| With the continuous consumption of various resources, the large amounts and renewable biomass resources are gaining public attention and regarded as the potential energy of the future material and resource material. General speaking, fresh biomass material has a higher water content, especially as the focus of future biomass utilization of aquatic biomass, among which the water content is much greater. The inherently high moisture content of biomass is the disadvantage for many treatment processed, because prior drying bring about high operating costs. Thus, water content is one of the important limiting factors that affect the treatment process of biomass. Therefore, this dissertation work is carried out encompassed resource re-utilization technology of the high water content biomass, and aimes at supporting the commercial re-utilization of high water content biomass. Via experiment and analysis, the following conclusions were obtained:(1) Hydrothermal treatment attracts many interest for its effectively, environmental benign on organic matter treatment. Considering the characteristics of hydrothermal treatment, which inducing decomposition in the water, and the higher water content in fresh biomass, we proposed to treat those biomass by using hydrothermal process, in which the high moisture content could be used advantageously to produce commercially viable valued-added matters without prior drying or other expensive chemicals. A prep-experiment that the high moisture biomass was hydrothermally treated directly without adding a external water, which was different from prior hydrothermal process, was carried out. The results showed that this process can degrade the biomass into its corresponding monomer. After hydrothermal decomposition of the biomass, value-added matters like amino acids, proteins, disaccharides and bio-crude could be recovered through the liquid product.(2) Effects of different watenfeed ratio on the hydrothermal conversion of biomass into resource were tested by response surface experiment. The results showed that the adding water amount during hydrothermal process had great effect on the value-added matters recovery and the biomass hydrothermal decomposition, and too low adding water amounts had a disadvantage effect on the biomass decomposition. As for the hydrothermal process without adding external water, it was recommended that higher than 85% moisture content is appropriate for directly hydrothermal conversion of the high moisture content of biomass.(3) Vegetable waste, aquatic biomass and two component mixture of waste biomass materials (aquatic biomass and bird market squid material) were selected as three different sources of high moisture content biomass waste model. These three biomass were hydrothermal treated under the 423-553 K of reaction temperature and reaction residence time of 0-60 min to view hydrothermal treatment effects. The results show that:in the set processing temperature and reaction residence time, all the three kinds of biomass materials could happen degradation reaction. The main components of cellulose and hemicellulose in lignocellulosic biomass could be split into their units successfully, and the amount of hemicellulose and cellulose decomposition was increased with the elevated reaction temperature and reaction retention time as set in this experiment, so did the amount of solid product. However, because there is existed a phenomenon of re-concentrated during hydrothermal process, it was very different to completely decompose the cellulose and hemicellulose components in the biomass without the presence of a catalyst such as acid and alkali, especially in subcritical water condition. The conversion of lignin in hydrothermal process usually needed a higher temperature, and in this experiment, only in the 553 K of reaction temperature with a longer retention time, the lignin appeared degradation phenomena. Thus, there still existed certain amounts of fiber in solid product. These residue lignocelluloses could benefit solid product, which contain a certain amounts of humus and nutrient fertilizer like N, P, K and other mineral nutrients, to re-use as a organic fertilizer to increase soil fertilizer via increasing the soil carbon content and buffering power of the soil. Moreover, reaction temperature and retention time had a great effect on the resource recovery of protein, amino acids and simple sugars from the biomass and constituents of the bio-crude oil. thus in practice, it was very important to set the hydrothermal condition according to the matter recycling targets. In addition, strong antioxidant and antimicrobial activity of liquid product obtained after hydrothermal treatment was also provided a new way to value-added re-utilization of the product in medicine and health products industries.(4) Kinetic experiments of pyrolytic and hydrothermal decomposition of lignocellulose were carried out to analyze and compare the biomass conversion process during the two thermo chemical treatment. The results showed that:a lower reaction temperature was needed for the lignocellulose biomass decomposition in hydrothermal treatment than that of the pyrolysis treatment. In the temperature range of 473-553 K, the calculated apparent activation energy 90 KJ/mol for hydrothermal treatment, significantly lower than the apparent activation energy of 130-116 KJ/mol calculated in the same temperature range of conventional pyrolysis, which also shows that at lower reaction temperature, hydrothermal technology was more appropriate to decompose the lignocellulosic biomass for re-utilization. |
PDF Full Text Request