2种农林废弃物热解与发酵对产物养分保留的影响OA

Two types of biomass,grass scraps(GC)and elephant grass(ES),were used as raw materials and treated by high-temperature pyrolysis(350,450,550 ℃)and composting fermentation,to investigate the effects of different treatment methods on nutrient retention in the products.Scanning electron microscope(SEM),energy-dispersive X-ray spectrometer(EDS),and X-ray diffractometer(XRD)were used to characterize the products.The variations in the contents of nutrient elements,including carbon,nitrogen,phosphorus,and potassium,in the raw materials and products were determined to explore the patterns and mechanisms of nutrient retention.The results showed that compost-fermented products retained abundant carbon-,oxygen-,and nitrogen-containing functional groups on their surfaces.As the pyrolysis temperature increased,the pore structure of biochar gradually developed and the mineral crystal components continuously accumulated.Compared with raw biomass materials,fermented grass scraps(FGC)and fermented elephant grass(FES)obtained via composting fermentation possessed higher nitrogen contents.Compared with ES,the total nitrogen and alkali-hydrolyzable nitrogen contents of FES increased by 107.71%and 167.78%,respectively.Compared with GC,the total nitrogen and alkali-hydrolyzable nitrogen contents of FGC increased by 81.11%and 116.76%,respectively.Pyrolysis-derived biochars,namely grass-scrap biochar(BGC)and elephant-grass biochar(BES),were enriched in phosphorus and potassium.Compared with GC,the total phosphorus content of BGC550(grass-scrap biochar produced at 550 ℃)increased by 777.91%.Compared with ES,the total phosphorus content of BES550(elephant-grass biochar produced at 550 ℃)increased by 168.74%.The total potassium and available potassium contents of pyrolytic biochars increased markedly compared with the raw biomass.Meanwhile,the total phosphorus and total potassium contents of elephant-grass biochar were markedly higher than those of grass-scrap biochar,and both increased with rising pyrolysis temperature within 350-550 ℃.In conclusion,composting fermentation is conducive to elevating total nitrogen and alkali-hydrolyzable nitrogen contents in the products,whereas pyrolysis treatment can facilitate the fixation and retention of phosphorus and potassium.