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A large amount of livestock manure has caused seriously ecological pollution, as the rapid development of livestock and poultry industry. The black soldier fly larvae (BSFL) are a good candidate for poultry and livestock manure treatment. The harvested insect bodies and feces can also be used as animal feed and organic fertilizer. The usage of BSFL can be efficient and environment-friendly to treat pig manure, but the heavy metals in pig manure have posed a great impact on the BSFL transformation process. In this study, the 7-day-old BSFL were used to transform pig manure at 30℃, in order to explore the BSFL growth and the transformation efficiency of manure, as well as the changes of heavy metals (Cu, Zn, Cr, Cd, As) in the BSFL bodies and feces. After 8 days of transformation, the larvae were about to enter the prepupal stage, where the transformation process terminated. The results showed that the dry weight of BSFL bodies increased with the prolongation of growth time during 8 days, and reached the highest value on the 8th day. The growth rate was the lowest from 0 to 2 d, whereas, the highest from 4 to 6 days. The conversion rate of pig manure increased with time, where the maximum value of 11.5% on the 6th day, and then decreased on the 8th day. The concentrations of Cu, Cr and As in BSFL bodies on the 8th day decreased by 24.5%, 21.7% and 33.0%, respectively, compared with those on the 2th day, indicating an obvious decrease in the concentrations of heavy metals with the larval growth. The content of Cd in BSFL increased with the larval growth, and the Cd concentration on the 8th day increased by 75.4%, compared with that on the 2th day. The changes of Cu, Cr, As and Cd concentrations in the BSFL feces were opposite to those of the bodies. The contents of Zn in the BSFL bodies and feces did not change significantly with the larval growth time. After 8 days of transformation, the Cd content in BSFL feces was significantly lower than that in pig manure, while, the contents of Cu, Cr, As and Zn were not significantly different from those in pig manure. The bioaccumulation factor of Cd by BSFL was the highest (reaching 3.8), and the values of other metals were lower than 1. The bioaccumulation of heavy metals was ranked in order Cd > Zn > Cu > Cr > As. After transformation, the heavy metals Cu, Cr, As and Zn in pig manure were mainly distributed in BSFL feces, accounting for 83.6%-92.7%; whereas, the distribution of Cd was 30.3%-50.2% in BSFL bodies and 49.8%-69.7% in feces. Compared with pig manure, the biological activities of Cu and As in BSFL feces increased, while those of Cr and Cd decreased. The biological activity of Zn did not change significantly after the transformation process. This finding can provide a potential data basis for the resource utilization of livestock manure by BSFL and the safety of transformed products. [ABSTRACT FROM AUTHOR]

The effects of Na2CO3-NaOH molten salts and nickel on the pyrolysis of 3 components of biomass, i.e. cellulose, hemicellulose and lignin, were studied in the thermogravimetric (TG) analyzer and fixed bed reactor. In the TG experiment, the addition of molten salt makes the peak of cellulose TG curve appear ahead of the TG curve of cellulose without catalyst. The corresponding differential thermogravimetric (DTG) curve has 2 separation peaks, while there is only one peak appearing in the DTG curve of cellulose without catalyst. In DTG curve of hemicellulose, compared with the hemicellulose pyrolysis alone, the temperature corresponding to the maximum pyrolysis rate of the peak is decreased by 82 ℃ after adding molten salt. As for lignin, the DTG and TG curve with catalyst basically coincide with that without catalyst, indicating that the low dose addition of molten salt and nickel had little effect on the pyrolysis of lignin. The results of fixed-bed experiment show that the molten salt can effectively absorb CO2, which promote the increase of H2 and the reduction of CO simultaneously in water-gas shift reaction. In the process of catalytic cellulose pyrolysis, the OH- contained in molten salt motivates the rearrangement of the ring-opening products of cellulose monomer at relatively low temperature, and the rearrangement products are easily decomposed, thus leading to an acceleration of cellulose decomposition. The Na+ contained in molten salt can react with phenolic hydroxyl groups in lignin structural units and decrease activation energy of ring-opening reaction of hemicellulose monomer, resulting in an easy decomposition of both lignin and hemicellulose. Under the optimum conditions, the amount of hydrogen produced by cellulose, hemicellulose and lignin can reach 913, 738 and 1 148 mL/g, respectively, and the content of H2 can reach 85.6%, 78.2% and 90.7%, respectively. The CH4 content can be reduced by the synergistic effect of molten salt and nickel, under which the CH4 yields of cellulose, hemicellulose and lignin are decreased by 35%, 24.5% and 12.0%, respectively compared with the single addition of molten salt. The synergistic effect of molten salt and nickel can effectively reduce the content of CO, CO2 and CH4 in syngas, which is beneficial to the pyrolysis of biomass to produce hydrogen-rich gas. Under the optimum conditions, the contents of CO, CO2 and CH4 in the lignin are only 0.5%, 0.4% and 5.9%, respectively. Meanwhile, in the presence of molten salt and nickel, the maximum hydrogen yields of cellulose, hemicellulose and lignin reach 910, 714 and 1 106 mL/g, respectively, and the contents of H2 are 77.6%, 77.8% and 91.6%, respectively. From 700 to 900 ℃, with the increase of temperature, the reaction of residual carbon and H2O, CO is promoted, so high temperature is conducive to the conversion of residual carbon. At the same time, CH4 production tends to decrease with the increase of temperature, because CH4 is easily decomposed at high temperatures. It can be seen that high temperature is conducive to the production of H2 and CO, and promotes the cracking of CH4, which is in favor of biomass pyrolysis to produce hydrogen-rich gases. [ABSTRACT FROM AUTHOR]

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Gasification is one of the most important biomass energy utilization techniques, which is clean and efficient. The pressurized biomass gasification has the advantages of large capacity, high efficiency and low cost compared with the atmospheric gasification of biomass. Meanwhile, thermogravimetric analyzer is a widely used for studying biomass gasification. The researches on atmospheric gasification in thermogravimetric analyzer have been widely reported, but there are a few papers about the pressurized gasification. In this work, the processes of pressurized pyrolysis and CO2 gasification of pine powder were performed in a pressurized thermogravimetric analyzer, which pressures were set as 0, 0.3, 0.6 and 0.9 MPa. The pressure of thermogravimetric analyzer was controlled by a pressure electromagnetic valve which could be operated by computer. Air was removed firstly by a vacuum air pump in order to avoid the influence of the air, and then N2 and CO2 were pumped in. When the pressure in the thermogravimetric analyzer reached the setting pressure, the temperature was increased to 1400 at the heating rate of 10 /min. The Malek method was used for in ℃ ℃ ferring the most probable mechanisms of pressurized pyrolysis and gasification, and the effects of pressure on pyrolysis and gasification process as well as their kinetics characteristics were investigated. The results showed that pressure had a significant effect on pyrolysis/gasification of pine powder. The release of volatile matter was inhibited and the maximum weight loss decreased from 73.80% at 0 MPa to 71.40% at 0.9 MPa with the increase of pressure under the N2 atmosphere. According to the results of Malek method, the pressurized pyrolysis was divided into two stages, and the secondary reaction mechanism and the random successive nucleation growth were proved to be the most probable mechanisms for the first and the second stage of pressurized pyrolysis, respectively. The activation energy in the first stage of pressurized pyrolysis increased from 41.15 kJ/mol at 0 MPa to 52.41 kJ/mol at 0.9 MPa. Under CO2 atmosphere, the high pressure inhibited the release of volatile matter in pyrolysis stage which also happened under N2 atmosphere but promoted the char gasification in the gasification stage. The maximum weight loss rate increased from 0.101%/min to 0.162%/min and their corresponding temperatures decreased during the process of char gasification. Furthermore, the two-dimensional diffusion (cylindrical symmetry) was proved to be the most probable mechanism for pressurized CO2 gasification. The activation energy of char gasification increased from 201.94 kJ/mol at 0 MPa to 230.73 kJ/mol at 0.9 MPa. Meanwhile, the frequency factor rose from 4.55E+06 to 7.04E+07 min-1. Additionally, when the value of carbon conversion was in the range of 0.6-0.95, the reaction rate of CO2 gasification gradually increased with the increase of pressure, and the finish temperature of the char reaction shown a downward trend. The results provide a theoretical basis for the efficient and clean utilization of biomass. [ABSTRACT FROM AUTHOR]

At present, all of the sugarcane planting machines are not equipped with buds-injury-prevention mechanism and all of the machines have the problem of high injury rates of buds. In order to solve this problem, a buds-injury-prevention system based on induction-counting in sugarcane-seeds cutting was designed, which not only could detect and count the buds that were located at the sugarcanes with different diameters to make the planter meet the planting requirements, but also could ensure the integrity of buds to improve the yield of sugarcane. In this system, we had designed a resistive induction-counting mechanism which was used to convert the signal of protuberant sugarcane buds into electrical signal in the process of conveying the sugarcane seed. The electrical signal would be input into the voltage comparator to compare with the reference voltage after it was amplified by amplifying circuit. According to the result of comparison, the comparator would output a signal of high level or low level which would be input into MCU (micro control unit) to implement the counting operation of buds. Every sugarcane seed should contain 2 buds according to the agronomic requirements. When the count reached 2, the MCU would send out a control signal to trigger the relay to force the hydraulic pump to supply the hydraulic cylinder with oil by controlling the electromagnetic valve. For the cylinder was fixed, the piston would move down to push the cutter to cut off two-bud sugarcane-seed, and then the function of buds-injury-prevention could be achieved. When the cutting was completed, the piston would force the cutter to return quickly. Meanwhile, the MCU would reset the counter, and the system would get into the next circle of counting and cutting automatically. In order to optimize the performance of the system, the integrity of sugarcane seeds and buds should be the prerequisite. Having a force analysis and a buds-injury-prevention analysis on the cutting process of the system, the optimal installation distance between induction-counting mechanism and cutter could be determined, which could make sure that the cutter had completely avoided the buds when the counting was meeting the requirement. Then the buds-injury-prevention function during the cutting could be achieved. In order to verify the buds-counting and buds-injury-prevention performance of this system, the physical prototype of the system was manufactured. When conducting the test, the reference voltage should be set reasonably. Through a lot of experiments, the system could achieve high precision when the reference voltage was 2.9 V. In addition, to illustrate whether the buds-injury-prevention performance of the system is good or bad, a set of comparative tests needed to be designed. And the comparative test machine was 2CZ-2 multi-functional sugarcane planter from Nanning Wuling Guihua Vehicle Company, which was not installed with buds-injury-prevention system. The test results showed that the accuracy rate of buds counting of the system was 98.87%, while the average rate of the injury buds was 1.57% that was 6.3% lower than the 2Cz-2 sugarcane planter, which showed that the system’s buds-injury-prevention performance was remarkable. The results can meet the design requirements and the research can provide a reference for the design of sugarcane planting machinery. [ABSTRACT FROM AUTHOR]