Study On The Characteristics Of Anaerobic Fermentation Of Straws Under Different Chemical Pretreatment Conditions

Biogas，as renewable energy, is focused by the central and local levels of government，which is under conditions of the current shortage of energy resources and increasingenvironmental pollution. It is one of the largest ranges of promotion of clean energy usepatterns, forming mature technology. Rural biogas has an important role in promotingaquaculture, supporting production and improving living conditions in rural areas, which isone of the important strategic measures to deal with environmental challenges and ruralenergy problems. Research of biogas in China is mainly reflected in multiple levels of rawmaterials, technology and research methods. Thus, chemical pretreatment for corn straw isresearched in this study, by anaerobic fermentation technology under the thermostat. Thestudy aimed to obtaine the optimal concentration of each pretreatment, aiming to providesome value for the future straw pretreatment technology of anaerobic fermentation.Cornstalk is studied as raw material, under anaerobic conditions with a constanttemperature of35℃. The mass fraction of pretreatment reagent of acetic and hydrogenperoxide, sulfuric and hydrochloric acid is1%,2%and3%respectively. Anaerobicfermentation characteristic of each pretreatment is the purpose. Each treatment group startsfaster by anaerobic fermentation process, with a fermentation period average of60d. Biogasoutput rate, cumulative gas production, VFA, pH, ammonia nitrogen, TS, hemicellulose andother indicators were fluency indices for the research. The main results obtained in this paperwere listed as the followings:（1） The cumulative biogas production of each sulfuric acid pretreatment are lower thanthe CK. Total biogas production: S1> S2> S3, with8952ml,6021ml,1012ml respectively;VFA peak: S2> S3> S1; TS production rate of biogas: S1> S2> S3,118.84ml.g^-1,88.44mlg^-1and17.65ml.g^-1respectively; hemicellulose degradation: S3> S2> S1. VFA degradationrate of the each concentration is lower than that of the CK. The pH of S1, S2and S3offermentation liquid fluctuate between5.7-7.8,4.5-7.4,3.3-5.3, which were weakly acidicenvironment.（2） CL1is the best process conditions, with the highest cumulative biogas production,which raised27.72%than the CK. Total gas production: CL1>CL2>CL3,20416ml,1414ml and960ml respectively; VFA peak: CL2CL3> CL1; TS produced gas rate: CL1> CL2> CL3,310.88ml.g^-1,22.64ml and18.17ml.g^-1respectively; hemicellulose degradation: CL3>CL3> CL2.（3） Anaerobic fermentation characteristics of each acetic acid preteeatment withcornstalk were reflected as follows: total gas production: COO1>COO3>COO2,22641ml,17264ml,22016ml respectively; VFA peak: COO3> COO2> COO1, with10268.5mg/L,10263.5mg/L and9973.5mg/L; TS production rate of gas: COO3> COO1> COO2,410.00ml.g^-1,314.89ml.g^-1,277.43ml.g^-1respectively; hemicellulose degradation: COO3>COO2> COO1.（4） The cumulative gas production of1%,2%and3%of hydrogen peroxidepretreatment of cornstalk is approximate, raised47.99%,41.96%and38.95%than CK.TS-gas production rate raised95.62%,170.92%and107.52%than CK respectively. The pHrange of fermentation liquid of HO1、HO2and HO3fluctuated between6.9-7.4,7-7.6and6.9-7.5, all of which were maintained in a neutral environment and suitable for the microbial（especially methanogenic bacteria）growth.（5） Comparison of the total biogas volume of different pretreatment by anaerobicfermentation and effect anaerobic digestion with the same process concentration had done inthe paper. Results obtained were that anaerobic fermentation potential of straw by hydrogenperoxide pretreatment is very good, which is good chemical pretreatment condition for straw.