METAGENOMICS COMBINED WITH HIGHTHROUGHPUT SEQUENCING REVEALS THE METHANOGENIC POTENTIAL OF FRESH CORN STRAW UNDER THERMOPHILIC AND HIGH OLR

Dry corn straw(DCS)is usually used in anaerobic digestion(AD),but fresh corn straw(FCS)has been given less consideration.In this study,the thermophilic AD of single-substrate(FCS and DCS)and co-digestion(straw with cattle manure)were investigated.The results show that when FCS was used as the single-substrate for AD,the methane production was 144 mL·g^(−1)·VS^(−1),which was 7.5%and 19.6%higher than that of single DCS and FCS with cattle manure,respectively.In addition,the structure of FCS was loose and coarse,which was easier to be degraded than DCS.At the hydrolysis and acidification stages,Clostridium_sensu_stricto_1,Clostridium_sensu_stricto_7 and Sporosarcina promoted the decomposition of organic matter,leading to volatile fatty acids(VFAs)accumulation.Methanosarcina(54.4%)activated multifunctional methanogenic pathways to avoid the VFAs inhibition,which was important at the CH_(4) production stage.The main pathway was hydrogenotrophic methanogenesis,with genes encoding formylmethanofuran dehydrogenase(K00200-K00203)and tetrahydromethanopterin Smethyltransferase(K00577-K00584).Methanosarcina also activated acetotrophic and methylotrophic methanogenesis pathways,with genes encoding acetyl phosphate(K13788)and methyl-coenzyme M reductase(K04480,K14080 and K14081),respectively.In the co-digestion,the methanogenic potential of FCS was also confirmed.This provides a scientific basis for regulating AD of crop straw.

Effects of different heating patterns on the decomposition behavior of white pine wood during slow pyrolysis

This study investigated the effect of different heating rates on the pyrolysis behavior of the white pine wood residues.The raw materials were tested via two heating patterns with variable heating rates and compared with three other heating patterns with constant heating rates.The yields and characteristics of products such as char,pyrolysis oil and non-condensable gases under different heating rates were also determined.The gas,liquid,and solid phase yields of the products via heating with decreasing heating rates were similar to the yields obtained from constant heating rate at 2.3℃/min.The pyrolysis process by decreasing heating rates resulted in 30.04% char,44.53% bio-oil,and 25.43% non-condensable gases,which displayed higher char yield and pyrolysis gas than the other heating patterns.The results of thermo-gravimetric analysis showed that variable heating rate significantly changed the weight loss profiles during pyrolysis.It was observed during gas chromatography test that CO and CO_(2) were released earlier than CH_(4) and H_(2).The analysis of the chemical components confirmed that the bio-oil produced by heating process with decreasing rates contains less macromolecular organic matter content than the other patterns.