

5. Why was the biogas harvesting performed twice a week?

6. How did Bahr and his colleagues evaluate the biogas in a diluted water ?

7. What is the effect of the increased CO2 removal in the treated biogas?

8. What is the composition of the microalgae population in the HRAP 383?

9. What was the effect of the increased CO2 concentration in the upgraded biogas?

10. What is the effect of the low starch content of the algal-bacterial biomass in stage?

11. How much CO2 and H2S-REs were removed from the upgraded biogas?

12. What is the potential of the algal-bacterial biomass to support an integral upgrading of biogas?

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Citations

Biogas upgrading and utilization: Current status and perspectives

A review on the state-of-the-art of physical/chemical and biological technologies for biogas upgrading

Microalgal Cultivation in Treating Liquid Digestate from Biogas Systems.

Innovation in biological production and upgrading of methane and hydrogen for use as gaseous transport biofuel.

Nutrient removal and biogas upgrading by integrating freshwater algae cultivation with piggery anaerobic digestate liquid treatment.

References

Protein Measurement with the Folin Phenol Reagent

Standard methods for the examination of water and wastewater

Biodiesel from microalgae beats bioethanol.

Progress in bioethanol processing

Techniques for transformation of biogas to biomethane

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