太空生存太空生存太空生存 (7).pdf
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1、Electricity generation directly using human feces wastewater for lifesupport systemDu Fangzhou,Li Zhenglong,Yang Shaoqiang,Xie Beizhen,Liu Hong?Laboratory of Environmental Biology and Life Support Technology,School of Biological Science and Medical Engineering,Beihang University,Beijing 100191,China
2、a r t i c l e i n f oArticle history:Received 30 July 2009Received in revised form15 December 2009Accepted 18 December 2009Available online 18 February 2010Keywords:Microbial fuel cell(MFC)Life support systemHuman feces wastewaterElectricity generation capacityWastewater treatmenta b s t r a c tWast
3、ewaterreuseandpowerregenerationarekeyissuesintheresearchofbioregeneration life support system(BLSS).Microbial fuel cell(MFC)can generateelectricity during the process of wastewater treatment,which might be promising tosolve the two problems simultaneously.We used human feces wastewater containingabu
4、ndant organic compounds as the substrate of MFC to generate electricity,and thefactors concerning electricity generation capacity were investigated.The removalefficiency of total chemical oxygen demand(TCOD),Soluble chemical oxygen demand(SCOD)and NH4reached 71%,88%and 44%,respectively with two-cham
5、ber MFC whenit was fed with the actual human feces wastewater and operated for 190h.And themaximum power density reached 70.8mW/m2,which implicated that MFC technologywas feasible and appropriate for treating human feces wastewater.In order to improvethe power generation of MFC further,human feces w
6、astewater were fermented beforepoured into MFC,and the result showed that fermentation pretreatment could improvethe MFC output obviously.The maximum power density of MFC fed with pretreatedhuman feces wastewater was 22mW/m2,which was 47%higher than that of the controlwithout pretreatment(15mW/m2).F
7、urthermore,the structure of MFC was studied andit was found that both enlarging the area of electrodes and shortening the distancebetween electrodes could increase the electricity generation capacity.Finally,anautomatic system,controlled by time switches and electromagnetic valves,wasestablishedtopr
8、ocessonepersonsfeceswastewater(1L/d)whilegeneratingelectricity.The main parts of this system comprised a pretreatment device and 3 one-chamber air-cathode MFCs.The total power could reach 787.1mW and power densitycould reach the maximum of about 240mW/m2.&2010 Elsevier Ltd.All rights reserved.1.Intr
9、oductionIn manned space activity,the life support system playsan important role to allow astronauts to survive in outerspace.Water reuse and power supply are critical tech-nologies of the system.There are many water resourceswhich can be recovered and reused in manned spaceactivity,such as human fec
10、es wastewater,urine,gray waterand so on.These kinds of wastewater can be purified by thewater cycle regeneration system and then reused as potablewater or domestic water 1.Although the treatmenttechnology of human feces wastewater and urine has madea certain achievement,the process is complicated,no
11、tstable and with high energy consumption.Microbial fuel cell(MFC)is an emerging technology inthe field of environmental protection and power genera-tion.It makes use of microbial metabolization underanaerobic condition to convert the chemical energyContents lists available at ScienceDirectjournal ho
12、mepage: Astronautica0094-5765/$-see front matter&2010 Elsevier Ltd.All rights reserved.doi:10.1016/j.actaastro.2009.12.013?Corresponding author.Tel./fax:+861082339837.E-mail address:LH(H.Liu).Acta Astronautica 68(2011)15371547contained in the organics to electricity,so that waste-water disposal and
13、power generation take place simulta-neously in normal condition.Theoretically,almost allthe substrates that can be metabolized by microorgan-isms are able to act as the fuel of MFC 2,such assimple molecules,urban sewage,food industry waste-water and so on.Moreover,it has been reported thatswine wast
14、ewater can feed MFC 3.Therefore,MFC hasspecial features and advantages suitable for life supportsystem.Human feces wastewater contains abundant organics4,which can be degraded to small organic moleculesapplicable for MFC.Disposing human feces via MFC canpurify water quality and recover the power in
15、them at thesame time.This will be a great of help for power andwater supply in life support system.In this paper,wefocused on the feasibility and improvement of MFC fed byhuman feces,and then we constructed an automatichuman feces MFC system to recover energy and disposethe feces produced by one ast
16、ronaut in one day.2.Materials and methods2.1.Activated sludgeThe inoculating sludge was obtained from the anaero-bic digester of sewage treatment plant,and its MLSS andMLVSS were 27g/L and 14g/L,respectively.The pH valuewas around 7.2.2.Experimental wastewater and culture mediumThe glucose culture m
17、edium,mineral solution andvitamin solution were prepared as Liu and Lovley hadreported 5,6.Phosphate buffer contained 4.22g/L NaH2PO4?2H2Oand 2.75g/L Na2HPO4?12H2O.Human feces wastewater were obtained from theseptic tank.Firstly,we filtered the human feces waste-water to remove the insoluble matter,
18、and then dilutedthe solution according to the requirement of experiment.Artificial human feces wastewater was composed of8g starch,2.5g casein,5g oleic acid,4.97g NaH2-PO4?2H2O,2.75g Na2HPO4?12H2O,0.31g NH4Cl,0.13gKCl,per liter 7.Add 12.5mL mineral solution andvitamin solution per liter.2.3.MFCs2.3.
19、1.Two-chamber MFCAs shown in Fig.1,carbon paper(6cm?8cm)servedas the anode,and carbon paper(4cm?5cm)with 40%platinum served as the cathode.The volume of anode andcathode chamber were 1L each(10cm?10cm?10cm),and they were separated by PEM(6cm?6cm,Nafion117).During the experiment,the cathode-chamber w
20、asaerated by air to keep dissolved oxygen(DO)at a highlevel.2.3.2.One-chamber MFC with two membrane electrodeassemblies(MEAs)The membrane electrode assembly(MEA)is a kind ofelectrode,whose anode,PEM and cathode are pressedtogetherto makethedistance between anodeandcathode as small as possible.Two ME
21、As covered bothsides of the anode-chamber and acted as electrodes in theone-chamber MFC(Fig.2).And baffle plates were fixes inthe chamber to make the mass in the chamber mix fullyduring the continuous-flow operation.The details of thisMFC were described in Table 1.2.3.3.One-chamber MFC with one MEAI
22、t was described in Table 1 and Fig.3.2.3.4.Adjustable two-chamber MFCTwo column chambers with actual volume of 628mLwere separated by PEM(4.9cm2).The length of the bridgeconnecting them was adjustable so that the distancebetween anode and cathode could vary from 4 to 24cm.Carbon paper with 40%platin
23、um served as the cathode(4cm?5cm)and carbon paper served as the anode(9cm?6cm)(Fig.4).2.4.Fermentation pretreatment deviceThe column reactor was made of PMMA,and its actualvolume was 2.5L.There was a blender system for stirring(Fig.5).Fig.1.Two-chamber MFC schematic diagram.Fig.2.One-chamber MFC wit
24、h two MEAs(1-Fender;2-MEA).F.Du et al./Acta Astronautica 68(2011)1537154715382.5.Experimental2.5.1.Feasibility of human feces MFCA two-chamber MFC was inoculated with anaerobicsludge(terminal concentration was 5g/L),the anode andcathode chamber were filled with glucose culture med-ium and phosphate
25、buffer,respectively,during the startupphase.The data acquisition system(Personal Measure-ment Device,PMD-1608FS,USB-1608FS,US)was used totest the output voltage of the MFC every one minute andrecord those data.We operated the MFC in batch modeandrefreshedtheanolyteaftertheoutputvoltagedecreased obvi
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