Microbiological Analysis Of Two-phase Anaerobic Digestion And Research On The Mechanism Of Syntrophism

A large sum of organic waste is produced every year,going along the fast development of our country,which contains considerable biomass energy.If so much organic waste can’t be disposed of properly,there would be a serious waste of resources,and the environment would be contaminated seriously at the same time.By anaerobic digestion（AD）technology,organic can be used to produce biogas,which can be used to generate electricity or used as natrural gas after purified,and the discharge of waste and greenhouse gas can be reduced at the same time.AD technology is a powerful tool to deal with the severe resources and environment problems.Though AD has be put in use both at home and abroad,the lack of theoretical direction Seriously hindered the industrialization of AD technology.The lack of knowledge about the microoganisms involved in AD has become the bottleneck problem which hinders the development and application of AD.This research is mainly on two-phase AD,analysing microbial community characteristics of the system in several different conditions.The effects of condutive nano-particles when added into the system are also studied.There are three parts of the experiments and results:（1）The substrate is chicken manure.The thermophilic-mesophilic two-phase AD reactors is operated under three different OLRs（5 gVS/（L·d）,8 gVS/（L·d）,11 gVS/（L·d））and stabilized.high-throughput sequencing is used to analyse the microbial community characteristics of the system.Combining the microbial community characteristics with the operation of the reactor,the change of the microbial community in different conditions is analysed,as well as the adaptive capacity to different environment of different microoganisms.（2）Three kinds of conductive particles are studied by batch experiments,namely nano-particle of gold,nano-particle of iron（nano-iron powder,nanoα-Fe₂O₃ and nano-Fe₃O₄）and graphite powder.The nano-particle of gold and nano-Fe₃O₄ promoted the biogas production of the system（around 10%）,by promoting the direct electron transfer and syntrophism between microoganisms.The addition of nano-iron powder delayed the biogas production of the system,but the content of the methane in the biogas produced is much higher than the other groups,which reaches 90%.This dues to the reaction between iron and the acid in the system.As α-Fe₂O₃ is not conductive,it inhibites the biogas production of the system.The addition of graphite powder also promoted the biogas production,especially during the early period of the experiment.（3）Graphite powder is added to the methane phase of the continuous fermentation,but the result is not so good as expected,which is because the acetotrophic methanogens those transfer eletrons by direct eletron tranfering are rare.