CO 2 fixation, lipid production and power generation by a novel air-lift-type microbial carbon capture cell system

Transcription

1 1 Supporting Information CO 2 fixation, lipid production and power generation by a novel air-lift-type microbial carbon capture cell system Xia Hu, Baojun Liu, Jiti Zhou*,Ruofei Jin, Sen Qiao and Guangfei Liu Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Linggong Road 2, Dalian , China *Corresponding author. Prof. Jiti Zhou, jitizhou502@163.com Summary This supporting information contains a total of 8 pages, including 2 figures S1

2 Calculations Determination of CO 2 fixation rate The CO 2 fixation rate R CO 2 (mg L -1 d -1 ) was calculated as 1 : R = C CO 2 c M P( M CO 2 C ) 27 Where Cc is the carbon content in the biomass (%, w/w), which was measured by elemental analyzer (Elementar vario EL III); P is the biomass productivity (mg L -1 d -1 ); MCO 2 is the molar mass of CO 2 ; and MC is the molar mass of carbon. equation: The biomass productivity (P, mg L -1 d -1 ) was calculated using the following X P = t Where X is the variation of biomass concentration (mg L -1 ) with cultivation 34 time; t is the cultivation time (d) S2

3 Determination of lipid content and productivity The band around cm -1 of FTIR spectroscopy could well characterize the lipid content changes and thus be used to detect quantitatively the lipid content and its accuracy has been validated by traditional methods. 2, 3 For the determination of lipid content, egg phosphatidylcholine (egg-pc) was chose as an external standard. An infrared spectrometer (Bruker VERTEX 70, Germany) was used to record the characteristic peak areas of egg-pc at cm - 1, yielding the calibration equation: A = T (R = 0.993). Where A is the characteristic peak areas of lipid; T (mg) is the weight of lipid. The lipid content L c (%) was calculated by the following equation: T L c = 100% M Where T (mg) is the weight of lipid; M (mg) is the dry weight of microalgae. The lipid productivity L P (mg L -1 d -1 ) was calculated by the following equation: L = P p L c Where P (mg L -1 d -1 ) is the biomass productivity; L c (%) is the lipid content of microalgae S3

4 Energy consumption of pumping system was estimated as 4 : QγE P = 1000 Where P is power requirement (kw), Q is flow rate (m 3 s -1 ), γ is 9800 N m -3, and E represents the hydraulic pressure head (m). For the anolyte feeding, Q was m 3 s -1 (0.8 ml min -1 ). The measured hydraulic pressure head loss was m for the anolyte. Therefore, the power required was kw for the pump. Dividing by the flow rate ( m 3 h -1 ) yielded a pumping energy requirement of kwh m S4

5 Field emission Scanning Electron Microscopy (FE-SEM) Microalgae cells cultivated in the three reactors (ALMCC, MCC and ALP) were collected by centrifugation (8000 rpm for 5 min) and fixed in 2.5% glutaraldehyde for 24 h. The collected cells dehydrated in ethanol for 10 min under a concentrations ranging from 50%, 70%, 80%, 95%, 100%. Samples were dried at 35 o C for 12 h in vacuum dryer and then examined with FESEM (Hitachi SU8010, Japan) with an accelerating voltage of 5 kv S5

6 Figure S1. The standard curve for biomass concentration of microalgae against calibration of absorbance (690 nm) S6

7 Figure S2. Biomass concentrations of microalgae under different CO 2 levels S7

8 References (1) Ho, S. H.; Chen, C. Y.; Chang, J. S. Effect of light intensity and nitrogen starvation on CO 2 fixation and lipid/carbohydrate production of an indigenous microalga Scenedesmus obliquus CNW-N. Bioresour. Technol. 2012, 113, (2) Meng, Y. Y.; Yao, C. H.; Xue, S.; Yang, H. B. Application of Fourier transform infrared (FT-IR) spectroscopy in determination of microalgal compositions. Bioresour. Technol. 2014, 151, (3) Pistorius, A. M.; DeGrip, W. J.; Egorova-Zachernyuk, T. A. Monitoring of biomass composition from microbiological sources by means of FT-IR spectroscopy. Biotechnol. Bioeng. 2009, 103 (1), (4) Kim, J., Kim, K.; Ye, H.; Lee, E.; Shin, C.; McCarty, P. L.; Bae, J. Anaerobic fluidized bed membrane bioreactor for wastewater treatment. Environ. Sci. Technol. 2011, 45, S8