Enhancement Of Biohydrogen Production By Psb Biofilm On Support Biomaterial Based On Spectral Beam Splitting Technology

Hydrogen is considered as an important energy of great research value in the 13 th five-year plan of China,because of its high heat value,cleanness and abundant utilization types.Biohydrogen production by photo-fermentation is one promising way owing to the high purity of produced hydrogen,available light spectra and extensive substrate source.In recent years,the biofilm technique has been applied into biohydrogen production by photo-fermentation,and it shows great potential with prominent advantages of high biomass concentration in per volume,a short light path to biofilm and high resistance against inhibitors.However,this technology is still facing some problems in large-scale applications,such as low and inhomogeneous light distribution,unnecessary heat transfer path,high energy consumption and difficulty of biofilm formation.Therefore,the improvement of light transfer in biofilm photobioreactors?BPBRs?,the research of support materials which are expected to enhance the adsorption capacity of cells and control the temperature of biofilm and design of high performance BPBRs based on this support material are of significant importance to the hydrogen production perfermance and industrial application of photo-fermentation using biofilm technology.In this work,we focused on the biofilm technology for hydrogen production using photo-fermentation.Firstly,in order to improve the luminous intensity and distribution,we proposed a novel BPBR using light guide plate?LGP?as the light guider and biofilm support material.Secondly,to simplify the heat transfer in the traditional BPBRs,we proposed the photo-thermal conversion material of LaB₆ nano-particals based on the spectral beam splitting technology.Thirdly,we proposed a novel BPBR using GeO2-SiO2-chitosan-medium-LaB₆?GSCML?as support material based on the spectral beam splitting technology to control the temperature condition and light distribution on PSB biofilm.Experimental results indicated that the luminous intensity and distribution of BPBR using LGP can be improved.The biomaterial based on La B₆ can enhance the heat transfer and utilization efficiency.The GSCML BPBR can improve the biofilm growth and hydrogen production performance in the BPBR.The main conclusions of this thesis are as follows.?1?.A BPBR using LGPA novel light guide plate?LGP?biofilm photobioreactor?BPBR?was proposed to improve the luminous intensity and the luminous uniformity.In addition,SiO2-chitosan-medium?SCM?biomaterial was utilized to modify the surface of light guide plate to improve the biocompatibility and roughness of the surface.The luminous intensity on the surface and the average hydrogen production rate?HPR?of the light guide plate BPBR and the SCM light guide plate BPBR were 10.1 W/m2,8.9 mmol/h/m2,7.8 W/m2 and 11.6 mmol/h/m2,respectively.Those results were 2.7,0.6,1.7 and 1.1 times higher than that of the traditional polymethyl methacrylate?PMMA?flat-plate BPBR.In addition,the morphology and thickness of the biofilm on BPBRs have been statistically analyzed,indicating the well biofilm growth on those proposed BPBRs.In summary,the biofilm growth and hydrogen production performance of BPBR can be improved by optimization of luminous intensity,surface morphology and composition.?2?.Photo-thermal material of LaB₆ nanoparticlesTo realize direct heat transfer from biofilm support material to PSB cells and enhance the light and heat utilization efficiency,a photo-thermal conversion biomaterial based on lanthanum hexaboride?LaB₆?and chitosan was fabricated.The absorption spectra and photothermal properties of biomaterial with different LaB₆ particles were investigated in the visible spectrum.The result shows that the biomaterial will transmit light in the spectrum of 510-650 nm for hydrogen production and growth of PSB,and other light energy will convert to heat energy for PSB.In addition,the absorption and photothermal performance of La B₆ particles were significantly affected by the particle size.When the average hydraulic diameter of La B₆ particles in the biomaterial was 296 nm,the rate of temperature rise is 0.41 ?/min over 12 minutes,which is 5.4 times of glass slide.In summary,the biomaterial based on LaB₆ and chitosan shows great capacity of photo-thermal conversion in the visible spectrum and property of spectral beam splitting,which can provide light energy and heat energy for PSB.?3?.A BPBR using GSCML biomaterialTo improve the light and heat transfer in BPBR and enhance bacterial adhesion and biofilm activity,a novel photothermal biomaterial,which named as GeO2-SiO2-Chitosan-Medium-LaB₆?GSCML?,was prepared for immobilization of photosynthetic bacteria?PSB?cell.This biomaterial can directly control the temperature and light intensity on biofilm by controlling the outside light conditions and the coating density of La B₆.In addition,we proposed a BPBR based on this biomaterial.The support material physicochemical properties?i.e.surface morphology,microstructure,and composition?were investigated.In addition,the biofilm formation and hydrogen production performance of BPBR were investigated.The results suggested that the average heating rate during the first 10 min and the luminous intensity of the light transmitted through the GSCML were 0.4 ?/min and 64.5 W/m2,which is of 44.3% of the total LED light source.The average biofilm growth rate and hydrogen production rate of the biofilm on the created biomaterial were 0.05 mg/ cm2/day and 2.92 mmol/h/m2,which were 3.4 and 4.1 times higher than those of the glass slide,respectively,suggesting that the light-use efficiency was improved by using the prepared GSCML biomaterial.In conclusion,this biomaterial shows the potential for large-scale immobilized photosynthetic bacteria culture and biohydrogen production in the future,because of the good temperature regulation,surface light intensity,biocompatibility,and surface roughness.In conclusion,the proposed BPBR using LGP and BPBR using GSCML biomaterial as support material show a promising prospect for large-scale immobilized PSB culture and photo-fermentative biohydrogen production in the future owing to the uniform luminous property,photothermal conversion capacity and great physicochemical characteristic on the surface.