Experimental Study On Characteristics Of Different Products From Microwave Hydrothermal Of Dead Chicken

With the expansion of livestock and poultry industry,the major problem that threatening ecological security is the large bumber of dead livestock and poultry carcasses were generated every year.Improper disposal of dead livestock and poultry will cause the spread of bacteria and viruses,which will endangering the health of humans and animals,while the livestock and poultry carcasses are rich in nutrients,such as fat,protein,N/P/K etc.At present,the common treatment methods for dead livestock and poultry are burial and incineration,which still have the potential of secondary pollution and lead to a large amount of waste of resources.Hydrothermal treatment is a green and efficient biomass conversion technology,which has been widely used in the treatment of various types of biomass waste.In addition to the advantages of high thermal efficiency and shorter reaction time,the non-thermal effect of microwave heating is also beneficial to the conversion of organic components.The microwave hydrothermal technology combined with hydrothermal treatment and microwave heating also has certain advantages in the treatment of biomass waste.In view of this,this article selects the fresh chicken instead of sick chicken as a model livestock and poultry,using microwave hydrothermal technology carries on the transformation,Study the effect of different process parameters?reaction temperature,holding time and solid-liquid ratio?on the microwave hydrothermal products distribution.Explore the effect of different process parameters on the distribution of key nutrients migration.Study the effect of the microwave-conventional hydrothermal and the type of catalyst on characteristics of main target products?aqueous product and bio-oil?,these studies will provide certain theoretical basis for the resource utilization of dead livestock and poultry.The main conclusions as follows:?1?Through the full factorial experiment,the effects of different reaction parameters on the microwave hydrothermal products were studied.The results showed that all of the three process parameters had significant effects on the distribution of hydrothermal products?P<0.05?.Reaction temperature had a significant effect on the distribution of hydrothermal products.Holding time and solid-liquid ratio had different effects on the distribution of hydrothermal products in different temperature ranges.Aqueous product and bio-oil are the main microwave hydrothermal products under the high temperature reaction conditions.With the increase of temperature,the yield of bio-oil and gas product are increase,the yield of solid product is decrease.The yield of aqueous phase product increase first and then decrease with the increase of temperature.The maximum yield of gas product no more than10%.At 240°C,the organic components of chicken could be completely transformed and solid yield was only 6.1%?9.08%.The lipids as the main source of bio-oil,the fatty acids has the largest proportion in bio-oil by GC-MS analysis.It also contains partially unhydrolyzed esters.There are few alkanes and aldehydes in the bio-oil obtained at low temperatures.The bio-oil obtained at high temperatures contain a high proportion of amides and N-containing heterocycles.?2?There are large differences of the influence of process parameters on distribution of the key nutrient elements?N P K Ca?.The potassium is easily dissolved in the aqueous products.At a lower temperature,more than 50%of potassium migrated to the aqueous products,the potassium content in the aqueous product gradually increases with increasing temperature,and almost completely dissolves into the aqueous product at 240°C.The nitrogen mainly migrated to aqueous products,in the form of ammonia nitrogen and organic nitrogen.The ammonia nitrogen content of the aqueous increase with the increase of temperature,and the TN and organic nitrogen content of the aqueous increase first and then decrease.At high temperatures,more nitrogen migrated to the gas product and the bio-oil.The Phosphorus and Calcium are mainly distributed in the solid product,and a small amount of phosphorus is present in the aqueous product in the form of orthophosphate.?3?The effects of conventional hydrothermal and microwave hydrothermal treatment on the characteristics of main target products were compared.The TN content of aqueous phase that obtained in the two reaction modes were increased first and then decreased with the increase of temperature.The TN content of aqueous phase is higher under conventional hydrothermal reaction.Under the conventional hydrothermal reaction,the total yield of amino acids increased with the increase of temperature,while the total amino acid yield under microwave hydrothermal reaction increased first and then decreased with the increase of temperature.The yields of bio-oils obtained by conventional hydrothermal and microwave hydrothermal were inceased with the increase of temperature.In the low temperature conditions?120-160??,conventional hydrothermal can promote the production of bio-oil more than microwave hydrothermal.In the high temperature conditions?200-240??,microwave hydrothermal has more advantages in improving the yield of bio-oil.The bio-oils produced by conventional and microwave hydrothermal(34.98?37.22 MJ·kg^-1)has higher calorific value.With the increase of temperature,the content of oxygen in the bio-oil gradually decreases,the content of nitrogen gradually increases,and the calorific value of the bio-oil also gradually decreases.Under the same hydrothermal reaction condition,the bio-oil obtained by microwave hydrothermal has higher calorific value than that obtained by conventional hydrothermal,and its relative content of nitrogen is less.The bio-oil obtained by conventional hydrothermal and microwave hydrothermal had no obvious differences in main components,the relatively high content of the components are fatty acid substances.The nitrogen is mainly in the form of amides and N-containing heterocycles in the bio-oil,under the same hydrothermal reaction conditions,the bio-oil produced by microwave hydrothermal has better flammability and comprehensive combustion characteristics,and microwave heat has a positive effect on improving the combustion characteristics of hydrothermal bio-oil.?4?Different types of acid-alkaline catalysts?HCl/CH₃COOH/K₂CO₃/KOH?have different effects on the distribution of target products.Both acid-alkaline catalysis showed inhibition of formation for bio-oil.The yield of bio-oil in each catalytic test group was lower than that of non-catalytic.K₂CO₃had the largest inhibitory effect on the generation of bio-oil.The bio-oil yield of the test group was:Non-catalysis?59.41%?>HCl?52.92%?>CH₃COOH?52.44%?>KOH?29.67%?>K₂CO₃?25.65%?,the alkaline catalyst was not suitable for conversion of the high-fat biomass.All of the acid-alkaline catalysts are have the effect of inhibiting the migration of nitrogen to the bio-oil,and K₂CO₃also has the strongest inhibitory effect.When the organic acid act as a catalyst,it promotes the migration of nitrogen to the gas product,which is disadvantageous for the migration of nitrogen to the aqueous product for recycling.Different types of catalysts had no significant effect on the total recovery of amino acids.Compared with the non-catalyst,the alkali catalyst can inhibit the decomposition of aspartic acid,the acid-alkaline catalysts are beneficial to the recovery of glycine and alanine.